Choosing The Best Appliance Dealer For A Heat Pump Water Heater

For appliances like heat pump water heaters or heat pump dryers, you can ask for a quote from your preferred plumber/contractor. For less personal service, you can purchase and arrange installation from a local big-box store like Lowes (AOSmith) or Home Depot (Rheem), for ease of delivery and return in case of problems. Shop on-line to see all models, because your local store might not have ANY samples for display, and water heaters are usually shipped from a regional warehouse. Carefully check all ratings and evaluations. Here’s an article from one of our coaches. You can usually have Lowes or Home Depot deliver to your house, either free or for a small fee (~$50).

My local Home Depot would not haul away my old water heater. For a small fee, I could have rented a Home Depot van or pickup for transport of the water heater and a quantity of other surplus metal to a local metals recycling center; instead, I arranged for a local scrap dealer (advertising on my neighborhood blog) to pickup my scrap metal and tank.

Brands and Types of Water Heaters

Brands

AO Smith and Rheem heat pump water heaters are very similar. If you need LOW noise, because the water heater is located near living quarters on main floor of your house, then there is a newest AO Smith Signature 900 “HPS” (also called Voltex HPTS, or Voltex 130 Series Proline XE). These come in various gallon capacities and have a (very low) 45dBA noise spec. HOWEVER, PERSONAL EXPERIENCE AND RECENT CUSTOMER RATINGS/COMMENTS INDICATE POOR RELIABILITY OF ALL OF THESE AO SMITH MODELS (both 240 volt models and 120 volt models)

My AO Smith Signature 900 heat pump water heater, installed 11/2023, arrived DOA - the factory said the symptoms indicated it had been erroneously shipped on its side. The replacement had several independent component failures in the first three months. The control assembly in the unit did a great job identifying the various faults - it even detected its own failure. A replacement controller died within 2 months. The second dead tank was then replaced by a third tank, whose heat pump died after 11 months of operation. A special AO Smith/Lowes service number is now denying replacement tanks under warranty (normally 10 years warranty for parts, and 1 year warranty for labor). The service number asks for a video conference to inspect the tank installation. If installed in a utility closet with less than 450 cubic feet volume, the warranty is cancelled (even with fully louvered double doors).

120V Plug-in Water Heaters

Click here for a review of 120 volt plug-in water heaters - four 120 volt models are available.

Comparison of Different Types of Water Heaters (Gas, Electric, HP)

The table below has a side-by-side comparison of the 5 types of water heaters and their initial cost, cost of operation, and greenhouse gas emissions (tons of CO2 equivalent) per year. Compared to the common electric and gas water heaters, whether tankless or with a tank, the operational cost and amount of emissions for a heat pump water heater is much smaller. As you can see, the payback period, for operational cost to pay for the greater initial cost of a heat pump water heater, varies between 2 years to 4 years.

Comments on Specific Heat Pump Water Heater Models

Comments are provided here for AO Smith Voltex AL; Rheem Proterra Plug-in; Rheem Proterra Plug IN w/hydroboost.

I HAVE RECENT EXPERIENCE WITH HEAT PUMP VERSIONS OF RHEEM 60 GALLON AND AO SMITH 50 GALLON.

AO Smith Voltex AL (model HPS10-50H45DV200 ) (240 volt, 50 gal): horrible failure rates (2/25/2025 data from Lowes distributor). 5 STAR RATING ARE OFTEN CUSTOMERS WHO HAD AN EARLY HEAT PUMP TANK FAILURE, BUT GAVE HIGH RATING BECAUSE OF THE EASE OF REPLACING DEFECTIVE WATER TANKS (these 5 star ratings may quickly drop to 1 star, if these replacement tanks subsequently fail).

Following is AOSmith Voltex AL new 120 volt version. Model # differs by 1 character from the 240 volt version. Similar failure rates (2/25/2025 data from Lowes distributor)

AO SMITH NOT CURRENTLY RECOMMENDED. (HIGH INFANT MORTALITY FAILURE RATES for both 240 volt and 120 volt models of AO Smith)

• duplicate side and top hot/cold water connections

• Side connections are typical electric water heaters

• Top connections are typical gas water heaters (easier to connect to existing house pipes)

• 45 dBA is low sound emissions from the heat pump

Rheem Proterra Plug-In.

Rheem Ads recommend installing the 120 volt versions ONLY in warmer regions of the U.S.

• requires a DEDICATED 15 amp circuit

Rheem Proterra Plug In w/”Hydroboost”

• share a 15 amp (share an electrical circuit and outlets)

• This is a VERY new breed- good for older houses with lower amp panels and wiring difficult to upgrade. Competitors likely to quickly follow.

• Stores water at HIGHER stored internal temp: then mixes with cold water to lower hot water to 120 degrees.
  Allows a smaller tank to have same immediate water capacity as a larger sized tank

• Check reviews before buying

Rheem Performance Platiunum Hybrid Electric

Rheem-performance-platinum.pdf has specifications and dimensions of available models. The first page has features; the second page has the specs- including dimensions of Rheem heat pump water heaters.

Ventilation requirements of various sized rooms

The figure below illustrates the ventilation required.

• >700 cubic foot room: no ventilation required

• <700 cubic foot room: need louvered door

• <450 cubic foot room: need louvered door AO SMITH REQUIRES EXTERNAL DUCTING (of cold exhaust air) TO AVOID AUTOMATIC CANCELLATION OF FACTORY WARRANTY

Installation Hints

These comments are based upon experience with 65 gallon model XE65T10H45UO $2163 (10/2022) from Home Depot (not in stock- ordered on-line).

NOTES: Include a drain pan installed under the hot water tank. (All tanks eventually leak; all my tank leaks have been relatively slow drips, and must be either self-draining, or alerting) For insurance, run a pan drain line - add a small diameter drain hose to outdoors. An optional version of Rheem, and the standard AO Smith heat pump water tanks, have a built-in leak detector- it will send your cell phone an alert if it detects water in the pan. The latest AOSmith has an auto-shutoff valve on the cold water line. (If the valve auto-closes, it can be easily manually overridden to keep water flowing until tank is repaired/replaced).

The heat pump behaves like a dehumidifier, so a drain is required for heat pump water heater condensate . Condensate drains from an opening ~4.5 feet high. Run a pipe to any convenient drain, such as a nearby clothes washer sewer drain. Or, drain into a small sump pump, and route that sump hose to most convenient washer drain or utility sink.

Financial Info

REBATES: $750 rebate fromPSEG or JCP&L. https://residential.energysavenj.com/jersey-central/products/;

TAX CREDITS: (currently effective)

PLUS IRA 30% Federal Tax credit for heat pump water heater under section 25C

See https://www.rewiringamerica.org/app/ira-calculator/information/heat-pump-water-heater

PLUS IRA 30% TAX Credit for electrical panel update (credit capped at $600)

Your personal IRA calculator is at: https://www.rewiringamerica.org/app/ira-calculator

IRA REBATES (Available ~7/1/2025 in NJ. Initial plans provide low income families with HIGH rebates, and multi-family buildings will be a major focus. No further information at date of this article (date at bottom of page)

Overall Recommendations

For the latest model appliance like heat pump water heater , I recommend using Lowes or Home Depot. Shop on-line to see all models (on-line will show local store inventory – BUT local store might have NO sample for display and the water heater or dryer would be shipped from a regional warehouse). Choose based on ratings and evaluations. You can have Lowes or Home depot use their own contactors to install. With your own contractor (or yourself), Lowes or Home Depot will deliver to your house (free or $50) but they dont haul away the old water heater. AO Smith and Rheem heat pump water heaters are very similar. If you need LOW noise (water heater is near living quarters on main floor of your house) , HOLD OFF ON BUYING the newest AO Smith Signature 900 “HPS” (also called Voltex HPTS, or Voltex 130 Series Proline XE Voltex). These come in various gallon capacity- and have a (low) 45dBA noise spec. BEWARE: this early model AOSmith heat pump water heater suffered SEVERAL early failures of internal hard-to-replace sensors, and also failure of the heat pump (requires a total tank replacement)

Further Info On Heat Pump Water Heaters

• 2023-7-12 “Plug-In Heat Pump Water Heater Field Study Findings & Market Commercialization Recommendations“, NBI, 120 volt water heaters lessons learned.

• 2022-11-10-Heat pump water heaters can replace gas water heaters

• 2022-7-12 Heat Pump Water Heater Reviews by electrifynow.net; video clip (beginning ~22min- installations to avoid; last 3 minutes: heat pump water heater has small effect on overall building heating/cooling performance; slides

My Experience With Rheem And AO Smith Heat Pump Water Heaters

Recent Experience

…with Rheem 65 gallon and AO Smith 50 gallon heat pump water heaters installed professionally in two different houses. Both contain (programmable and optional) electrical heat rods, and therefore require a 30 amp 240 circuit. Designs are very similar. Both have a display panel, and have Wifi-connected App to cell phone for control and display of any errors.

AO Smith Experience

AO Smith was selected because the low noise level (45 dbA when the heat pump operates) which makes this suitable for installation in a small furnace room off a center hallway in this single story house on a slab. AO Smith tank was DOA upon installation, Oct, 2023. Factory support said the symptoms indicated the tank (in its shipping box) was likely on its side for part of the shipment (contrary to written directions on outside of box). This caused the refrigerant to “pool”. The tank had to be returned for factory repair. A 2^nd identical tank was shipped and installed 2 days later. It worked well for a few days. However, the tank began reporting repeated failure of control assembly “internal error” every 4 or 5 days, (reset by turning off beaker, a short wait, and then back “on”). Then 2-3 weeks later the control assembly also reported an external thermistor fault. The factory shipped free replacements. In the meantime, I was able to set the controller to use only the electric heating rods and bypass the heat pump. When the parts arrived, I installed them -design is modular (2 hours of my time), and the tank then worked for 2 months, until it stopped working when the controller identified failure of the “heat pump coil temperature sensor”, again shipped free from AOSmith Tech Support for homeowner to arrange installation. I arranged for the tank supplier to replace the complete wiring harness containing the “Heat pump coil temperature sensor” and other sensors on that harness. However, upon tank turn-on the control assembly indicated an internal component failure and neither the heat pump nor the electric heating rods would operate. The tank supplier threw in the towel on this lemon, and ordered another tank replacement, which occurred two days later. (During the ensuing 2 days, the home had NO hot water). The third tank twice indicated controller fault on Jan 5, 2025, and has since been in “hybrid mode”, but the heat pump is not operating, and the electric heating rods are maintaining temperature. HOWEVER, the LowesAO Smith trouble line reviewed the installatin with video (on my cell phone), and declared the failure was caused by the environment, and NOT caused by the factory. Therefore, the factory warranty was void. According to the trouble line, the fully louvered double doors and 96 cubic feet furnace room did NOT provide sufficient ventilation, and was a violation of the 450 cubic feet requremenn the installation manual (I have not seen that requirement in my vintage ~2023 installation manual). RECOMMENDATION: avoid AO Smith purchase until all bugs are worked out, as verified by customer reviews of this otherwise feature-rich heat pump water heater.

Rheem Experience

Tank installed Nov, 2022 in my unheated basement (lowest temp is ~52 degrees) and has worked flawlessly. Initially installed without ducting, and it worked fine. The little basement alcove -with one open wall- was definitely colder (maybe 10 degrees) when the heat pump operated (but quickly warmed to basement temps when the heat pump was not working). Later, I improved the efficiency a little by ducting the cold exhaust air into the open basement. The photo below shows the 90 degree elbow, and the 8 inch dia. flexible ducting extending the cold air exhaust about 30 feet. The temperature change, within a larger area of unfinished unheated basement, is not noticeable. It has worked great with no problems. In the summer, the heat pump water heater is like a small air conditioner that intermittently cools and dehumidifies the air.

Instructions for locating heat pump water heater in a small area laundry/utility room: A vent adapter kit is available. Shown in above photo, screwed to the shiny 8 inch elbow, is the black plastic adapter (~$130 from a supply house) covering the side exhaust vent for Rheem tanks. Also shown in the photo is an inexpensive 8 inch flex duct used to direct the cold exhaust air through a wall register to a larger room. See photo of adapter, elbow, connected to ~30 feet of flexible duct. My hot water tank is in a small alcove in my basement and condensation drains into a utility sink, and find it is a great basement dehumidifier.

HVAC contractors, during webinars, have said customers have not noticed any larger area cooling effect from the heat pump in the laundry room. Addition of exhaust ducting to the outdoors (or into garage) is NOT recommended. It is unlikely to make a noticeable difference in house temperature, but WOULD create a net loss of conditioned air. To replace that conditioned air volume (maybe a few cubic feet per second?), the owner would need an intake opening or duct for an equal air flow into the house; that incoming air then requires energy to be heated or cooled and dehumidified, (depending on season).

My biggest concern is noise level. Location of the Rheem heat pump water heater in a basement is unlikely to be a noise concern. Location in a laundry room depends upon location of the laundry room relative to livings/sleeping quarters. My Rheem heat pump noise emission is both a steady-state low-frequency drone, plus a higher frequency “whine”. (I estimate the Rheem total sound intensity is somewhat less than a clothes washer on spin portion of the wash cycle).

If noise is an issue because the heat pump location is near living or bedroom areas, then IN THE FUTURE I recommend the AO Smith Voltex AL because the heat pump noise level is 45dBA. This noise level is quite low- about the noise of the flames of a gas burning furnace and/or lower level noise than the associated air blower. HOWEVER, as of 2/25/2025 AO SMITH VOLTEX AL INFANT MORTALITY IS VERY HIGH, and the factory warranty is invalidated, in a utility closet of less than 450 cubic feet (even with fully louvered doors). Such an installation requires a dedicated exhaust vent to a larger room,

CREDITS: WATER HEATER PHOTOS are from 2023-1-18 “Tankless Gas Water Heaters The Infamous Methane Puff” by ElectrifyNow slides here; recording here.

Electrical Panel/House Panel Recommendations

Newest (120 volt low power) HPWH models are becoming available from Rheem, (BUT ARE CURRENTLY NOT ADVISED FOR NORTHERN CLIMATES). Some models can be plugged into any shared outlet. Other models require a dedicated 15 amp outlet. (By contrast, the “hybrid” heat pump high powered water tanks require a dedicated 30 amp circuit to power the electric heating rods.) A plan should be created to ensure electrical panel capacity needed in the next 10 years, after full electrification of a house using IRA benefits. If the home electrical panel is small (rated at 100 amps) the 120 volt low power heat pump water tank should be considered.

Electrification may include following (among other appliances):

• Replacing a gas furnace (& AC) with a heat pump. My 3 ton heat pump, which replaced an earlier 3 ton A/C, draws about 8 amps at 240 volts, but requires a 30 amp breaker.

• A combo clothes washer/heat pump dryer uses only ~10 amps plugged into a 120 volt outlet (see comments below);

• An induction stove;

• One or two EVs.

There are now many add-on solutions that allow sharing of circuits, for older houses that are difficult to upgrade the amperage from pole to the house. My recommendation (to avoid a several $thousand panel upgrade) is to first follow the advice given in “The Watt Diet” beginning page 18, of https://www.redwoodenergy.net/research/a-pocket-guide-to-all-electric-retrofits-of-single-family-home

What I Did

My existing 200 amp panel was completely filled with 15 and 20 amp breakers, and all possible dual/miniature breakers had been changed-out. The high number of breakers is due to many circuits of ~45 recessed ceiling fixtures originally containing 120 watt incandescent bulbs that have long-ago been swapped for 16 watt LED recessed ceiling fixtures.

My electrician installed an overflow 125 amp (max) panel slaved from a 100amp breaker inserted into my existing 200 amp panel. The new panel is mostly dedicated to 240 volt appliances (heat pump water heater; heat pump pool heater, one heat pump furnace; room for future 2^nd heat pump heat pump furnace, future induction stove, and future 240 volt plug-in EV charger (we currently have a PriusPrime plug-in hybrid that consumes a small amount plugged into a 120 volt outlet, and have a combo clothes washer/dryer (~10 amp max) that plugs into 120 volt outlet in the laundry room)

Updated 2/25/2025

https://docs.google.com/document/d/e/2PACX-1vS7dXC17tQZmroLd386AjpDHq-XZIlSOul4S8RvnGPPVqHHquzV_Vql3cFXXLJ3SSRHScCtTap9l7P0/pub?urp=gmail_link

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This note covers the replacement of furnaces and boilers that heat at least a few rooms, if not the entire house, with one or more ccASHPs (cold climate air source heat pumps). [Here we will only consider split systems (where there are separate indoor and outdoor units connected by refrigerant piping) and systems that supply warm air (e.g. only air-to-air HPs).]

Installing a HP to replace a furnace or boiler can be a complicated process and unfortunately many homeowners don’t find this out until they are faced with estimates (quotes, proposals) from HVAC contractors. The homeowner then finds out that, not only do the systems recommended differ greatly in terms of price, but they often also differ on:

· Types of HPs: centrally ducted, ceiling ducted, ceiling, wall or floor non-ducted

· How “large” the system needs to be (i.e. the maximum heating ability or capacity needed to heat the home or each zone)

· Whether to install a cold-climate HP or a non-cold-climate HP and what if any backup heat system is needed

Another factor complicating this process is that many contractors may not be fully knowledgeable about HP systems and so may be biased in favor of fossil fuel systems.

So, what’s a typical homeowner to do?

Reading this document can be a good starting point. The material can be a little complex but with a little effort, interested homeowners should find it to be a helpful guide. It may take more than one reading (e.g. before you meet with contractors and again once you receive their quotes) and you may find it helpful to print it out and mark it up or dig a little deeper elsewhere on some of the points. A heat pump or electrification coach can also be a big help with this.

To begin with you should be familiar with your current heating system. What fuel is used(oil, propane or natural gas)? Are there furnaces blowing hot air or a boiler circulating hot water through baseboards or radiators? If it is a hot air system, where are the ducts located, and do they seem to be in good condition? You should also make a list of issues or problems you are having (such as rooms that are too cold in winter or too hot in summer).

To begin we will focus on a home that has the most common type of typical fossil fuel heating system, one with full-sized ducts supplying most, if not all, of the living space. (Even if your home does not have this type of system, you should read on as this example will provide information useful for replacing any fossil fuel system). The fossil fuel heat source can be either a furnace or a boiler. Furnaces are often in a basement and the burner is within the “air handler” part of the duct system with a blower that forces air across the burners and then out through the duct system. If it is a boiler system, the hot water is piped into the air handler to a “coil” where the hot water is the heat source rather than a burner. If the home has central air conditioning (remember, a one-way HP) the parts of that system that get cold are also inside the air handler/ductwork usually just downstream from the heating elements. Homes such as these are most often converted to a HP by removing the central air conditioner (usually a split system so both indoor and outdoor parts) which is then replaced by with a ccASHP to make what is called, according to the Energy Star Heat Pump Specifications Version 6.2 for 2025, a “conventionally ducted HP system”.

Usually, the ductwork for a central air conditioning system is large enough for the new ccASHP. If the home has no central air conditioning, the ductwork will need to be checked to make sure it is large enough for a HP system (as the warm air put out by the HP will not be quite as warm as the old system). However, the existing ductwork is often found to be large enough for a HP, usually because the furnace was larger than the home needed or because the insulation has been added to the home. In any case, when putting in a conventionally ducted HP system the existing ducts need to be carefully evaluated (for disconnections, leaks, sagging, lack of insulation etc.) and problems corrected.

One common concern is whether a ccASHP can provide enough heat on the coldest days we see in NJ. If the unit is not a ccASHP, this would be the case, and the unit would need “electric-resistance” type heating strips to provide “supplemental” heat (the same as electric baseboard heating which uses about 3-times as much electricity to produce heat as a HP itself does). However, in NJ, a normally running ccASHP that was “sized” correctly when it was put in (see below), may not need any supplemental heat, even on the coldest winter days (in part because the sizing methods include some “safety factors” so that units typically can heat the home even if it dips a bit below the design temperature, also described below). If you are still concerned and have a centrally ducted system, you can have electric resistance heat strips as backup heat installed in the ductwork. (Another reason you may choose to install resistance heat could be for the uncommon situation when the HP malfunctions and can’t effectively pump heat from the outside to the inside but can still blow air over the resistance heaters).

[Dual fuel heat: One option with a conventionally ducted system is to install a HP but keep the furnace (or install a new furnace). The system is then set to switch to the furnace when the outside temperature drops below a certain level (often around 30 degrees). These are called “dual fuel” systems. With this arrangement, a non-ccHP, which is likely to be slightly less expensive, can be installed. Similarly, a boiler system can be kept in place as a duel fuel setup.]

Determining the size heating system will need to be by determining the home’s “heat load”

It is important that a HP of the proper size is installed. Too small can lead to not enough heat but too large can also lead to problems (other than just paying more than you need to). Heat pumps can be most efficient when running steadily and not ramping up and down or even worse, repeatedly turning on and off. In addition, this turning on and off may lead to moisture problems during warm weather. Two common but incorrect ways to size a new HP are 1) using “rules of thumb” (such as, 500 square feet will need “ton” of heating) and 2) basing it on the size of the system being replaced (which may have been larger than needed when it was installed or is now too big because the home has been weatherized).

To determine the correct size for a new heating system a heating load calculation needs to be done. The load is the rate of heat supply (e.g. heat provided per hour) needed to keep the home warm in the coldest weather. For the coldest weather, the “design temperature” for where you live is used and is defined as the 1% cutoff for the coldest temperatures all year (so 99% of the time it is warmer than the design temperature, sometimes 99.4% is used). In NJ, the design temperature is usually in the range of 10-20 degrees. The home heating load then is usually given as British Thermal Units per hour (e.g. Btu/hr or sometimes simply as Btuh). If the home has more than one heating zone, then the total home load will need to be divided into the amounts needed by each zone, more on this below.

There are two common, reliable ways to estimate the heat load. The first is if you can accurately estimate how much heat your home needs to stay comfortable through a cold period. For example, how much natural gas your 80% efficient furnace used over a cold month last winter. The other is to do a “manual J”, or similar-type calculation. This is a very involved process using measurements of the living space (volumes, how much is below ground, size of walls exposed to the outside, size and number of doors and windows), often a test to measure air leakage is done measured (blower door test) and assessments of the construction materials and insulation levels of all home envelope surfaces (including windows, doors, attic, basement) and ductwork (location, insulation and leakage). This is usually done with the help of a software package and needs to be done by someone trained in the process and the software. (The full report is likely to include things like R-values and U-values for insulation; what materials make up the envelope walls and ACH air leakage values from a blower door test). It is worth taking a close look at the report and perhaps even doing some double checking of things like floor areas, ceiling heights and lengths of walls, whether the level of insulation in areas such as the attic seems correct and to see if the ductwork was evaluated. Also, keep in mind that if it is decided, after the heating load is determined, that major ductwork (e.g. change in location, size, number or length of ducts) is needed, the heating load may need to be adjusted. (If major ductwork is done a full ductwork assessment will be needed such as duct sizing, room-by-room loads and pressure testing).

Once the heating load is known, the “size” or “heating capacity” of the unit is addressed. In general, HP sizes start at ½ ton and go up in ½ ton increments to up to about 5 tons (1 ton is 12,000 Btu/hr). What is typically done at this stage is to “round-up” the calculated heating load to the nearest ½ ton size so the system installed would be “slightly” oversized but not enough to cause the problems mentioned earlier. If significant weatherization is planned for after installation, however, reduce the HP size by an amount proportionate to the expected decrease in heating energy use.

What’s a ccASHP?

In general, to qualify as a ccASHP the heat output at 5 degrees must be very similar, if not the same as the heat output at 47 degrees and often heat output is still similar even at temperatures below 0. (Non-cold climate HPs will have a much lower heat output at 5 compared to 47 degrees). It’s probably worthwhile only considering units with Energy Star version 6.1 cold climate heat pump certification. A good marker for energy efficiency is the HSPF2 value (heating system performance factor), where the higher is better. Fortunately the HSPF2 is done assuming a climate zone that has NJ at the center. Note: in split systems, the ability to perform as a cold climate HP only depends on the outdoor unit (matching a standard indoor unit with a cold climate outdoor unit will still be a ccASHP).

Installation

Good installation practices are vital to the long-term functioning of the system. Some states and cities have requirements and checklists for installation (e.g. NY, Maine, Portland OR) and it may be wise to discuss this with contractors. A voltage surge protector is not always mentioned, but installing one is probably a wise choice for a ccASHP because of its expensive electronics.

Removing or abandoning the existing ductwork

This may make sense if there are ductwork issues, or if you want to add the flexibility of multi-zone heating/cooling. Two possible reasons to abandon the existing ductwork are: 1) the proper installation of a conventional ducted ccASHP would require expensive modification of the existing ductwork and 2) it is decided that, to improve system efficiency, to no longer use ductwork in a suboptimal location such as an unconditioned attic or crawlspace. A reason to consider moving to a multi-zone system is if one or more of the rooms in the system is not commonly used for days at a time or for example if some rooms are only used during daytime hours and some only during nighttime.

Replacing a boiler system that circulates hot water to baseboards, radiators or radiant heat floors

Currently it is costly and difficult, though possible, to install a HP that can circulate warm water through a boiler piping system. This will usually require modification of the baseboards or radiators to work effectively (the water temperature from a HP is less than that for a boiler). It is even more difficult to have such a system that also circulates cool water to provide central air conditioning. For these reasons most homeowners will chose to install ccASHP units when replacing these systems.

Only a conventional ducted system or more?

If you are sure, you are only going to replace your ducted fossil fuel system with a conventional ducted HP system you can stop here. If you want a more flexible system, including being able to heat/cool your home differently by room or by time of day, read on.

Types of indoor units for a HP system

Each HP indoor unit that has a blower in it will have its own thermostat which makes the part of the house supplied by that indoor unit a “zone”. If you have more than one indoor unit, your home has a multi-zone system.

We will now focus on the various types of ccASHP indoor units.

There are 3 main “types” of ccASHP indoor units (if the indoor unit is part of a multi-split system, as described below, it may be called a “head”). Note: The Energy Star names for the types of units is used (and underlined).

1. Conventional ducted indoor units: We have largely covered this type of indoor unit already. Like a furnace, these have large boxy air handlers connected to full sized ductwork. These systems have power fans and are called high “static pressure” systems (0.5 inches water column or more).

2. Non-ducted indoor units: These come in 3 basic types: wall mounted (the original type of mini split), floor mounted and ceiling mounted. The floor mounted units may look a bit like a radiator, but they do contain a fan or blower, so they need to be in an area without obstructions. The ceiling types come as 4-way or 1-way units (sometimes called 2-way units). The 1-way units are narrow enough to conveniently fit between the wood supports above your ceiling which are usually separated by 16 inches. The smallest 4-way units are about 2 feet on a side so in most cases a wood support (joist) will need to be cut, and wood bracing installed.

3. Ceiling-mount blower coil indoor units: these come in low or mid static pressure systems (0.01-0.35 or 0.20-0.65 pressures respectively). The lower pressure limits mean the size and complexity of the ductwork will be limited compared to conventional ducted units and if more than one room is supplied, they need to be on the same level. These indoor units are typically only 8-10 inches high x 30 inches x 40-55 inches (at least 5 feet of space is needed for installation for the longest dimension to allow for connecting ductwork). They are usually mounted on bolts extending down from woodwork above the ceiling. They can be installed in a large closet or a nearby utility room near the area to be supplied. The ductwork is typically covered by framed wallboard (e.g. sheetrock) sometimes called an indoor soffit (this will reduce the ceiling height in that area by about 1 foot). However, they can also be mounted on a basement ceiling with supplies through the basement ceiling or in an attic with supplies through the attic floor.

Deciding on a good arrangement of indoor units for your home

You now need to decide what arrangement of indoor units might be best for your home. For example, do you have 2-4 rooms, all on the same level, that are close to each other, that could be supplied by a “ceiling mount blower coil” ducted indoor unit? If so, do you have a large nearby closet? If not, are the rooms on an upper level and can the blower and ducts be in the attic?

Perhaps you would prefer each room to be its own zone so then you may want to use 1-way ceiling cassettes.

Once the zones are decided upon, then the heating load for each zone will need to be estimated and with that, the appropriate size for each inside unit can be determined.

One outdoor unit for each indoor unit or multi-splits?

The final design consideration is whether you want each indoor unit to have its own outdoor unit or do you want outdoor units that support more than one indoor unit e.g. a “multi-split” arrangement. If you decide you need several different indoor units, you most likely will choose at least one multi-split setup.

Some outdoor units can supply up to 8 indoor units (8 zones) but more typically, multi-split outdoor units support 2 to 4 or 5 units. However, it is important to try to limit the total length of refrigerant lines so ideally the outside unit should be close to the inside units which then need to be close to each other.

Note: Some multi-split systems, rather than separate refrigerant line from the outside unit to each inside unit, the outside unit connects to a box which then sends separate lines to each inside unit. This may be called a branch box.

In a multi-split system, the sum of the heating capacity for all the indoor units should be no more than the capacity of the outdoor unit (though the sum can be up to 120-130% of the outdoor unit’s capacity if not all units will be running at full capacity simultaneously).

Many multi-split systems can also support a conventional ducted system (as described above these are high static pressure systems with an air handler and full-sized ductwork). This means one outdoor ccASHP unit can supply several rooms using a conventional ducted system, a compact ducted system and even non-ducted units. The main limitation then might be that the outdoor units currently available for ccASHPs are about 5 tons.

Summary

Many homeowners find that installing a HP can be a very difficult process, some go as far as getting quotes but don’t feel confident enough to proceed. Some find that after they switch to a heat pump they are left feeling they didn’t make the best choice or are unhappy with the way the system functions or may feel they are paying more in heating costs than they should be.

Using the steps described in this guide is likely to help you avoid any regrets with they system you chose. To help this process even more you may want to work with a heat pump or electrification coach who can guide you through the process.

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What is weatherization?

We will begin by explaining weatherization (we will use Wx to stand for weatherization).

The heated spaces within your home naturally lose heat (to the outside or into an unheated attic or basement). Wx, mostly through sealing air leaks and adding insulation, are the steps you can take to reduce this heat loss, which means you will spend less money to heat your home. The rooms within your home that you heat (or cool) are called the “conditioned” space. The walls, ceilings and floors between the conditioned and unconditioned space make up the thermal envelope (or thermal barrier) of your home. For a 2-story home with an unheated basement and attic would, the envelope would be 1) the floor of the first story 2) all first and second story walls (with their windows and doors) exposed to the outside air and 3) the ceiling of the second story.

For a home to be “well Wx” the envelope needs to be 1) “air sealed” so there are no gaps where heated air can escape freely and 2) have insulation levels comparable to what a recently built home in the same area would be required to have. For example, a new home in northern NJ (which is climate zone V), would have to meet the 2021 IECC efficiency code (chapter 4) which for example, requires an insulating value of R60 for the “ceiling” (actually the attic floor) which means about 17 inches of blown-in cellulose insulation (and thicker for fiberglass). This is much more than most existing homes in NJ have. It is also likely that most existing homes would not meet the 2021 code for walls, basements, windows and doors.

Estimating savings

Wx is a financial investment. You spend (or borrow) money now, in hopes that, by having lower energy costs over time, you will get back your investment and more. One factor you should consider when deciding to Wx is how long you plan to be in your home. Wx is unlikely to significantly increase the market value of your home, so if you are likely to move in a few years, you won’t have time to “make back your investment”. However, Wx increases the comfort and livability value of your home by decreasing drafts and uneven temperatures.

You can quickly estimate how much Wx may decrease your annual energy bills. For whichever energy you use for heating (electric, oil or gas) take the difference between the bills for the coldest and warmest months in the last year. Your annual heating cost will be about 2.5 times this amount. As an example, say your natural gas bills were $900 and $100 for January and July so your annual heating cost would be about $2,000 (($900 - $100) x 2.5). Wx of an older home in NJ can decrease heating costs by 20-30%, so for this example you would save about $400-$600 per year. These annual savings could then be compared to any quotes from contractors to estimate how many years it might take to recover your costs.

If you are a Do-It-Yourselfer, you can recoup your investment much more quickly. Using tax credits (described below), you could buy $4,000 worth of weatherization material for $2,800 by claiming a $1,200 tax credit. This is likely to be enough to fully weatherize a normal-sized attic.

Estimating Costs and Accessing Rebates/Credits

How much might it cost you to have someone weatherize your home? Most NJ homeowners will be able to receive some financial support for Wx. The financial support depends on your household income level (low, moderate, no limit), the source of the support (the state or your utility) and federal tax credits (if you have enough tax liability to use them).

The low-income Weatherization Assistance Program

The low-income program Weatherization Assistance Program, or WAP, is very generous, covering most if not all of the cost of Wx. Information on this program can be found at the NJ Department of Community Affairs website.

In addition, beginning in 2025, there will be new low- and moderate-income state/utility programs. These are part of the “Triennium 2” programs (the second of the formal three-year cycle of plans from the NJ Board of Public Utilities) approved at the end of October 2024, meant to be in effect from 1/1/25 to 12/31/27. Details on these programs are not yet available.

The no-income-limit state/utility programs

The no-income-limit state/utility programs are also part of the Triennium 2 programs. These are called the Whole House or Whole Home Wx programs. Only preliminary material is available describing these programs, so we will update this as more information becomes available.

Described are two options: Option A will be used by all the utilities, except PSEG which uses Option B. For both Options, the process starts with a home energy audit. The information gathered at the audit is used to develop a quote.

Option A (which appears to be comparable to the previous “Home Performance with Energy Star” program), requires at least a 5% reduction in modelled home energy use in order to receive ANY rebate. The rebate is $2,000, plus $200 for each % reduction above 5%, to a maximum or $7,500, which is reached if the modelled energy use is reduced by 32.5% or more.

Because the rebate is dependent on how the contractor modelled your home’s energy use, and how he predicts that the various measures will contribute to an overall reduction in energy use, it is difficult to know if you, and the utility ratepayers who provide the rebate money through a surcharge, are getting a good deal. It may make sense for you to get one or more additional estimates to be sure that what you will pay is reasonable, and that the measures being suggested make sense. Alternatively, as a price check, you could get estimates for the expensive items from another insulation company without doing another full home energy audit. You should also ask your auditor to

1. Give you a copy of all the data collected on the home

2. Provide separate costs for each part of the weatherization work (e.g. air sealing, attic insulation, wall insulation etc.) and

3. To include a description of the energy modelling work, along with the inputs used and the full set of results. This information may be very helpful for working things through with your coach.

Option B (for PSEG customers) is very vague, saying only that up to 75% of the Wx costs are covered.

Federal Tax Credits

These are the Residential Energy Credits on IRS form 5695. The limit for Wx is up to $1,200 per calendar year and the maximum your credit can be is what you paid in total for the year is (your total tax should be line 24 on your tax return). I.e. your tax credit cannot exceed the total tax that you pay for the year.

The allowable Wx items are: insulation materials, doors, windows and the cost of an energy audit. BUT there are a number of restrictions:

1. 30% of the cost of each item is allowed, but each item, except for insulation materials, has a limit lower than $1,200;

2. Labor costs may not be included, and the cost is computed AFTER any rebates have been deducted.

3. Windows and doors must meet Energy Star criteria, which means that they will most probably not be on the low-cost end. In particular, windows must be rated Energy Star Most Efficient, which are likely to be only triple-pane windows.

Additional related guidances

• Home energy audits (planned for future)

Last updated: 1/13/2025

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How a heat pump works

(Hint: just like your refrigerator)

Heat pumps take up heat in one location and deliver it to another location. For example, your heat pump refrigerator collects heat from the inside of your refrigerator and freezer and delivers it to the air in your kitchen where it leads to a slight warming of the room.

What if you could run the heat pump in your refrigerator in reverse so that it collects heat from your kitchen air and sends it into your refrigerator? The temperature inside your refrigerator would increase to well above your kitchen air temperature. This is exactly what a heat pump does to keep you comfortable inside your home. Unlike your refrigerator, which circulates in only one direction, a heat pump, because it is reversible, can pump heat into your home in winter and then pump heat out in summer.

For those who are interested, this paragraph gives a little more technical description of how heat pumps work. They use a chemical (or a mixture of a couple of chemicals) that is circulated in a loop by piping between the area where heat is taken up to where it is removed (and then around using a return pipe to complete the loop). The heat pump uses electricity to compress the chemical that makes it hot so it can release heat, then decompression makes it cool so it can take up heat. Because the original use for heat pumps was for cooling, these special chemicals are called “refrigerants”.

In the past, heat pumps, however, had a problem on cold days like we see in NJ. Fortunately, this is no longer a problem, read on.

Types of heat pumps

Newer heat pumps for cold climates like NJ (ccHP systems)

Until relatively recently, once the temperature dropped to 40 degrees or below, most heat pumps would have been unable “pump” enough heat to keep a home in NJ warm without switching to inefficient and expensive back-up heat. Now, newer “cold climate” heat pumps can provide plenty of heat for even the coldest NJ winters without needing any back-up heat. While initially, cold-climate heat pumps were more expensive, their costs have come down to where there is little difference in price. In fact, only cold-climate heat pumps are eligible for federal tax credits of up to $2,000 per year and NJ state-backed utility rebates of $2,000 per heat pump. (Iin the Building Decarbonization part of the utility programs, if a gas or oil appliance is being fully displaced, rebates can be up to 50% of the cost up to $10,000 or for moderate income households, 60% of the cost up to $12,000). So, for NJ, it makes sense for home heating to only install cold-climate heat pumps. (To make things a little easier, we will use the abbreviation: ccHP).

Split-system HPs

Most residential ccHPs are what are called “split” systems. There is an indoor part and a separate outdoor part, connected by refrigerant piping. Central air conditioners are split systems where the indoor part, often in a basement or attic is where the cool air is released into a ductwork system, and the boxy outdoor part, usually on the ground outside, where heat is released. Examples of a non-split or single-package air conditioner are window unit or those in the outside wall of a hotel or motel room.

Air-source, ground-source and water-source HPs

So far, we have been describing what are called “air-source” HPs where, when they are in heating mode, they take heat from the outside air making “air” the source of the heat (the indoor air, where the heat is released would be called the heat “sink”). There are also “ground-source" and “water-source” HPs that involve pipes underground or into a body of water. These tend to be expensive, and they are not suitable for most homes. If they make sense for your property, your coach can help. (We plan a future guidance to cover ground- and water-source HPs).

HPs that heat water, instead of air, to warm your home

So far, we have been talking about HPs that directly heat (or cool) the air inside your home. (They do this by having a fan blowing over tubing containing the heated or cooled refrigerant). There are HPs, that instead of directly heating the air inside your home, use the heated refrigerant to heat water that then circulates through your home just like a boiler system which circulates warm water to radiant heat floors, radiators or baseboards. (If the outdoor piece is air-source, this would be called an air-to-water HP). Unfortunately, if your home has a boiler system, you cannot usually simply replace your boiler with an air-to-water HP because current HP systems do not heat water as hot as a boiler does so you may need to replace your radiators or baseboard. The good news is that before long there may be HPs that can provide hotter water. There is still some bad news, however, these systems are problematic for providing central air conditioning. We plan a guidance for these systems.

What is the most common type of HP?

So, based on what we’ve covered so far, what is the most common “type” of HP a NJ homeowner is likely to need? It would be a: split-system, air-source, air-sink ccHP. The common abbreviation for these is ccASHP (the abbreviation includes AS for air-source, the split-system and air-sink aspects are assumed).

Ducted and ductless HPs

Now we will cover the last common feature of a home HP, whether it is a ducted or a ductless system.

ccASHPs come in two types of systems for spreading the warm or cool air throughout your home: ducted and ductless (or non-ducted). The first ductless systems were small split systems which became called “mini-splits”. These evolved so that they are no longer always small or always ductless. The term is still used however, sometimes leading to confusion.

Ducted:

Energy Star describes two common types of ducted systems.

1. The first type is called a “conventional ducted system”. They are also called centrally-ducted systems. If you have a central air conditioner, it is a centrally ducted system (they use large ducts with a powerful fan, usually called an “air handler”).

2. Energy Star calls the second type a “ducted ceiling-mount blower coil” system. These are smaller systems with lower fan pressures for supplying one large room or a couple of rooms, or sometimes an addition to the home. They are also referred to as concealed duct or compact duct systems. These systems are not commonly used in homes mainly because they require new ductwork, which can be expensive (even though the amount of ductwork needed is much smaller than a centrally-ducted system), and often there is no suitable hidden spaces for the ductwork.

Ductless:

These blow warm or cool air right from the mounted box into the room (no ducts). These include the typical mini-split oblong box mounted high on a wall, but there are versions that can be mounted flush with the ceiling or near the floor like a small radiator.

When a few ductless units or one centrally-ducted system is not enough

Larger homes sometimes need more complicated systems. This brings us to multi-zone systems. This is when there is one outdoor unit but more than one indoor unit, each with its own thermostat. (These are also sometimes called multi-split units, but as a zone is defined by having a separate thermostat, multi-zone is a better term). This allows one outdoor unit to provide different temperatures in different rooms. Multi-zone outdoor units can typically support 3-5 indoor units, one of which could be a centrally ducted system, and with the rest being ductless units.

Larger homes may even sometimes need more than one multi-zone system, for example, two multi-zone outdoor units each supporting a centrally ducted system and one or more ductless units.

Other Important Considerations

There are some other important things to know about a home HP system and we will cover these in other short introductory articles. What follows is a short list of some of these topics.

• Financial support: a guidance is planned to cover utility rebates, low-interest loans and on-bill paying and federal tax credits.

• Electric supply: HPs generally run on 240-volts. Putting in a HP to replace a central air conditioning system is usually not a problem as they already are powered by 240 volts. New ductless units, however, may not be near any 240 circuits. In some situations, you may need to put in a new higher amperage electrical panel, especially if your current panel only allows 100 amps or less. However, there may be tax credits or rebates that can help offset the cost.

• Energy audits and weatherization of your home: heat will always pass between the outside of your home and the inside that you heat and cool. Weatherization in the form of insulation and sealing air leaks reduces heat leaking out in winter or leaking in in summer. Improving the weatherization of your home means you can install a smaller (and less expensive) heating/cooling system. An energy audit will evaluate how well your home is weatherized. Tax credits, rebates and 0% loans may help with weatherization.

• A correctly “sized” HP will cost you less to run than one that is too large (oversized). It will also cost less to buy. Figuring out the correct size HP you need is not always a simple matter. If you plan to weatherize after you install a HP, make sure you take this into account when you decide on the size of the HP you install.

• Centrally ducted systems need special attention to make sure things like the duct sizes are appropriate, they don’t leak, they are not in an area that is exposed to very high or low temperatures (e.g. an attic or crawlspace), or if they are, are they well insulated).

• Installing a HP may take a little longer than replacing a boiler or furnace, so if you think your current system is “on the way out,” start now planning for a HP system. Keep in mind that if it takes a couple of days longer to get the right heat pump, you can always buy, borrow or rent some small electric heaters to get you through a few cold days.

• Ground and water source heat pumps: a guidance is planned.

• Air-to-water heat pumps for space heating: a guidance is planned (will include ground-to-water and water-water as well).

Article #: HP1, Last updated: 1/3/2025