Air to Water Heat Pump - Building Block Installations

Complete air-to-water heat pump (AWHP) installations can be costly. I believe an effective way to get started selling this type of system is through "building block installations". This means using an AWHP when replacing any major HVAC appliance in the home. The idea is to install the AWHP as a basic building block and build on it over time. You can also use this as leverage to retain your account. Maybe offer a discount on future updates.
Let's assume the home has two existing heat pumps, one for each area. One of the compressors has failed and needs to be replaced. This is a perfect time to offer an AWHP and move slowly into the electrification of our industry. Over time, you can build on the basic system. The buffer tank should be included when the AWHP is installed. It can be added later, but it could cause the AWHP to short-cycle.

Here is a checklist that is needed before you do the AWHP; (don't take shortcuts)
1. Where the homes' heat loss and heat gain can be reduced by air leak sealing, adding insulation, and windows/doors if the homeowner has not kept up with this throughout their home ownership
2. Do a complete Manual-J heat loss. This is particularly important when choosing the proper AWHP size, given the varying supply water temperatures at different OD air temperatures. The AWHP may be larger than the existing heat pumps
3. Verify the AWHP is of a varying output style
4. In most applications, you will need one OD unit even though there are multiple indoor units. One exception would be large homes
5. If using air handlers, you may decide to add electric back-up to the air handlers or use a boiler to boost water temperature when needed. (follow the manufacturer's instructions)

Below is a drawing using an AWHP sized for the total needs of the home and replacing a single heat pump on a two-heat pump home.

Eventually, the second heat pump will fail, and you then add the second air handler with a water coil instead of a refrigerant coil, but not a second OD unit. You will have to get water lines to the air handlers.

Staying on this subject, no hydronic heat system, let's assume the homeowner wants to finish off his basement to usable space or is going to add a garage, we have the option of adding radiant floor heat as another zone.

Another choice, if there is hydronic heat in the home already and the home also has one or multiple zones of air conditioning, you can do the hydronic heat connections at the time of original installation. As the a/c units fail and need to be replaced, add them on as needed. If an air conditioning unit fails and you decide to use an AWHP, connect the air handler to the AWHP. The hydronic system can be connected in parallel, with the existing boiler serving as a backup on freezing days. You will save on milder days when using the heat pump. The other option, with an existing boiler and one of the a/c units failing, is to leave the hydronics system alone. The boiler can be connected to the AWHP either next year or when it fails. My choice would be to use the AWHP on milder days and extend the boiler's life when it is not used as heavily.

I will add that if your company is not into solar photovoltaic, today is the time to consider this expansion to your company, especially if you are doing new construction. This is a newer and rapidly growing industry that can add an income stream to your bottom line.

Disclaimer:The information found on this website is for informational purposes only. All preventive maintenance, service, and installations should be reviewed on a per-job basis. Any work on your heating system should be performed only by qualified, experienced personnel. Comfort-Calc or its personnel accepts no responsibility for any improper information, application, damage to property, or bodily injury resulting from the application of information found on this website, as a professional should review it.