Heat Pump Residential Registered Vendor FAQ

Below you’ll find answers to some of the most common questions about our residential heat pump program we hear from Residential Registered Vendors.

1. Can multi-zones be part of a rebated whole-home heat pump upgrade?

Yes and no. Yes, the heating capacity of multi-zone heat pumps counts towards the 80%/100% of home’s peak heating load, but no, their cost isn’t rebate-eligible.

Example: Two single-zones on the first floor and a multi-zone serving the second floor bedrooms. The heating capacity of the single-zones and multi-zone combined could count toward the peak heating load at design temperature. If the cost of the two single-zones exceeded $10,000, the system could qualify for the maximum rebate.

2. How can I find the heating capacity of heat pumps at or below design temperature?

We recommend you contact your distributor.

3. How can I find the heating capacity of previously installed heat pumps (especially if they’re a brand I’m not familiar with)?

We recommend asking your distributor (who may need to direct you to another distributor) or searching the web.

4. What are the advantages of single-zone heat pump systems?

The advantages of single-zone heat pumps are 1) they provide backup for one another 2) they provide better comfort, and 3) they cost less to operate.


1. Backup

If one, single-zone heat pump needs service, the other heat pumps will continue to operate. With a multi-zone, any failure can lead to a “no heat” situation.

2. Better comfort

a. Single-zone heat pumps can more effectively dehumidify homes as a result of their ability to run longer at lower capacities.

b. Using multiple, single-zone heat pumps allows for the option to run them in different modes simultaneously (e.g., heat in one room, dry-mode in another, fan-only in a third, etc.) Multi-zone indoor units all need to operate in either heating or cooling mode simultaneously.

c. Single-zone, heat pump compressors turn off when there’s no heat needed. With multi-zone heat pumps, if any indoor unit calls for heat, hot refrigerant flows through all indoor units, even the ones not calling for heat. This is worsened by the fan that runs to sample room temperature. The result can be overheated rooms.

3. Cost less to operate.

There are three reasons that single-zone heat pumps offer lower operating costs.

a. One reason is that they are simply more efficient. Their AHRI HSPF ratings are up to 15.2 compared to just 12.8 for multi-zone systems.

b. Another reason that single-zone heat pumps cost less to operate is that they have better turndown ratios (i.e., the ratios between their highest and lowest rated capacities). This means that when heat demand is low (fall and spring) they can run continuously at slow speed rather than having to inefficiently cycle on and off View Example. Single-zone heat pumps also offer more capacity at lower temperatures compared to multi-zone heat pumps View Example.

c. The third reason that single-zone heat pumps cost less to run is that users can turn off one single-zone heat pump at a time to further avoid short cycling.

5. What are the ideal homes for this program?

There are several types of homes that are ideal for this program. Here are a few examples:

1. New construction where heat pumps eliminate the expense of fuel tanks, boilers, chimneys, ductwork, and radiators.

2. Homes heated with expensive fuels (electric baseboard, propane, kerosene) where the potential for cost savings is the greatest.

3. Houses that just need one or two more heat pumps (small, well-insulated, open concept, heated by single pellet/gas stove or wall furnace) where rebates can cover a significant portion of cost.

6. What types of supplemental heating are acceptable to meet 100% of home’s peak heating load requirement?

Supplemental heat can be provided by anything except for the primary, fossil-fueled heating system: cordwood, pellets, electric baseboard, electric radiant floor, or even a fossil-fuel room heater.

7. Are Efficiency Maine rebate-eligible heat pumps also eligible for federal tax credits?

When paired with the indoor units shown in the CEE Database (select “CEE Tier 2 – North and Canada” for ductless heat pumps or “CEE Tier 1 – North and Canada” for ducted heat pumps), all the outdoor units on our list of rebate-eligible heat pumps are federal tax credit-eligible.

8. Are heat pump federal tax credits available for new construction or rental homes?