Questions from The Field
Dec 02, 2020
Throughout 2020, the NW Ductless Heat Pump Project presented at multiple conferences and delivered more than 20 installer training webinars. We have compiled and responded to some of the most interesting and useful questions below.
Q: Are displacement applications eligible for utility rebates, and if so, does the Project’s quick and easy load calculation method satisfy utility requirements for rebated installations?
A: Yes, rebates for ductless heat pumps (if present in your area) call for displacement of electric resistance heat. To our knowledge, no utility requires a load calculation in their rebate program. However, Northwest utilities encourage contractors to properly select a ductless heat pump. This requires understanding the space’s heating requirement, which you can do by using the quick and easy load calculation method. Always check with your local utility to confirm their rebate requirements. You can start here.
Q: Can you share the quick and easy load calculation chart for a simple sizing calculation?
A: For new construction and major remodels, we still recommend room-by-room heating load calculations. For this reason, the NW Ductless Heat Pump Project and BetterBuiltNW encourage the use of the HVAC Sizing Tool software.
For displacement of electric resistance heating, our quick and easy load calculation method is available, and it uses the heating load factors found in the table below. Users choose the column that best represents the winter design temperature at their location. Next, they choose the row that most closely applies to the construction type. The corresponding cell provides the heating load factor. Multiply the total floor area of the main living area by this load factor to get the heating load of the space. It’s a quick and easy way to calculate a heating load when installing a ductless heat pump in the main living area of an electrically heated home.
A table for a quick and easy heating load calculation
Q: What defines a large electric heating load?
A: To understand the electric heating load, ask the homeowner how much they pay for electricity in the coldest winter months (an approximate answer will work). Then, ask them how much they pay for electricity in a typical month during the shoulder season. If the difference between winter and shoulder season electricity use is 30 percent or more, then the home has a large electric heating load. The home would be a good candidate for heating displacement with a ductless heat pump.
Q: What are the maintenance needs of cold-climate ductless heat pumps?
A: When the NW Ductless Heat Pump Project began ten years ago, the best advice was to follow the manufacturer recommendations. This is still applicable, but years of experience has taught us that all ductless heat pumps require regular maintenance, including cleaning the indoor unit. Filters require regular checking, and cleaning frequency depends on the dust levels within the space. In some cases, the indoor unit will need a deep clean, which includes cleaning the coil and fan blade surfaces and flushing the drain lines and condensate collection pans to remove particle buildup. For the outdoor unit, debris can build up around the outdoor unit and reduce effectiveness of the defrost cycle. In addition, cottonwood fuzz and other airborne debris can clog the outdoor coil surface. To improve overall performance and achieve the desired energy savings, it is important to clean heat exchanger surfaces and fan blades.
Q: I would like to develop a maintenance plan to offer my customers when they purchase a ductless heat pump. What kinds of services would be beneficial to include in my company’s maintenance plan for customers?
A: Many customers are willing to pay contractors for annual maintenance services that ensure maximum system performance. Consider offering the following services in your maintenance plans:
- Confirming that the outdoor unit is level
- Confirming that line set covers are still attached and fully intact
- Cleaning the indoor unit air filter
- Cleaning the indoor and outdoor fan blades and coils to remove debris and particle buildup that can hinder the outdoor unit’s operation
- Cleaning the condensate drain pan on the indoor unit and flushing the condensate drain line