Ducted heat pump water heaters
Heat pump water heaters use the heat in the air around them to heat water, cooling and dehumidifying the space they are in. While this can be beneficial in the summer months, it can make spaces like basements less comfortable in the winter. With many models, homeowners have the option to have ducting kits installed, which will allow the heat pump water heater to vent cold exhaust air to the outdoors (or a different room in the home) and/or bring in air from outdoors. Ducting can be a valuable option for some homeowners, for example in cases where the space your water heater is installed in is too small for sufficient air circulation—or if it is beneficial to bring in air from a warmer room/blow cold exhaust air into another area. Some homeowners may want to blow cold air into a pantry to keep it cool or into an attic or crawl space to keep the basement from getting too cold.
However, in Massachusetts, ducting with the outdoor air entails seasonal considerations. Bringing in outdoor air will only work during the summer where warmer air can potentially improve the performance of the system; during colder months, the intake air will be too cold to allow the heat pump water heater to operate. Ducting cooled air outdoors and not ducting air back in will depressurize your home, increasing air infiltration from the outdoors, which can reduce comfort.