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.

Split and solar-assisted heat pump water heaters

While most heat pump water heaters available in the US today have the heat pump co-located with the hot water tank, split systems are also becoming available. Split systems include an indoor hot water tank and an outdoor compressor unit connected by refrigerant lines. The outdoor compressor heats the refrigerant by pulling heat from the outdoor air. Some outdoor units use an exterior metal panel that can absorb solar radiation to assist in heating the refrigerant; these types of systems are called solar-assisted heat pumps. The heated refrigerant then passes indoors and heats the water in the hot water tank before returning to the outdoor system. Split- and solar assisted heat pump water heater systems do not impact indoor air temperatures nor require condensation draining but are subject to weather-based variability in performance based on outdoor air temperatures or daylight. These two kinds of split water heating systems are typically more expensive to install but are well-suited to the unique requirements of some homes. These systems are beginning to be available in Massachusetts, but are still only offered by certain installers.

Split Heat Pump Water Heater – Indoor Unit

Split Heat Pump Water Heater – Outdoor Unit

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