Impact of Ducting on Heat Pump Water Heater Space Conditioning Energy Use and Comfort

Evaluation of the Demand Response Performance of Electric Water Heaters

“…The study also evaluated the impact of HPWHs with no ducting, with exhaust only ducting, and with supply and exhaust ducting on space conditioning and whole house energy use. The data indicate a much smaller space conditioning penalty than has previously been assumed in models exploring this issue (Larson et al, 2011;Wilson and Christensen 2012) and found HPWHs to save energy in all cases in the Richland, WA, climate (Widder et al 2014). Regarding the noise of HPWHs, HPWHs typically produce mechanical noise associated with the operation of the compressor and fan on the order of 45-60 decibels, which is commensurate with the noise made by a residential refrigerator.…”

“…Many of the installation and comfort-related concerns have already been addressed in the literature and other related research projects. Specifically, previous work in the PNNL Lab Homes has evaluated the space conditioning and comfort-related impacts of HPWHs venting cold air into conditioned space (Widder et al 2014). With regard to comfort concerns, the Lab Home research found no significant temperature impacts in adjacent conditioned spaces and, thus, did not anticipate a comfort concern in a majority of installations.…”

Summer Indoor Heat Pump Water Heater Evaluation in a Hot-Dry Climate

“…A recent Pacific Northwest National Laboratory (PNNL) study tested HPWHs in various ducting configurations at two PNNL lab homes that were heavily instrumented (Widder et al, 2014). The study found that in the Richland, WA climate, the penalty of installing a HPWH indoors may not be as large as modeling studies indicate.…”

“…An important goal in this project in addition to documenting HPWH field performance and operating characteristics is to try to quantify the cooling benefit that can be realized in a hot-dry climate. The recent PNNL HPWH report indicated a space-cooling benefit equivalent of approximately 1.5 kWh/day at a hot water usage level of 78.51 gallons per day (Widder et al, 2014). By measuring HPWH inlet and outlet air temperature and RH conditions and airflow rate 15 , one can calculate the sensible and latent cooling delivered by the unit.…”

Greenhouse gas emissions from domestic hot water: heat pumps compared to most commonly used systems

“…Powered by electricity, heat pump water heaters operate by transferring heat from the air into the tank . Although currently making up only about 1% of new water heater sales in the U.S., they are becoming more popular (34,000 and 43,000 units sold in 2012 and 2013, respectively; http://www.energystar.gov/) because of their high efficiencies and their potential to improve overall home energy use efficiencies . Their potential for reducing GHG emissions has not been evaluated up to now.…”