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Title: LOW COST HEAT PUMP WATER HEATER (HPWH)

Abstract

Water heating accounts for the second largest portion of residential building energy consumption, after space conditioning. Existing HPWH products are a technical success, with demonstrated energy savings of 50% or more compared with standard electric resistance water heaters. However, current HPWHs available on the market cost an average of $1000 or more, which is too expensive for significant market penetration. What is needed is a method to reduce the first cost of HPWHs, so that the payback period will be reduced from 8 years to a period short enough for the market to accept this technology. A second problem with most existing HPWH products is the reliability issue associated with the pump and water loop needed to circulate cool water from the storage tank to the HPWH condenser. Existing integral HPWHs have the condenser wrapped around the water tank and thus avoid the pump and circulation issues but require a relatively complex and expensive manufacturing process. A more straightforward potentially less costly approach to the integral, single package HPWH design is to insert the condenser directly into the storage tank, or immersed direct heat exchanger (IDX). Initial development of an IDX HPWH met technical performance goals, achieving measured efficiencies ormore » energy factors (EF) in excess of 1.79. In comparison conventional electric water heaters (EWH) have EFs of about 0.9. However, the initial approach required a 2.5" hole on top of the tank for insertion of the condenser - much larger than the standard openings typically provided. Interactions with water heater manufacturers indicated that the non standard hole size would likely lead to increased manufacturing costs (at least initially) and largely eliminate any cost advantage of the IDX approach. Recently we have been evaluating an approach to allow use of a standard tank hole size for insertion of the IDX condenser. Laboratory tests of a prototype have yielded an EF of 2.02.« less

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Building Technologies Research and Integration Center (BTRIC)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
930738
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: International Refrigeration and Air Conditioning Conference at Purdue University, West Lafayette, IN, USA, 20060717, 20060720
Country of Publication:
United States
Language:
English
Subject:
heat pump water heater; immersed condenser

Citation Formats

Mei, Vince C, and Baxter, Van D. LOW COST HEAT PUMP WATER HEATER (HPWH). United States: N. p., 2006. Web.
Mei, Vince C, & Baxter, Van D. LOW COST HEAT PUMP WATER HEATER (HPWH). United States.
Mei, Vince C, and Baxter, Van D. Sun . "LOW COST HEAT PUMP WATER HEATER (HPWH)". United States. doi:.
@article{osti_930738,
title = {LOW COST HEAT PUMP WATER HEATER (HPWH)},
author = {Mei, Vince C and Baxter, Van D},
abstractNote = {Water heating accounts for the second largest portion of residential building energy consumption, after space conditioning. Existing HPWH products are a technical success, with demonstrated energy savings of 50% or more compared with standard electric resistance water heaters. However, current HPWHs available on the market cost an average of $1000 or more, which is too expensive for significant market penetration. What is needed is a method to reduce the first cost of HPWHs, so that the payback period will be reduced from 8 years to a period short enough for the market to accept this technology. A second problem with most existing HPWH products is the reliability issue associated with the pump and water loop needed to circulate cool water from the storage tank to the HPWH condenser. Existing integral HPWHs have the condenser wrapped around the water tank and thus avoid the pump and circulation issues but require a relatively complex and expensive manufacturing process. A more straightforward potentially less costly approach to the integral, single package HPWH design is to insert the condenser directly into the storage tank, or immersed direct heat exchanger (IDX). Initial development of an IDX HPWH met technical performance goals, achieving measured efficiencies or energy factors (EF) in excess of 1.79. In comparison conventional electric water heaters (EWH) have EFs of about 0.9. However, the initial approach required a 2.5" hole on top of the tank for insertion of the condenser - much larger than the standard openings typically provided. Interactions with water heater manufacturers indicated that the non standard hole size would likely lead to increased manufacturing costs (at least initially) and largely eliminate any cost advantage of the IDX approach. Recently we have been evaluating an approach to allow use of a standard tank hole size for insertion of the IDX condenser. Laboratory tests of a prototype have yielded an EF of 2.02.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

Conference:
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