Desuperheaters on Residential Air-Source Heat Pumps

August 5, 2008Regional Technical Forum

Installation/Overview

Source: Turbotec Products, Inc. “ENVIRO-PAK Installation, Operation, and Maintenance Manual” http://www.turbotecproducts.com/Literature_files/Enviro-Pak%20IOM.pdf

Manufacturers

• Trevor-Martin Corporation manufactures multiple models under various brand nameshttp://www.trevormartin.com/index.asp

• Turbotec Products, Inc. manufactures the “Enviro-Pak”http://www.turbotecproducts.com/EPhome.html

• Others – Primarily Commercial/Industrial Equipment– Therma-Stor LLC– Doucette Industries, Inc.

Cost• Cost Components

– Equipment Purchase• Desuperheater

– Installation• Mount desuperheater• Recover Refrigerant• Install Refrigerant Lines between desuperheater and compressor discharge line• Install new storage tank (or drain existing tank if not using a storage tank)• Install Water Lines between desuperheater and storage tank• Charge heat pump with refrigerant• Insulate refrigerant and water lines• Commission the system

• Turbotec (source: Turbotec Representative)– Trade Price: $583– Installation: about $1000

• does not include storage tank option– Total Installed Cost: about $1500

• Trevor Martin (source: Trevor Martin Representative)– Online Retail: $425– Total Installed Cost: $900

• ORNL 1983 Report– Total Installed Cost: $600 in 1983 (or $1100 in 2008)

• Does not include storage tank option• Obtained through dealer quotes

Energy Savings

• ORNL 1983 Report:– Method: Monthly Bin Analysis– Assumptions:

• 20% of heating and cooling capacity available to heat water.

• 75 gallons/day hot water use evenly distributed throughout the day

– Energy Savings: (kWh/year) Summer Winter Total Portland 693 1360 2053 Seattle 518 1385 1903 Phoenix 1946 580 2526 Los Angeles 1097 520 1617

Cost Effectiveness• Assumptions:

– 5th Plan Assumptions– Measure Life: 10 years– Measure Load Shapes

• Winter Savings: ResSpHtHP• Summer Savings: ResCAC

CategoryMeasure

Cost

Site Savings (kWh)

TRC B/C Ratio

Desuperheater on ASHP Portland Low Cost $1200 2053 1.0

Desuperheater on ASHP Portland Medium $1500 2053 0.8

Desuperheater on ASHP Portland High Cost $1800 2053 0.7

Potential Issues1. Poor track record when installers are asked to add more complex equpiment to

a heat pump.

2. A second water tank should be installed to realize best savings.

3. In retrofit cases, installation costs will vary widely, depending on location of HP with respect to the water heater. The desuperheater should be located near the water heater (non-freezing area).

4. Summer savings will vary, depending on how much air-conditioning the house uses. How would a program pick out the high users effectively?

5. High efficiency equipment has less superheat.

6. In heating mode, how much is the supply air temperature affected (cooled)? Comfort issues?

7. Others?

Next Steps

• Consensus on pursuing this measure further?– Perform more detailed modeling?– Support a small real-world monitoring project?– Obtain better cost data?