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Lab Test Report on Sanden Split System CO2 Refrigerant Heat Pump Water Heater

Created 1/29/2014 by Ken Eklund
Updated 4/22/2014 by Ken Eklund
70 views • 3 comments
The Lab Test Report contains the performance test results for this CO2 refrigerant, split system heat pump water heater.  The results include the tests required for all heat pump water heaters for ranking according to the Northern Climate Specification.  The tested Northern Climate Specification Energy Factor is 3.2 and its Delivery Rating is 7.5.  This report is posted in order to share it with the Heat Pump Water Heater Collaborative and the Advanced Heat Pump Research Advisory Task Force.  The date of this report is 9/18/2013 and its author is Ben Larson.  It was produced under contract with Washington State University Energy Program which is funded by BPA to do this research.
Posted By: Ken Eklund 04/22/14 on 01:32 PM (Pacific Time)

Previous Versions (2)
Version 2.0 04/22/14 01:59:PM by Ken Eklund
Version 1.0 04/03/14 01:39:PM by James White
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Comments (3)
Ken Eklund on 01/29/14 on 02:05 PM (Pacific Time)
This heat pump water heater is a potential game changer with a 3.2 Northern Climate Specification Energy Factor and 7.5 Delivery Rating.  Read the lab report by Ben Larson and look for results of the field tests currently being conducted.
James White on 04/03/14 on 11:39 AM (Pacific Time)
The performance of this heat pump water heater (HPWH) at low and normal outside air temperatures is very impressive.  I also like the fact that this HPWH takes heat from outdoor air rather than taking it from air inside the building.  I believe that HPWHs that take heat from inside the living spaces are not going to succeed in the Pacific Northwest.  Ducted systems are also going to be difficult to implement in existing buildings.   
I do have a question about the Sanden split system HPWH.  Since the unit circulates water through the outdoor unit, I wonder how they keep the water from freezing in the pumps and associated lines when the pump is not circulating the water.
Ken Eklund on 04/22/14 on 11:59 AM (Pacific Time)

Very good question on the freeze protection strategy.  The outdoor unit has a freeze protection cycle that circulates hot water through the refrigerant to water heat exchanger when the system is not operating.  This is in addition to the defrost cycle that protects the air to refrigerant heat exchanger.  The lines between the compressor and the conditioned space are protected by thermostatically controlled electric resistance freeze protection.

 

Our field test is shedding some practical light on the situation.  The system installed in Corvallis, Montana functioned perfectly during a week where the average weekly measured temperature at the outdoor unit was -14 F.  The electricity used by the freeze protection for the lines was minimal.

 

The system design has one issue--what happens if the power goes out for a substantial period of time?  The manufacturer is aware of this issue and is working to address it in systems designed for cold climates.

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