Oikos Showcase: Iris Communications Air-to-water Heat Pump

Iris Communications, Inc.
World Headquarters
Air-to-Water Heat Pump

Index
Design
Foundation and Framing
Insulation and Air Sealing
Solar Energy
Heating and Ventilation
Interior
Appliances and Lighting
Recycled Materials
Landscaping
Certifications and Recognitions

The air-to-water heat pump has not lived up to our expectations. Repeated failures and costly repairs over the last four years have prompted us to seek estimates for a replacement. We might consider another brand of air-to-water heat pump (aka reverse cycle chiller) or we may simply convert the system to a gas-fired tankless water heater.

The original system (left) was installed in late 2004 by our general contractor. The system is a standard York heat pump mated to a heat exchanger made by Aqua Products.

A Good Beginning

The first heating season was trouble free and the system performed very efficiently. The coefficient of performance was measured 3.5 at 49°F. Even when temperatures dropped to the single digits, the system was able to heat the 1800 sq. ft. home without backup heat. After that first heating season we were pleased and optimistic.

Trouble Begins

In November of 2005, the system died. During this time, the house was heated by a single 4.5 KW electric element in the standard electric water heater that serves as the storage tank. In a perverse way, this was instructive. We were able to measure how much heating energy is required without the extra efficiency of the heat pump.

We called in a well-regarded heating contractor. Several months passed as the system was diagnosed and finally York agreed to provide a replacement compressor, while the local distributor paid the labor costs to install it. The work was finally completed in April 2006, two weeks before we shut the system down for the season. While the system is capable of mechanical cooling, we seldom use it. The new compressor performed well during the following heating season, and again we were optimistic.

Another Compressor Fails

The system stopped working again in November of 2007 due to a failed compressor. This time York agreed to replace the entire outdoor unit with a highly efficient member of the Affinity line. We paid our heating contractor for the labor. The work was completed in February of 2008. For the second time, the system was out of commission during the coldest part of the winter.

Just a week later, this new unit stopped functioning during a moderate cold snap — the temperature dropped to the mid 20s. York's factory representative was in town to meet with a group of HVAC contractors who had been experiencing problems with air-to-water heat pump systems. He dropped by to take a look and declared that all was well.

In December 2008, about six weeks after the system began operating for the season, the system began to cut out. The diagnostic code indicated high discharge line temperature. The York factory representative again visited the system along with local HVAC technicians. He suggested that the liquid line sensor be moved to a different location. That change has not prevented repeated cut outs, all showing the same high discharge line temperature code. Actually, it seems that the cut outs are more frequent now.

All these problems have occurred within the York heat pump, so we have asked that York cover the materials and labor to fix it. Citing the warranty, which does not cover labor, York has offered only to supply replacement parts.

We have decided not to invest any more of our own money in the York/Aqua Products system, and have started to research a replacement system. We might consider other reverse cycle chillers now available from Daikin and Unico. On the other hand, we may just install a gas-fired tankless water heater.

— Bruce Sullivan


	All Oikos pages copyright 1996 - 2009, Iris Communications, Inc.

	Iris Communications, Inc. World Headquarters Air-to-Water Heat Pump
	Index Design Foundation and Framing Insulation and Air Sealing Solar Energy Heating and Ventilation Interior Appliances and Lighting Recycled Materials Landscaping Certifications and Recognitions
	The air-to-water heat pump has not lived up to our expectations. Repeated failures and costly repairs over the last four years have prompted us to seek estimates for a replacement. We might consider another brand of air-to-water heat pump (aka reverse cycle chiller) or we may simply convert the system to a gas-fired tankless water heater. The original system (left) was installed in late 2004 by our general contractor. The system is a standard York heat pump mated to a heat exchanger made by Aqua Products. A Good Beginning The first heating season was trouble free and the system performed very efficiently. The coefficient of performance was measured 3.5 at 49°F. Even when temperatures dropped to the single digits, the system was able to heat the 1800 sq. ft. home without backup heat. After that first heating season we were pleased and optimistic.
	Trouble Begins In November of 2005, the system died. During this time, the house was heated by a single 4.5 KW electric element in the standard electric water heater that serves as the storage tank. In a perverse way, this was instructive. We were able to measure how much heating energy is required without the extra efficiency of the heat pump. We called in a well-regarded heating contractor. Several months passed as the system was diagnosed and finally York agreed to provide a replacement compressor, while the local distributor paid the labor costs to install it. The work was finally completed in April 2006, two weeks before we shut the system down for the season. While the system is capable of mechanical cooling, we seldom use it. The new compressor performed well during the following heating season, and again we were optimistic.
	Another Compressor Fails The system stopped working again in November of 2007 due to a failed compressor. This time York agreed to replace the entire outdoor unit with a highly efficient member of the Affinity line. We paid our heating contractor for the labor. The work was completed in February of 2008. For the second time, the system was out of commission during the coldest part of the winter.
	Just a week later, this new unit stopped functioning during a moderate cold snap — the temperature dropped to the mid 20s. York's factory representative was in town to meet with a group of HVAC contractors who had been experiencing problems with air-to-water heat pump systems. He dropped by to take a look and declared that all was well.
	In December 2008, about six weeks after the system began operating for the season, the system began to cut out. The diagnostic code indicated high discharge line temperature. The York factory representative again visited the system along with local HVAC technicians. He suggested that the liquid line sensor be moved to a different location. That change has not prevented repeated cut outs, all showing the same high discharge line temperature code. Actually, it seems that the cut outs are more frequent now. All these problems have occurred within the York heat pump, so we have asked that York cover the materials and labor to fix it. Citing the warranty, which does not cover labor, York has offered only to supply replacement parts.
	We have decided not to invest any more of our own money in the York/Aqua Products system, and have started to research a replacement system. We might consider other reverse cycle chillers now available from Daikin and Unico. On the other hand, we may just install a gas-fired tankless water heater.
	— Bruce Sullivan