Major advances in heat pump technology — Part 2

Part 2 of Mark Eatherton's in-depth study of heat pump technology

In last month’s column, we discussed some rough basic sizing and cost information. It should be noted that drilling costs fluctuate all over the board, and in some cases where the going gets tough, it may cost upwards of three to four times the cost that I projected last month.

The $10 per foot cost was based on “ideal” drilling conditions. I have had some jobs in the mountains where the drilling contractor would not guarantee a final cost, but instead would give a “range” and wanted an open-ended contract that would give him a significant out if he found himself drilling in solid rock conditions. I understand their reluctancyto want to give a fixed price per foot when they may not know the actual drilling conditions, but this makes it tough to have a solid, closed-ended contract with the consumer, and with budgets being as tight as they are today, it can be a deal buster in some cases.

Enter foreign agents

The Chinese and the Japanese have refrigerant based heat pump products with a proven track record for operating in the harsh environments of Northern Europe that are making their way into this country. These products are air based, and not ground-source based, which will significantly lower the installed cost of heat pump based systems. And these countries have taken the conventional concept of refrigeration to levels that I never thought would be attainable.

For example, one compressor with a reversible evaporator/condenser package to handle numerous remote reversible evaporator/condenser packages whereby the first remote unit in the series is doing heating, and the balance of the remote units are providing cooling, or vice versa. These first units were essentially air-to-air heat pumps, but the technology has now moved into the air-to-water market.

All of these foreign refrigerant packages are utilizing something that I have been asking for from American heat pump manufacturers, that being variable speed, soft start compressors, for what seems like forever. Finally, the ability to perform high-efficiency heat pump operation on a modulating basis. This change in compressor technology is known as inverter technology.

Inverter technology is nothing new to motor technology, it would just appear that these folks got smart and applied it to refrigerant technology. This change in technology represents numerous advantages as it pertains to overall efficiency gains and increases in equipment life expectancies. In the efficiency department, the heat pumps at their peak have COPs approaching five to one, with the ability to efficiently extract heat from cold air down to 5ºF before having to switch their compressors off and resort to an alternative energy source.

Here in Denver, that means that the heat pump would be the primary heat source for approximately 98% of the time during the heating season. The current systems are capable of providing water temperatures in the 120ºF range, which makes them very compatible to large surface radiant heating systems (floors, walls and ceilings) and can also be incorporated into some large surface area fan coil units. In addition to performing space heating needs, these wonderful new appliances are also capable of providing domestic hot water pre-heat. The compressors are so advanced, that the Air-Conditioning, Heating, and Refrigeration Institute’s standards are having a tough time catching up to them, but that will hopefully be resolved in the near future.

One of these manufacturers also has a “cascade” system that will generate water temperatures as high as 176ºF, making them a viable alternative for boiler replacement in high temperature systems typical to the North American market.

This high temperature technology is currently limited to the European market, but I would think that they will be bringing this technology to the North American market in the near future.

So, in a nut shell, the landscape is quickly changing as it pertains to heat pump technology. One of these manufacturers has answered my prayers and is coming out with a ground-source heat pump version with the inverter technology intact. The advantage of this is that it can also be used for doing waste heat recovery, as well as conventional ground-source applications.

The two companies referenced in this article are Daikin Altherma and Mitsubishi Industries. Watch for them coming to a wholesaler near you.

Tune in next month as we look at the color of heat. Until then, happy ultra high-efficiency hydronicing!

Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303-936-7606.

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TAGS: Hydronics