Starting to see heat pumps here. Any advise on pro's/cons?

Originally Posted By: kshepard
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This is the second time in two days I’ve been asked about Geothermal heat pumps. I’ve never run into one and don’t know much about them except for all the great things people who sell them say about them.


How well do they last? Are they inexpensive to operate? Any particular problems to be aware of?

Kent


Originally Posted By: lewens
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Think of them as a hot water heating system without the boiler and that is just about it. They are very inexpensive to operate. The only thing you are paying for is the electricity for the pump. Properly maintained, like everything else, they will last a long time.


Larry


Originally Posted By: ecrofutt
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The most noticeable differences for the homeowner are the cost and the temperature of the supply air.


Heat pumps supply air is typically 90-100 degrees and may feel "cold" if they are used to forced air furnaces. Plenty warm enough to heat the house, but not warm enough to give you that "ooooooh" feeling when you stand over the vent.


--
Erby Crofutt
B4U Close Home Inspections
Georgetown, Kentucky

www.b4uclose.com

Originally Posted By: phinsperger
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ecrofutt wrote:
The most noticeable differences for the homeowner are the cost and the temperature of the supply air.

Heat pumps supply air is typically 90-100 degrees and may feel "cold" if they are used to forced air furnaces. Plenty warm enough to heat the house, but not warm enough to give you that "ooooooh" feeling when you stand over the vent.


As Erby said the lower delta-T coming from a forced air system with a heat pump is probably the number one complaint. The air coming out can even feel cooler than the room air even when its not. So its imporat not to blast it out like a regular system. Better to run it longer at a slower velocity both for comfort reasons and for the efficiency of the heat pump. People who are used to a fossil-fuel fired system tend to get be disappointed until they see how much they are saving.

If the system was designed as an open loop system with a weep tile bed, there can more problems (Well run dry, freezing of tile bed, etc) that make them less reliable than a closed loop system. The open loop systems are less costly (for an allready very costly system) to install and that is why many people opt to install them.

Here is a great brand-neutral publication that will go into more detail

( Download File: HEATING_AND_COOLING_WITH_A_HEAT_PUMP_booklet.pdf )


Originally Posted By: jhagarty
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http://www.nachi.org/bbsystem/viewtopic.php?p=103060&highlight=geothermal#103060


Originally Posted By: dandersen
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One of the greatest differences in geothermal versus conventional heat pumps is that you are absorbing heat from groundwater (or other source of water) which is generally much warmer than the outdoor air. The more heat you need in the wintertime to heat the house, the less there is any care to absorb. Groundwater remains the same temperature for the most part throughout the year. It is easier to absorb heat from 54? water then 17? air. Also holds true for air conditioning. You’re trying to reject heat to 95? outdoor air versus cooling the condenser with 54? water.


Another obvious bonus is that a defrost cycle is not necessary to clear ice from the outdoor coil every 45 minutes. When a heat pump goes into defrost, the electric resistance heat comes on and the heat pump goes into air-conditioning!

Geothermal requires no auxiliary heat during normal operations or for defrost cycles.

Just before a conventional heat pump goes into defrost, the outdoor coil is generally restricted and is not absorbing very much heat (that's why it must go into defrost). The air being discharged during these conditions is cooler than normal. Also, under this condition there is a two-stage thermostat that operates both the heat pump refrigeration circuit and the auxiliary heat. Under extreme cold conditions, the auxiliary heat brings the house temperature up to set point and shuts off. The refrigeration circuit continues to run, blowing cooler air until the artillery heat turns back on.

Geothermal units are much more expensive initially, but are much cheaper to run. Water source is often a big problem and requires specialized maintenance. Restricted water flow causes the unit to cycle off on high pressure controls, and you have no backup heat. Circulating pumps are also a maintenance requirement and are much more expensive than fans to replace.


Originally Posted By: kshepard
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That did it, thanks guys.


Kent


Originally Posted By: dbowers
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Call the dealers to find out who the distributor is and then call them because they periodically have service classes for installers or techs. Sign up for 1 - very beneficial and usually only a 1/2 to 1 day session.