Switching to a Heat Pump

[Zaphod]

Hi Folks,

I live in lower Michigan about 30 miles norht of Indiana. My niece's husband who does heating and cooling has talked me into switching to an air transfer heat pump with electric back up. I currently have an oil furnace and Iive in an old two story farm house that has about 1,500 sq ft.

I have been thinking of an idea and have not yet discussed it with my nephew and I thought I would post it here and see if I get any comments.

I was wondering if the outside unit of an Air Transfer type heat pump could be put in a small greenhouse during the winter so the air around it would be warmer during the day?

Or maybe even put the outside unit in a small enclosure and run vents from the house to it so that when the heat pump is warming or cooling the house it would also be warming or cooling the air around the outside unit?

Would this even help at all in keeping the electric use down?

Thanks, David

[dadiOH]

No. When heating, the air around the compressor is cold, not warm. Vice versa when cooling.

[Jeff]

No in the winter the heat pump would quickly cool the greenhouse lower than outside temperatures. Spend extra money on a more efficient heat pump and beef up house insulation or really big bucks and upgrade windows.

[JimL]

The geothermals are more efficient but more expensive and designed to benefit from the heat in the earth. That's the way you should go if you have the room and installation cost.

My estimate is that your idea would save a little on your electric bill when the outside temp is below 40 degrees, but not nearly a much as you might think. Maybe 3 or 4 percent for the winter.

But then what are you going to do in the summer when the green house is hot?

[Pete C.]

Recommend ground source (aka geothermal) heat pump over air type. Vertical or horizontal loop as your lot permits. Ground source is more efficient due to stable ground temperatures vs. variable air temperature. They are also don't have a somewhat noisy outdoor condenser unit.

Pete C.

[Roy Starrin]

I live in VA. In the winter, when the temp gets below 35 (my arbitrary number) I turn off my 16i heat pump and turn on my oil fired hot water baseboard system, and vice versa. You can get automatic controls that will do this, but mine is a manual evolution. If the day is going to warm, I frequently start with oil and shift to HP. I turn all off at night. I burned 60 gallons of oil from October to February.

[trader4]

I'd do a lot of research before I converted to a heat pump, air based, system in Michigan. I seriously doubt it's a sound idea in that climate, but a heat pump/geo thermal system may be an alternative.

[Mark]

Agreed, or visit someone in your area with heat pump.... they work well in Phoenix, but maybe not so well in Michigan.

Mark

[udarrell]

In lower Michigan, what type of heat source are you using now, NG, propane, or fuel oil? The air source heatpump would only be useful during the seasonal changes. Geothermal will be costly upfront.

You will save the most money with a one-time cost by doing everything you can to reduce the heat-gain heat-loss of your home. That includes reducing air infiltration!

Try to get a scroll compressor and a TXV refrigerant control on the evaporator. Don't go any high than 13 or 14-SEER as there will be no payback in your climate. Get the high efficiency on the heating side of the equation. Read all the info you can!

- udarrell - Darrell

[Chris Lewis]

According to :

A air source heat pump will work reasonably well in Michigan climates, but _not_ with electric backup. Gas backup would work much better.