heat pumps

[snowstorm]

anybody install them? know about them? i have met with 3 dealers none of them agree on the size of the compressor or head units. 1 wants to use 2 9k heads the other 2 17k with a 24k compressor and the third wants a 24k and a 12k with a 36k compressor. i am thinking the last one?

[Crusarius]

all I know is oversizing the system will cause it to be inefficient. You do not want an oversize system that is constantly cycling.

[Southside]

You are in the Etna area right?  I would be really leery of the operating cost there.  My in-laws have one in eastern Oregon and the winters are similar - electricity is dirt cheap there compared to Maine - and the thing costs them dearly every winter, the auxiliary heating element comes on a lot when it gets cold out and they have a monitor heater to supplement it, all in a 2500 square foot house.  Their unit is only about 3 years old.  

[samandothers]

Can you explain the lingo. Are heads air handlers?  Is the 17 k a strip heat?  I assume the compressor is the exterior unit.

[samandothers]

We have a 2 and a 3 ton units with electric back up. Just replaced one after 25 years.  They are comfortable in our moderate climate. 
We plan LP back up in the mountains. Too many power outages.

[snowstorm]

i dont expect it to heat well in real cold. maybe help some it should work ok in the fall and spring and keep it cool in summer. so far the 3 installers i have talked to all had different ideas on what to use 

[DelawhereJoe]

Around here most people I know that have heat pumps spend $350-$500 per month to heat there home in the winter, the most being $800. I have seen the outside units encased in a block of ice, I personally wouldn't waste my time or money trying to heat my home with just a heat pump. I currently use LP supplemented with wood, first year I used 200 gal of LP with cooking too. For the past 3 or 4 years I've used about 350-400 gal, as we were trying to find out if our youngest was have  respiratory problems from the wood or smoke.

[00frick]

I didn't know that heat pumps were marketed in Maine. They are (were) not designed to operate at your temperature zone. Maybe they are now. They are normally sold Virginia - south. They are a "temperature maintainer" (with in there range) and work very well and efficiently in that range of operation if installed properly. "Temperature maintainer" is just a description term and does not, by any means, describe how they work.      

[snowstorm]

there is a lot of them up here. and the state is offering a 750 rebate for putting it in

[lxskllr]

Hmm... I'd pay $750 to *not* have one. Maybe they're better now, but my experience in mildish MD hasn't been positive.

[DelawhereJoe]

The state probably gets some sweet government kickbacks for reducing its emissions, no burning anything with a heatpump, just using electricity.

[Ianab]

Heat pumps loose efficiency badly as the temperature gets below freezing, and eventually they basically stop working (outside unit ices up etc). Then they have to fall back on straight electric heat. 

They are popular here in NZ as it seldom gets much below freezing in most areas, but you still need some winter heating.

Isn't "geothermal" heating more practical / popular in colder climates? Then the "outside" coils are buried deep in the ground and collect warmth from there. Works the same way, just you are pumping heat from under the back lawn (which isn't frozen 4ft down), rather than from the outside air, which is way too cold. 

[Larry]

Most HVAC contractors size the equipment based on their experience, which may be good or not so good or even really bad.

Manual J is the proper way to size equipment based on science, not guess work.  I would insist on the contractor doing it this way if their was any doubt.  I did a quick google and copied this.

"The correct way to size an air conditioning system is with Manual J, a protocol developed by the Air Conditioning Contractors of America (ACCA). Manual J HVAC load calculations determine how much heating and cooling a house actually needs."

Having said that, my HVAC contractor sized my heat pump based on his experience.  My house is a big box making it easy to get the right unit.

I've had heat pumps for 30 years now.  They get better every year.  My present unit does pretty good down to 25 degrees.  B-I-L has been using a ground source heat pump for 15 years.  Probably the best solution if you plan to stay in the house for 15 or more years.

[YellowHammer]

36K BTU is a 3 ton unit.  Although both electric heat strips and gas or oil heat have a flat efficiency curve irregardless of outside temperature, heat pumps have an efficiency curve that gets higher as the outside temps get more moderate and they loose efficiency when the air temp get below freezing. So the colder it is outside or the colder the air over the coils, the less efficient the unit, to point where it must be augmented with electric or other auxiliary heat.  There are some other new technologies, but I don't have personal experience with them. Some units are hybrids which can use electric or gas auxiliary heat, which have an excellent SEER rating in summers and HSPF (Heating Season Perfomance Factor) in winter.  One thing which is common, is in order to avoid the block of ice scenario, heat pumps have sequencers which will reverse the heat cycle and actually run the air conditioner for 15 minutes of every hour in a defrost cycle, which causes the outside coils to heat up, in the winter time.  During that time, the auxiliary heat kicks in to maintain a warm temperature while the outside coils are heated up to melt any ice.  The newer hybrid heat pump units will use the heat pump cycle until it loses efficiency when the outside air temp gets too low, then switches to gas.  Supposedly the best of both worlds.  
In the south here, heat pumps are king but I believe they fall out of favor about north of Kentucky or so.  I'm surprised anyone would propose such a system way up north, unless it was a hybrid unit using gas or oil auxiliary heat instead of electric strips, or using geothermal coils.  

[Hilltop366]

Lot of them around here, people seem to like them, I figure they would be ok for the shoulder seasons and for some ac and dehumidification in the summer. 

Technically a backup heating system is required here but some have used them as replacement system when their oil boilers life ended, so two winters ago I walked into the local hardware store right after a week long cold snap and the guy working there say we got anything you want unless you want heater fans or plumbing fittings, I said huh? he said heat pumps :.

 

[Al_Smith]

I've got a "water furnace " 5 ton geothermal unit that does really well considering .During the winter it seldom uses more than 300 dollars worth of electricity ,well fed not a loop system . This unit was installed by myself in 2008 but I had to replace the compressor due to my own fault from failing to remember I had installed two sets of air filters and the inside set clogged blocking the air flow .Live and learn they say .

With a geo the outside air temp doesn't matter because it's pumping 53 degree water not zero degree air .

During periods of high humidity during cooling  I run the fan on medium speed because it gives a longer run time which in turn dehumidifies the air more .

I've added extra safety devices to the original design for try to save from a fault that could harm the system .One being an adjustable thermostat on  the discharge water ,a freeze stat on heating and a high temp setting on cooling .A three minute timer  on the discharge water after a cooling or heating cycle to make sure the head pressure on the compressor drops off .A magnehelic differential pressure gauge to make sure I know the condition of the filters .

I will install a high temp shut down in the discharge air with the top limit of around 95 degrees because anything much above 90 idicates a blocked air flow .Haven't got around to it yet but I have the components .---more ---

[Al_Smith]

In addition to the geothermal the house has radiant ceiling heat ,cheaper than base board but still expensive .Being retired now I doubt I have high power bills because my insert wood burner heats the house well and now I have the time to keep the fire fed .However I don't even bother with it until the mercury drops into the 20's .Which that could be in December .

[Larry]

When I bought my first heat pump 30 years ago, an option was propane backup instead of electric strips.  It worked great.  In 18 years the only repairs were two contactors for the compressor.