Woodstove backups, Heat Pumps?

velvetfoot said:

Alas, I have a two story house.

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I have a two story as well, but had two systems installed. One in my upstairs attic and one in my unfinished basement. There was existing duct work in the attic from the AC that I had, though we had it replaced since the cost wasn't high.

That way stuff is not in the attic, which is good.

velvetfoot said:

That way stuff is not in the attic, which is good.

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My attics a spray foamed so no big deal to have ducts and equipment up there.

begreen said:

I have a 2 story old farm house too. Instead of trying to duct heat to all 4 rooms upstairs I ran only 2 ducts. One up the wall cavity to the hallway and one up in corner of a bathroom closet to the master bedroom. This has worked out pretty well. The other bedrooms and bathroom get enough heat via convection from the large open staircase. The heat pump covers us to around 24F and then switches to resistance electric. But when it is that cold (not too often) we have the wood stove carrying the load 24/7.

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Unfortunately for us Puget sounders, when it gets down into the 20s we are often banned from burning due to air pollution.

Geothermal is great under many conditions but not all. As stated, if you are retrofitting a house without ductwork it can be a big problem in cost and in the ability to get ducts where they need to go at all. I did install ductwork in my home after the fact and it was much higher than a few grand. The cost of well drilling is variable, depending upon what is in the earth under you. Drilling through solid rock can be prohibitively expensive compared to sand and gravel. Also, geothermal works best (pretty well mandatory) to have a great deal of ground water to move temparate water onto your underground pipes. Not all areas have enough water within a reasonable distance to the surface, although it can easily work with sour water as easily as sweet water, since you are using the energy, not the water itself.
The cheapest way to do it is if you have a large pond on your property. They can run the piping at the bottom of your pond and you eliminate the huge expense of drilling. I've got a 12 acre swamp right beside me but it is a restricted wetland zone. Never fool with environmentalists who work for the gov't.

DougA said:

Geothermal is great under many conditions but not all. ....

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There is a good discussion on the relative merits of air vs ground heat pumps at green building advisors:

http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/air-source-or-ground-source-heat-pump

and here

http://www.greenbuildingadvisor.com...e-affordable-ground-source-heat-pumps-horizon


The new ASHP are as efficient as the GSHP under many conditions ( often the GSHP number do not factor in the energy to pump and circulate the water because " the new ISO standard eliminated all pumping energy from COP calculations" ) , and a lot less costly ( you don't have to drill a well for the heat exchanger)

My GSHP was around the same cost ( plus or minus 1k ) as if I were to have installed an ASHP with a propane furnace after the 30% rebate. The problem that I have with a lot of these articles is that they do not take the cost of cooling into affect. They only talk about heating. A GSHP is a lot cheaper to cool with than ASHP.

My GHSP cools 2100 sqft for less money that it took a 10 SEER AC unit to cool 1400sqft. While the AC is running I am also making free hot water.

sloeffle said:

....

My GHSP cools 2100 sqft for less money that it took a 10 SEER AC unit to cool 1400sqft. While the AC is running I am also making free hot water....

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Do you have a SEER for your GSHP?

FWIIW, my 12krls2 Fujitsu mini-split ASHP has a SEER of 25 (the 9000 btu/hr go to 27) . The new ASHPs with the variable speed DC condensors are very efficient .The higher the number the better the uinit

The Fujitsu site shows the SEER dropping from 27 to 21 as the unit size increases from 9k to 14.5 k BTU/hr. You can install multiple small units to keep both the SEER and capacity high

http://www.fujitsugeneral.com/wallmountedRLS2_specs.htm

There are 3 numbers to use when evaluating a heat pump that can cool ( SEER) and heat (HSPF) and both (EER).

DougA said:

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The cheapest way to do it is if you have a large pond on your property. They can run the piping at the bottom of your pond and you eliminate the huge expense of drilling.

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that may be cheapest in the short term. It also means there is limited things you can do to the pond after the geo is installed in it. No machinery in the pond, no digging, ect. The pond must be able to maintain the temp needed also (read deep enough)

The best we found is trenches with loops installed. I do not like the idea of wasting so much water to heat and cool with as in drilling a well for it. The ground trenches require nothing once installed and do not restrict the use of the ground above the loops.

Still not clear at what BTU point these mini splits go from requiring 240v vs. 120v. Or if it varies by mfr. (1st had assumed that they were all requiring 240v, then noticed some 1 ton (12000 BTU) units were only 120v. (it's an issue for me since the main box is close to being tapped out).

Dave A. said:

Still not clear at what BTU point these mini splits go from requiring 240v vs. 120v. Or if it varies by mfr. (1st had assumed that they were all requiring 240v, then noticed some 1 ton (12000 BTU) units were only 120v. (it's an issue for me since the main box is close to being tapped out).

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Probably varies by manufacturer.. even the 3/4 ton fujitsu (9 k btu/hr) units require 240 v

georgepds said:

Do you have a SEER for your GSHP?.

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According to the Waterfurnace web site the EER is 30 and the COP is 4.8.

http://www.waterfurnace.com/products.aspx?prd=500A11

The green building article does make some good points about finding the correct installer. They all do it their own way and you need to wade through the BS to find the correct person. One installer wanted to put 600' of pipe in the ground. My current system has 2400'.

I guess the point I am trying to make is that the informed consumer needs to pick the best solution for their problem. In my situation I would need probably 5 mini splits on my house due to the layout. It is a ranch with lots of small rooms. IMHO this does not make sense even if they give me the most bang for my dollar. If I lived in a house with a open floor plan then it probably makes more sense.

I was against getting GSHP at first due to the up front cost. Then I started comparing numbers and it won. But if I had to drill wells or dig a pond an ASHP with propane backup would of won.

We had an LG mini split AC/Heat Pump system (LMU369HV) installed this past November. It's rated at a heating capacity of 41,000 BTU @ 47° F but that drops down to 26,000 BTU @ 17°F. There are three, 12,000 btu heads for it, two in the main living area on the main floor, and one in the finished portion of our basement, where my office is located. So far, it's done a great job of providing the only heat in the basement (other than the heat that comes off the oil burner itself), as well as providing much of the heat we need on the main floor and in the two bedrooms situated in a loft above the living/dining room. I really like the system - it heats the whole space evenly and it's whisper quiet. Even the outdoor unit is pretty quiet - you can't hear it at all from anywhere inside the house unless you open the doors or windows. I'm sitting about 20 feet away from the outside unit right now - it's on the other side of the concrete foundation wall - at about eye level with me sitting down - and I can't hear it.
We do use the oil burner when the temp gets down into the twenties and below - first: because the overall efficiency for the mini split system falls off and second: because I don't want the pipes from the oil burner to the upstairs radiators freezing overnight - they're enclosed in the exterior wall on the north side of the house.
I'm sure it will take some time to recoup the cost of having this system installed, but so far it's saved us quite a bit - I'd say we're at about half of what we spent to heat the house with oil last winter at this same point - and back then we hadn't even moved in then so we had the temp set at 62°.
I can't wait to see how well it cools the house come summertime - last summer we had moved in - and it was wicked hot and humid in the house. One morning I went to take a shower and there actually were mushrooms growing from a gap in the vinyl floor in the downstairs bathroom. We can't install window AC units because all the windows are crank out casements - we really suffered.

DougA said:

The cheapest way to do it is if you have a large pond on your property. They can run the piping at the bottom of your pond and you eliminate the huge expense of drilling.

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What about a covered-over swimming pool? Ours hasn't seen much use in the last decade--took too much effort to keep clean and repaint. Now that it needs a new filter pump and the waterline tiling redone, I was thinking it might be better to fill it in anyway. But it's retained water well for all these years, and is situated close to our current water heater and ASHP. I have a feeling a 9-ft (on the deep end) residential pool wouldn't cover the needs of a 2,400 sq. ft house, but it might cut down on the trenching enough to make geothermal worthwhile.

begreen said:

We've had our American Standard central heatpump system for 8 years now. It has a very high efficiency dual-stage compressor and a dc-motor variable speed air handler. The system works well from about 23F on up. It has a large electrical coil system in it for backup but we've only used that once when returning from vacation in the winter and I wanted to warm the house up from 55F quickly. The heatpump is used exclusively when outdoor temps get above 45-50F. It is always on and sometimes comes on if I am slow on reloading the stove. The cost of running the unit is small, almost laughably so as compared to when we were heating with propane and wood.

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Our power is cheap, under 10 cents per kwh, and our climate is mild. We in the PNW are prime candidates for heat pump heating. I just have had too many friends, relatives, and coworkers need to replace their heat pump systems with 5-7 years of use at a cost of nearly 10k$ for the replacement. If they were more dependable and/or cheaper I would expect to see more of them.

There are a lot of bad HVAC techs out there, as well as ones that will sabotage existing systems when business gets slow to get the replacement business. Stats have shown that folks that get annual 'checkups' on their heat pumps get a shorter equipment service life than those that don't.

They are essentially zero maintenance units (unlike oil burners that are now up to >$200/year), change the air filters regularly, and keep the outdoor unit clear of leaves and debris...done. I'm at 8 years and counting with a 'cheapo' 'builder-grade' 4-ton Goodman. I budgeted 10 years for my ROI calcs, might get 15, who knows? I'm running it hard...>2000 hours of compressor runtime per year.

Have a buddy who just had his gas furnace and AC 'check-up'. He leaves the tech alone while he is working, there is an enormous 'clang' noise, and he runs back. The tech says "Your heat exchanger is cracked, you need to buy a new furnace, or replace the exchanger [for 70% of the price of a new furnace]"!! What do you think that noise was?

Good to see I am not the only one running Goodman units, mine have held good so far for the past 5 years. I have have two 1 ton units, one in crawlspace and one in the attic each heating/cooling 600 sq feet, well the upstairs gets run more in the winter as the wood insert is only good upstairs till we get into the lower 30's with no wind (no insulation in my walls).

I was actually thinking about having the tech come by and service it but I think I will hold off, it is running good.

I used to pay Honeywell building services to maintain industrial AC equipment. We paid for uptime not for service so they only did the service that was needed to keep the equipment running reliably. On air cooled units they replaced the filters and checked the belts. On an infrequent basis they checked the temps out. That was about it. On water cooled units, they acid cleaned the coils yearly and changed the filters. These units were in nasty conditions (paper and pulpmill with corrosive atmosphere).

One big caveat is to make sure that the power feed to the unit is good. Run adequate sized conductors so that there isn't voltage drops.

Well, my streak came to an end on Mondays cold snap. Turned on the downstairs Goodman heat pump Sunday night for the first time this year and came down Monday morning to find the emergency heat was stuck on and the downstairs was 76 degrees, only way to get it to shut off was flipping the breaker. Called my friend who installed it and it turns out the heat sequencer went up and also took out my blower control, looking at $200 max in parts and labor. Apparently this is a common issue for Goodman units.

Just an FYI, if you ever find you can't shut the system off via the thermostat and the Emergency heat is stuck on more than likely it is the sequencer, the blower will always run if the emergency heat is on so it won't melt down the heat coils.

We installed an air source heat pump when we bought and renovated the house we are living in, problem is we also installed the wood stove at the same time, so I have yet to really put our heat pump to the test in the cold of winter since we pretty much heat exclusively with wood. In the meantime the heat pump functions as an awesome central air conditioning system in the summer time when we think that we "NEED" cooling.