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Existing Heat Pump + New Wood Stove

nafterclifen

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Joined
Nov 22, 2014
Messages
525
Location
Poconos, PA
Looking for some advice/input for my home, not the garage. Hope this is OK. My small attached garage is already sufficiently heated (7,500 W electric) and cooled (12,000 BTU).

2.5 story Colonial home. Total sq ft = 2500 (1000 1st floor, 1000 2nd floor and 500 3rd floor). Existing heat pump is a York 4 ton, 10 SEER. Only one zone/thermostat on 1st floor. It's certainly less than ideal but we are not the original owners and this is the way we bought it. It works but not great.

Two issues...
1. Electric has become way too expensive to heat the entire house.
2. The 3rd floor is not sufficiently conditioned - it's always much warmer in the summer and much cooler in the winter.

I have a supply of wood but I don't have a fireplace. I am considering adding a free-standing wood stove on the 1st floor on an exterior wall. I suspect it'll heat the entire 1st floor but that's where the single zone thermostat is. So then the issue/concern becomes - how are the 2nd and 3rd floors going to react? Not even sure what is possible or feasible but in my head, I thought it would be good if there was a way to keep the existing 1st floor thermostat and add a 2nd thermostat to the 2nd floor. Only one of them could ever be active at a time. And with a flip of a switch, I could isolate the 1st floor but cutting off the supply vents with electric dampers so that the wood stove would be the only source of heat for the 1st floor. Then the heat pump would only have to supply the 2nd and 3rd floors which would be controlled by the newly installed thermostat on the 2nd floor. The hope is that this would fix the '3rd floor not sufficiently conditioned' issue since the heat pump now only has to condition 1500 sq ft instead of 2500. At any point should we choose to stop using the wood stove, we could simply flip that switch to open 1st floor supply vents, activate 1st floor thermostat and now we're back to the way we started - no wood stove and 2500 sq ft of space that the heat pump needs to condition.

Now after typing this all out, I'm starting to realize that adding a wood stove might only be a bandaid. Maybe the right move is a newer, more efficient, multi-zone HVAC system. The challenge with that is all 3 floors are finished and no attic. Only a crawlspace which is where the current utilities are (pressure tank for well, hot water heaters, air handler, etc).

Any/all input is appreciated as I'm looking increase my knowledge of options and possibilities before engaging any contractors. I will not be doing any of this work myself besides the electrical (if any needed).
 
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fitter30

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Jun 23, 2019
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2,986
Location
Peace Valley,mo
2.5 stories really needs three systems to do it right. Between first and second floors do any closets line up if so refrigerant lines and wiring could be brought up and possibly a space pak unit could be installed for the second floor. .5 floor a u shaped window unit for ac could find a heat pump in that configuration.
 

theoldwizard1

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Joined
Feb 22, 2011
Messages
43,216
Location
SE MI
Two issues...
1. Electric has become way too expensive to heat the entire house.
2. The 3rd floor is not sufficiently conditioned - it's always much warmer in the summer and much cooler in the winter.
Older central heat pumps frequently used a resistance strip to augment the heat output. This can be ridiculously expensive ! If you have this, it is time to upgrade that heat pump.

Mini-split for the 3rd floor. Improve you insulation.

Insurance companies hate wood stoves. Some will not even sell you insurance if you have one.
 

pvanderlugt

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Joined
Nov 14, 2010
Messages
334
A relative just finished a similar project, old house, no ducting/ac, but has radiant heat…. Ended up installing a couple of high end multi head mini split units… one each outside unit on each side of the house… nice install, took some time, but they were able to install everything with minimal disruption/visually to the house…. Units cool the house during the summer, and heat during the “in between “ season, untill the main boiler takes over in the winter…. Works great, able to set the temp in individual rooms…nice back up as well…….. pretty happy with all the results
 
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P0234

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Aug 6, 2012
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3,241
Location
NoVA
Its funny you are worried about the heat distribution. What you should be worried about is how much time you are going to spend feeding that stove!

I heat mostly with wood, though I do have a 20 SEER 5 Ton to fill in the gaps. I'm about 1.5x your SQ FT, but a lot further south. I'm on the edge of zone 3/4, I think you are 4 close to 5. Depending on the wood stove, you probably could heat the whole house most of the winter. I mostly run on a 50k BTU stove but I have one that will put out 100k when its super cold and I have to run two. The bitter cold days you will probably need the heat pump or another source of heat or wear sweaters. The key will be running the HVAC fan to distribute the heat.

Heating with would however is a labor of love and a love for frugality. I either pay to have someone take my wood away or use it for fuel. When it gets cold, keeping a wood stove going is a LOT OF WORK. For a pyromaniac like me, most of the time its fun. For 99% of the population, its going to be a drag. In Jan/Feb I'm using 3-4 ATV carts full of wood a week. I'm dumping 5 gallon buckets of ash every few weeks. Did I mention its a lot of work????
 

Jackfre

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Joined
Dec 26, 2010
Messages
4,411
Location
N CA
YOur current HP as OW pointed out, somewhere below 47* going full electric. The old single stage HP units cannot heat as heat pumps below that temp. The mini-splits you read about here and elsewhere are able to heat down to -20*. Adding the woodstove can help you when you are home, but as a primary source it takes a lot of time and effort. Are you willing to put that in? First step in any change is to analyze what you have. Start with the ductwork. Do not assume it is ok. Is it good and does it deliver the air it is supposed to the places you need it? Can it be saved and at what expense? Zoning is not cheap and throws the system inot fits, but as you are running straight electric at that point maybe it is a solution. Perhaps installing a gas furnace, LP or NG can work but then you have the AC issue. Can the HP provide that or do you need a conventional AC unit. Rather than the wood stove I would install a Rinnai EX38 in the first floor, again either LP or NG. It is not cheap but a simple install and reliable and efficient. Rather than a wholesale system change you can creep up on your final solution,
 
OP
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nafterclifen

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Joined
Nov 22, 2014
Messages
525
Location
Poconos, PA
You might ask a local HVAC contractor to visit the property and give you a proposal.
That will happen. Was hoping to educate myself just a bit before engaging them. Don't want to waste anyone's time.

Older central heat pumps frequently used a resistance strip to augment the heat output. This can be ridiculously expensive ! If you have this, it is time to upgrade that heat pump.
Yes, I have a two-stage 15kW heating element and when it gets down into the 20's and teens, it kicks on.

Its funny you are worried about the heat distribution. What you should be worried about is how much time you are going to spend feeding that stove!
Agreed, I know. I'm still relatively young and willing to do the work for at least 10 years.

Rather than the wood stove I would install a Rinnai EX38 in the first floor, again either LP or NG. It is not cheap but a simple install and reliable and efficient. Rather than a wholesale system change you can creep up on your final solution.
Thanks for the suggestion. Wasn't aware that such slim units existed. NG is not available but I could get LP. Have added this to my list to look into.
 

Highbeam

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Feb 15, 2011
Messages
2,292
Location
Mt Rainier foothills, WA
We heat 100% with wood and have for about 17 years at this house. It's not as hard as some make it seem. Key is having a good woodstove with a long burn time and of course good fuel. I added a minisplit last year to reduce our 9 month heating season down to maybe 6 or so plus the cooling is really nice.
 

pcmeiners

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Joined
Aug 13, 2009
Messages
7,934
Location
In the only town in Pennsylvania, Bloomsburg.

Heating Fuel Comparison Calculator


You need to change the fuel variables in the spreadsheet to today's value.

As an example I needed to change the electric cost to $.11, the HSPF to 13.8, the air source heat pump efficiency to 400% (this is the toughest variable to find). Mind you the 400%, and HSPF 13.8 are higher then normal as the units I have are high efficiency units.

"I'm dumping 5 gallon buckets of ash every few weeks. Did I mention its a lot of work????"

If you think 5 gallons is work, you should see how much a coal boiler produces. :thumbup:



 
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