# Backfit Air Source Heat Pump - Where to Begin?



## velvetfoot (May 1, 2012)

How would I begin to look to into this?  My house is 2000 ft2 6 year old colonial in zone 4B (I think) with just baseboard oil heat.
I hear a lot about mini splits, but don't know anything about them.  I like the area heating/cooling concept.
Ball park?  I guess I could talk to a heating outfit and get an estimate as well.
Thanks.


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## semipro (May 1, 2012)

Based on what I've read here and elsewhere you should really consider mini-splits. 
We have central HVAC but if I was building new I'd probably go with mini-splits. 
Mini-splits installations are zoned by nature, require no duct work (a big retrofit expense) only running power and refrigerant lines, and some are very efficient, operating well at low temps. 
You could even maintain your oil-baseboard setup as backup for extreme cold events and avoid having to install resistive elements in the mini-split system.


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## velvetfoot (May 1, 2012)

I've begun to look at the mini splits and they look promising.


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## begreen (May 1, 2012)

Cost will depend on the number of area you want to heat/cool and how one chooses to do this. (ie 2 single head splits, 2 dual head splits, 1 - 3 head split with a bigger compressor, etc.). Try to stick with the best brands like Mitsubishi, Daikin, Fujitsu, Sanyo.


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## woodgeek (May 2, 2012)

The minisplits will be a lot cheaper than oil to run, even down to low temps.  If you are trying to compute costs per BTU, remember that the cost per BTU is that for electric resistance heat divided by the SCOP, and that SCOP = HSPF/3.4.  The HSPF listed for the units is confusing....the figure depends on your climate and the listed value is for a place like Atlanta.  You should assume your HSPF would be 25-30% less than the one listed.


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## maverick06 (Aug 20, 2012)

This thread may be OBE at this point, but i will revive it as its worth it.

I had to replace my AC unit (single unit in the house and was able to put in a heat pump). The majority of my heat is derived from my insert, but the thermostat is used. The heat pump is AMAZING. The costs compared to oil are astronomical. For me the details of the unit were simple, I just replace the centeral AC. If you are doing a full install, a dual unit might be better, depending on how you use your house.

You are in NY, not much north of Philly. Its been one of the best financial decisions I have made (next to the wood stove).... between the two i am saving about $2-3k per year, at no degredation in my quality of life (I maintain that its been increased). AND the dollars are going to US fuel sources (coal/nuclear/wood), not someone in the mid east.


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## woodgeek (Aug 20, 2012)

Just to confuse the issue....they DO make minisplits that run into ducts with multiple 'heads'. So, if your space was divided up, you could have one split heat three rooms on one end of the house, and another to do three rooms on the other end. If you don't want the air handler hanging on the wall, they make units that fit in the ceiling joist cavity between two finished floors. Lastly, the makers of traditional split systems (that resemble slightly upsized central AC units) have started to adopt some COP-enhancing features such as variable speed compressors and smarter defrost controls. One such line I believe is called 'Greenspeed'.

When I retrofitted a 2300 sq ft 1960s, oil-hydronic house in 2008, I went for a single, cheapo dumb ASHP, about $5k for the hardware and $5k for the retrofit ducting in my attic + install. I figured/hoped it would last 10 years, and I would get a much more eff unit then. Four years in, HPs have evolved nicely. MY cheapo 4 ton Goodman gets maybe COP ~ 2.1 at January average temp: 30°F. Tweaking the defrost controller myself, I got the COP up to ~2.5. Minisplits/Greenspeed **might** do 20-30% better? Right now my winter heating bill is ~$1200, vs $2000/yr for oil.  The higher eff units might save me another $250/year...not going to lose any sleep over it given they are a lot more expensive.

FYI, my unit really struggled when I put it in, and now it sings cuz I airsealed the place and dropped the BTU demand >25%. Before the airsealing, I used the oil boiler as a second stage, afterwards, I was able to disconnect it. Obviously, dropping your demand before you install a new heater is a no-brainer.

So, price out minisplits and high end and low end central units, and make a call.


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## velvetfoot (Aug 20, 2012)

I can't see retrofitting traditional ductwork.
It would be really nice to get off oil though.
An acquaintence is in the process of put up some pylons with solar pv panels, solar hot water, several mini splits, propane boiler backup.  I'm going to go over and check it out when he's finished.


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## woodgeek (Aug 20, 2012)

Every situation is different.  With the minisplits, a lot of the problems/solutions with heat circulation will be familiar to wood burners.  Except you also need to circulate coolth in the summer.  Some folks put 'em on the first floor and in the winter they have heat there and upstairs.  But in the summer, the downstairs is cool, and the upstairs isn't.

Also...it would be great if you knew your BTU/h load at a typical January low temp.


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## Highbeam (Aug 27, 2012)

Wouldn't it be great if they all could use the minisplit technology to heat domestic water or even hydronic systems. There is only one off-brand that has a model that can do it. No mainstream companies that I have found.


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## begreen (Aug 27, 2012)

Funny you should bring that up. I was just reading about them. Robur makes units for the European market.
http://www.robur.com/products/pro-solutions/pro-gahp-line-ws-series/description.htmlhttp://www.robur.com/products/pro-solutions/

As for domestic hot water, this is what the Geyser system does. There are a few threads on this unit in the Green room.
http://www.nyle.com/water-heating/geyser-r/


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## Highbeam (Aug 29, 2012)

begreen said:


> Funny you should bring that up. I was just reading about them. Robur makes units for the European market.
> http://www.robur.com/products/pro-solutions/pro-gahp-line-ws-series/description.htmlhttp://www.robur.com/products/pro-solutions/
> 
> As for domestic hot water, this is what the Geyser system does. There are a few threads on this unit in the Green room.
> http://www.nyle.com/water-heating/geyser-r/


 
No, I mean the actual split design with an outside unit making full btus at 10 degrees quietly and then a silent inside unit either part of or inside the storage tank. It coulod look and act just like these minisplit heat pumps. I don't want some noisy thing in my residence dumping cold air into the home as is the case with current HeatPumpWaterHeaters.

I also have an infloor radiant system to heat 1800 feet of concrete slab and with cheap electricity, a heat pump boiler could be a great option.


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## begreen (Aug 29, 2012)

From what I can tell, the Robur units are like the mini-splits with the compressor outside.


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