Solar Water Heater to heat vented crawl space....any thoughts?

[BucksCoBernie]

I moved into my house in April 2008 so last winter was the first winter in the house. We have a forced hot air oil burner as the primary heat (this winter we plan to burn 24/7, still have to install the insert I picked up). Most of the house is built over a basement except to 2 bedrooms in the back, the master and the 2nd bedroom, they are built over a vented crawl space. It got really freaking cold in those bedrooms last winter....like 55-60 degrees at night because the previous owner never insulated between the floor joist, they just put in carpeting and i guess that was enough to kinda keep the room semi-warm. we ripped up the carpets to get to the hardwood flooring. I insulated the crawl space in like Jan. of last year with fiberglass rolls, it made a difference but it was still chilly back there.

My idea now is to heat the space with a water/anti-freeze mixture heated by a solar unit that will sit on the roof. I dont want to heat the flooring (dont want to have to rip the insulation out and drill holes for the tubes), i just want to lay the tubes on the crawl space floor to raise the air temp in the crawl space to a somewhat comfortable degree.

the crawl space is probably around 400sqft.

do you think it would work?

 

[peakbagger]

Much as I am a solar advocate (I have PV and SHW) its not a great application for solar space heating. Compared to the up front cost for an installed SHW system, you would be better off trying to rig up a glycol coil off your wood stove somehow and buy the extra wood. The major issue is that you would need to size the SHW system for maximum load when there is the least sun plus figure out a way for storage when the sun doesnt shine.

Anything is possible but not neccessarilly economically feasible.

 

[SolarAndWood]

I built 1000 sq ft of solar south facing roof and did the analysis on space heating with the solar guys. It wouldn't even put a dent in it. I think you are probably better off heating your dhw with solar and using space heaters in the bedrooms even if they are electric.

 

[Wet1]

I agree with the others, but if you are going to do it... Don't lay the tubes on the floor of the crawlspace, put them in up with the joist where they belong.

 

[smokinj]

I heat my crawl space with a loop off the wood furance thinking about looping in the solor as well but your going to need anoter source of power than just solar

 

[BucksCoBernie]

Thanks for the responses. Well hopefully the Regency will provide enough heat so the back bedrooms are comfortable, we have a 2000sqft rancher with the master bedroom being the furthest away from the fireplace and insert. If not we do have a small electric space heater. I guess ill find out in a few more months lol.

 

[SolarAndWood]

we have a 2000sqft rancher with the master bedroom being the furthest away from the fireplace and insert.

I have a similar setup/challenge. A fan on the floor in the doorway to the bedroom blowing cold air towards the stove makes a big difference. It is much more effective than trying to blow the hot air with a fan on a pedestal towards the bedroom.

 

[Gooserider]

What did you do to air-seal the floor after putting in the fiberglass? It is worth noting that FG is not real good at draft stopping, and neither is plain poly as it still allows convective flows. I would consider covering the bottoms of the joists with taped and sealed foam board, 1" would probably be enough, 2" would be better. That will greatly increase your air sealing, and prevent thermal bridging via the joists... Might give you an even bigger boost than the fiberglass did.

Gooserider

 

[BucksCoBernie]

What did you do to air-seal the floor after putting in the fiberglass? It is worth noting that FG is not real good at draft stopping, and neither is plain poly as it still allows convective flows. I would consider covering the bottoms of the joists with taped and sealed foam board, 1" would probably be enough, 2" would be better. That will greatly increase your air sealing, and prevent thermal bridging via the joists... Might give you an even bigger boost than the fiberglass did.

Gooserider

thanks for the suggestion! the foam board would probably help a lot.

 

[smokinj]

What did you do to air-seal the floor after putting in the fiberglass? It is worth noting that FG is not real good at draft stopping, and neither is plain poly as it still allows convective flows. I would consider covering the bottoms of the joists with taped and sealed foam board, 1" would probably be enough, 2" would be better. That will greatly increase your air sealing, and prevent thermal bridging via the joists... Might give you an even bigger boost than the fiberglass did.

Gooserider

thanks for the suggestion! the foam board would probably help a lot.

I used tigher foam its cost more but much easier to work with and seals better than cutting foam board

 

[SolarAndWood]

I used tigher foam its cost more but much easier to work with and seals better than cutting foam board

How do those kits work out cost wise compared to having a contractor come in and blow it? I assume the main advantage is you can do a room at a time?

 

[smokinj]

I used tigher foam its cost more but much easier to work with and seals better than cutting foam board

How do those kits work out cost wise compared to having a contractor come in and blow it? I assume the main advantage is you can do a room at a time?

cost me 1600.00 in product my labor was free. my crawspace is bullet proof and nerver enve check what a contractor would wont I like doing things myself to make sure it is done the way it needs to be. its in the 50-60 r range 4-5 in. on the walls and in between the joist and band board and done the floors with fiberglass 19r

 

[begreen]

Our crawlspace is super dry and we have a nice gutter system on the house, so it stays dry. Taking advantage of this, I turned our crawlspace into a conditioned space by insulating it (interior walls). The results have been great. It never gets below 60 degrees. In the summer I open it up to breathe, but in the winter, it is closed off and tightly insulated. This results in nice warm floors and no drafts coming from below.