Hydronic through unheated crawlspaces

Rob_7

Yes the spaces are small...totalling a little more than a couple hundred sq. ft. and about 2 to 2 1/2 feet high inside. I neglected that dimention, as well as the fact that the floor above is not insulated so some heat must radiate downward. There is an old tarpaper type vapor barrier under the flooring boards, if I recall (when I had the carpet up last).
There are no pipes at all under the crawlspace areas, just in the main basement which is heated well enough.
I don't like the anti-frezze idea, either, but I think the constant circulation or small hot water bleed might be a good idea to try.
Thank you both for your food-for-thought!

Rob_7

In order to convert my prsent home to hydronic heat from scorched air, I need to run some of the piping to baseboard units through 2 unheated, unventilated, dirt floor crawlspaces. These are about at grade level and walled at the perimeter by brick approximately 8" thick.
There are about 170 sq. ft. of crawlspace underneath one part I need to heat, and another 80 sq. ft. the same way on the opposite end of the house.
I have just enough access to crawl in them from the basement, so they get little incidental heat from the rest of the basement. It's not uncommon here in Iowa to have ten to twenty below temperatures days or weeks at a time...plus a lot of non-stop wind!
I'm really concerned about the heating pipes freezing under there during the off-cycle.
I know that no one can possibly tell me with any certainty how to avoid this without, at least, looking at the situation in person, but still I wonder if anyone has any ideas about whether it would be better for me to insulate these spaces (Which would be a hellish if not impossible job for me) or to just insulate my heating pipes well, and/or maybe use an anti-freeze in the system?
Thanks.

Mike T., Swampeast MO

Crawlspaces

Any domestic water piping currently running through them? If so, do you have to take measures to prevent them from freezing?

Perhaps you put a container of water (or remote-reading thermometer) in the farthest reaches of the crawlspaces this winter to see if they froze?

Since warm air rises (and the crawlspaces sound smallish) they [likely] don't freeze as long as the heat is on in the house and good pipe insulation [should] be sufficient. Insulating the floors themselves could actually contribute to the problem--not to mention cause problems with condensation in the insulation during the summer.

I believe most will say to avoid anti-freeze if possible as not only does it transport less heat than water, but it requires regular monitoring and maintenance to avoid very expensive problems.

J. Morse

Dirt crawlspace

If you've got dirt then you've got moisture being drawn from the crawlspace up into your home. I'd strongly urge you to cover the dirt with a vapor barrier such as Tu-Tuff which is specifically made for the purpose. You can find it at www.energyfederation.org to name one supplier. This will benefit you in more ways than one. It will stop the sometimes gallons of water being drawn from the dirt into your house each day. It will make it very easy to slide around under the house as you install your heating system. You'll be a lot cleaner at the end of the day. As far as freezing tubing, what about a constant circulation type setup?

Good Luck,
Jim

Tom M.

Is there any way to go

through a wall upstairs? A pipe can sometimes be hidden in a cabinet or closet or even a baseboard enclosure from another zone. Antifreeze can get expensive with testing and replacement and constant pumping and insulation don't help much in the case of an extended power outage. This may be an option for you.

Fred Harwood

Pipes in unheated space

I've had some success by installing the pipes as close to the flooring as possible and then carefully insulating underneath the full depth of the floor joists. That will let the house heat keep the pipes from freezing and the insulation will also increase the comfort in the home by raising the floor temperature.
Also, be sure and cover the dirt with a vapor barrier, as mentioned in another post. That water will do bad things to your house.

Rob_7

Combo?

Thanks, guys.
I may do a combination of putting the piping close to the flooring and insulating as well as a constant circulation if need be.
There just isn't any way to cross the door on one side or the fireplace on the other to get to that half of the living room.
Then again, it may not be a problem...I'm getting married this month and we may decide on a different house after she moves in...maybe one with a full basement, I hope.
Too bad its nearly impossible to find a house with hot water heat already in it, here in the midwest.
Its going to be nice to put it in myself though and do it the way I want it...pumping away! (and with radiant under the kitchen and bathroom)
I'm pretty excited...
Thanks, Dan, by the way, for all the good books!
My fiance's never lived with hydronic before and was concerned whether she'd like it or not.
I told her, "Nobody doesn't like hot water heat!"

Rich_2

pex

I did a job with a crawl space like that, used pex pipe worked great! & winter just ended, one of the coldest in awhile (NY) haven't herd from them .You'll be able to get it close to the floor like you want (I didn't)& if it did freeze it wont break like copper.Did I mention no solder joints(awesome)

john_24

I have good luck with constant circulation on jobs like this but i have installed an aquastat on the return line to monitor temperature. if the water temp in the line falls below 50 degrees it turns on the heat to that zone long enough to warm the water in the pipes. I also wire in an outdoor thermostat to shut down the constant circulation when the outdoor temp becomes mild. all this may be a little overkill but has never failed me yet. exept when the power goes out then you may wish you had some antifreeze in the system.

John R

Rob_7

Hmmm

Maybe PEX, too...
Another good idea. I don't want to solder in a crawlspace!