Looking to do radiant floor heat

jakefinley

Hello i have a 1 story 900 sq ft cabin with a pellet stove and was looking to add radiant floor heat. I was only going to do about 600 sg ft, Kitchen bathroom and two bedrooms as one gird. I was looking for some input on what i should use to heat the water right now i have a 11 gallon electric water tank for my main hot water needs. I was looking into using another hot water tank for the supply but dont know what size i should get but i am also open to other suggestions, also on what kind of pump i should use. Thanks for the help

Ironman

Proper DESIGN is the first step. And for that, an accurate heat loss calculation is needed. You can download SlantFin's free app and do it yourself. Just enter the correct data and choose the right construction type and you'll get an accurate calc.

An electric water heater cannot produce enough btus, unless your load is 15k btus or less.

jakefinley

Thank you for your reply. I forgot to add that this is a second house and im not there much so the heat is kept around 50 by a propane furnace. I think it would be hard to calculate heat loss cause i never get the place warm enough the pellet stove is in the living room and really only warms up that area about 300 sg ft and it usually runs every hour in the winter. That's why i was looking into radiant heat because the back bedrooms never get warm and i dont want to waste the propane for when im not there. Also the house is 26' by 36' i was thinking if i could get the tile in the kitchen and bathroom as long with the floors in the two bedrooms warm it would help take the chill out of the place. If you dont recommend a hot water tank would you rather go with a boiler or a thankless option and if i cant calculate heat loss just go with a bigger setup to be on the safe side?

Ironman

You CAN and SHOULD do a heat loss calc. Your pellet stove has nothing to do with it. It's based upon the construction of your house: the glass, insulation thickness,etc.

The heat loss is needed for designing and sizing EVERYTHING in the radiant system.

And no, bigger is not better when it comes to boilers. But, we don't know what size boiler you need, how much tubing, the spacing, the pipe and pump sizes, without a heat loss calc.

delta T

Heat loss is a must!!!!! As Iron man said, there is not any good way for us to help you without this. This will determine the size of the heat source and possibly dictate its type, it will determine what flow rates are required, how the tubing should be installed, everything. Do not skimp on this part, or you will be guessing and hoping that the system will work. Heat loss is really pretty simple, but expect it to take you a few hours.

jakefinley

ok thank you i will be going there this weekend and try to get a heat loss number

bulldoglax

Slant/fin is good but just know it will oversized by about 15-20 percent I would find a local distributor you are going to buy from and see if they can do one through rightsoft or uponor.

Also you can do a 50deg indoor and 70 and see if the modulating boilers turndown fits in that window.

Chances are any of the newer taco veridian or 007e pumps will be more than enough but again everything falls back in heat loss and design

jakefinley

Ok so I got a heat loss of 8463 that is including my craw space basement that is not heated with a concrete floor and concrete wall with out the basement it is 7748

Ironman

8463 btus / 900 sq. ft. = 9.4 btus per sq. ft. I would seriously doubt that number to be correct unless your cabin is in Fla.

Where is your cabin and what did you use for design temp?

20 - 25 btus per sq. ft. Would be a more likely number in moderately cold weather climates.

rick in Alaska

Not sure about that number either. I guess it depends on the insulation in the "cabin". My house in Alaska runs about 13 btu/foot, but is also well insulated, and in what is considered a moderate climate.
8463 btu's doesn't look right though. Something is probably missing in the heat loss.
Rick

jakefinley

I used slant/fin and it is located in upstate NY. I filed out everything in slant/fin also inside temp was 66 and out side was 55. The only thing that is left blank is cold partition length

KC_Jones

jakefinley said:

I used slant/fin and it is located in upstate NY. I filed out everything in slant/fin also inside temp was 66 and out side was 55. The only thing that is left blank is cold partition length

So the coldest it gets there is 55°? I have a feeling that isn't true.

jakefinley

Oh no it can get pretty cold it's definitely been in the negatives. I was just putting the current temps in the app

Brewbeer

Put in -10 F for the outside temp and tell us what you get.

jakefinley

I changed indoor to 72 and lowest I could go for outside was 0 with slant/fin but new number is 68761

lefty1cad

We are doing an exterior loading dock. We wanted to do a reverse return radiant heat pex piping system the dock is 84' x 12' is it feasible.

hot_rod

lefty1cad said:

We are doing an exterior loading dock. We wanted to do a reverse return radiant heat pex piping system the dock is 84' x 12' is it feasible.

Snow and ice melt? Where is it located?
It will be a big load with two or more exposed surfaces