More radiant heat questions

Jim_65

What is the heat loss of the intended area you are trying to heat from under the floor? Do you know the R-value of the carpet floor covering?

super_2

More radiant heat questions

I am a radiant novice but I am converting my boiler system from base board to suspended radiant tubes (Before I install drywall on the basement ceiling. I have a 1,200 sq. ranch. 9 1/4" joists @ 16" centers. 1/2" to 3/4" subfloors, and the rooms are either carpet, hardwood, or ceramic tile.
My questions are:
1)Can I get away with 8" runs of 3/8" pex?
2)Do I need a Reflective barier above my R-19 batting?
3)Is it O.K to have the PEX 1/2" suspended?
4)My basement will still be using baseboard heat (just 3 8' long units with 3/4" copper pipe. Because I can get the 3/8" tubing way cheap from a buddy, how many 3/8" runs would it take to equalthe flow rate of 3/4" (approx)

super_2

More radiant heat questions

I am a radiant novice but I am converting my boiler system from base board to suspended radiant tubes (Before I install drywall on the basement ceiling. I have a 1,200 sq. ranch. 9 1/4" joists @ 16" centers. 1/2" to 3/4" subfloors, and the rooms are either carpet, hardwood, or ceramic tile.
My questions are:
1)Can I get away with 8" runs of 3/8" pex?
2)Do I need a Reflective barier above my R-19 batting?
3)Is it O.K to have the PEX 1/2" suspended?
4)My basement will still be using baseboard heat (just 3 8' long units with 3/4" copper pipe. Because I can get the 3/8" tubing way cheap from a buddy, how many 3/8" runs would it take to equalthe flow rate of 3/4" (approx)

super_2

I don't know the R-value. Its a short nap burber type carpet with that thin wavy rubber underlay. I would guess between R-2 & R-4.

Jim_65

It depends

With that high of an R-value plus the subfloor you will be limited on how many btu's you can successfully deliver. Even suspended tube operating under high temperatures will only be able to provide approximately 15 Btu's per sq.ft. or less.

I would look into some type of extruded aluminum heat transmission plates. This will allow for greater heat transfer with lower operating temperatures.

I still suggest to calculate the heat loss of the intended heated space. Depending on the results you may have to provide supplemental heat at design conditions.

super_2

I was including the wood with that R2-4 range and the carpet makes up about 1/4 of the house (2 rooms with wide open doors.

Jim_65

Heat loss x 2

I am assuming that your buddy that you referred to is a heating professional since he has the tubing to distribute. I would suggest having him perform a heat loss calculation for you so that you can determine the heat loads for the intended areas.

If not try "Find a Professional" on this site. Depending on who you contact you may even be able to find a pro who will consult you throughout the process. This will ensure you that you won't have to do the installation a second time because you did the math from the start. Even cheap tubing can cost more in the long run if installed in the wrong application.

Unknown

I second the demand for a heat load. Also your questions definitely indicate that you are not familiar with radiant, so you need some guideance.

The load calc will tell you what you need (suspended, light or heavy plates), the water temps, whether this will even keep up with your heat loss... important stuff.

super_2

Thanks for your help. Since my boiler and house isn't changing and my present system works fine, is there a way to figure it out based on my baseboard heaters?

Unknown

Only if the person who originally put in your baseboard did their math. If they didn't, someone should.

See "free heat loss calcs" in the sidebar? it may not be spot on, but at least it will get you to the ballpark. Feel free to post your questions on parameters here if you need to.