Need Radiant design advice

frank s

Hello fella's long time no talk. I have a homeowner with a bonus room over the garage, 900 sq.ft, wants radiant, wants to keep the floor as low as possible (read no pour) garage is rocked painted insulated, staple up not a real option, staple down is. Supply house tells me 3000' of 3/8 4" on center, I say they're high! We've cosidered putting down another layer of plywood and routing it out....what do you think? or ripping the plywood and putting down sleepers..........Remember low floor profile. The room has 3 outside walls....25x36 80 sq.ft of windows. over unconditioned space, no attic above, manifolds would be located on front side of house ( as opposed to centrally)anything you can offer me will be greatly appreciated. Thanks for your knowledge,
Frank

frank s

I forgot.......

to mention that the floor of choice is hardwood.......possibly .......possibly pergo. Thanks

Alan(CaliforniaRadiant)Forbes

Some type of

heatboard material seems best suited for your installation; like Thermalboard, Climate Panel (Wirsbo's product is called QuikTrak) or, if you're down to the joists, use Warm Board which is the subfloor that has a thick aluminum skin and is routed for your tubing.

The first place to start is to do your heat calc's.; from that, you can make make sure one of the above products will give you the heat output you need.

Hardwood shouldn't be a problem.

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hr

Surely you jest!

3000' feet of tube in a 900 sq. ft. room! Did someone do a heatloss for that room? My opinion is if 8" oc won't meet the load 4" is probably not going to get you there either.

Unless this is a snowmelt


Stop everything and do, or have, a heat loss done.

ThermoFin U track would work nicely also. Rip plywood strips to fit the O.C. spacing you calculate.

hot rod

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frank s

heat loss is Approximately 28000 btu

heat loss calc for room was 28,000 btu, or about 80' of baseboard, it's those damn 11' ceilings !

hr

Doing the math

28,000 load divided by 900 sq, ft. = 31 BTU/ sq. ft. A little on the high side for floor alone.

Using the RPA Rad Pad 31 BTU/ ft would be around 86 degree surface with 70 degree air temp. A little on the warm side for surface temperatue, depending on the useage. Are you sure about that load? Did you use a radiant design software?

hot rod

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frank s

hey Hot Rod

Actually I used the slant fin program and thats what I came up with. The supply house told me it would be much less with radiant, and also asked me how much recessed lighting would be going in cause that would also make a difference. Thanks for taking the time to reply to me, I read most of your posts, and value your opinion.
Thanks,
Frank

Chris Maderia

Radiant Design

Your Heat Loss for the room based on your information is 11,334 btu/hr. I would recommend Wirsbo's Quick Trak. You should have 7 Loops of 212 and 1 of 219 all 7" OC. Total Flowrate is 1.28gpm @ 6.57ft head. Your design water temp will be 91.5 degrees @ o. Your unit heat load is 14.2 btus per sqft. This will give you a surface temp of 74.3 degrees.

Also your heat loss for a conventional baseboard system would be 18,887 btu's hr

frank s

Thanks for the info

I'll be emailing you. Thank you,
Frank