Radiant heat source

Plumbingpainter

Hey guys, I am still trying to supply my 320 sqft concrete slab system with heat. I am wondering if an elec wtr htr would do the job? I am not sure how to do the math on necessary btu/hr and recovery rate. My loss is appx 17K. Floor is uncovered. Tankless seems unmanagable and combi tank is expensive and probably oversized. Is there a site to learn how to do the math or an opinion on dual element water heater? Thanks for any help.

Plumbingpainter

Radiant heat source

Please.

kevin coppinger_4

maybe...

presumming 30 btu/ sq. ft.... thats 9600 btu.
A water heater ( 20 gallon , 240 volt) w/ a 4500 watt element in it would give you 15,345 btu... well w/in the presumption... what did you come up w/ a heatloss #...? kpc

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AL_29

Why are you trying to heat only 320'. Talk about wasting money on install. I have tried one 52 Gallon electric heater for 600' of garage. The home owner insited it would work. Against my better judgement I went ahead and installed it. Guess what it DIDN'T WORK. so I read a thread that said, PLEASE. I am going with that one. Buck up and put in a tankless heater.

Plumbingpainter

Radiant heat source

Thank you Kevin for response. Al, this is a room addition to a cabin. Elevated slab with polished finish. Old part of cabin is slab on grade with forced air wall furnace. I initially just wanted rad for cold floor in winter, but then woundered if it could hold minimal temp in the entire spac during the week when we are not there. Very low investment till now. Thanks agin for your help.

Plumbingpainter

Radiant heat source

Al, what type of tankless did you go with on that 600' install? I guess my fear is that a tankless on such a small floor will be overkill. What do you think. I placed my heat loss at 17-19K/hr depending on how you view my exposed beam and deck vaulted ceiling.

hot_rod

A small 6 gallon

electric tank would be an option. They use a standard screw in element, so you can build the output to what the room requires.

I have a few running 1500W 120V (5100 btu/ hr) element, and some with 5500W 240V at 18,7000 BTU/hr.

If the room is attached to the rest of the buliding the loads could be anywhere from 15- 30 BTU/ ft. a quick load calc would help you select he correct element.

I use the Eemax brand now, actually a Bradford White tank. If you remove the anode rod on top you have a perfect spot for and air vent.

hot rod

Weezbo

hello.

i have a "tool" that amounts to a very beat up version of the tidy heat source with distribution manifold Hot Rod presented you. right now, it is maintaining heat in over 2000 sq ft while the sheetrockers thrash rock ,mud ,primer texture and paint about within the building envelope. at the moment it has already rolled through some -43 F weather...it has an antifreeze solution within the three zone system, so ,...the available heat though minimal is sufficient to "hold against the cold". my electric camera froze and bounced off the ground a few times and just don act right anymore or i would send you a jpeg of its current living arrangement..

Rich L.

53 btu/ sq ft?

Excuse my ignorance if i'm missing something simple here but if you have a 17,000 btu/h heat loss in 320 sq/ft doesen't that equate to 53 btu/ sq ft? Isn't that "off the charts" for practical radiant heat? At least without an auxilary heat source?

Plumbingpainter

Radiant heat source

Thank you Rich L, Weezbo, & hot rod for responses. Very helpful. Rich, the wall furnace I refered to blows from 8' away into this room and provides base line of btu. This room is open to balance of space and my primary interest is warming floor for winter months. Design days (+10deg)very infrequent in Kansas. Any other thoughts are appreciated.