radiant with a water heater

frank s

Customer had a 38 gal. water heater installed in the attic to heat an addition, the room is 15x16 , 8 sky lights , 11 windows and a door, max water temp is 145 for the heater, the tubing is suspended under the floor, 3/4 and1/2 inch ply with thin set and tile, r 19 below with styrofoam blue board and 3/4 ply, over unconditioned space, actually it's like a deck with a room built on it, My calcs say They need supplemental, can I save this job with the water heater(electric) or do more drastic measures need to be taken? Tube is 12" OC not enough, 1/2"pex, would plates and 8" centers help? The installer also has the supply coming out of the inlet(cold ) of the heater, do water heater s work? Any words of wisdom are appreciated. thanks
Frank

Dan Peel

electric tanks

Electric water heaters only operate one element at a time, in a 38 gal. your highest output will be 4500W (15Mbtuh) and may only be 3000W (10Mbtuh). If those numbers won't meet or exceed the heat loss you're behind before you start. In my geography the skylights alone could such that much heat out of a room. G'luck..... Dan

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frank s

thanks

for your input Dan Heat loss as appr. 8800btu's. I appreciate your input. I think the insulation is touiching the tube

Floyd_5

Plates will help....

a bunch......don't think I would counterflo the heater, and there are 5500W elements out there... make sure your using #10 wire with them, they will pull 25 amp and burn up #12...
If that hot water heater is in unconditioned space you could be loseing a ton just from the lack of insulation that most of them have

PS. If the water temp is staying at 145, you got enough heater and not enough emitter...if it is dropping then you are short on heater and long on emitter.....

that will at least show you where the problem lies....

frank s

The temps

The temps are dropping but the delta T is only about 10*.
Do you think the water heater with closer tube spacing and plates will do the job? I need to make up a couple 1000 btu's, that I can't get from the floor, I was thinking some Runtal rad panels, any ideas? Homeowner does'nt want baseboard. Thanks
Frank

Radiant Wizard

Hey Frank!!!!

Are you cheating on me now? Get rid of the water heater and take that zone off the boiler. I know the homeowner doesn't want too but that's the answer. Walk away from the job if you can't do it the right way.

Mad Dog

The Wizard is correct....stop wasting your time

water heaters are a cheap substitute for a boiler. By the time you set the water heater up safely, with the proper relief valve backflow, spill switch, et cetera, you might as well have spent the extra 500 for a real boiler. Done it both ways. Mad Dog

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Jed_2

So where is the spill switch located on an electric wtr htr?(NM)

n

frank s

you are a ......

-ick . know I can't print the 1st letter of the 1st word with out getting banned from the site, I think I have them going from the boiler, I had them read all the posts, high temps smoke the floor and to hell with'em, whaddya say?

Mad Dog

Listen Jed Clampett...you know I meant on a gas water heater

cut the crap. Do you use electric water heaters on all your jobs???? Tell me more.....Mad Dog

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Jed_2

You're right, I was being smart

> cut the crap. Do you use electric water heaters

> on all your jobs???? Tell me more.....Mad

> Dog

>

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> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 299&Step=30"_To Learn More About This Contractor,

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Jed_2

You're right, I was being smart

Matt. No, although I was asked to size an electric for
a commercial sidewalk SIM. Not all that large, but Jeeezz.
Switched him to an Ambassador Apria 29E(Embassy). Not full
input modulation, but it does have a high & low input. Seems o.k. for what it will asked to do.

I was just thinking on topic, which was for an electric.

Regards

Jed

Mad Dog

awww shucks Jed...let's go get some white lightnin'

and go down the catfish pond.....I hear ya...their ok for some applications. It just seems like Frankie is wasting his time trying to get a pig entered in the Belmont Stakes. I'm still waiting to see his response to Radiant Wizard....seems like some bad blood there. I don't knoiw the story, but I've had that happen to me: A guy picks your brains about something that you KNOW is the right way to do it, they appear to agree, but then they listen to someone else who don't know Jack....Mad Dog

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Radiant Wizard

> and go down the catfish pond.....I hear

> ya...their ok for some applications. It just

> seems like Frankie is wasting his time trying to

> get a pig entered in the Belmont Stakes. I'm

> still waiting to see his response to Radiant

> Wizard....seems like some bad blood there. I

> don't knoiw the story, but I've had that happen

> to me: A guy picks your brains about something

> that you KNOW is the right way to do it, they

> appear to agree, but then they listen to someone

> else who don't know Jack....Mad Dog

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 299&Step=30"_To Learn More About This Contractor,

> Click Here to Visit Their Ad in "Find A

> Contractor"_/A_

Radiant Wizard

Mad Dog!!

Frank is a friend of mine and I do all his radiant design work. The major problem with this room is that one, the room needs supplemental heat (3,000 btu's to be exact). There is a ton of glass ie Solar gain. What's happening here is that all day long that circ is off because the therm is satisfied so when that big heat tab in the sky goes down the responses time is too slow to get the room up to temp.

The water heater can be used if we rip open the bays, use 3/8" radiant trak plates, 8" occ and get 3,00 btu's of supplemental in there/