electric water heater for radiant?

Dave_61

We have a radiant loop for our master bath floor that is approximately 20x15 in size. This is one of the 5 zones of our heating system. The other zones are 3 coils for air handlers and a 60 gallon indirect hot water heater.
We have had problems with the 300 MBH boiler short-cycling, etc and I am wondering if it might make sense to buy a cheap electric hot water heater and use that for the radiant floor, which runs 24 hours per day at about 110-115 degrees.
Wouldn't that be a cost savings since we don't have to have this huge boiler cycling to keep the floor warm? Then the boiler would be for just the 3 hydro-air units and the indirect.
What do you think? Any problems filling the hot water heater with a water/glycol mix as this radiant loop is in a cantilevered part of the house.
Thanks.
Dave

hr

You can

knowing, of course, they are not listed for this use

I add a 30 lb. relief valve but leave the factory installed, or supplied, T&P in place.

Size the element to your design load to minimize cycling. I have used both 2-1/2 gallon and 6 gallon tanks for small bath radiant.

Think I would remove the anode if you really need glycol, or use a multi metal glycol, Noburst al, so the anode rod gets along with the glycol. Really no need for an anode in a sealed system, especially with inhibited glycol added.

I like to run the pump continously and get a contactor sized to the elememt current to cycle the element on and off.

I'll bet a 2K element, or smaller, might get you through the night

Stay at, or below, 1500 watt @ 5000 btu/hr. and you could get by with a 120 volt element. 17 btu/ sq. ft./ hour = 1500 watts.

Throw in a tekmar 500 series stat with floor sensing and you have a nice package.

hot rod





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Dave_57

Is 007 pump too big?

Currently, the way my radiant is hooked into the boiler circuit, it is being fed by a Taco 007 pump.This is all plumbed with 3/4" copper tubing that travels across the basement ceiling. Once it reaches the wall, the tubing switches to rubber with oxygen barrier.
The pump on your system looks much smaller. Is the 007 overkill?

hr

Ideally

you would calculate the heat load, determine the amount of tube installed, determine the flow needed (gpm) and pressure drop THEN size the pump to that.

Short answer the 007 is probably close enough, a flowsetter could be added to "tune" it to the exact requirement IF you have that data.

My chioce is the 3 speed Grundfos Super Brute. It gives you some futher adjust-ability with the various speeds.

hot rod

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Weezbo

*~/:)

It is as Hot Rod says, not Listed ...i have a small water heater with a 4.5 KW (18,000 ish BTU)that i use as temporary auxillary heat during construction phase of homes with radiant...you can use anti freeze in them however my experience over the years seems to suggest that anti freeze can Combust so while i use anti freeze i prefer not to do so.the added safety i think is also an excellent idea. basically what my tool can do is ,load thermal mass and gradually hold against the most severe cold and distribute btus all over the place:) it has mobility and ease of installation as the finer point,it is consistent, can be easily dialed down,and to date hasnt had any problems ....and it doesnt require feeding oil into it every day ,or special venting and or fuel lines and fuel storage systems to be installed on the fly.oh..one other thing,i use the bottom tap(cold)as my supply side header,that way when the water comes back from the"Field" it mixes with whatever heat is there and channels the mixed flow across the element and out into the Field,the temp gauge i put on this side of the equasion to determine the out going temps...i must say that i tend to run it at higher pressure than a boiler.and use a brass body Sweat taco as my pump of choise.this thing has seen six winters, empty or running hauled here there and everywhere garage slabs ,three story with vaulted ceiling ,all sorts of larger shop slabs...thrown out in the snow bank on a piece of blue foam ...it is tough enough.

colbydoglvr

electric heater...

I use a 2 1/2 gallon electric hot water heater filled with cryo-tek anti freeze to power my 4x8 radiant heated doghouse...

Bill Nye_2

I used a

I used a 30 gallon electric to heat an addition, just because we could, and because the old steam boiler had rusty returns and I didn't want to use condensate. I thought it would plug up the tube.

It worked great! That was until he got the electric bill! It went from $87 to $300! in one month.

I'll post a pic if I can hook my scanner back up.


p.s. I ended up getting a used steel oil fired boiler, I'ts been going on 4 yrs now, works great. My garbagemans house.

Weezbo

I installed a firehydrant as a watering post for the dog of

a friend*~/:)runs winter or summer:)

Weezbo

interesting.... Did you also take a day to day temp reading

indoors and out doors? and check the cost of energy for the month based on similar KW useage for that time period? i did the math and did exactly that and more...seems the energy bill for the elec and oil vs. simply KW conversion and disribution turned out 30 dollars less for using electricity alone. i know what i am sayin as i paid the bill for the experiment.meaning every day i took all kinds of readings ,i will say that some times i would test parameters and it probably cost me way more that the 30 dollars i earned:)

Sweet_2

cool

Very cool Hot Rod, thinking outside the box Im always learning from use guys. Ya cant get this stuff any where else.

colbydoglvr

lol weezbo