I suppose it would depend upon the recovery rate of the hwh. A small electric boiler, used for baseboard heat, is 10KW or about 33,ooo btuh. But, with only 1 1/2 gallons of water in the boiler, the recovery rate is fast. You might look along that line.

It against code to use potable hot water for heat. There is a water heater though that has seperate taps for that kind of purpose,,, well sorta. Its gas fired instead of oil and designed for use with a hot water coil instead of fin tube baseboard. Google Apollo Hydro Heat, maybe they can direct you towards an oil fired heater for that purpose.

Is it against code to use a hot water heater, not connected to the house plumbing for his purpose?

.

I used a conventional hot water heater for my radiant heat in my house . . a closed system; ie completely isolated from ANY potable water except the fill; which is through a backflow preventer. It's not against any codes here . . your locale may be different . . . recovery rate for a small space is not likely to be a big deal. Remember too; that recovery rate is based upon a certain incoming temp . .. and the water returning from your heating loop will probably be much higher. You've also got a good bit of thermal mass stored in all the gallons of hot water in the tank. Your basic idea seems quite sound to me; and not against any codes I know of . . . .

Bob

baymee, read the original post again. The guy wants to tap into his existing water heater. This is what I'm advising against. Last time I looked a water heater has only 2 taps. Hot and Cold. So how are you supposed to seperate that into one heating loop and one for potable hot water? A question like this can only be answered by checking with local codes in the particular area where you live, but I could almost guarantee the majority of locals will not allow a water heater to be used for heat if its purpose is to produce hot potable water. Besides baseboard is usually sized for 180 degree water. What kind of BTU value do you think he'll get out of 120 degree water?

I guess I didn't take "tapping off" his hwh as actually using it for two purposes. By code or not; bad idea.

OK, I heard you. And I would not do anything to violate that code But speaking academically, is there anything wrong with forming a copper piped loop and pumping hot water around that loop? What does it do to change the potability of that water? The pump would have to be special as to not contaminate the water, correct?

They say a man's home is his castle and the King in his castle would use his hwh, a bronze Taco pump and some copper to keep his Princess warm, if he had his mind set upon the idea.

"What does it do to change the potability of that water?"

I expect the problem is when the heating loop
is shutdown for the Summer. All sorts of nasties
can grow in there. Then come next heating season
it'll get mixed up with the water to the faucets.
Gross if nothing else.

Excellent point by saltcedar. Can anything grow in a closed loop? It may indeed be unhealthy. I can think of more gross things.

I pulled my well pump up this summer after 30 years. It pulls water from 260 feet but the column of water above that gets bugs and whatever in the water. Never test it and never get sick from it. My friend and his neighbour get their water from a spring, with an open pipe and 60# of pressure coming down the mountain. Sometimes there are dead mice and spiders, etc in the water. They don't treat the water or get sick either. There are all sorts of gross things around our water.

quote
"I expect the problem is when the heating loop
is shutdown for the Summer. All sorts of nasties
can grow in there. Then come next heating season
it'll get mixed up with the water to the faucets.
Gross if nothing else."

Yes, draining the loop is easily done.

Wouldn't even more evil nasities grow if there
were air in a warm, dark, damp loop?

I don't know; maybe somebody else knows. I have dead legs in my house that might get used only once a year, yet they are still in the piping of my drinking water and I've never noticed anything. We need a micro biologist to weigh in on the matter.

Guys - this is a constant subject of threads over at heatinghelp.com.

Legionnaires disease can come at you from water that is not hot enough to kill the bacteria. See the link for a ton of threads on it.

Here is a link that might be useful: Heatinghelp.com link

What specific page? at heatinghelp.com

First you have to have bacteria in the supply. My water never gets hot enough to kill bacteria.

Guys,

The Legionnairs is nothing to fool with. My neighbor got it TWICE from the hot water tank. The 2nd time the health department finaly figured it out. What happen is hes an old guy living alone and wants to save money. He turns the tank off when he doesn't shower then turns it up just enough to take a warm shower. Then off it goes.

The health department said the clourean in the water is there to kill the bacteria. When you HEAT the water it kills the bacteria and takes way the clourean. The problem is when you only WARM the stagnet water in the tank. This actually grows the bacteria .... then you shower and breath it in. YOU MAY DIE and they may not know why. SO DO NOT turn your tank that low that it makes bacteria. The link in the post above I'm sure will help.
Live Good ...Scott

I looked over the information about Legionnaires disease and everybody that uses mixing valves and a 120º hot water heater has to be concerned. Looking at the numbers, I am more worried about slipping on a banana peel.

I think the best solution is to get an electric boiler which is meant for this type of job, run some 6 gauge wire and forget about the hot water heater idea.

There are many people who want to use the hwh for an extra heat loop, not me, but if it were me, I wouldn't lose any sleep over it.

quote
"I think the best solution is to get an ELECTRIC boiler which is meant for this type of job, run some 6 gauge wire and forget about the hot water heater idea"
---------------------------------------------------
E__Easy for you to say. At 20 cents/Kwh, I don't think so.

And FYI, Legionnaires disease is a problem with a stagnant unchlorinated water supply between 85 and 105 degrees F. Good idea to be safe and keep it at 140 (or below 70 if you are vacationing)

"between 85 and 105 degrees F."

Those would be ambient temp's in summer around
here. I'm sure Connecticut is cooler but how will you
keep it the loop for summer?

Sorry, I'm only the messenger.

One addendum. If your water is even slightly acidic, you will have pinhole leaks in your baseboard, probably after the first year. Continuously oxygenated water was never meant for baseboards.

If you are gong to be spending all that money on electricity to heat a small room by heating a water tank then why not save yourself the time and energy setting it up and just go with an electric baseboard heater in stead? Seems like they would use about the same amount of energy to run, especially if you only plan on using it a small amount of the time.

Posted by scott2006 on Sun, Feb 18, 07 at 20:32...

"Guys,
The Legionnairs is nothing to fool with. My neighbor got it TWICE from the hot water tank. The 2nd time the health department finaly figured it out. What happen is hes an old guy living alone and wants to save money. He turns the tank off when he doesn't shower then turns it up just enough to take a warm shower. Then off it goes."

Wow...this was not an issue for me. Our apartment in Singapore used a small 15 litre electric HW tank on a timer switch. This is a relatively common arrangement in the Lion City. Just push a button 20 minutes before needing hot water, and I was good-to-go. The timer ran only for an hour at a time. I'd have to push the button again if I wanted more. In a tropical climate, that was rarely necessary.

We would sometimes go a couple of days between heating the tank. Other times, I'd forget to hit the timer until it was too late. It was warm water for my shower or the dishes at this point. I'd shut it off right after I was done, as there was no need for the heater to finish it's cycle.

The hot (or sometimes warm) water fed the the shower, kitchen sink, and bathroom sink. I showered, washed dishes, and drank without ever getting sick from it. As-far-as-I-know, no-one has gotten Legionnaire's Disease from using luke-warm water in Singapore.

I just wish more Asian countries would use S-traps for sinks and showers. P-traps are common in Singapore. No traps are common in Indonesia. Yuck. I guess that's a discussion for another thread.

Peace.

Marco

Like I said before: I'm more worried about slipping on a banana peel than Legionaires disease and the stats support me.

baymee, its a scientific fact that banana peels in the range of 85 to 105 degrees are the most slippery so be extra careful! :-0
I was always under the impression the biggest culprit for Legionairees Disease was the disgusting shmegma laden condensate water laying in the bottom of unmaintained A/C condensate pans.

"unmaintained A/C condensate pans."

And that would be your forte !!