Joe, I guess no one quite knows what you mean by a hydronic panel heater. I've seen electric panels that sit in a 2x4 drop ceiling grid or the kinds that can be surface mounted to a conventional ceiling but I don't believe I've ever heard or seen anything like what you're mentioning here. Could you maybe explain it a little more?

Mr Hvac,

Thanks for explaining the lack of response. I was wondering where the gurus were.

All I mean is that the outer heater configuration is a panel, rectangular in shape, say about 2 feetx 3 feet with coiled copper finned tubing attached to the back, just like the baseboard. So basically it is a wide baseboard. They are available in low pressure models but I can't find one that is designed for 70 psi working pressure.

Why 70 PSI, couldn't you just install a pressure reducer???

Mr Hvac,

No, because I am looping thru my hot water heater, whicb is at 70 psi.

Thanks for asking.

Joe

OIC, well Joe if I hear of something like that or come across something you might find interesting I'll keep you in mind. I would tend to think what you are looking for would be of EUROdesign and mfg.
I wonder why the LP ones can't handle higher pressure. Are they soldered copper?

mr hvac,
I'm guessing that with copper being so expensive and the market being mostly LP, that they may draw out the standard copper tube and thin out the wall just enough to sustain the lower pressures.
BTW, Myson and Runtal make the panel radiators, but for LP.
I will keep searching.
Thanks again for your help.
Joe

You might want to rethink that idea. Unless your water tank
is set up for dual duty, as in heating domestic potable
water and for space heating ( there is a sticker on the tank ). You will violate and cancel your water tank's U.L.
acceptance. Insurance companies love that. They don't have to pay if your fiddeling causes damage from any part of the water tank's circulation system.

Kalining,

Thanks, I looked into that and according to the heater mfr,national accepts it; now looking into local code .

Joe,

Regarding Legionella, are you going to be heating with this panel all year long? Or are you going to drain it at the end of the heating season?

The last thing you want is for water to sit in the heater all summer, stagnate, and then, at the beginning of the heating season, be released into the domestic hot water supply.

140 deg. water will keep Legionella at bay, but I don't think it will kill an active colony rapidly enough to be effective in a home where water may be drawn faster than the bacteria's death rates.

There's some good information on Wikipedia that matches with everything I've ever seen on the bacteria's heat/time resistance.

Here is a link that might be useful: Legionella

Kframe,
Thanks for your input.
I plan to drain it and when I restore it I will bump up the heating for at least several hours.
I also have read the ominus reports and find it interesting that swimming pools, where the temps are in the range where Legionnella growth are most prominent are not identified as a problem, since chlorine does not seem to inhibit growth. Also, I have seen data that for copper ions in water in excess of .6PPM bacterial growth is contained. My water supply is in excess of 1PPM but I'm not counting on it for help.