HWT for in floor heating...

hot_rod

for the water heater manufacturers.

I suspect the soft tissue lawsuits have, so far, outweighted the CO ones!

Water heaters, by design, have a pretty sloppy and forgiving heat exchanger. They need to be able to accept 50F or colder return, so to speak, temperatures. Measure the flue gas temperature to see what I mean.

I have seen some pretty ugly scaled over burners from water heaters, and boilers also, running low temperature slab radiant jobs.

hot rod

PeterGriffin

Other than..


Other than it being grossly inefficient (76%?[and heating 40 gallons of extra water]), are there any other negatives of using a hot water tank as a "boiler?" I was at a service call the other day for a call unrelated to the heat, but noticed it as I was shutting off the water main. It was also missing a n airscoop, I mentioned it to the homeowner, but I don't see my self getting a call to put one in.

P.S., I'm now officially addicted to the wall.

Thanks,

Rankin

hot_rod

Condensing mode

You need to run them at least 130- 140 and mix down so they don't run continously in condensing mode.

If they do run cold their entire cycle the will rust, and flake down on the burner. A potential CO generating monster.

In many areas they do not past muster as a "boiler" without an ASME label. But then again not all modcons have ASME.

That Combi2 available from Bradford White, or Lochinvar actually is a fairly good option for DHW and some small hydronic loads. it is built and listed for that purpose at least.

hot rod

Rob Blair

Hot Rod, here is a question..

If you should run them at the temps you specified to stop condensation and early failure, then why do the manufacturers have you set the temperature on them to run at 120 to prevent scalding? Aren't they concerned about failures? I don't ever remember a warning in the installation or operational manuals on this subject.

Rob