Separating Potable Water from Heating Water Loop

[dparent55]

I live in Maine. My heating and hot water system is a bit unorthodox. The system is designed around an 80000BTU/h hot water heater that is used for both potable and hot water. The system is 18 years old and works great. The hot water feeds a radiant floor heating system that continually circulates the water in a heating loop with hot water injected into the loop as needed. Piping and Fittings are polyethylene rated for this use with a few copper fittings here and there.

I am told that the system is not to code due to the mixing of potable and HW. Can I install a heat exchanger between the two circuits? One plumber says that code requires the use of a hot water boiler. Another plumber says no. Multiple pro's seem to disagree. To me it doesn't make sense to use a boiler since my system does not require high water temperatures. What does the code truly require?

[hrhofmann]

Check with your local building department

[HeyBub]

Water from a water heater is not potable. Maybe legally it is, but water from a water heater should never be consumed. It is used for bathing, washing, etc., but not for cooking or drinking.

[trader4]

+1

I see companies selling heat exchangers for that purpose. So apparently they are permitted, at least in some places.

[Ed Pawlowski]

Not seeing your system, it is impossible to say. It is possible and done frequently, to add a heat exchange on a regular boiler to make potable hot water separate from the heating system.

This is one of many systems that work with a regular heating boiler. I don't know if it can be adapted to your setup or not.

Efficient boilers and heat exchangers here too.

Since you are still alive, I guess your system works, but no way would I buy your house like that.

[Attila Iskander]

Why ? What is the problem if you keep your heater clean, have clean water go in, and the temp is high enough to prevent growth of anything live ?

[HeyBub]

Ah, that's just it; the water heater temperature is NOT sufficient to kill anything alive. For example:

"On the side of most water heaters youll find a warning that says water temperatures of 125 degrees Fahrenheit can cause burns or death. To be safe, the water coming out of the plumbing fixtures in a home shouldnt be any hotter than 120 degrees.

"At temperatures below 135 to 140, Legionellae bacteria, which is responsible for Legionnaires Disease, can survive and even multiply in the water heater tank. Estimates by LegionellaPrevention.org say that up to

600,000 cases of Legionnaires Disease are misdiagnosed as pnemonia each year, because this is something that isnt tested for in hospitals."

It takes a temperature of 158 degrees to kill the Legionnaire's Disease bacteria.

See:

[trader4]

Has anyone gotten legionaires from drinking water though? All the cases I've heard of I thought it was aspirated, like from misting systems, spray fountains, showers, etc?

Even if a hot water tank is kept hot enough so bacteria isn't a problem, the water coming out, in my experience, isn't fit to drink if you don't have to. The tank has all kinds of sediment build-up and if you taste the water it doesn't taste very good at all.

[TimR]

In these combination systems I don't think you expect to drink the hot water. You just get your heating water and your domestic hot water from the same boiler. If you have a water softener you shouldn't drink hot water anyway, it has salt in it.

We installed a couple of these systems at work years ago, I think the brand was Apollo. They met code in Virginia. I was skeptical but they worked fine.

When we lived in Germany we had an oil fired boiler that supplied both hydronic heat (heated tile bathroom floors - very nice on a cold morning!) and the hot water for showers etc. Germany is very strict on code (DIN).

[trader4]

ter.  You just get your heating water and your domestic hot water from th e same boiler.

In the system in question, he doesn't have a boiler, he has a conventional water heater that's being used to supply hot water to the house and for radiant heat. But the issue of legionaires in hot water would apply to any tank type water heater.

as salt in it.

Don;t most residential water softening systems feed softened water to the cold water taps too?

nd was Apollo.  They met code in Virginia.  I was skeptical but they wo rked fine.

dronic heat (heated tile bathroom floors - very nice on a cold morning!) an d the hot water for showers etc.  Germany is very strict on code (DIN).