Water heater used for space heating

Dan_29

As a homeowner, I went through this process 4 months ago.

During a remodel, my ex-plumber tied two fhw kickplate heaters into my domestic hot water heater. He said he had done "dozens" of these jobs and no inspector had ever had a problem with it. Three boiler techs who came by to estimate my steam boiler replacement said this is a major no-no. The reason being, stagnant water in the heater loop will mix with domestic hot water in the next heating season. I made a decision to disconnect the fhw loop from the hot water heater and tie it into my new steam boiler.

I posted my problem in this forum and a number of heating pros commented that fhw loops tied into a domestic hot water heater is a major no-no. Oddly enough, I went to talk to the local plumbing inspector, at city hall, who said there was no MA. State Plumbing Code rule against doing this according to his research.

If you are a cautious person, as I am, disconnect the fhw loop in your domestic hot water system and tie it into your boiler or some other SEPARATE heat source.

Dan

One of pro posters in my preious query suggested I Google "bacterial magnification in domestic hot water supplies" for some sobering research.

Tony Shupenko

Water heater used for space heating

1st time seeing a water heater used for space heating and heating domestic hot water, so bear with me (and I've been doing building inspections for almost 20 years).

The heater outlet had a "tee" - one to a circulating pump that fed baseboard units, the other to the home for domestic use. No valving, flow valves, etc were present. The return loop tied into the cold water pipe, via another tee, back to the heater.

This arrangement bothers me - the main concern (or am I off my hinges) is that water that stagnates in the baseboard units, in the non-heating season, can get awfully funky. Isn't this a health risk?

Any light that be shone on this would be appreciated.

Regards,
Tony



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Brad White_9

Ask Dave Yates what he thinks!

Yes, Tony, you hit on a concern to Dave and many more of us as we progress. Legionella is the primary but I am sure not only concern.

Generally not an issue in a closed system dedicated to heating, but to drink the stuff sitting in stagnant pipes all summer? Aerosolized in the shower?

I will defer to others for more detail but you have hit on a high octane subject indeed.

Tony Shupenko

Brad and Dan:

You confirmed my suspicions - I did this inspection for a purchaser of a home and will advised accordingly.

Regarding codes - these documents cannot address every odd-ball item that people may install.

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Empire_2

Just another thought.

The DHW does not have the recovery capability of a boiler and the supply temps are generally to lo to effectively heat the multiple convectors. In addition the constant introduction of micro air in to the system would surely kill the pumps. I bet they weren't Bronze style pumps were they?

My .02

Mike T.

Tony Shupenko

It was a small Taco type circulator that I often find in re-circ systems.

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