Thread: Unusual heating set up

I came across this today, and while I don't think heating off a hot water heater is very economical, it is possible.

Since it's the only system in the home, my immediate thought was backflow from the heating loop into the domestic hw. There is no backflow prevention to the domestic. I did notice there are 2 pairs of feeds/returns, so there is a possibility of separate chambers within the heater. I am not aware of such a water heater (not boiler, which I know exists), and plan on calling the mfg to confirm.

Any input?

I will post pics when my son gets home, I cannot figure out how to resize them.

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There are water heaters which have separate and independent heating system coils in the heated potable water.

They are, however, specifically listed and rated for that use.

Yup, they make dual units. The first time I saw one I had to take a double look, same as you, as I thought it was a water heater with a return loop then noticed the fourth line. That was about 18 years ago??? If I remember right, it was labeled "domestic use" and "heat use", or something along those lines, on the unit.

Was it an Apollo unit? We have a lot of them in my area.

Originally Posted by Jack Feldmann

Was it an Apollo unit? We have a lot of them in my area.

The unit is a Bradford White. I noticed the additional hook ups and suspected a dual unit. This is a new one for me.

Originally Posted by Steven Turetsky

The unit is a Bradford White.

Propane Gas Combination Water Heaters Atmospheric Vent | Bradford White Water Heaters. Built to be the best.

There are open-loop hydronic heating systems that use the domestic hot water for both the fixtures and home heating. Does not need to be kept separate. Most hot water heaters plumed for dual use do NOT have a separate coil inside. Just two sets of attachments. Couldn't tell you if the open-loop or closed-loop system is more common.

Originally Posted by Kyle Smith

There are open-loop hydronic heating systems that use the domestic hot water for both the fixtures and home heating. Does not need to be kept separate. Most hot water heaters plumed for dual use do NOT have a separate coil inside. Just two sets of attachments. Couldn't tell you if the open-loop or closed-loop system is more common.

Respectfully beg to differ on the open-loop part Kyle. There are many reasonsto keep the systems separate, code only being one of them. A"regular" domestic water heater is not listed as a device for heatingunless specifically noted and if it ain't noted, it ain't allowed.

The water in the heating loop(s) becomes stagnant over the summer and when the circulatingpumps are kicked on in the fall that stinky, slimy, smelly, stagnant, waterfinds its way out of the shower head and right in your face.

I am a little embarrassed to say I know all of this because I have done it andlearned my lesson the hard way.

Am I proud? Heck yes, I learned a lesson. Would I do it again? Nope, don't believe I would.

Originally Posted by Rod Butler

Respectfully beg to differ on the open-loop part Kyle. There are many reasonsto keep the systems separate, code only being one of them. A"regular" domestic water heater is not listed as a device for heatingunless specifically noted and if it ain't noted, it ain't allowed.

The water in the heating loop(s) becomes stagnant over the summer and when the circulatingpumps are kicked on in the fall that stinky, slimy, smelly, stagnant, waterfinds its way out of the shower head and right in your face. .

Sorry to hear you had such a bad experience. My permitted and approved open system used a "dual-use" gas hot water heater for combined space/water heating. And when there was no longer a demand for heat you turned a valve that made the water be first pulled through the floor before entering the hot water heater. (Water was never sitting around.)

On a side note: As mentioned above, I don't think it was any more efficient and changing the temperature took forever. Dogs loved it tho..

I have seen boilers with a heating loop, hot water loop, and "Bathroom" loop. The bathroom was kept nice and toasty while the rest of the house could be raised and lowered as desired.