The Tank › Dangers of soft water with a tankless heater
- December 29, 2021 at 1:44 pm #26669Larry JonesParticipant
After replacing my tank gas water heater every three years, multiple times, I found this site, which specifically pointed the finger at my water softener. I purchased the powered anode, and my current tank is going strong at 6+ years. Thank you, thank you, thank you.
However, both the heater and boiler run through a power vent on the back of the house. The boiler is 30+ years old, the double walled vent is rotting, the vent is noisy. I am thinking about a high efficiency condensing boiler, but to get rid of the vent, I would need to get a combi unit with a tankless water heater.
I get the impression that soft water with the tankless heater isn’t a problem, but I want to make sure I am not shooting myself in the foot. Should I be worried about soft water killing the water heater side of a unit like this?
LarryDecember 29, 2021 at 4:00 pm #26670Randy SchuylerKeymaster
My friend Larry Weingarten may want to add something, but I don’t see a problem unless the boiler will have a storage tank. If that is the case, make sure the tank is not made of stainless steel because softened water WILL be hard on that, and if it is glass-lined, consider a powered anode for it, too.
Randy SchuylerDecember 29, 2021 at 5:06 pm #26673Larry WeingartenParticipant
Hi, A high efficiency or condensing boiler will likely have plastic pipe for venting. Often it is just 2″ PVC pipe. Might it be possible to keep your present water heater and go with the boiler for heating only? It’s commonly done, and there might be room for both vents. If the water heater has atmospheric venting, it can’t be combined with a power vent unit anyway. Hope that helps!
Yours, LarryDecember 29, 2021 at 7:15 pm #26674Larry WeingartenParticipant
A ps, To answer your question about softened water damaging a tankless heater, no it won’t if the softening is done right. You do not want to remove all hardness, bu leave 60 to 120 parts per million of calcium and magnesium hardness in the water. A very thin film of scale is good for metal in a domestic water system.
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