Limited Hot Water

[Peter 631 plumbing]

My boiler is very old about 25 years, and I haven't many issues with it until lately. It has a tank-less coil and the mixing valve is shut completely for the highest temperature. When someone takes a shower the hot water is there but limited. This happens even when no one else in the home is using the hot water. I was thinking it was a dirty coil, so I shocked it a few times by opening and closing the the supply to the coil while having a faucet open. It works a little bit better now. Anything else I can do? For those following my threads this is my second home without Hydromx installed. (yet) Thank you

 

[Jadnashua]

After 25-years, the interior of the coils are probably heavily coated with mineral deposits, and turning the water on and off won't break them free. You'd need to isolate the inlet and outlet, and then either use some vinegar or other acid that can dissolve the deposits, flush it out, then restore the normal connections for fresh water. They do make a valve kit for this, and a small pump and a bucket with some fittings, you'd pump the acid solution through it for several hours, to maybe overnight, and that may resolve the issue. That type of system is very energy inefficient, though, as it requires the boiler to remain on with a fairly high storage temperature 24/7 so you can have hot water. You might want to consider an indirect water heater tank, and treat that as a separate zone. That part would be usable with your replacement boiler. That would allow you to turn down the standby storage temp in the boiler itself, and it would only go up when there was a call for heat. You'd size the tank to your biggest use, and it would typically be smaller than a stand-alone WH, since the boiler has (most of the time) lots more heating capacity than a stand-alone tank, whether electric or hydronically heated.

 

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[Peter 631 plumbing]

Thank you for the response. I did give an indirect a thought I think it would be a good idea then in a few years switch my boiler. I'll probably just that for now since there was always an issue of limited hot water when using multiple appliances or showers