Descaling Modcon HX (Munchkin)

drosner

Have a Munchkin 140m from 2008 and have run new water through the system many many times for various reasons so have introduce my super hard well water with lots of minerals. I'm not having any problems with my 7 heating zones but seeing short cycling with DHW that points to potential scale issues on heat exchanger.

I see lots of information on flushing DHW coils but very little on mod-con boiler heat exchangers on the water side. Is this typical maintenance and if so what is a good target citric acid dilution to use? I've got a DHW descaler with 40% citric acid which i'm sure is too strong for a stainless steel HX.

Besides getting acid dilution right and neutralizing afterwards anything else i need to be aware of that could do damage?

hot_rod

If you are in doubt just get a bottle of the cleaners designed for the boiler.

Most important is to try and isolate the boiler and run the cleaner. If you add the cleaner to the entire system it dilutes it to the point of little usefulness.

Personally I would open it up and clean the fire side along with the internal waterways. There are a number of brands available