cleaning boiler's heat exchanger coils

Nom_Deplume

I have a Munchkin. I vacuum out the coffee grounds every year and spray CLR.  The inside is clean, except for the stainless steel coils being badly stained especially around the bottom. They have been that way since the early days, when I didn't clean the first year and quite a lot of coffee grounds collected there.



Will scrubbing with Barkeepers Friend take the stains out? Is this a good idea? CLR certainly doesn't affect the stains in any way.



Are the stains a problem for the functioning of the boiler?? Am I worrying about something no one will see and which makes no difference in practice?

hot_rod

clean HX surfaces

are always the best. Both inside and out



But if it is just a light scale build up, sometimes the cleaning chemicals can do more harm than good. Check to see what cleaners, if any, the manufacturer allows to be used.



If the HX is discolored it could be caused by overheating conditions. Not enough flow caused by improper pump sizing or the inside of the HX is getting restricted.



if you have a boiler that takes on fill water on a regular basis, you could be fouling the HX and causing problems like this example of overheating and discoloring of the HX.



If the fill water is hard the problem can be seen in a short period of time. Hard mineral deposits are attracted to hot surfaces. An electric water heater element is a good example.



With radiant in-slab especially, it is always wise to confirm the system is leak free by a pressure test. with the fill valve in the off position, of course.

Steve Whitbeck

cleaning

Don't worry about any staining of the heat exchanger. Just clean the coffee grounds off the heat exchanger and run a feeler guage between the tubes from 3 o clock to 9 o clock.

Never use strong chemicals on any giononi heat exchanger.

Expecially anything with clorine. ( hydrocloric acid )

flush the drain lines.

Nom_Deplume

thanks!

Thanks for the replies. Coils don't look as bad as that photo! Just some dark patches.



I have no idea what they look like on the inside, of course. I know water heaters get calcium deposits from hard water,  but only on the water side, not on the heat side. System is leak-free i.e. holds water pressure for years with makeup water turned off.



Regarding HCl, I did use Rydlyme for a few years (HTP recommends it in the manual).  I have stopped now.  I don't know if it did permanent damage. The HX coil surfaces feel rough to the touch.

Nom_Deplume

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