View Single Post
  #4   Report Post  
John Carlyle-Clarke
 
Posts: n/a
Default

"Richard" wrote in
:

How do I descale the heat exchanger on my gas fired central
heating system.


I descaled the plate heat exchanger on my oil-fired combi. I removed
it from the system and put it in a bath of decaler. I tried a few
varieties (I've had the boiler apart a few times now, and every time I
dump the heat exchanger in descaler while I am working, just for the
hell of it) but they all seemed similar.

There are some weak, enzyme based ones for plastic kettles and irons
and the like, which often need to be warm, but they are so slow!
Better is something chemical like Kilrock or similar. Just get
something from a hardware store. My heat exchanger was stainless
steel and copper, and seemed unharmed by even a fairly strong
solution.

The real problem is that a plate heat exchanger is a funny shaped
device internally, so you need to keep turning it in the liquid bath,
both to get the stuff into all the crannies inside, and to let the gas
out (which will act to keep the liquid off the scale if it builds up).

I gave it about 48 hours in solution, turning it constantly for the
first half hour or so, then occasionally after that. It cured the
original problem (no hot water) so it must have done something.

Two plumbers have told me these can't be descaled and have to be
replaced. I can't swear that it it 100% clear of scale, but it
certainly seems to be working very efficiently again.

Hope that helps.