descaling heat exchanger

[Richard]

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

[Andy McKenzie]

Not really an answer - but my father in law was told that the rattling noise on his 4 or 5 year old, wall mounted, boiler was due to scaling up, and that he needed a new heat exchanger, and surprise surprise this wasn't covered in his service plan. He asked the engineer how this scaling had occurred in a sealed system (not combi), that the same large ex nationalised company had maintained since installation - cue no good answer. It took us about 30 seconds to fix the rattle - the casing was slightly loose and vibrating against the wall!

Andy

[Dan delaMare-Lyon]

Boiler Noise Silencer/Descaler?

Fernox/Purimachos/Sentinel do them.

I've used Purimachos to great effect in my open ventes traditional system.

Cheers Dan.

[John Carlyle-Clarke]

"Richard" wrote in news: [e-mail]:

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.

[raden]

In message , Richard writes

If it's badly scaled up, you need a descaling pump and the appropriate chemical (see the Fernox or Kamco websites)

As it happens ... I have a descaling pump, I'm in Watford

[IMM]

The plumbers may mean econonically de-scaled. In the time taken it may be cheaper to replace the plate.

[IMM]

Maxie, how much do these cost to buy?

[raden]

In message , IMM writes

I would have thought you would have known such things. I have no idea what mine cost, but they're not cheap.

For anyone interested

be a useful site to look at

[Thomas Prufer]

For a one-off, those cheap pumps that are driven by a drill are sufficient. Rubber vanes in a plastic case. They build up sufficient pressure to push through a bit of crud. Mine at least reverses well enough, littel arrows notwithstanding, so you can cycle backwards and forwards to get all the littel pipes clean.

There is also enough pressure to pop carelessly secured hoses off, spraying acid all over the place.

Thomas Prufer

[IMM]

Maxie, I don't buy one every week.