WB 26CDi Extra Suspected blocked secondary heat exchanger

[tryitandsee]

Attended this boiler today with our regular gas safe engineer and he suspects the above. (Sounds like the SHE is full of water).
The boiler makes a gurgling sound and the gas flame never really gets going, flames then seem to choke and extinguish. Boiler cuts out and goes into slow red flash.

He managed to get the condensate out and cleaned all that up. He then tried to blow compressed air back up the plastic drain pipe that leads from the SHE to the condensate trap, hoping to clear suspected blockage.

We ran out of time and will have to come back. I just wondered if any one has had the same problem and knows of a way of clearing this blockage without having to take the SHE right out, as it is located right at the back of the boiler.

It is a non servicable part, but being stainless steel I was hoping that it can be cleaned/cleared of blockage.

Thanks if anyone can pass on any tips

 

[nickso]

oh dear, the ultra turd.

i seem to remember replacing the SHE on one of these many moons ago. dont remember how bad it was to do. iirc the condensate connection was a **** to get back on but i think that was more to do with the boiler position than anything else.

mine was sludged up along with the main H/E. would probably get the crap out with the sonic machine these days.

 

[tryitandsee]

Yes the expansion cylinder is right up tight to the protruding pipe. I could not get my hand to it, as I was trying to push some 'wire' up the tube, hoping to unblock.

Plumber said this was a first try for wb at Condensing, all mistakes learnt on this one!!!!!

 

[davebgas]

Mr Muscle or caustic soda. Put in AM go back PM and flush very throughly

 

[tryitandsee]

Thanks daveb

Worth a try if you can recall, should I introduce this by taking off the flue bend and pouring it in there, where the flue bend enters the exchanger (top left looking at boiler).

 

[davebgas]

Well, the gas engineer should anyway

 

[tryitandsee]

Yep of course

He's well used to me by now, although he will be impressed with this idea, as it was going to be quite a pain to take it all apart, especially renewing all the o rings etc.
Thanks again.

 

[davebgas]

Not 100% guaranteed mind you!

 

[tryitandsee]

To conclude this thread.
It was the SHE blocked at the bottom, where the small curved metal outlet pipe connects via a rubber tube to the condensate trap.

We tried the Caustic soda and boiling water but no joy.
Had to take the majority of the boiler apart to get the SHE out. When out, it was still quite a job to unblock the small drain tube, it was well and truly plugged. The SHE was full of condensate water and therefore not allowing the flue gases to get to the outside, thus the gurgling noise.

Once unblocked flushed through with caustic and boiling water.

Put back and she runs as good as new. Am quite impressed with these boilers, as they don't get treated with any kindness and this one is getting on a bit.