Blocked heat exchangers in boiler

[pemba]

Hi there i've previously posted about a noisy boiler after fitment of a couple of new radiators and it ended with me saying I was going to call out a CORGI registered plumber to identify the problem.

Well he duly came out and informed me that both heat exchangers were blocked causing a restriction in the water flow throuth them. This apparently causes a pressure build up resulting in the boiler stopping heating until the pressure reduces and then firing up again (hence the noise). While he was there he offered to ensure it wasn't the pump (i'd paid for the first 3/4 of an hour so thought why not!). So he swapped out the pump but it didn't change anything however, as he put my old pump back in he extracted a largish piece of wood (probably 1cm by 3mm by 3mm). So, obviously I was praying that was the blockage removed - no such luck. System reinstated and same old noise.

So the plumber recommended replacing both heat exchangers at a price of approx £650. Bearing in mind that the boilder is over 8 years old now I am obviously reluctant to spend this sort of money and then for it to pack in for a different problem in a couple of weeks! So is there any way to remove the heat exchangers and "back flush" them like you would a car radiator in olden days? obviously this would still incur the cost of removal and fitment but not the cost of the new ones (and I hate this mentality of simply replacing things when they exhibit a problem!).

Any advice appreciated

Pemba

 

[mcmoby69]

what make and model is the boiler?

 

[Andygasman2010]

You had wood in your boiler?

Assuming it's a combi with a main heat exchanger and a plate, generally you can clean them. What boiler is it?

 

[Agile]

You had wood in your boiler?

Why not? Its obviously a wood boiler!

He seems to have chosen a firm which expects to charge more for a simple repair than a new boiler can cost!

All I can say is that I would be very surprised if I could not repair it for less than £200 in my local areas!

Tony

 

[Andygasman2010]

No, it isn't 'obviously' a wood boiler. What do you mean?

 

[pemba]

Guys thanks for all the interest and sorry I should have said its a Valiant Combi boiler that has worked without problem for 8 years. When we had the system installed we retained 2 of the original curved radiators that fitted around the bay windows (although they were flushed through to remove as much gunk as possible) but replaced all the rest and the pipe work. Now i've got no idea how a piece of wood could've got into the system but the plumber certainly removed it from the boiler at the same time as he was re-fitting the old pump.

So do you think it is sensible to get a plumber who is more interested in fixing it than simply replacing parts?

Wish i'd never had the 2 new rads fitted! (the wife wanted to stick with an oil heater!)

Pemba

 

[Agile]

Cleaning blocked boilers is a common repair which we do.

Many prefer to just replace the part. This is usually more expensive and time consuming.

I can go to a boiler and clean it chemically or physically on the spot. Those who replace parts need to come back with them another day.

Thats usually the British Gas or Homeserve method as the employees have no interest in speedily sorting out the problem but rather meeting their target for the number of visits per day.

 

[nickso]

Thats usually the British Gas or Homeserve method as the employees have no interest in speedily sorting out the problem but rather meeting their target for the number of visits per day.

Part of the performance target is fixing the boiler first time so that kind of shows you know **** all and are talking out of turn....again. Cock.

In a perfect world we would all be doing one job a day like you Glazier, some of us like a bit of a challenge though.

 

[pemba]

many thanks to you both for your comments however its not too clear to me what the answer was (perhaps due to the snipping!). Any chance of a clear answer to the question please.

Pemba

 

[DP]

Well he duly came out and informed me that both heat exchangers were blocked causing a restriction in the water flow throuth them. This apparently causes a pressure build up resulting in the boiler stopping heating until the pressure reduces

News to me. First time I have heard that pressure rise will switch the boiler off. I wonder why the PRV does not let by if pressure is the problem.

So he swapped out the pump but it didn't change anything however, as he put my old pump back in he extracted a largish piece of wood (probably 1cm by 3mm by 3mm).

So, your plumber did not see the piece of wood when he fitted the new pump but did when he replaced the old pump. I think he is pulling your leg. Are you sure it was not a matchstick that was lying around?

I would be inclined to get someone else to look at the boiler, preferably not a plumber who just changes parts. What if the problem is elsewhere?

 

[mysteryman]

A powerflush with a chemical cleaner may help.

I agree with you about the sniping; this Forum would be better without it.

 

[onlyfitidealboilers]

Dose SD40 will sort this

 

[pemba]

Thanks for the responses guys, is SD40 actually Fernox DS-40?

Assuming it is then I see that it is about £60 for a box and it is designed to be used in a powerflushing unit (although it does note that it can be added direct to a radiator) - so is this something I can do myself or should I get a plumber with the right kit and know-how to do it?

Thanks again for the help guys

Pemba

 

[compheat]

What part of Lancashire do you live ??

 

[dcawkwell]

Run the filling loop and drain cock open for a while to flush the system out a bit. Add come chemicals to the system check the fernox website for suitable ones and let them run around for a while.
A lot cheaper than £600.