glow worm economy 50plus kettling and knocking

[kofi2003uk]

hello ,
my boiler has been kettling and also the largest radiator in the house (ten radiators) has been knocking when the it gets hot.when the heating is turned off, it knocks continously for about three times and stops.

the boiler workd fine apart from this. the boiler thermostat has been turned to the very minimum but the boiler is still noisy and kettles intermittently.

just been told that my central heating needs chemincal descaling and power flush. this will cost me about £500 so i just want to make sure that is what will solve the problem.
please advice. i dont want to pay £500 and then find out that the problem is still there.
many thanks.

 

[Fluffster]

A powerflush will clean the system you may need a seperate heat exchanger descale.
Check out the cost of a replacement heat exchanger
Pete

 

[kofi2003uk]

many thanks,Pete.i will investigate the cost of the heat exchanger.

 

[Eternal Heating]

how did you get on with this? i've just been told i have the same problem

 

[Broondog]

All,

My boiler is whilstling loudly also. Can you please advise if you have actioned this cleaning and if it has worked.

My problem is described below:

When the boiler fires from cold, everything appears to work quietly. I assume therefore that pump and fan are ok. The whilstling is after about 5 minutes when evidently the water temperature is approaching working temperature.

I have pin pointed the fault down to either;

Heat exchanger blockage causing kettling (although Im not convinced)
Problem with burner as the noise is only evident when the boiler is firing
Or the thermostat being faulty (i.e. not cutting burner off at right temp - the overheating is causing kettling and steam release)
The seal being broken between the 90o bend and the boiler flue.

Can any body help trace the fault.?

The fault is purely when the water temperature is hot and the burner is firing

 

[kofi2003uk]

well, i spoke to the engineer about the heat exchanger being scaled. he said he has to dismantle the boiler to get to the heat exchanger and that will mean replacing seals and other items on the boiler.he suggested we first try a liquid descaler which he will add to the system tomorrow. this will have to be left in the system for some time and he will come back and drain/refill the system.
i suppose if this does not work then we will have to go to the next step which will be the cleaning of the heat exchanger. i an not a heating engineer but the impression i get is that ,power flust should probably be the last and final thing to do to stop the kettling and knocking of the radiators. i stand corrected on this by the expects.
i will let you guys know how i get on. can you post any info you have on this as well?
thanks

 

[kofi2003uk]

Broondog,
i assume you have the same boiler as i have. if you come up with any updates, can you let us know,please? i will keep you updated if i come up with any info. my is glow worm economy 50 plus and installed in 2000.
thanks

 

[kofi2003uk]

i put fernox in one of the radiators yesterday so fingers crossed.i am told i hae to leave it for about a week. hopefully this should stop the kettling and knocking.

 

[Soggy_weetabix]

Its very easy to remove the heat exchanger on this boiler.

I have successfully fully restored them with D Block, as well as a DS40 system cleanse.

David

 

[Broondog]

I have not tried system cleaning yet but I can honestly understand how this problem would have come on so suddenly.

Co-incidently, I had a poor service done on this 1 month prior to this problem starting.... I saw the guy taking the front off the boiler so there is a chance that all the muck that was brushed off, was not removed.

In addition to this, there is the possibility that when he turned the burner off, it was not reset properly. I see from the O&M manual that the flame height has to be commissioned properly.

Damn gas boilers.... and
Damn heating engineers... £60 per hour, thats £450 per day.
I am in the wrong job