Central Heating Noise - Please help

[jazzie]

Hi

Boiler Glow-Worm Fuelsaver 45F
Approx 20 Years Old
Medium sized detached house 10 Radiators

I have a problem with my central heating I would be grateful for some advice with.

After the boiler has been on from cold to heat the house and before it cuts out (20-25 mins) noises, kettling? can be heard from what appears to be above the boiler. Upon restarting, after a short while, it does the same again and again until the desired room temperature is reached. The noise can be reduced by reducing the temperature on the boiler thermostat. The noise is the same for the hot water but with the smaller circuit comes on much quicker.

2 years ago, I had the problem but with much worse noise and a complete drain, flush, not powerflush, and clean was done with Fernox F2 Boiler Silencer and F3 Cleaner. This took it's time but removed the noise. This time it is nowhere near as bad but very niggly and can wake us at night as the main bedroom is above the kitchen.

I am wondering why it has come back, albeit not as bad, and why it doesn't appear to come from the actual boiler but very close to it. Could it be the boiler making the noise but the noise is somehow transmitted slightly away?

Any advice as to what it is and what to do next would be much appreciated.

Thanks

 

[Puddle]

The noise will probably be coming from the boiler as heat exchanger is scaling up again,noise can travel quite easily around the system due to the metal pipes and fittings
Did you but inhibitor in after you cleaned before,the inside of the heat exchanger is probably not as smooth as it used to be and allows limescale/corroded materials to build up easier,you could have a small leak in the system and new system water is entering the system through header tank bringing fresh corrosion in with it,maybe first tie ball valve up in header tank and see if tank empties over a week or so.also check no pump over at tank.If ok add a mild cleaner,and let run for a few weeks,see if improves,if not,back to what you did before,you could also try getting the burner gas pressures checked and lowered slightly if possible

imho

 

[jazzie]

Thank you for your reply, much appreciated

Can you tell me what you mean by 'check no pump over at tank' ?

Late last year we fitted a new pump and drained the whole system, so this would have removed the Fernox boiler silencer and any inhibitor but we did replace the inhibitor via a funnel into the tall bathroom radiator at the end of the job. If we just want to get some boiler silencer and more inhibitor back into the system what's the best way to do it? Do I need to drain out the whole system to get them in? Should we be cleaning the system again before adding inhibitor and silencer?

Does this sound like a good idea? Once I know we don't have a leak, I drain off enough water from the lowest radiator to empty the header tank and then add inhibitor and silencer to the header tank. Will this prevent us from having to flush out and clean the whole system or do I need to put in mild cleaner and flush out whole system first?

Can you recommend a mild cleaner if that's the way forward. As I said in my first post the noise is no where near as bad as a few years ago.

Thanks again

 

[Puddle]

'check no pump over at tank',make sure no system water is being pumped up the open vent into tank when system on

If all ok and water in system still clean,problem probably caused by removing inhibitor last year and as said heat exchanger pit holed inside allowing debre to attach easier

Do as you say drain off enough to empty tank and then maybe one bucket full and add mild cleaner into tank and refill,I would use sentinal 400,it is a mild cleaner,stay away from anything to strong,leave in the system , after hopefully noise dies down,could take a few days/week could take up to 4 or 5 weeks,sound from boiler should get progressively quieter though, then drain and add inhibitor,here I go for fernox,if sound still remains you may have to take further action but if noise just started,hopefully above will do the trick

imho

 

[jazzie]

I will do as you have suggested.

When we removed the inhibitor last year we did put a new lot straight back in, would removing the old yet still replacing it, have made much difference to the water?

Thanks again, much appreciated.

 

[jazzie]

Hi

It's been 3 weeks since we put the sentinel cleaner in the central heating system. It seems to be improving the noise on the central heating but on the hot water when the smaller circuit is in use the noise is still pretty bad albeit slightly better. Should we be seeing more of an improvement yet or do we need to wait longer?, you said to leave it in 4-5 weeks.

When we drain and refil the system we plan to put Fernox F2 boiler silencer in with the inhibitor as this is what we did when we last had the noise. Do you think that is a good idea?

Also I believe when we last had the problem 2 years ago the burner pressure was turned down slightly. Would this mean it cannot be done again?

If you need any more information please let me know.

Really appreciate any help.

Thanks

 

[Puddle]

Good to see an improvement and will take a while yet however should be getting better on both circuits,as you say the hot water circuit is smaller ,the difference here is that the boiler reaches temp quicker,I wondering it boiler thermostat is slightly out of calibration and boiler getting to hot when full temp achieved,try turning boiler thermostat down slightly and see if improvement,if so ,get thermostat replaced
The gas pressure were probably reduced last year to take some of the strain from the heat exchanger at high temperatures however this has to be done by a qualified person,who can set within the range stated by the manufacturer ,try turning boiler thermostat down first and see how you go

imho

 

[jazzie]

Thanks for your reply

We have already turned the boiler thermostat down which relieved some of the noise, this was before I posted the problem 3 weeks ago.

Looks like we will have to be patient.

Thanks again for your advice.

 

[jazzie]

Hi
I am pleased to let you know the boiler noise has stopped when both the central heating and hot water are being heated.
I would like to know if it is possible to leave the cleaner in until we return from holiday late September as that is when the heating will be on again properly. I am concerned that if we drain the system now the new inhibitor we put in will not get mixed into the water as only the hot water circuit is currently being used and will be throughout the summer months.
At present there is inhibitor in the system with the sentinel X400 cleaner as we only drained a small amount when we put the cleaner in.
Basically can we leave it as it is and then drain and refill putting the new Fernox F1 Protector and F2 Silencer in late September?
Thanks

 

[pobsdad]

No,don't leave it in that long.When you put the inhibiter in,turn on the heating for 15 minutes,that will mix it up.

 

[jazzie]

No,don't leave it in that long.When you put the inhibiter in,turn on the heating for 15 minutes,that will mix it up.

Thank you for the advice