Boiler kettling

[Largemoo]

I have an Ideal mexico CF 40/60 floorstanding boiler that is situated on the ground floor. There is a hot water tank on the 1st floor which is gravity fed from the boiler.

When the boiler fires up, there is a knocking noise from the boiler which echoes around the house. I'm fairly sure that the problem is kettling (also confirmed by a plumber) but no matter what I do I can't seem to cure it.

I desperately need a solution as the boiler starts up at 6:00am every morning, which wakes up my 4 year old. Anyone with kids will know that within 5 minutes the entire house is up and watching cebeebies!!!

I've tried the following:

1. drained the system and refilled adding x200 and inhibiter.

2. drained the system again and added more x200 and inhibiter

3. turned the boiler thermostat down to between 1 and 2 (54 to 60 deg C)

Would fitting a pump to the primary circuit help? this would speed up the flow through the heat exchanger and I believe in theory reduce the chance of the water boiling? If so, does anyone know what pump I should install?

Is the boiler "knackered", is it time to replace?

Any other advice??

thanks

 

[chrishutt]

Boiler silencer products like Sentinel X200 take some time to work, possibly several weeks, so perhaps you need to be a little more patient.

If boiler silencer doesn't work, you could treat the boiler with a stronger chemical to break down the scale and sludge. I've used Fernox DS3 successfully, but it needs to be flushed out after it's recommended period in the boiler.

 

[Soggy_weetabix]

if its a seroius sludge problem I would dare to suggest DS40.

Now I just wait or the backlash from plumbers that are too scared to use it.

David

 

[Largemoo]

Thanks - the X 200 was in the system for 1 month first time round and the second lot has been in for about 2 months now - hence I think that it's not going to work!

I'll try DS3 first - what is DS40 and why would anyone be scared?

Again, thanks for the help

 

[Nige F]

Fernox boiler silencer done 3 with great sucess i

 

[dal5band]

They say water gets trapped under the scaling and boils locally so you have to tackle the scaling.

 

[kevplumb]

I'll try DS3 first - what is DS40 and why would anyone be scared?

ds3 is a descaler it wont work

ds40 is what makes rads dissapear in an old system

 

[bab]

DS 40 is fine if u follow the instructions. Some only fear it because its a little agresive but u gota get rid of years of scale in a castiron heat exchanger so it time to get agresive. X200 s not so bad on a low water content boiler but its that weak u can leave it in permanently. the worst that can happen is the DS 40 will clean the system that well it will highlight the weak points in the system that will need addressing sooner or later. I recomend u try this nxt to aviod wasting any more money & time.

 

[Largemoo]

So, it sounds like DS40 is the Daddy of descalers?

I spoke to a mate of mine who said that if I'd used X200, DS3 wouldn't do much good. He said DS40 would do the job.

I must say I'm still a bit apprehensive.......

I'll post my results.

Cheers

 

[chrishutt]

Ask Fernox what they would recommend. I expect they will say DS3 since it's a descaler, which is what you want. But what do they know?

 

[kevplumb]

take a cast h/e out of a boiler
fill with DS3
end result



sweet FA

and yes i have

 

[ricarbo]

How do you know the thermostat on the boiler isn't faulty and allowing it to go overtemperature and boil? Until that's confirmed, the rest, though interesting, is a bit academic.

 

[Largemoo]

The safest solution so far appears to be to take the HE out of the boiler and fill with DS3.
However, I think thats a bit beyond my skills!

I've tested the Boiler thermostat - all is OK.

whats the worse thing that can happen with DS40? (anything major that does happen will be punished by death by the missus)

Thank for all the help so far

 

[ricarbo]

I would have thought that if you can remove the heat exchanger then you can safely descale it with anything you like, because you won't contaminate the rest of the system. So, you coud use kettle descaler, vinegar etc. I don't know and I haven't tried it, but I would imagine these are stronger than products made for adding to central heating systems, which must be very diluted by the water in the whole system. Cheaper too.
If it's a question of harmony at home, rather than taking a functioning boiler to bits at this time of year, I'd probably reset the timer to a later start and use an electric panel heater with timer and thermostat in the kids room etc. Obviously, you'd have to buy the heater(s) and you'd use more electricity, but you'd save some gas. What are the relative values of - a)domestic bliss and b) poor old Dad's bank balance?

 

[ricarbo]

I would have thought that if you can remove the heat exchanger then you can safely descale it with anything you like, because you won't contaminate the rest of the system. So, you coud use kettle descaler, vinegar etc. I don't know and I haven't tried it, but I would imagine these are stronger than products made for adding to central heating systems, which must be very diluted by the water in the whole system. Cheaper too.
If it's a question of harmony at home, rather than taking a functioning boiler to bits at this time of year, I'd probably reset the timer to a later start and use an electric panel heater with timer and thermostat in the kids room etc. Obviously, you'd have to buy the heater(s) and you'd use more electricity, but you'd save some gas. What are the relative values of - a)domestic bliss and b) poor old Dad's bank balance?