My central heating is controlled by a combi boiler. Occasionally the
hot water doesn't come on when the hot water tap is turned on. Having
spoken to a plumber he says that the problem a valve in the boiler
getting stuck because of a build up of limescale. The boiler also
‘buzzes' a bit when the heating is on. He has advised me to descale
the system using descaler fluid.

Can anyone advise me how to descale the system – the plumber advised
on draining a radiator and topping it up with the fluid – how do I do
this ?

Cheers
Nick

"Nick" wrote
| My central heating is controlled by a combi boiler. Occasionally
| the hot water doesn't come on when the hot water tap is turned on.

Is this *a* hot water tap or *any* hot water tap?

If the problem is one particular tap, it's probably a tap problem; google
for tap reviver as this was discussed a few weeks ago.

Owain

In message , Nick
writes
My central heating is controlled by a combi boiler. Occasionally the
hot water doesn't come on when the hot water tap is turned on. Having
spoken to a plumber he says that the problem a valve in the boiler
getting stuck because of a build up of limescale. The boiler also
€˜buzzes' a bit when the heating is on. He has advised me to descale
the system using descaler fluid.

Can anyone advise me how to descale the system €“ the plumber advised
on draining a radiator and topping it up with the fluid €“ how do I do
this ?

Does it come on for a short period ?
This would indicate limescale

I think you would be wise to post more details to the group in order
that a proper diagnosis might be made

what boiler for example

--
geoff

Hi

Thanks for youre responses.

I don't know much about boilers and plumbing but here's a description
of what's (I think) is happening.

When I turn on any hot water tap, sometimes there's no hot water. I
turn the tap off and then back on an there's an audible click from the
boiler and the boiler fires up - producing hot water from the tap €“
this can take several attempts. A plumber has advised that in the
boiler there a valve that switches between hot water and heating. He
stated that a build up of limescale may prevent this valve from
working efficiently. Adding descaler to the system, he said, would
cure it.

I don't know the details of the boiler - I will get them and post them
tomorrow if this helps

Cheers
Nick



raden wrote in message ...
In message , Nick
writes
My central heating is controlled by a combi boiler. Occasionally the
hot water doesn't come on when the hot water tap is turned on. Having
spoken to a plumber he says that the problem a valve in the boiler
getting stuck because of a build up of limescale. The boiler also
€˜buzzes' a bit when the heating is on. He has advised me to descale
the system using descaler fluid.

Can anyone advise me how to descale the system €“ the plumber advised
on draining a radiator and topping it up with the fluid €“ how do I do
this ?

Does it come on for a short period ?
This would indicate limescale

I think you would be wise to post more details to the group in order
that a proper diagnosis might be made

what boiler for example

My combi boiler had the same problem. The method of fixing depends on the
boiler.
Check the boiler manufacturers web site for the installer/service manual
quite a few manufacturers make them available on the web.

My boiler use the venturi effect and diaphragm to actuate a micro switch.

The fault diagnostics that I went through were

1) Draw hot water at a high rate
2) Do you get hot water, No
3) Manually actuate the DHW microswitch, Do you get hot water, Yes
4) Check water pressure and clean inlet filter, Do you get hot water, No
5) Check diaphragm for leaks and actuating rod for limescale / corrosion,
Yes to limescale / corrosion on actuating rod
6) Replace actuating rod so it moves freely, Hot work now works.

Adding a descaler to the system won't help much as side of the system you
need to descale in the DHW side not the central heating side.
So it's difficult and probably dangerous to put descaler in your mains water
supply.
The only way to descale them would probably be to remove the parts and
descaler separately. (or just replace them as I did).

Andrew


"Nick" wrote in message
om...
Hi

Thanks for you're responses.

I don't know much about boilers and plumbing but here's a description
of what's (I think) is happening.

When I turn on any hot water tap, sometimes there's no hot water. I
turn the tap off and then back on an there's an audible click from the
boiler and the boiler fires up - producing hot water from the tap -
this can take several attempts. A plumber has advised that in the
boiler there a valve that switches between hot water and heating. He
stated that a build up of limescale may prevent this valve from
working efficiently. Adding descaler to the system, he said, would
cure it.

I don't know the details of the boiler - I will get them and post them
tomorrow if this helps

Cheers
Nick



raden wrote in message
...
In message , Nick
writes
My central heating is controlled by a combi boiler. Occasionally the
hot water doesn't come on when the hot water tap is turned on. Having
spoken to a plumber he says that the problem a valve in the boiler
getting stuck because of a build up of limescale. The boiler also
'buzzes' a bit when the heating is on. He has advised me to descale
the system using descaler fluid.

Can anyone advise me how to descale the system - the plumber advised
on draining a radiator and topping it up with the fluid - how do I do
this ?

Does it come on for a short period ?
This would indicate limescale

I think you would be wise to post more details to the group in order
that a proper diagnosis might be made

what boiler for example