Recently moved house and found we have a very noisy/clanking boiler.
When the boiler has been on for about 20 minutes it starts for a few
minutes then cuts out and starts up again. This is a typical example
when the boiler is on. Air in the system you may say, but I have bled
the radiators about 30 times with little or no air coming out now. We
have been here 2 months and drained the system twice because of a
previous problem and a radiator relocation.

Any ideas?

"Jayne" wrote in message
.com...
Recently moved house and found we have a very noisy/clanking boiler.
When the boiler has been on for about 20 minutes it starts for a few
minutes then cuts out and starts up again. This is a typical example
when the boiler is on. Air in the system you may say, but I have bled
the radiators about 30 times with little or no air coming out now. We
have been here 2 months and drained the system twice because of a
previous problem and a radiator relocation.

Any ideas?

This is kettling I reckon. Do you have TRVs fitted to all your radiators? If
so leave one open and see what happens. Are the radiators getting hot?

Generally with TRVs if they are fitted to all radiators then the boiler
heats up, the TRVs close when the room is warm enough and the boiler can't
dissipate the heat inside so it boils. You should have one radiator open all
the time, ideally the one in the same room as your room stat if you have
one.

--
MAlc

In article ,
says...

"Jayne" wrote in message
.com...
Recently moved house and found we have a very noisy/clanking boiler.
When the boiler has been on for about 20 minutes it starts for a few
minutes then cuts out and starts up again. This is a typical example
when the boiler is on. Air in the system you may say, but I have bled
the radiators about 30 times with little or no air coming out now. We
have been here 2 months and drained the system twice because of a
previous problem and a radiator relocation.

Any ideas?

This is kettling I reckon. Do you have TRVs fitted to all your radiators? If
so leave one open and see what happens. Are the radiators getting hot?

Generally with TRVs if they are fitted to all radiators then the boiler
heats up, the TRVs close when the room is warm enough and the boiler can't
dissipate the heat inside so it boils. You should have one radiator open all
the time, ideally the one in the same room as your room stat if you have
one.

--
MAlc

We have 11 rads in total, 4 have TRV's (bedrooms). All radiators are
getting hot. It does actually sound as though the water is bubbling
(red hot). Any chance the thermotat could have gone in the boiler?

Jayne wrote in message d.com...

We have 11 rads in total, 4 have TRV's (bedrooms). All radiators are
getting hot. It does actually sound as though the water is bubbling
(red hot). Any chance the thermotat could have gone in the boiler?

I had similar trouble with a boiler a few years ago which was caused
by sludge and scale build up. As I understand it this can clog up the
heat exchanger meaning that heat from the burners is not dissipated
quickly enough causing the boiler to overheat and clank. I solved the
problem with a couple of doses of a pretty caustic product from Fernox
(DS40 as I recall) and a lot of flushing. Search the archives on
Google, there are several threads on this.

However, my clanking started up pretty much as soon as the boiler came
on. I can't explain why yours should take 20 minutes to start.

In article ,
says...
Jayne wrote in message d.com...

We have 11 rads in total, 4 have TRV's (bedrooms). All radiators are
getting hot. It does actually sound as though the water is bubbling
(red hot). Any chance the thermotat could have gone in the boiler?

I had similar trouble with a boiler a few years ago which was caused
by sludge and scale build up. As I understand it this can clog up the
heat exchanger meaning that heat from the burners is not dissipated
quickly enough causing the boiler to overheat and clank. I solved the
problem with a couple of doses of a pretty caustic product from Fernox
(DS40 as I recall) and a lot of flushing. Search the archives on
Google, there are several threads on this.

However, my clanking started up pretty much as soon as the boiler came
on. I can't explain why yours should take 20 minutes to start.

I have just had the plumber round and he thought he sorted it. All the
time he was here nothing happened. Typical. He said it was air in the
system. He bleed the pump and lots of air came out. It didn't make a
noise and didn't cut out. Until now. It's started again, back to
square one :O(

"Jayne" wrote in message
.com...
In article ,
says...
Jayne wrote in message
d.com...

We have 11 rads in total, 4 have TRV's (bedrooms). All radiators are
getting hot. It does actually sound as though the water is bubbling
(red hot). Any chance the thermotat could have gone in the boiler?

I had similar trouble with a boiler a few years ago which was caused
by sludge and scale build up. As I understand it this can clog up the
heat exchanger meaning that heat from the burners is not dissipated
quickly enough causing the boiler to overheat and clank. I solved the
problem with a couple of doses of a pretty caustic product from Fernox
(DS40 as I recall) and a lot of flushing. Search the archives on
Google, there are several threads on this.

However, my clanking started up pretty much as soon as the boiler came
on. I can't explain why yours should take 20 minutes to start.

I have just had the plumber round and he thought he sorted it. All the
time he was here nothing happened. Typical. He said it was air in the
system. He bleed the pump and lots of air came out. It didn't make a
noise and didn't cut out. Until now. It's started again, back to
square one :O(

Hmmm. Either you have a leak which is causing air to get into the system or
it could be that your stat is cream crackered as you said earlier. Does the
problem go away if you turn the boiler stat down? If there's air getting in
where is it coming from? Are there any tell tale leaks or patches of rust on
the radiators?

--
Malc

In article ,
says...

"Jayne" wrote in message
.com...
In article ,
says...
Jayne wrote in message
d.com...

We have 11 rads in total, 4 have TRV's (bedrooms). All radiators are
getting hot. It does actually sound as though the water is bubbling
(red hot). Any chance the thermotat could have gone in the boiler?

I had similar trouble with a boiler a few years ago which was caused
by sludge and scale build up. As I understand it this can clog up the
heat exchanger meaning that heat from the burners is not dissipated
quickly enough causing the boiler to overheat and clank. I solved the
problem with a couple of doses of a pretty caustic product from Fernox
(DS40 as I recall) and a lot of flushing. Search the archives on
Google, there are several threads on this.

However, my clanking started up pretty much as soon as the boiler came
on. I can't explain why yours should take 20 minutes to start.

I have just had the plumber round and he thought he sorted it. All the
time he was here nothing happened. Typical. He said it was air in the
system. He bleed the pump and lots of air came out. It didn't make a
noise and didn't cut out. Until now. It's started again, back to
square one :O(

Hmmm. Either you have a leak which is causing air to get into the system or
it could be that your stat is cream crackered as you said earlier. Does the
problem go away if you turn the boiler stat down? If there's air getting in
where is it coming from? Are there any tell tale leaks or patches of rust on
the radiators?

--
Malc

Can't see any leaks or patches at all. The plumber said the stat on the boiler
isn't supposed to work as the wall stat and the water stat control the
boiler. The problem seems to get a little quieter when you turn the
boiler down, but this doesn't ring true with what the plumber is saying.

In article ,
Jayne wrote:

The plumber said the stat on the boiler
isn't supposed to work as the wall stat and the water stat control the
boiler.

"I am not a plumber", but I thought the boiler *had* to have a
thermostat in order to operate properly, so that the circulating water
doesn't get too hot.

My own boiler is forever turning itself off (every couple of minutes
after the first 15 minutes) before the CH is up to heat, because its
thermostat is telling it to cool down a bit: opposite problem to yours.

Sounds to me like you have the classic CH problem: too many permutations
of the components involved for an easy diagnosis to be made. And one of
those components is the most expensive: the plumber/heating engineer.

I would just *love* to meet a plumber who says "Sorry mate: I can't
figure this one: try another plumber!"

(As you can tell: I, also, have experienced exactly what you have. It
was only cured a couple of years later when we got in a different
plumber, who actually said / alleged that the previous bloke had coupled
up the boiler the wrong way round. Whatever: after the second one had
finished, we didn't have the same problem any more.)

Best of luck!

John

On Tue, 16 Nov 2004 21:07:05 GMT, Jayne strung
together this:

The plumber said the stat on the boiler
isn't supposed to work as the wall stat and the water stat control the
boiler.

Get yourself a non-dangerous plumber who hasn't just finished reading
'the ladybird book of boilers'.
--

SJW
A.C.S. Ltd