Hi,

I need some expert advice before I call the plumber out again !

Some background info...

We have a 2 bed semi with cetnral heating and water heated via a Baxi
wallmounted boiler in the kitchen - about 20 years old.

The only problem we have had until recently was the boiler cutting out
due to air in the system (a few years back) - plumber found the vent
pipe wan't venting due to an air seperation thingy problem. He didn't
replace this but did something that involved cutting the feed pipe to
it and all was fine.

About a year ago we had an extension fitted where the unused kitchen
rad was moved to the extension and plumbed off the feed/return pipes
to the boiler - a cheap option. The plumber never got this working to
my satsfaction ,so I ended up draining the system bleeding it all and
its now fine. I didn't put any inhibitor in as I didn't know any
better :-(

Recently there have been banging noises from the pipes/ boiler - it
wakes us up in the morning.

the plumber came and did a boiler service and injected some furnox
boiler silencer to the bathroom rad. This was fine for a week then
the noise came back. I had a look in the feed/expansion tank and saw
rusty gunk on the surface of the water - I assume this is what the
furnox does ?

I bialed this out and drained the system using all 3 drains on the
rads. This again fixed the noise for a week and it then came back.

It only seems to be for the first 5 mins of the boiler heating up.
After that it is still there when boiler switches off/ on - but not as
loud.

I then got some sentinel x100 + x200 and partially drained the system
and added via the tank.

It hasn't worked and the noise is getting worseand I'm £25 worse off !

So, my question (eventually!). Why has the noise gone then come
back? Is this somehow related to the initial problem with the vent
pipe / air separator ? could there be some rust/gunk in the system
cuasing it ? Is there some air in there causing/adding to the problem
- should I have done any draining/bleeding at the boiler?

Would it have fixed it if I had fully drained the system then added
the chemicals?

I can't afford a new boiler, so it there anything else I/ the plumber
could do to fix it?

thanks for any advice and for reading all this!

Ian
--

What we have here is a failure to communicate.

Blonks wrote:
Hi,

I need some expert advice before I call the plumber out again !

Some background info...

We have a 2 bed semi with cetnral heating and water heated via a Baxi
wallmounted boiler in the kitchen - about 20 years old.

The only problem we have had until recently was the boiler cutting out
due to air in the system (a few years back) - plumber found the vent
pipe wan't venting due to an air seperation thingy problem. He didn't
replace this but did something that involved cutting the feed pipe to
it and all was fine.

About a year ago we had an extension fitted where the unused kitchen
rad was moved to the extension and plumbed off the feed/return pipes
to the boiler - a cheap option. The plumber never got this working to
my satsfaction ,so I ended up draining the system bleeding it all and
its now fine. I didn't put any inhibitor in as I didn't know any
better :-(

Recently there have been banging noises from the pipes/ boiler - it
wakes us up in the morning.

the plumber came and did a boiler service and injected some furnox
boiler silencer to the bathroom rad. This was fine for a week then
the noise came back. I had a look in the feed/expansion tank and saw
rusty gunk on the surface of the water - I assume this is what the
furnox does ?

I bialed this out and drained the system using all 3 drains on the
rads. This again fixed the noise for a week and it then came back.

It only seems to be for the first 5 mins of the boiler heating up.
After that it is still there when boiler switches off/ on - but not as
loud.

I then got some sentinel x100 + x200 and partially drained the system
and added via the tank.

It hasn't worked and the noise is getting worseand I'm £25 worse off !

So, my question (eventually!). Why has the noise gone then come
back? Is this somehow related to the initial problem with the vent
pipe / air separator ? could there be some rust/gunk in the system
cuasing it ? Is there some air in there causing/adding to the problem
- should I have done any draining/bleeding at the boiler?

Would it have fixed it if I had fully drained the system then added
the chemicals?

I can't afford a new boiler, so it there anything else I/ the plumber
could do to fix it?

thanks for any advice and for reading all this!

Ian

I had a similar problem a couple of years ago. The noise and vibration when
the boiler fired up was attrocious. A British Gas engineer then almost
condemned the system due to leakage of flue gases into my loft, most likely
caused by the vibration damaging the flue. I fixed the flue problems
myself, some of which were definitely due to vibration, but also partially
due to shoddy building work. British Gas quoted me a little over £2000 to
cure the problem, involving fitting a new boiler.

I then drained absolutely everything, including primary & secondary
circuits. At one point I panicked because I had lost all my hot water
supply & heating, but I perservered. In the end I regained a good working
system. The problem was simply an airock. I then added Fernox and bled all
the radiators. The result is that I now have had a quiet & efficient system
for over two years. Total cost about £25 plus a lot of time. I
subsequently cancelled my service contract with BG. If I'd never paid into
their so-called service contract, I would now have had more than enough to
replace my boiler.

The problem with professional service, especially with central heating, is
that fault finding and subsequent cures can be very time consuming and
therefore the professionals will choose the quick (and generally very much
more expensive) fix.

Terry D.

Blonks wrote:

The only problem we have had until recently was the boiler cutting out
due to air in the system (a few years back) - plumber found the vent
pipe wan't venting due to an air seperation thingy problem. He didn't
replace this but did something that involved cutting the feed pipe to
it and all was fine.

It sounds like someone may have placed the expansion pipe (i.e. the one
that runs from the main heating circuit to over the top of the header
tank), too close to the "suction" side of the pump. This can cause gobs
of air to be drawn into the system as the pump starts up. The cure is to
move the pipe to the other side of the pump (or combine it with the feed
pipe from the header tank).

Recently there have been banging noises from the pipes/ boiler - it
wakes us up in the morning.

Could be one of several things, scale in the boiler causing "kettling",
you could have lots of air or gas in the system. The pump could be
failing - hence giving a lower flow rate, this is also likely to cause
kettling as the water will get hotter with each pass though the boiler.
A failing pump can also introduce vibration of its own.

If the system has spent much time running without inhibitor any of the
above are quite likely to occur. Also since air in the system acelerates
corrosian, and corrosian produces gas... you have a degenerating situation.

the plumber came and did a boiler service and injected some furnox
boiler silencer to the bathroom rad. This was fine for a week then
the noise came back. I had a look in the feed/expansion tank and saw
rusty gunk on the surface of the water - I assume this is what the
furnox does ?

No this is what corrosion does ;-)

I bialed this out and drained the system using all 3 drains on the
rads. This again fixed the noise for a week and it then came back.

Sounds like air/gas in the system could be the cause then.

It only seems to be for the first 5 mins of the boiler heating up.
After that it is still there when boiler switches off/ on - but not as
loud.

Also could be air - as it circulates it will disperse through the water
reducing the effect. After pump stops and the water cools the air will
begin to separate out and accumulate somewhere in the system ready to be
swept off again next time it starts up.

I then got some sentinel x100 + x200 and partially drained the system
and added via the tank.

It hasn't worked and the noise is getting worseand I'm £25 worse off !

So, my question (eventually!). Why has the noise gone then come
back? Is this somehow related to the initial problem with the vent
pipe / air separator ?

I would guess this is the cause...

could there be some rust/gunk in the system cuasing it ? Is there some air in there causing/adding to the problem
- should I have done any draining/bleeding at the boiler?

The fact that you have had an airlock in the past suggests that there
may be some of you pipe work that is routed in such a was as it collects
any air circulating (normally you would expect the air to accumulate in
a radiator when it could be bled out).

Would it have fixed it if I had fully drained the system then added
the chemicals?

Not if you still have a problem with air being draw into the system via
the expansion pipe for example. (a blocked feed from the header tank can
also cause similar problems).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Mon, 29 Mar 2004 03:37:20 +0100, John Rumm
wrote:

Blonks wrote:

The only problem we have had until recently was the boiler cutting out
due to air in the system (a few years back) - plumber found the vent
pipe wan't venting due to an air seperation thingy problem. He didn't
replace this but did something that involved cutting the feed pipe to
it and all was fine.

It sounds like someone may have placed the expansion pipe (i.e. the one
that runs from the main heating circuit to over the top of the header
tank), too close to the "suction" side of the pump. This can cause gobs
of air to be drawn into the system as the pump starts up. The cure is to
move the pipe to the other side of the pump (or combine it with the feed
pipe from the header tank).


The pipes have been this way since day-one, so probably not

Recently there have been banging noises from the pipes/ boiler - it
wakes us up in the morning.

Could be one of several things, scale in the boiler causing "kettling",
you could have lots of air or gas in the system. The pump could be
failing - hence giving a lower flow rate, this is also likely to cause
kettling as the water will get hotter with each pass though the boiler.
A failing pump can also introduce vibration of its own.


I think there is mild kettling ,but I think an air lokc osunds the
most likely - probably due to a gunged up air separator?

If the system has spent much time running without inhibitor any of the
above are quite likely to occur. Also since air in the system acelerates
corrosian, and corrosian produces gas... you have a degenerating situation.

the plumber came and did a boiler service and injected some furnox
boiler silencer to the bathroom rad. This was fine for a week then
the noise came back. I had a look in the feed/expansion tank and saw
rusty gunk on the surface of the water - I assume this is what the
furnox does ?

No this is what corrosion does ;-)

I bialed this out and drained the system using all 3 drains on the
rads. This again fixed the noise for a week and it then came back.

Sounds like air/gas in the system could be the cause then.

It only seems to be for the first 5 mins of the boiler heating up.
After that it is still there when boiler switches off/ on - but not as
loud.

Also could be air - as it circulates it will disperse through the water
reducing the effect. After pump stops and the water cools the air will
begin to separate out and accumulate somewhere in the system ready to be
swept off again next time it starts up.


That sounds good to me. I've got a real plumber coming around next
week to have a look.
I then got some sentinel x100 + x200 and partially drained the system
and added via the tank.

It hasn't worked and the noise is getting worseand I'm £25 worse off !

So, my question (eventually!). Why has the noise gone then come
back? Is this somehow related to the initial problem with the vent
pipe / air separator ?

I would guess this is the cause...

could there be some rust/gunk in the system cuasing it ? Is there some air in there causing/adding to the problem
- should I have done any draining/bleeding at the boiler?

The fact that you have had an airlock in the past suggests that there
may be some of you pipe work that is routed in such a was as it collects
any air circulating (normally you would expect the air to accumulate in
a radiator when it could be bled out).

Would it have fixed it if I had fully drained the system then added
the chemicals?

Not if you still have a problem with air being draw into the system via
the expansion pipe for example. (a blocked feed from the header tank can
also cause similar problems).


Many thanks for the advice

Ian
--

What we have here is a failure to communicate.

Blonks wrote:


The pipes have been this way since day-one, so probably not

Not a guarentee - my system was installed like that and must have run
for several years pumping air round the pipes before I moved in and
sorted it (after a further few years!)

Also if you have added radiators or rebalanced the system then the flow
resistance of the whole circuit will have changed which could make the
problem more acute.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/