Chaps hi,

hoping for a bit of advice here. I have recently moved house to a
property which was built circa 1987. One item picked up on the survey
was that when the bolier came on (ch or hw) it made lots of loud
banging noises. So it has been doing this for at least 6 months

This didn't bother us too much but now we have started to use the CH
with the onset of winter it is waking us up every morning with a
*very* loud BANG. Having recently had the old analogue programmer
fail (and having to update it and the thermostat myself) I have
decided that it has to be worth an attempt at self diagnosis - and
then possibly trying to fix it myself or get some one in.

I have looked through similar posts but was hoping that this might
make sense to someone out there.

Here is all I can tell you about the system.

System type: Fully pumped, Mid Position valve system, install 1987 by
builders
Boiler: Thorn EMI apollo fanfare i
Pump: Grundfos Selectric (TF110 IP42)???
Mid position valve: Sunvic SD2752

The rest of the kit (stat, programmer etc seems fine)

The bang happens when the heating or HW comes on, normally makes 3 or
4 bangs and then is quiet until the next time it goes off for a while.
I have checked the rads and there is no significant air in the
system, the noise seems centred around the cupboard where the boiler,
pump, HW tank are installed. The bangs seem to travel through the
pipes and it seems that one pipe has now broken the plastic clip it
was in - symptom not cause though I think. The only other thing I can
think to add is that in some rooms as the CH or HW comes on the
radiators make a sort of rattle - like some hard sediment in them is
bein disturbed by the water flow?

Any tips as to what I should look for gratefully received

Tim

"Tim" wrote in message
m...
Chaps hi,

hoping for a bit of advice here. I have recently moved house to a
property which was built circa 1987. One item picked up on the survey
was that when the bolier came on (ch or hw) it made lots of loud
banging noises. So it has been doing this for at least 6 months

This didn't bother us too much but now we have started to use the CH
with the onset of winter it is waking us up every morning with a
*very* loud BANG. Having recently had the old analogue programmer
fail (and having to update it and the thermostat myself) I have
decided that it has to be worth an attempt at self diagnosis - and
then possibly trying to fix it myself or get some one in.

I have looked through similar posts but was hoping that this might
make sense to someone out there.


Two ideas spring to mind:

1. Air in the boiler- especially if the neither of the water pipes exits the
boiler at the top and continues 'up' . (If they don't, air can get trapped
in the boiler and it will stay there- in the extreme enough can collect to
stop the boiler lighting.) There is (usually) a bleed valve in the boiler
at the top of the heat exchanger.

2. Is the pump starting up reliably? If it 'sticks' the water in the heat
exchanger could be boiling, making the 'bangs' and the shock kicks the pump
to life.


--
73
Brian
G8OSN
www.g8osn.org.uk
www.amateurradiotraining.org.uk for FREE training material for the UK
Foundation and Intermediate Licences
www.phoenixradioclub.org.uk - a RADIO club specifically for those wishing
to learn more about amateur radio

Brian Reay wrote:
"Tim" wrote in message
m...
Chaps hi,

hoping for a bit of advice here. I have recently moved house to a
property which was built circa 1987. One item picked up on the
survey was that when the bolier came on (ch or hw) it made lots of
loud
banging noises. So it has been doing this for at least 6 months

This didn't bother us too much but now we have started to use the CH
with the onset of winter it is waking us up every morning with a
*very* loud BANG. Having recently had the old analogue programmer
fail (and having to update it and the thermostat myself) I have
decided that it has to be worth an attempt at self diagnosis - and
then possibly trying to fix it myself or get some one in.

I have looked through similar posts but was hoping that this might
make sense to someone out there.


Two ideas spring to mind:

1. Air in the boiler- especially if the neither of the water pipes
exits the boiler at the top and continues 'up' . (If they don't, air
can get trapped in the boiler and it will stay there- in the extreme
enough can collect to stop the boiler lighting.) There is (usually)
a bleed valve in the boiler at the top of the heat exchanger.

2. Is the pump starting up reliably? If it 'sticks' the water in the
heat exchanger could be boiling, making the 'bangs' and the shock
kicks the pump to life.

I had the same problem a few years ago - very loud banging noises whenever
the heating fired up. The British gas solution to the problem was an offer
to relieve me of £2200 for a new boiler etc. My solution was to drain
absolutely everything containing water, then to flush the heating system
with Fernox, and then fill with Fernox inhibitor. The problem must have
been an airlock somewhere in the system. I then had a worrying time when I
lost the shower and all hot water, but I persevered and got it all working
eventually. This was over two years ago and it's still working fine.
Central heating is really somewhat of a black art and problems take time to
solve. Unfortunately the professionals don't take the time - you couldn't
afford it if they did. For example, a full heating system balance could
take a full day - would you be prepared to pay for this? - this is why it's
never done properly unless you DIY.

Terry D.

(Tim) wrote in message om...
Chaps hi,

hoping for a bit of advice here. I have recently moved house to a
property which was built circa 1987. One item picked up on the survey
was that when the bolier came on (ch or hw) it made lots of loud
banging noises. So it has been doing this for at least 6 months



Tim,

Exactly the problem I had when we moved into our house built in about
1987 (Myson Appollo 40k btu, fully pumped Y plan, and lots of banging
on startup. The banging was preceded by the boiler whistling. No sound
from the pump until the banging then a very obvious hiccup and lots of
circulation noises. I verified that in about 50% of the time the pump
was not starting immediately that the boiler fired up, the water in
the boiler heat exchanger boiled and made the explosive banging noises
and the vibration in the pipes kick started the pump.

Eventually the pump failed to start completely (coldest day of last
winter) and BG replaced it (I was away at the time so my wife called
out BG under the service agreement which is why I have it) no further
problems...just minor circulation noise. BG wanted to replace the heat
exchanger or preferrably the entire boiler before I pointed out by
phone that the pump was not working.

More recently I finished the job by a complete primary system flush
and clean according to Andy Hall's procedure and replaced valves with
TRVs. The system is now like new..even the minor circulation noises
have gone.

Cheers

Ian

Thanks guys,

I think I will try and clean out / flush the system, check the pump is
starting whe it is supposed to and go from there.

I have eleven rads in the house, all of which get hot nicely but none
have TRVs. I am going to install 9 trv's and leave them off the small
rad in the en suite shower room (I think it might be the bypass as it
comes on with HW or with CH) and the rad in the entrance hall (this is
always a cold room and the room stat is installed here - I have read
the trv and stat *may* interfere with eachother).

How much of a pain is the flushing? Is it worth trying to install all
9 valves in one hit when the system is empty?. Also I would like to
move a downstairs radiator a foot or so in order that I can make a new
internal doorway - as this means digging up the concrete do you think
I should try and do it all at once?

Thanks for the help it is much appreciated and I wait for the day that
someone asks a Q on here that I have the answer to ;o)

Tim

If you live in an hard water area the banging is almost certainly what is
known as "Kettling". This is caused by a build up of chalk/lime inside the
boiler. The build up reduces the water flow and volume with in the boiler
which will cause the water to boil thus producing the Kettling/banging. Some
time just reducing the water temperature or speeding up the pump will stop
the Kettling temporarily but if it is due to the furring up of the boiler
the only cure may be to replace the boiler.

"xEcute" wrote in message ...
If you live in an hard water area the banging is almost certainly what is
known as "Kettling". This is caused by a build up of chalk/lime inside the
boiler.
Thanks for the comments but I am not sure they apply to me, I have
tried to explain why.

Well I do live in a hard water area *but* bearing in mind that the
CH/HW is pretty much a sealed system, unless there are leaks and thus
constant entrance of new water OR the system has been drained over and
over I am not sure that I can see how sufficient scale would get in
the heat exchanger. There will only be a finite amount of Calcium etc
in the water and even if the water is saturated the unless water
leaves the system an equilibrium will soo establish...won't it?

The build up reduces the water flow and volume with in the boiler
which will cause the water to boil thus producing the Kettling/banging. Some
time just reducing the water temperature or speeding up the pump will stop
the Kettling temporarily but if it is due to the furring up of the boiler
the only cure may be to replace the boiler.

Another reason I am not sure about this causing my particular problem
is that it only ever happens when the heating comes on. Is there any
reason that the kettling would not happen randomly whenever the
heating comes on? I think it is more likely that the water pressure
jolt kicks off the pump.

Perhaps it's all just wishful thinking and I need a enw boiler, any
other comments?

Tim

On Thu, 30 Oct 2003 11:52:22 +0000, Tim wrote:

"xEcute" wrote in message ...
If you live in an hard water area the banging is almost certainly what is
known as "Kettling". This is caused by a build up of chalk/lime inside the
boiler.
Thanks for the comments but I am not sure they apply to me, I have
tried to explain why.

Well I do live in a hard water area *but* bearing in mind that the
CH/HW is pretty much a sealed system, unless there are leaks and thus
constant entrance of new water OR the system has been drained over and
over I am not sure that I can see how sufficient scale would get in
the heat exchanger. There will only be a finite amount of Calcium etc
in the water and even if the water is saturated the unless water
leaves the system an equilibrium will soo establish...won't it?

The build up reduces the water flow and volume with in the boiler
which will cause the water to boil thus producing the Kettling/banging. Some
time just reducing the water temperature or speeding up the pump will stop
the Kettling temporarily but if it is due to the furring up of the boiler
the only cure may be to replace the boiler.

Another reason I am not sure about this causing my particular problem
is that it only ever happens when the heating comes on. Is there any
reason that the kettling would not happen randomly whenever the
heating comes on? I think it is more likely that the water pressure
jolt kicks off the pump.

Perhaps it's all just wishful thinking and I need a enw boiler, any
other comments?


Kettling happen due to a combination of excessive heat, lack of flow and
debris in the heat exchanger. It tend to happen on older boilers which
have had more time to build up hardened particle of crud inside the water
way.

Having checked that the pump is working. Sometimes the pump are governed
by the boiler which includes are a themostat to keep them running if the
boiler is hot. These can and do fail and cause the pump to stop when it is
needed most.

Sometimes if you have TRVs on all radiators in mild weather there can be
no flow - there 'ought' to be some provision for this but...

Kettling can be anything from mild wheezy wooshy sounds up to full scale
banging and clonking that would make you think there was a detached metal
part inside the boiler.

It is likely that your system is a fully sealed type (see FAQ below) and
open vented system whilst the water is recirculated do suffer problems
over time.

If all the basic checks fail to bring releif then the best product by far
is Fernox [30 quid-a-tube] boiler silencer gel - this is injected directly
into a radiator and IME is the only think that can make the noise
less/less harsh.

HTH

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

OK,

I am wondering if my motorised valve might be the problem... please
see point 2 below.

Last w/e I went out and bought 2 litres of non acidic descaler, added
these to the system via the header tank (perhaps my system is not
sealed as per your definition Ed!) and flushed it through to make sure
that the descaler got into circulation. I also gave all the rads a
good bleed

The banging continued ( I am not sure how long it takes for the
descaler to work but presumably a while as it will only work on
contact = thick layers of deposition will take a while to go).

Couple of days ago I bit the bullet and fitted a replacement pump -
got a Grundfos Alpha+ 15-50 as every one seems to think they are good
here. The noise has definitely reduced. Now there is perhaps one
bang (was 3/4) and no or little pipe groaning building to the bang.

However there is still a bang. Diligently I sat by the boiler at 6.30
this morning waiting for it to come on and notice two things

1) When it did come on there was one medium bang and then it sounded
like the water flow through the system really took off (lots of
whooshing)

2) Before the heating came on the HW circuit was energised but not
running yet (HW tank stat was not calling for heat) All the pipes
were cold (ie bolier had not run) BUT the valve cover and body was
really hot - say 45C or so yet the water temp in the pipes was
ambient. Would you expect the valve to run hot like this? can the
valves fail in this way and...could the valve also be responsible for
making the flow sluggish on system start up hence the banging???

Thanks again for all your response - very much appreciated

Tim

On 5 Nov 2003 03:09:33 -0800, (Tim) wrote:

OK,

I am wondering if my motorised valve might be the problem... please
see point 2 below.

Last w/e I went out and bought 2 litres of non acidic descaler, added
these to the system via the header tank (perhaps my system is not
sealed as per your definition Ed!) and flushed it through to make sure
that the descaler got into circulation. I also gave all the rads a
good bleed

The banging continued ( I am not sure how long it takes for the
descaler to work but presumably a while as it will only work on
contact = thick layers of deposition will take a while to go).

Couple of days ago I bit the bullet and fitted a replacement pump -
got a Grundfos Alpha+ 15-50 as every one seems to think they are good
here. The noise has definitely reduced. Now there is perhaps one
bang (was 3/4) and no or little pipe groaning building to the bang.

However there is still a bang. Diligently I sat by the boiler at 6.30
this morning waiting for it to come on and notice two things

1) When it did come on there was one medium bang and then it sounded
like the water flow through the system really took off (lots of
whooshing)

2) Before the heating came on the HW circuit was energised but not
running yet (HW tank stat was not calling for heat) All the pipes
were cold (ie bolier had not run) BUT the valve cover and body was
really hot - say 45C or so yet the water temp in the pipes was
ambient. Would you expect the valve to run hot like this? can the
valves fail in this way and...could the valve also be responsible for
making the flow sluggish on system start up hence the banging???

Thanks again for all your response - very much appreciated

Tim

They do run a little warm when active, simply because the motor is
powered in a stalled condition to hold the valve open.

It's possible that the valve is sticky through being crudded up or in
general due to age. You can test this by removing the head and
checking how easy it is to turn the spindle.

However, unless the flow were really being restricted, I don't think
that this directly relates to the boiler banging.

I just looked through the earlier thread now, and I think it would be
worth doing a check as to whether the heat exchanger has a build up of
assorted sludge. This tends to create local boiling in the exchanger
and hence the noise. Is it a cast iron type of exchanger or low
water content (i.e. tubes)? I think that I would work out a way to
flush it through. I'd also take a look at a radiator to get an
idea of whether there is significant sludging in the system in
general. If you are thinking of adding TRVs, then it makes sense
to do a thorough clean out at the same time.

While you have the system drained down, you could fit drain cocks and
lever ball valves to either side of the boiler to be able to isolate
it and also to be able to hook up hoses to flush it through. If you
do this, I would add two further things. First of all a pressure
release safety valve on the boiler side of any valves, and secondly a
strainer on the return side to catch any circulating grot.

Given the circumstances, I would probably consider taking the heat
exchanger off and outside and flushing it, simply so that it could be
inverted - especially if it's a cast iron one - but obviously this is
a more significant job.

You could also consider doing a power flush - the equipment and
chemicals can be hired. BG and other contractors will charge an arm
and a leg for this and it's a gamble as to whether it's satisfactory.

Also, I think you need to consider the age of the boiler. It is
getting towards the end of its useful life and if you end up having to
do power flushes or heat exchanger replacements then the costs are
going to add up quite rapidly to the point where it really is throwing
good money after bad. I wouldn't spend any more than £100-200 on
fixing this.

In a boiler of that vintage, especially cast iron, it is going to have
an efficiency of 65% or less. If you replace with a new condensing
boiler, you can achieve 90% efficiency ratings to the SEDBUK seasonal
model. In practice, it's possible to achieve something like 25-30%
gas savings. I did such a swap a year ago and have achieved this.
So once you consider the mounting maintenance costs (in time as well),
plus the saving to be made in swapping the boiler; the actual real
additional outlay becomes quite small.

Personally, unless you can achieve an easy fix, I would dump the
boiler and concentrate on cleaning up the rest of the system and
fitting the TRVs.

..andy

To email, substitute .nospam with .gl

Andy having read your comments, and considering my situation, I have
decided that I will do a full system drain, flush everything I can,
take the opportunity to me a radiator and then fill her back up.

ONE MORE QUESTION though...

I can seem to find any draincock lower than the ground floor rad
valves. Do modern houses *always* have one fitted at the lowest level
of the system??? Usually outside or on the patio? If there is no
other draincock how do I get the water out of the bottom of the
system? I am wondering because when I try and move a ground floor
radiator (pipes in screed) I am looking at it all draining out
there...arrrghhhhh

thanks

Tim


They do run a little warm when active, simply because the motor is
powered in a stalled condition to hold the valve open.

I thought this might be the case...still I will check and see if it
turns easily

I just looked through the earlier thread now, and I think it would be
worth doing a check as to whether the heat exchanger has a build up of
assorted sludge. This tends to create local boiling in the exchanger
and hence the noise. Is it a cast iron type of exchanger or low
water content (i.e. tubes)? I think that I would work out a way to
flush it through. I'd also take a look at a radiator to get an
idea of whether there is significant sludging in the system in
general. If you are thinking of adding TRVs, then it makes sense
to do a thorough clean out at the same time.

Looks like I will do a full system drain down then. Ideal time to
have a good look at the boiler and heat exchanger.

While you have the system drained down, you could fit drain cocks and
lever ball valves to either side of the boiler to be able to isolate
it and also to be able to hook up hoses to flush it through. If you
do this, I would add two further things. First of all a pressure
release safety valve on the boiler side of any valves, and secondly a
strainer on the return side to catch any circulating grot.

Good advice - it was soo simple changing the pump because someone did
the job properly and fitted gate valves either side

Also, I think you need to consider the age of the boiler. It is
getting towards the end of its useful life and if you end up having to
do power flushes or heat exchanger replacements then the costs are
going to add up quite rapidly to the point where it really is throwing
good money after bad. I wouldn't spend any more than £100-200 on
fixing this.

Fair point too

Personally, unless you can achieve an easy fix, I would dump the
boiler and concentrate on cleaning up the rest of the system and
fitting the TRVs.

On 5 Nov 2003 06:36:37 -0800, (Tim) wrote:

Andy having read your comments, and considering my situation, I have
decided that I will do a full system drain, flush everything I can,
take the opportunity to me a radiator and then fill her back up.

ONE MORE QUESTION though...

I can seem to find any draincock lower than the ground floor rad
valves. Do modern houses *always* have one fitted at the lowest level
of the system??? Usually outside or on the patio?

I think it depends on whether you believe in fairies and the
completeness and professionalism of the construction trades.

Logically you are right, but I think the reality is not going to be
that.

If there is no
other draincock how do I get the water out of the bottom of the
system? I am wondering because when I try and move a ground floor
radiator (pipes in screed) I am looking at it all draining out
there...arrrghhhhh

thanks

Tim


Then I think that you will need to drain as best as you can. A
wet/dry cleaner ought to be able to pull most of the water out of the
pipes in the screed if you can figure out a way to hook it up to a
radiator valve union reasonably well.

Given the circumstances, it would be an idea to perhaps go for
radiator valves with a drain on the pipe side or alternatively fit a
drain cock below each valve. Then you can at least flush at each
place.


..andy

To email, substitute .nospam with .gl