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Combi Boiler Pressure Drop



 
 
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  #1  
Old November 18th 05, 07:20 PM posted to uk.d-i-y
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Default Combi Boiler Pressure Drop

First of all I know very little about boilers, so please be patient!

Having got a decorator to remove and drain out a radiator so as he could
paint behind it, on reconnecting and turning the hot water inflow back on,
we noticed the pressure on the system drop from about 1.2 to almost zero.
This didn't surprise him as basically we took out a fair proportion of the
water in the system (total of 4 radiators in our flat).

Problem is now we can't see away of replenishing the water back in.
Examining the pipe work underneath the boiler, the chap helping me saw that
the two pipes to the RHS of the photo below should be connected by the
flexible silver pipe just hanging over it!

http://www.philrichards1.pwp.blueyonder.co.uk/Boiler.jpg

At that point he gave up and said to get expert advice! Fortunately we have
a fixed service contract with British Gas who only 7 months ago carried out
a service check and presumably this didn't appear out of the norm. They are
due out Monday morning.

On speaking to someone else, from my descriptions he reckoned the system is
sealed. There is no water tank in the loft, all water comes in from the
mains and he reckoned sometimes once a boiler like this is set up and the
system filled up with water, often the water supply is disconnected.

So my questions a

1. The boiler seems to run OK on a much lower pressure, with the radiators
at their normal heat. The only difference is you can hear air in the
system. Is it safe to keep the system running this until the engineer comes
out Monday, especially as the current cold weather is forecast for the
weekend?

2. How on earth is a system supposed to be refilled easily when radiators
are drained out? Or is there another way of allowing mains water into the
system.

3. How easily would it be for the engineer to get the pressure back? I only
hope that especially as British Gas have already examined the system (on
two occasions, once after it developed a fault, the other a service check)
they will not say I've tampered it or it is a design fault.

Many thanks.

--
Phil Richards
London, UK
Home Page: http://www.philrichards1.pwp.blueyonder.co.uk
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  #2  
Old November 19th 05, 12:51 AM posted to uk.d-i-y
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Default Combi Boiler Pressure Drop

Owain wrote:

http://www.philrichards1.pwp.blueyonder.co.uk/Boiler.jpg
2. How on earth is a system supposed to be refilled easily when radiators
are drained out? Or is there another way of allowing mains water into the
system.


By connecting the flexible silver pipe between the cold water main and
the radiator circuit, and turning the taps on until the pressure gauge
goe up to whatever it should be.

Are you saying there are now no screw-on connection points for the
flexible pipe?
3. How easily would it be for the engineer to get the pressure back?


Very easy assuming there are screw-on connection points for the flexible
pipe. I don't know what British Gas will say - be prepared for them to
tell you you need a new boiler.


Perhaps not too clear from the photo I took, there are screw on connections
on both pipes on the RHS. I can see now how easy the job will probably be.
What I don't understand is why they effectively got sealed off presumably
after the boiler and radiator system were installed making it difficult to
top it up after, say what I did, by draining out one radiator.

I don't know what British Gas will say - be prepared for them to
tell you you need a new boiler.


Well I hope not.....

--
Phil Richards
London, UK
Home Page: http://www.philrichards1.pwp.blueyonder.co.uk
  #3  
Old November 19th 05, 01:19 AM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

In message , Phil Richards
writes
Owain wrote:

http://www.philrichards1.pwp.blueyonder.co.uk/Boiler.jpg
2. How on earth is a system supposed to be refilled easily when radiators
are drained out? Or is there another way of allowing mains water into the
system.


By connecting the flexible silver pipe between the cold water main and
the radiator circuit, and turning the taps on until the pressure gauge
goe up to whatever it should be.

Are you saying there are now no screw-on connection points for the
flexible pipe?
3. How easily would it be for the engineer to get the pressure back?


Very easy assuming there are screw-on connection points for the flexible
pipe. I don't know what British Gas will say - be prepared for them to
tell you you need a new boiler.


Perhaps not too clear from the photo I took, there are screw on connections
on both pipes on the RHS. I can see now how easy the job will probably be.
What I don't understand is why they effectively got sealed off presumably
after the boiler and radiator system were installed making it difficult to
top it up after, say what I did, by draining out one radiator.


I understand that it is correct for the silver tube to be removed but,
usually, you can just screw it back on and open the taps to fill the
system.

Are the pipes capped and sealed? Or will the caps pop off to allow you
to screw the pipe on?

--
Richard Faulkner
  #4  
Old November 19th 05, 04:52 AM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

Phil Richards wrote:

All the information and some background as to how your system works can
be found he

http://www.makewrite.demon.co.uk/SealedCH.html

So my questions a

1. The boiler seems to run OK on a much lower pressure, with the radiators
at their normal heat. The only difference is you can hear air in the
system. Is it safe to keep the system running this until the engineer comes
out Monday, especially as the current cold weather is forecast for the
weekend?


Depends on how low the pressure is... some boilers will refuse to fire
without enough in the system. Sounds like yours is running OK though.

2. How on earth is a system supposed to be refilled easily when radiators
are drained out? Or is there another way of allowing mains water into the
system.


Via the "filling loop" (i.e. that hose of yours). There are two
connection points: one is a tap - this is on the cold main supply. The
other is a non return valve on the heating system. This lets water into
the heating system but not out.

The only slight extra wrinkle with your setup is it looks like someone
has screwed caps onto the filling loop connection points. This is no bad
idea since it keeps dust and other crud out of the ends of the valves
etc. You should find the caps unscrew easily by hand. No water should
come out when you take the caps off.

It is "correct" to disconnect the filling loop once the system is
filled. (basically it is another safeguard that prevents any possibility
of contaminanted dirty water out of your heating system getting back
into the drinkable mains supply)

3. How easily would it be for the engineer to get the pressure back? I only


Very easy. Connect up the loop and open the tap. Watch the pressure
guage and turn off when at the right pressure. Bleed any air from the
radiators. Top up the pressure if neccessary. Repeat until there is no
more air to bleed. See the FAQ for a full description.

hope that especially as British Gas have already examined the system (on
two occasions, once after it developed a fault, the other a service check)
they will not say I've tampered it or it is a design fault.


No, your system looks fine. Topping up the pressure is one of those
tasks that you will usually only need to do should you remove rads etc.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/
  #5  
Old November 19th 05, 09:25 AM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

In article ,
Phil Richards writes:
Perhaps not too clear from the photo I took, there are screw on connections
on both pipes on the RHS. I can see now how easy the job will probably be.
What I don't understand is why they effectively got sealed off presumably
after the boiler and radiator system were installed making it difficult to
top it up after, say what I did, by draining out one radiator.


The filling loop must be disconnected when not being used.
This is to prevent any remote chance of the radiator water
getting back into the fresh water supply. I can't see clearly
in the photo, but the supply end should have a tap and the
heating end should have a one-way valve to prevent water
coming back out.

--
Andrew Gabriel
  #6  
Old November 19th 05, 09:26 AM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Combi Boiler Pressure Drop

John Rumm wrote:

Phil Richards wrote:

All the information and some background as to how your system works can
be found he

http://www.makewrite.demon.co.uk/SealedCH.html


snip

No, your system looks fine. Topping up the pressure is one of those
tasks that you will usually only need to do should you remove rads etc.


Many thanks to John, Owain & Richard for all their help. I must say out of
the many newsgroups I read this seems to be one of the friendliest & most
helpful!

--
Phil Richards
London, UK
Home Page: http://www.philrichards1.pwp.blueyonder.co.uk
  #7  
Old November 19th 05, 04:42 PM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

On Sat, 19 Nov 2005 11:20:28 +0000, me9 wrote:

On 19 Nov,
(Andrew Gabriel) wrote:



The filling loop must be disconnected when not being used. This is to
prevent any remote chance of the radiator water getting back into the fresh
water supply. I can't see clearly in the photo, but the supply end should
have a tap and the heating end should have a one-way valve to prevent water
coming back out.

It must be one of a few that comply. Most seem to leave the filling hose
connected. There appears to be a tap on the right of the photo , over which
the hose iis draped. It looks as if the filling point and supply are capped
with brass compression stop ends.


More likely 1/2" BSP brass caps.
This year a boiler I had installed was inspected and was told that I had
left the filling loop connected. I was sent a letter telling me to go and
disconnect it.

I disagree that the best practice is to disconnect the loop, but that's
what our lords and masters require, eh. A small quantity of water
dribbles out of the loop after disconnection (OK so you can use a cloth to
catch it). Also a small amount of air is introduced into the system when
it's reused. Also dust caps are not supplied with most filling
loops so these have either to be supplied or the possibility of 'foreign'
matter getting in has to be endured.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at
http://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


  #8  
Old November 19th 05, 05:50 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Combi Boiler Pressure Drop

In article .uk,
Ed Sirett writes:

I disagree that the best practice is to disconnect the loop, but that's
what our lords and masters require, eh. A small quantity of water
dribbles out of the loop after disconnection (OK so you can use a cloth to
catch it). Also a small amount of air is introduced into the system when


Yes. I connect up the supply end first and very loosely connect
the heating end, turn on the water so it blows most of the air
out of the loose connection, before tightening it up to force
the water through to the heating system.

it's reused. Also dust caps are not supplied with most filling
loops so these have either to be supplied or the possibility of 'foreign'
matter getting in has to be endured.


or of young enquiring minds thinking
"what happens if I turn this knob?" ;-)

Mine's in a rather shallow cupboard, and the door won't stay shut
if the filling loop is left connected anyway.

--
Andrew Gabriel
  #9  
Old November 19th 05, 08:08 PM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

On Sat, 19 Nov 2005 01:19:04 +0000, Richard Faulkner
wrote:

Are the pipes capped and sealed? Or will the caps pop off to allow you
to screw the pipe on?


From the photo, it looks like they are indeed sealed with brass,
threaded caps.
  #10  
Old November 21st 05, 02:04 PM posted to uk.d-i-y
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Posts: n/a
Default Combi Boiler Pressure Drop

On Sat, 19 Nov 2005 00:51:52 +0000, Phil Richards wrote:

Owain wrote:

http://www.philrichards1.pwp.blueyonder.co.uk/Boiler.jpg
2. How on earth is a system supposed to be refilled easily when radiators
are drained out? Or is there another way of allowing mains water into the
system.


By connecting the flexible silver pipe between the cold water main and
the radiator circuit, and turning the taps on until the pressure gauge
goe up to whatever it should be.

Are you saying there are now no screw-on connection points for the
flexible pipe?
3. How easily would it be for the engineer to get the pressure back?


Very easy assuming there are screw-on connection points for the flexible
pipe. I don't know what British Gas will say - be prepared for them to
tell you you need a new boiler.


Perhaps not too clear from the photo I took, there are screw on connections
on both pipes on the RHS. I can see now how easy the job will probably be.
What I don't understand is why they effectively got sealed off presumably
after the boiler and radiator system were installed making it difficult to
top it up after, say what I did, by draining out one radiator.


Because you are NOT supposed to leave the flexi pipe permamantly connected,
although everyone actually does.
 




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