I need advice on the difficulty of the following:

I need to replace a radiator valve in the upstairs bedroom.
My GCH system has a combi boiler, fed off the water mains directly.

So far, I understand I need to do the following:

1-Shut down the boiler & let it cool off
2-Shut the water mains
3-Drain the system at the draining valve downstairs
4-Change the valve on the upstairs radiator
5-Refill the system
6-Bleed the air out the radiators
7-That's it!

So! Here are the questions:

-Did I forget anything in the above steps?
-If I drain the system, I also drain/introduce air in the boiler. Is
this not a problem for the boiler? Will all the air be flushed out
when I bleed the radiators?
-When I refill the system, do I need to mix some anti-corrosion fluid
of some description with the water? If so, how do I do that
considering my system is fed off the mains.

Thanks for your help !

GM

-Did I forget anything in the above steps?

You don't need to shut down the water mains. There shouldn't be a permanent
connection between your sealed pressurised primary circuit and the mains
supply.

There should be a braided hose connecting the mains to the system. This
should normally be physically disconnected (but frequently is not) and the
valves shut off. When refilling, you attach the hose and open the valve.
When finished, you ensure that all valves are off and the hose is
disconnected.

When refilling, ensure the automatic bleed valve is on, if it has have one.

It is easist to refill with two people. One sits by the filling loop topping
up when the pressure goes down. One goes round opening the radiator bleed
valves. With only one, it takes longer because you need to keep going back
to refill.

-If I drain the system, I also drain/introduce air in the boiler. Is
this not a problem for the boiler? Will all the air be flushed out
when I bleed the radiators?

The majority of the air will come out through the automatic bleed valve and
when bleeding radiators. There is also a substantial amount of air entrained
in fresh mains water. You should, therefore, keep the automatic bleed valve
open for a while and rebleed the radiators a week later after this air has
come out of solution. Also, bleed manually if the system sounds funny, with
clanking and other unusual sounds.

-When I refill the system, do I need to mix some anti-corrosion fluid
of some description with the water? If so, how do I do that
considering my system is fed off the mains.

You MUST install inhibitor, such as Sentinel X100. To introduce corrosion
inhibitor into a sealed system, there are many solutions. You can prefill a
radiator with it before reconnecting it, you can get syringes for squirting
it into a bleed valve. Best of all, when the system is drained down, install
an additive filler point, which is just a short vertical stub in pipe,
preferably near the top of the system, with an isolation valve in the
middle. You just open the valve, insert a funnel and pour the chemical. You
don't need to buy expensive proprietary solutions, but don't forget to close
the valve before refilling!

Christian.

You MUST install inhibitor, such as Sentinel X100. To introduce corrosion
inhibitor into a sealed system, there are many solutions. You can prefill
a
radiator with it before reconnecting it, you can get syringes for
squirting
it into a bleed valve. Best of all, when the system is drained down,
install
an additive filler point, which is just a short vertical stub in pipe,
preferably near the top of the system, with an isolation valve in the
middle. You just open the valve, insert a funnel and pour the chemical.
You
don't need to buy expensive proprietary solutions, but don't forget to
close
the valve before refilling!

Christian.

I installed an additive filler point when I fitted my new gas boiler - very
nice it looks too.

6 Inches of vertical pipe at the very top of the system. I did not bother
with an isolation valve. Instead I just used one of those plastic end cap
fittings - like the plastic pipe joints but closed at one end. I just
DEPRESSURISE THE SYSTEM FIRST!!! Then pop the cap off. Drop in some X100
using a funnel, and put the cap back again.

Geoff

from what i know...when cleaning your rads with fernox you have to leave this
for a period and then flush through system.With regards to the steps
illustrated above they seem all in order, generally when re-filling from my
experiences yet to come across air-lock. Go for it and good luck.

"GB" wrote in message ...
You MUST install inhibitor, such as Sentinel X100. To introduce corrosion
inhibitor into a sealed system, there are many solutions. You can prefill
a
radiator with it before reconnecting it, you can get syringes for
squirting
it into a bleed valve. Best of all, when the system is drained down,
install
an additive filler point, which is just a short vertical stub in pipe,
preferably near the top of the system, with an isolation valve in the
middle. You just open the valve, insert a funnel and pour the chemical.
You
don't need to buy expensive proprietary solutions, but don't forget to
close
the valve before refilling!

Christian.

I installed an additive filler point when I fitted my new gas boiler - very
nice it looks too.

6 Inches of vertical pipe at the very top of the system. I did not bother
with an isolation valve. Instead I just used one of those plastic end cap
fittings - like the plastic pipe joints but closed at one end. I just
DEPRESSURISE THE SYSTEM FIRST!!! Then pop the cap off. Drop in some X100
using a funnel, and put the cap back again.

Geoff


Thank you Gentlemen, I shall have a go at it this week-end!

GM

I just DEPRESSURISE THE SYSTEM FIRST!!! Then pop the cap off.

Yes, I can see that it could cause problems if you forget to drain the
system down first! Perhaps an isolation valve is still a good idea? They
cost about 80p, probably less than a push fit stop end.

Christian.

"Christian McArdle" wrote in message
t...
I just DEPRESSURISE THE SYSTEM FIRST!!! Then pop the cap off.

Yes, I can see that it could cause problems if you forget to drain the
system down first! Perhaps an isolation valve is still a good idea? They
cost about 80p, probably less than a push fit stop end.

Christian.



80p - where???

80p - where???

Looks like I've been paying too much. Screwfix do them for 49p.

http://www.screwfix.com/app/sfd/cat/...06425&id=13483

Christian.

"Christian McArdle" wrote in message
t...
80p - where???

Looks like I've been paying too much. Screwfix do them for 49p.

http://www.screwfix.com/app/sfd/cat/...06425&id=13483

Christian.


Hmmm. Very good I'm sure that I've paid Screwfix more than that. Are
their catalogue prices different from the web-site?

On Wed, 15 Oct 2003 16:36:53 +0000 (UTC), "GB"
wrote:

Are their catalogue prices different from the web-site?

Yes, they freely volunteered that during a phone call once. Also the
content can vary between the two. The numbers for items appears to be
consistent though.

It's worth checking the paper versus the screen where an item is
listed in both forms, as it can produce savings on odd occasions.

Take Care,
Gnube
{too thick for linux}

Well, I am pleased to report that I now have good heating in all my
radiators! I followed your instructions to the letter. Everything went
nice and smooth, My system is now back online, with X100 added and
all.

Thanks a million for your help!

GM

(grandmainger) wrote in message . com...
"GB" wrote in message ...
You MUST install inhibitor, such as Sentinel X100. To introduce corrosion
inhibitor into a sealed system, there are many solutions. You can prefill
a
radiator with it before reconnecting it, you can get syringes for
squirting
it into a bleed valve. Best of all, when the system is drained down,
install
an additive filler point, which is just a short vertical stub in pipe,
preferably near the top of the system, with an isolation valve in the
middle. You just open the valve, insert a funnel and pour the chemical.
You
don't need to buy expensive proprietary solutions, but don't forget to
close
the valve before refilling!

Christian.

I installed an additive filler point when I fitted my new gas boiler - very
nice it looks too.

6 Inches of vertical pipe at the very top of the system. I did not bother
with an isolation valve. Instead I just used one of those plastic end cap
fittings - like the plastic pipe joints but closed at one end. I just
DEPRESSURISE THE SYSTEM FIRST!!! Then pop the cap off. Drop in some X100
using a funnel, and put the cap back again.

Geoff


Thank you Gentlemen, I shall have a go at it this week-end!

GM