Hi,

I have a combi boiler on a sealed system (worcester greenstar 25si), I
want to remove/replace a radiator but it doesn't have an isolating
valve on one side so I have to drain down the system.

Is this as easy as turning off the boilers electrical supply at the
switch, connecting a hose to the drain cock and then opening up valves
for it to drain?

And to refil use the water inlet at the boiler which tops up the
pressure and then bleed rads as necessary and fill more etc.

Thanks

In message .com, dp
writes
Hi,

I have a combi boiler on a sealed system (worcester greenstar 25si), I
want to remove/replace a radiator but it doesn't have an isolating
valve on one side so I have to drain down the system.

Is this as easy as turning off the boilers electrical supply at the
switch, connecting a hose to the drain cock and then opening up valves
for it to drain?

And to refil use the water inlet at the boiler which tops up the
pressure and then bleed rads as necessary and fill more etc.

Yep, that's it. If you want to fully drain down then you will need to
open at least some of the bleed valves on the rads. But no need just for
doing one rad.

Don't forget to refill with inhibitor. Either use the one that comes in
big syringe type affair, use ordinary package stuff and connect a
flexible pipe to a rad top tapping and then put a funnel in the end of
that and pour in via that, or if you have ladder type towel rad it may
have tapping on top, just fill through one of those.
--
Chris French

On Sat, 02 Sep 2006 06:09:35 -0700, dp wrote:

Hi,

I have a combi boiler on a sealed system (worcester greenstar 25si), I
want to remove/replace a radiator but it doesn't have an isolating
valve on one side so I have to drain down the system.

Is this as easy as turning off the boilers electrical supply at the
switch, connecting a hose to the drain cock and then opening up valves
for it to drain?

And to refil use the water inlet at the boiler which tops up the
pressure and then bleed rads as necessary and fill more etc.

See the SealedCH FAQ


--
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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

Thanks for the replies!

I'd actually read the Sealed CH faq Ed but it didn't mentioned draining
down, only refilling.

Another question I have is I have had the new combi fitted on an old
system. A few of the radiator joints have been leaking a little and the
pressure drops slightly each day. I know you won't be able to say for
sure but do you think if I redo all the compression joints with PFTE
tape (As it was a open system before there is none on the current
joints) will that be enough or do you think all the pipework should be
replaced?

In message . com, dp
writes
Thanks for the replies!

I'd actually read the Sealed CH faq Ed but it didn't mentioned draining
down, only refilling.

Another question I have is I have had the new combi fitted on an old
system. A few of the radiator joints have been leaking a little and the
pressure drops slightly each day. I know you won't be able to say for
sure but do you think if I redo all the compression joints with PFTE
tape (As it was a open system before there is none on the current
joints) will that be enough or do you think all the pipework should be
replaced?


There should be no need to replace the pipework. If it is compression
joints that are leaking then just nipping them up a little tighter will
probably do the trick.

--
Chris French

On Mon, 04 Sep 2006 12:08:51 -0700, dp wrote:

Thanks for the replies!

I'd actually read the Sealed CH faq Ed but it didn't mentioned draining
down, only refilling.

Another question I have is I have had the new combi fitted on an old
system. A few of the radiator joints have been leaking a little and the
pressure drops slightly each day. I know you won't be able to say for
sure but do you think if I redo all the compression joints with PFTE
tape (As it was a open system before there is none on the current
joints) will that be enough or do you think all the pipework should be
replaced?

I suppose I thought the draining down was so obvious that it required no
explanation. Anyway it's boiler off and open the required drain
point(s). The points will have any or all of the following 'features'.

a) They will be indoors.
b) Even if outdoors they won't be over a gully.
c) They will be the light pattern type which will leak profusely when you
open them.
d) Even if they are the heavier pattern with O-ring seals on the spindle
they will come apart and leak.
e) the washer will have welded itself onto its seat and the button on the
jumper will pull out of the washer. This will make the flow only a trickle
but if you try to extract the washer you may get a bit wet.
f) alternatively the rubber washer will have turned to charcoal and break
into two fragments. One of which remains stuck to the valve seat the other
will partially block the outlet of the drain point. If you now reclose the
valve it won't stop the flow of water. g) The point will not be the lowest
point on the system. h) The point will only have been fixed to either flow
or return pipes so preventing you from draining half the pipes below the
level of the lowest rad. i) The outlet of the drain point will have been
installed so close to the floor that it is impossible to get a tray
underneath or to attach a hose without it kinking.

A smear of silicone grease or PTFE resin is the best way to improve
leaking screwed and compression joints (IME).


--
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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards