I'm in the process of converting my open vented system to sealed in
readiness for installation of new condensing boiler. Plan is to run
flow/return pipework to new location and get Corgi fitter to fit boiler
and run new gas pipe. HW cylinder, controls etc already replaced and
updated to latest building regs.

Existing (ancient) backboiler is a Glow Worm 240/6 or 246. My question
is whether I can run this unit as a sealed system in the interim after
converting to sealed but before fitting new boiler ?

I can't find any manuals on the Glow Worm web site (far too old) but
neighbour downstairs has identical model and has been running as sealed
from new (approx 20 years ago!). Mine was open vented from new due to
loft space being available (top floor).

Ed's FAQ mentions the boiler needing "secondary overheat protection".
Is there any way I can check? I can't see any reset button on the
boiler itself ? Could this be an additional component that would only
be fitted to the boiler in the event of it being used for sealed
operation ?

Also, is it insanity to try and pressurise an old boiler? All existing
rads have been replaced, underfloor pipe work in good condition so
leaks there should not be a problem.

My only reason for wanting to run the old system temporarily is that
when I get quotes for the new boiler the existing system is proven as
working.

Thanks for any help with this.

On Wed, 19 Oct 2005 06:12:28 -0700, andy.hide wrote:



Ed's FAQ mentions the boiler needing "secondary overheat protection".
Is there any way I can check? I can't see any reset button on the
boiler itself ? Could this be an additional component that would only
be fitted to the boiler in the event of it being used for sealed
operation ?

I used to have a GW Galaxy BBU - in fact its still in place
except for the gas valve and burner. It did not have any form of overheat
cutout and I doubt yours has.

Operating this sort of boiler on a sealed system is outside the permitted
use and therefo
a) illegal.
b) possibly dangerous.

Thermostats can and do fail on these sort of boilers - let's say it had a
50% chance of going in the next 100 months? That's plausible given its
current age. The boiler will then boil. Steam will be raised. The pressure
fluctuations will be intense and could well do some damage - it'll
let everyone know something BAD is happening. The steam will be sent out
then the boiler is dry! So you will then have an empty boiler being
roasted.

Also Gas valves could in principle jam on. The pilot valve would be able
to shut the boiler down automatically but only if there is an o/h cutout.

The noise of a _vented_ boiler going uncontrolled is bad enough that all
people it happens to (i've met so far) don't want the old one repaired!
They view it with suspicion from then on.

--
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

Thanks Ed. I had my doubts about doing this hence my question so will
hold off on the sealed conversion until the new boiler is fitted.

Andy.

Ed Sirett wrote:
On Wed, 19 Oct 2005 06:12:28 -0700, andy.hide wrote:



Ed's FAQ mentions the boiler needing "secondary overheat protection".
Is there any way I can check? I can't see any reset button on the
boiler itself ? Could this be an additional component that would only
be fitted to the boiler in the event of it being used for sealed
operation ?

I used to have a GW Galaxy BBU - in fact its still in place
except for the gas valve and burner. It did not have any form of overheat
cutout and I doubt yours has.

Operating this sort of boiler on a sealed system is outside the permitted
use and therefo
a) illegal.
b) possibly dangerous.

Thermostats can and do fail on these sort of boilers - let's say it had a
50% chance of going in the next 100 months? That's plausible given its
current age. The boiler will then boil. Steam will be raised. The pressure
fluctuations will be intense and could well do some damage - it'll
let everyone know something BAD is happening. The steam will be sent out
then the boiler is dry! So you will then have an empty boiler being
roasted.

Also Gas valves could in principle jam on. The pilot valve would be able
to shut the boiler down automatically but only if there is an o/h cutout.

The noise of a _vented_ boiler going uncontrolled is bad enough that all
people it happens to (i've met so far) don't want the old one repaired!
They view it with suspicion from then on.

--
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

In an earlier contribution to this discussion,
wrote:

Thanks Ed. I had my doubts about doing this hence my question so will
hold off on the sealed conversion until the new boiler is fitted.

Andy.

If your new boiler is a system boiler, it will duplicate many of the
components which you would have to buy to convert to pressurised, anyway.

If you're worried about testing the existing system, could you temporarily
disconnect the F&E tank and pressure test the pipework - cold, of course?
--
Cheers,
Set Square
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