I was called around to my sister's to "replace some radiators because
they're too small to heat the rooms".

In actual fact, the bathroom towel rail rad was straight across the
boiler feed/return and the lock-shield was full open. That adjusted, and
a first crude attempt to balance the rads appeared to solve most of her
problems (even the particularly confusing one of the living room rad TRV
turning itself permanently off, once the room was up to temp... go
figure???, do TRVs require a certain pressure behind the pin-valve to
work properly???)


Anyway, that said, she was explaining that she had to fill the CH
circuit every day or so, and was "advised" by the installer "Anywhere up
to the red line is okay" - that being 3-bar, the pressure at which the
Pressure Relief Valve actuates, and dumps the water out of the relief pipe.

Having educated her in RTFM for the boiler (a Baxi something 80) which
indicates normal pressure 1-2bar, min 0.5, max 2.5 she's agreed not to
go above 2-bar on filling.

But, the question remains, what is causing the pressure drop?

I've now got a container collecting anything from the pressure-relief
valve, to check that that's working ok; I've been under the ground-floor
(I job I really don't enjoy) and checked all the joints on the CH system
- no leaks evident. I've not yet checked under the upstairs flooring,
since that's a much bigger job for another day. I've checked around the
boiler and there's no obvious leak.

So, my question is (and I know there's not much to go on) - is there any
likely "gotcha" on a closed system where I can look for a leak or
anything?; I'm not competent to repair anything, but if I can spend my
time finding the puddle of water, maybe I can help save her some cash
when she needs to get an engineer / plumber in.

As always, any help gratefully received.

Mike

Hi
You don't specify the type of system you have as sealed systems these days
normally suggest 'Combi ' boilers but conventional systems can be sealed.
That said the task is still the same Find the leak!
A few pointers .Have you had any work done recently (floors removed/refixed?
Moved or relocated any large objects? Had a new carpet fitted?
Think back to when the problem first started (if known) and try and relate
anything done around that time.
Moving a wardrobe caused a leak once when the new location crushed a badly
fitted rad pipe in a bedroom.
Carpet fitters (sorry to all good carpet fitters) have IME sometimes
punctured a pipe whilst fitting edge trims or loosened rad conections
causing a minor leak which the new carpet absorbs.
The most common is creaky floor boards,you screw them down only to clip a CH
pipe.
All are a pain to locate.

HTH
CJ

Mike Dodd wrote :
So, my question is (and I know there's not much to go on) - is there any
likely "gotcha" on a closed system where I can look for a leak or anything?;
I'm not competent to repair anything, but if I can spend my time finding the
puddle of water, maybe I can help save her some cash when she needs to get an
engineer / plumber in.

They can be very difficult to find....

It doesn't take the loss of much actual water to cause the pressure to
fall.

One way is to drain the system and pressurise the system with air. Air
can escape more easily than water, so you might be able to hear the air
blowing out of the spot where the leak is.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Tue, 27 May 2008 21:10:16 +0100, Mike Dodd wrote:

As always, any help gratefully received.

Have you looked at
http://wiki.diyfaq.org.uk/index.php?... sure_dropping

(or if that wraps on your newsreader go to
http://wiki.diyfaq.org.uk/index.php?...Heating_Repair and
navigate to the section "system_pressure_dropping")

--
John Stumbles

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