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Care and feeding of pressurised heating system

On Wed, 19 Nov 2008 21:57:19 +0000, Pete Verdon <...@verdonet.organisation.unitedkingdom.invalid

I have a fairly standard combi-boiler pressure heating system, which for
the year since I moved in I've mostly left to its own devices (had a gas
safety check since I have lodgers, but nothing related to its
effectiveness at providing heat). However, I'm thinking I should
probably pay a bit of attention to it if I want to keep it in good nick
and avoid wasting gas. The boiler is installed in (and so presumably
dates from) an extension which I believe was done in 2000ish. The rest
of the system would be about ten years older than that.

1. I don't think the system is at all properly balanced - the radiator
at one end of the living room never heats up (and that end of the room
is noticeably cold) but my bedroom (and most of the rest of the
upstairs) can become sauna-like at times. I've not balanced a system
before; any pointers to some good instructions? I do have an IR
thermometer :-)

2. I have no idea if the system has been properly treated with rust
inhibitor etc (something my dad goes on about at great length, together
with showing off his before & after jam-jars-with-nails-in :-) ). I also
can't see any obvious way of adding it; are there special gadgets that
feed it in via the filling loop (and what if the system is already up
near max pressure?). Are there any general cleaning/unbunging tonics
that might be worthwhile on an unknown system?

3. I have TRVs everywhere (the boiler has a bypass loop) and no
thermostat or timer apart from the simple circuit stat and timer on the
front of the boiler. Temperature can be erratic, mostly I assume due to
the lack of balancing and TRVs being set randomly, but timing-wise the
heating is generally ok in terms of being on when it's wanted and not
when it's not. Once I sort out the balancing, is there likely to be much
to be gained from anything more sophisticated?

4. This morning I had a low-heating-circuit-pressure warning on the
boiler, and had to top it up via the filling loop. I have had to do this
a couple of times before as well. There aren't any obvious leaks or damp
patches, but should I be worried about where the water is going?

On the plus side, the air-pressure warning I mentioned recently has not
recurred; perhaps it was just the wind after all. I might yet blow
through the pressure switch next time I'm working on the boiler though,
just in case.

Any other pointers to things to watch out for in a heating system?

Cheers,

Pete



On Wed, 19 Nov 2008 16:09:41 -0800 (PST), Martin Pentreath <...@hotmail.com

Hi Pete,

For balancing the rads there is a FAQ here:
http://www.diyfaq.org.uk/plumbing/rad-balance.html
However, it the system is fitted with TRVs then balancing should be
less important. For example, in the situation you describe the TRVs in
the bedroom should shut the flow to those rads off when things start
to get sauna-like, meaning that the cold rad at the end of the living
room should then get the benefit of the full blast of the boiler. If
that's not what's happening the cold bits could have more to do with
sludge than with balancing problems. You could check this by turning
off all rads except for the cold one and then seeing if it heats up.
If it does then it's not a sludge problem.

The sludge suspicion fits in with your doubts about inhibitor and your
question about chemical treatments. It might well be worth considering
a good old dosing with Fernox DS-40 to clear the system out:
http://www.fernox.com/?cccpage=DS40&sub=2
There are syringe-type devices to inject stuff into your system via a
radiator bleed valve, but I never like them much. You'd probably have
to depressurise the system to get these to work anyway. I find it
easiest to depressurise and drain off a few pints of water from the
system drain valve, and then to remove the boss from the highest rad
in the system (which now should have no pressure in it) and to feed
whatever I need to feed in via a funnel.

I don't think the need to top up every year or two is too much to
worry about. I have to do the same with mine. No idea where the water
goes, I guess there must be a tiny leak somewhere, but I've never
found it, and it's so slow that the water must evaporate quicker than
it leaks out.

Cheers!

Martin

On Thu, 20 Nov 2008 00:19:47 +0000 (GMT), "Dave Plowman (News)" <...@davenoise.co.uk

In article <...@news.aaisp.net.uk Pete Verdon <...@verdonet.organisation.unitedkingdom.invalid

See the FAQ for instructions.

The normal way is to add concentrate via a radiator bleed screw - it comes
with a tube which crews into this and you force it in with a sealant gun.
Applies to both inhibitor and cleaner. You obviously need to partially
drain down a rad to make room for it.

The temperature shouldn't be that erratic if you have TRVs - perhaps some
are stuck? You can tell by unscrewing the head and seeing if you can press
the valve down by hand and that it returns under spring pressure.

Yes.

--
*Why doesn't Tarzan have a beard? *

Dave Plowman dav...@davenoise.co.uk London SW
To e-mail, change noise into sound.

On Thu, 20 Nov 2008 09:00:40 +0000, Pete Verdon <...@verdonet.organisation.unitedkingdom.invalid

OK. Guess I need to find out if and where I have a drain valve. Haven't
noticed one before. I guess if necessary I could drain at least part of
the system through the (disconnected) filling loop.

I meant more erratic from place to place (some areas hot and some cold)
rather than from time to time. I'll bear in mind the possibility of
sticking though.

Damn. Any suggestions on tracking it down? I believe that the pipes for
upstairs run in the floor (where I would probably notice a leak on the
downstairs ceiling) whereas downstairs are presumably buried in concrete.

Cheers,

Pete

On Thu, 20 Nov 2008 10:05:17 +0000 (GMT), "Dave Plowman (News)" <...@davenoise.co.uk

In article <...@news.aaisp.net.uk Pete Verdon <...@verdonet.organisation.unitedkingdom.invalid

Yes - that's usually the boiler drain point. I have a combined
lockshield/drain valve fitted to a rad closest to an outside door. So just
stick a length of hose on it and drain to the outside. There is another in
the cellar at the very lowest point but is a pain to use but not often
needed.

Well assuming the rads are getting normal circulation the TRV should set
the temp in that room so it should not get too hot. It can't do anything
about an undersized rad or one that's blocked etc. But balancing is still
a good idea even with TRVs - it will give even warming up throughout the
house. But it doesn't need to be done quite so carefully as without.

Best to check with the system cold but pressurized. When hot a small weep
can evaporate. By far the most likely places are lockshields and TRVs and
any compression connections. So look at the pump, three port valve and
every connection inside the boiler. Wipe a bit of kitchen paper round
every single one. It could be something more nasty but carefully eliminate
the likely ones first before panicking.

--
*Can vegetarians eat animal crackers?

Dave Plowman dav...@davenoise.co.uk London SW
To e-mail, change noise into sound.