Care and feeding of pressurised heating system

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 :-)

  1. 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?

  2. 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?

  1. 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

Reply to
Pete Verdon
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Hi Pete,

For balancing the rads there is a FAQ here:

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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:

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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

Reply to
Martin Pentreath

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.

Reply to
Dave Plowman (News)

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

Reply to
Pete Verdon

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.

Reply to
Dave Plowman (News)

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