Temperamental Hot Water

[Gregor Spowart]

Hi everyone,

I have a strange problem with my hot water and/or gas central heating. The system is a boiler that fires up when you either turn the taps on, or switch the heating on.

Up until a few weeks ago it had been fine, but now the downstairs heating doesn't seem to be as hot as it used to be (the boiler is upstairs and the upstairs heating is fine) and the hot water for the shower and taps seems to run hot, then cold, then lukewarm then stays cold, or a variation of these. Sometimes it'll run hot for a long time and other times it'll run hot for only a minute before running cold again. Turning the hot tap off then back on again can help but isn't guaranteed.

We've noticed that it runs colder when it's windy outside so we're wondering whether the wind is blowing into the air escape pipe from the boiler (flue? - can you tell I don't have much idea!) and causing the problem. The flue itself is just a vent - it doesn't have a covered area and vents at the side, it's just one big plant pot shaped grill that goes over the escape pipe from the boiler. I wonder if changing it for a covered one so that the wind doesn't blow in will fix it?

We phoned Scottish Gas, but they didn't think that the wind had anything to do with it so I thought i'd get your opinions.

One other thing that was mentioned was getting the pipes blasted, in case there is a blockage which is resulting in the downstairs heating not being as hot as it used to be. It was installed 10 years ago so I suppose this is plausible. It was also suggested to replace the boiler, but I'm loathe to do so considering they couldn't pinpoint the exact problem.

Sorry for the clueless language, and thanks for any help you can offer.

Gregor

[John]

Sorry but you don't sound as though you ought to consider touching the boiler yourself, however I would anticipate the problem may be due to the diverter valve not travelling across from heating to hot water position correctly. This may be due to a failing diaphragm or it could be simply stiff due to a coating of crud building up within the moving parts of the diverter. Its also possible your pump is losing performance either due to muck stuck in the impellor or simply age. The make and model of the boiler (combi) would make any diagnosis or suggestions much easier. It sure won't be due to wind by the way.

[Gregor Spowart]

Oh jeez yeah, I wouldn't be trying to fix it myself! :-) I was just looking for some guidance as to whether it was a new boiler issue or something else.

Anyway, we managed to get Scottish Gas to come and look at it, and the guy they sent spent a bit of time cleaning out the flue, which was apparently filled up with muck and grime.

Since he left, the problem appears to have disappeared so hopefully that's the end of it.

Thanks for your response though - much appreciated.

Gregor