valliant gas combi boiler

[oddjobchas]

the water goes hot for afew minutes thengoes cold for awhile and then warm again the water pressure to and in the boiler is ok anybody any ideas please

[The Rooster]

Hello Valliant,

My understanding of boilers is that they operate based on flow, so if your flow is insufficient or compromised in some way, you could experience hot and cold flashes. Since your pressure remains constant, try checking for restrictions in the system. Have you been experiencing reduced flow issues?

[oddjobchas]

no the flow is constant the whole time

[wilsarnie]

We had the same problem. It started off going cold for a short time and we could cope with it. The cold periods got longer and longer until eventually no hot water at all. Our plumber kept on trying different things but he wasn't fixing it.

All is not lost though! Turns out it was the fan inside that was dirty and couldn't spin. No fan = no boiler igniting as could overheat. We hadn't had it serviced.

If your plumber can't fix it like ours, I called the company who made the boiler and they sent someone out for a fixed flat fee. Efficient, on time and now we have hot water.

Good luck!

[oddjobchas]

thanks for your reply will telephone someone

[sbredfan]

I've had the same problem twice in ten years with a Saunier Duval (Hepworth ie Gloworm) Combi Boiler. The first time it was the fan as suggested by wilsarnie; I removed it, sprayed the bearings well with WD40 and spun the fan by hand until it was noticeably spun more freely, then sprayed with spray grease. That was ten years ago and is still running fine. On the second occasion, a year ago, it was the air pressure switch which detects that the fan is blowing and that the flue is clear. I made a small adjustment of the setting screw, but it would be safer to replace the air pressure switch unless you really know what you are doing and how to test it after adjustment.

[oddjobchas]

ok will srp fan downtks a lot

[Disco Fever]

My bro had a Vallaint boiler that was over 15 years old and had the same problem but it was just as cheap to get rid of it and buy a new up to date combi boiler as the parts were no longer obtainable and a new boiler has a better efficiency.