I've searched these forums and most problems seem to relate to this combi not delivering anything - I suddenly have the opposite problem!
On the control panel there are 2 rocker switches, one is boiler on/off and the other is constant/off/timer. About 4 weeks ago, when it was warm weather, with the boiler switch set on and the timer switch set to off (i.e. operating just for hot water), the boiler suddenly fired up and the central heating came on. No matter how I turned the timer switch it stayed on. If I switched the boiler off with its switch it did stop. So I tried turning down the therm in the room, and the temp controls on the panel, all with no effect. I noticed the temp of the hot water from the tap was scalding - a lot hotter than usual, almost like it was heating to the max. I thought this "glitch" might settle so left it like this for a while, but after half an hour I heard a loud clanking noise, went over to the boiler and actually saw the pilot extinguish itself. I'd never heard that before, so killed power at the wall. I tried relighting the pilot, which did initially, but the clanking started much quicker and it again shut off. There were also some drops of water coming from the bottom of the unit, not much but its wasn't there before. These drops didn't happen again.
Thinking this killing the pilot was a safety feature, I resigned to calling a plumber. However this took several days, and actually still hasn't happened, so about a week later I thought I'd try again. I checked the water pressure was good, it did need a top up (but not much) and when I switched it on all was perfect! It lasted a few days like this, then the same pattern repeated - all of a sudden the CH came on, water was scalding and I shut it down before it got the chance to start its clanking. Its since repeated this fixed-then-broken cycle twice again.
System is 15 years old and has had a major repair about 2 years ago, it needed a new pump plus some other stuff. No probs since. When its running, its perfect, the rads heat up real quick, the HW is perfectly controllable and the timer etc is all fine. So I'm reluctant to replace it knowing this, it just seems a control fault.
Sorry for going on a bit here but I figured the more info the better chance anyone has of spotting the fault, and in fact anyone coming to this post in future. All ideas welcome! Thanks.
On the control panel there are 2 rocker switches, one is boiler on/off and the other is constant/off/timer. About 4 weeks ago, when it was warm weather, with the boiler switch set on and the timer switch set to off (i.e. operating just for hot water), the boiler suddenly fired up and the central heating came on. No matter how I turned the timer switch it stayed on. If I switched the boiler off with its switch it did stop. So I tried turning down the therm in the room, and the temp controls on the panel, all with no effect. I noticed the temp of the hot water from the tap was scalding - a lot hotter than usual, almost like it was heating to the max. I thought this "glitch" might settle so left it like this for a while, but after half an hour I heard a loud clanking noise, went over to the boiler and actually saw the pilot extinguish itself. I'd never heard that before, so killed power at the wall. I tried relighting the pilot, which did initially, but the clanking started much quicker and it again shut off. There were also some drops of water coming from the bottom of the unit, not much but its wasn't there before. These drops didn't happen again.
Thinking this killing the pilot was a safety feature, I resigned to calling a plumber. However this took several days, and actually still hasn't happened, so about a week later I thought I'd try again. I checked the water pressure was good, it did need a top up (but not much) and when I switched it on all was perfect! It lasted a few days like this, then the same pattern repeated - all of a sudden the CH came on, water was scalding and I shut it down before it got the chance to start its clanking. Its since repeated this fixed-then-broken cycle twice again.
System is 15 years old and has had a major repair about 2 years ago, it needed a new pump plus some other stuff. No probs since. When its running, its perfect, the rads heat up real quick, the HW is perfectly controllable and the timer etc is all fine. So I'm reluctant to replace it knowing this, it just seems a control fault.
Sorry for going on a bit here but I figured the more info the better chance anyone has of spotting the fault, and in fact anyone coming to this post in future. All ideas welcome! Thanks.
