Boiler is downstairs in utility room, with "timer" alongside it. Hot water tank, pump, and valves are upstairs, almost directly above it.
Heating comes on when control clock is "off"
- Thread starter abenn
- Start date
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Does this problem only occur at night, when the boiler should be off, or can it happen during off periods in the day?
Forget that question - see next post
Does it get cold in the utility room, particularly at night?
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The utility room gets no colder than the rest of the house at night, but the problem only occurs at night -- usually somewhere around 2 o'clock in the morning, though I can't be precise on the time because I don't necessarily wake up as soon as it starts. As has been mentioned, it's "on" from 0700 to 2230 every day and "off" from 2230 to 0700 next morning.
If you're thinking that some frost-protection circuit is mistakenly activating, shouldn't it switch off after a while, as soon as the temperature is raised enough? I know for a fact that it kept going for 2 hours the other night, before I woke up and switched it off at the mains (the wife had woken up earlier and heard it, but went back to sleep). I switched it back on at about 5 o'clock (i.e. while the timer was still "off") and the pump and boiler both started immediately.
Apart from changing valve actuators and the timer, in an attempt to cure the problem, no change has been made to the system since it was installed about ten years ago, so incorrect wiring is unlikely, I believe.
If you're thinking that some frost-protection circuit is mistakenly activating, shouldn't it switch off after a while, as soon as the temperature is raised enough? I know for a fact that it kept going for 2 hours the other night, before I woke up and switched it off at the mains (the wife had woken up earlier and heard it, but went back to sleep). I switched it back on at about 5 o'clock (i.e. while the timer was still "off") and the pump and boiler both started immediately.
Apart from changing valve actuators and the timer, in an attempt to cure the problem, no change has been made to the system since it was installed about ten years ago, so incorrect wiring is unlikely, I believe.
Yes, I was thinking of frost protection.
The boiler has built-in frost protection, which should turn the boiler & pump on if the water temperature drops below 3C and turn the boiler of when the water temp reaches 10C. The pump carries on for a few minutes longer.
The frost protection could be faulty, or the signal is coming from outside the boiler. There's an easy way to test this, which you would have to do as you can't expect an engineer to turn up in the middle of the night.
When the system goes off at night, turn the power to the system off at the wall, e.g remove the fuse from the spur.
Remove lid from the Danfoss junction box.
You will see the three cables from the actuators.
The three grey wires will go to one terminal.
Make a note of which terminal, then disconnect the grey wires.
Replace lid, if possible, and turn the power back on.
If the problem still occurs, the boiler is faulty. If it stops, the fault is external, one of the three control circuits (2xCH, 1xHW).
It's then a case of repeating the test with only one grey wire connected at a time. The one which causes the fault is the culprit.
PS don't forget to reconnect the grey wires to the correct terminal (which you did make a note of, didn't you?). Otherwise you will have no heating and hot water during the day.
I don't want an engineer to turn up in the middle of the night
The last engineer who came was thinking along the same lines as you D_Hailsham. He installed a plug and socket in the line that goes from the valve he'd just checked to the junction box, so I could unplug it next time the fault occurred. I did, and it didn't stop the pump and boiler, so at least that ruled out that particular valve. Unfortunately he didn't install plugs and sockets on the other two valves.
But I still don't understand how a sticking valve could cause the heating to come on -- if it's sticking, it could prevent it coming on if it's stuck in the "off" position, or it could prevent it turning off if it's stuck in the "on" position, but having shut down properly at 22:30 (I check all the lights) surely it couldn't suddenly send an "on" signal to the boiler in the middle of the night, could it?
The frost-protection theory sounds favourite, except why does it keep running all night when, presumably, the water will have been warmed up enough after a short while? If the reason is that it's completely stuffed, why then does the frost protection not keep the the boiler going continuously during the day too?
The last engineer who came was thinking along the same lines as you D_Hailsham. He installed a plug and socket in the line that goes from the valve he'd just checked to the junction box, so I could unplug it next time the fault occurred. I did, and it didn't stop the pump and boiler, so at least that ruled out that particular valve. Unfortunately he didn't install plugs and sockets on the other two valves.
But I still don't understand how a sticking valve could cause the heating to come on -- if it's sticking, it could prevent it coming on if it's stuck in the "off" position, or it could prevent it turning off if it's stuck in the "on" position, but having shut down properly at 22:30 (I check all the lights) surely it couldn't suddenly send an "on" signal to the boiler in the middle of the night, could it?
The frost-protection theory sounds favourite, except why does it keep running all night when, presumably, the water will have been warmed up enough after a short while? If the reason is that it's completely stuffed, why then does the frost protection not keep the the boiler going continuously during the day too?
Sorry, duplicate post.
"To date they've oiled the valves, put new actuators on,"
New actuaters on all 3 motorized valves? What make of valves do you have?
"Unfortunately he didn't install plugs and sockets on the other two valves"
If the actuaters were replaced with brand new units then one would like to think they are not faulty.
Has that not crossed your mind?
Which makes me wonder why your engineer was meddling with 3 pin plugs in the first place. That's like something a dafty diyer would be doing on a weekend to quell the boredom.
New actuaters on all 3 motorized valves? What make of valves do you have?
"Unfortunately he didn't install plugs and sockets on the other two valves"
If the actuaters were replaced with brand new units then one would like to think they are not faulty.
Has that not crossed your mind?
Which makes me wonder why your engineer was meddling with 3 pin plugs in the first place. That's like something a dafty diyer would be doing on a weekend to quell the boredom.
At least two valves Norcon, in different visits. I don't remember him doing the one that controls flow to the hot water tank.
I believe he was thinking that, despite having oiled the valves, and felt that they're not sticking, maybe they are somehow sticking so that even a new actuator can't move them
I'm going to give it another week -- at the moment it's turning on almost every night, and I'm switching it off at the mains until morning -- and then call the engineer again. I'm busy for a few days, so don't want to do it right now.
I believe he was thinking that, despite having oiled the valves, and felt that they're not sticking, maybe they are somehow sticking so that even a new actuator can't move them
I'm going to give it another week -- at the moment it's turning on almost every night, and I'm switching it off at the mains until morning -- and then call the engineer again. I'm busy for a few days, so don't want to do it right now.
I know two have been replaced Norcon, but it's cost me nothing because I have a BG annual service contract. Those two are for zone 1 and zone 2 heating. If I was paying for it, I would hope they would spend more time trying to figure things out, instead of just replacing bits one piece at a time.
The actuators are BGMVSP-2; I can't see the names (if any) on the valves.
As I said earlier, I'm a bit busy at the moment, so I'm not calling the engineer out until next week, but I'll mention the light bulb to him when he comes.[/i]
The actuators are BGMVSP-2; I can't see the names (if any) on the valves.
As I said earlier, I'm a bit busy at the moment, so I'm not calling the engineer out until next week, but I'll mention the light bulb to him when he comes.[/i]
Well, things are moving on at last. Last week I called an engineer out again, and I seem at last to have got one who seemed to take it as a challenge. I suggested the frost protection, but he said my boiler doesn't have it because it's all indoors. But then, after a lot of head-scratching, and browsing through his company laptop, he agreed that it's unlikely to be the valves because they can prevent something happening if they stick, but it's unlikely they can make something happen when it shouldn't. Just to make sure, he asked me to set the thermostats to 10 degrees at bedtime for a week, and see if the boiler still came on at night.
On the third night it came on again so, at 3 o'clock in the morning, I then switched the boiler to "OFF" using buttons behind a drop-down panel on the clock unit, as he had suggested, the idea being that the fault would then continue until daytime, when he could come and see what's the cause. But the fault cleared itself at about 5 o'clock.
When I called BG, giving his employee i.d. number to get him back again, he phoned me back and said he'd been thinking about it and discussing with his colleagues, and had realised there is frost protection on my boiler. Today he returned and replaced two detectors on the feed and return pipes inside the boiler.
Hopefully that will be the end of it, as suggested by some of you here. Thanks for your input.
On the third night it came on again so, at 3 o'clock in the morning, I then switched the boiler to "OFF" using buttons behind a drop-down panel on the clock unit, as he had suggested, the idea being that the fault would then continue until daytime, when he could come and see what's the cause. But the fault cleared itself at about 5 o'clock.
When I called BG, giving his employee i.d. number to get him back again, he phoned me back and said he'd been thinking about it and discussing with his colleagues, and had realised there is frost protection on my boiler. Today he returned and replaced two detectors on the feed and return pipes inside the boiler.
Hopefully that will be the end of it, as suggested by some of you here. Thanks for your input.
After a month the problem came back I was so fed up with it that I just switched it off manually at bedtime, and on again when I got up, and didn't bother calling BG out again for a while.
A couple of days ago an engineer came to do the annual service, and reckoned the problem must be the hot water cylinder zone valve, which is the only control that hasn't been replaced. That certainly quietened down the system (when the fault occurred it made a louder roaring/rushing noise than usual), but that evening the pump and boiler were still going an hour after the clock had switched "off". Then yesterday the hot water stopped heating. Today another engineer came and I was able to demonstrate the heating on while the clock was "off" -- something I hadn't been able to do before the hot water valve was changed -- and he replaced the upstairs zone valve, which was new only last November. He tested the hot water valve and pronounced it okay.
Tonight neither the hot water nor the upstairs zone come on, though the hot water tank does seem to warm up a bit whenever the downstairs heating zone is on
I think my next heating system will NOT be a BG one. I'll go to a local engineer for supply, installation, and maintenance.
I was so fed up with it that I just switched it off manually at bedtime, and on again when I got up, and didn't bother calling BG out again for a while.A couple of days ago an engineer came to do the annual service, and reckoned the problem must be the hot water cylinder zone valve, which is the only control that hasn't been replaced. That certainly quietened down the system (when the fault occurred it made a louder roaring/rushing noise than usual), but that evening the pump and boiler were still going an hour after the clock had switched "off". Then yesterday the hot water stopped heating. Today another engineer came and I was able to demonstrate the heating on while the clock was "off" -- something I hadn't been able to do before the hot water valve was changed -- and he replaced the upstairs zone valve, which was new only last November. He tested the hot water valve and pronounced it okay.
Tonight neither the hot water nor the upstairs zone come on, though the hot water tank does seem to warm up a bit whenever the downstairs heating zone is on
I think my next heating system will NOT be a BG one. I'll go to a local engineer for supply, installation, and maintenance.
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