My heating has developed a new and unwelcome quirk just recently, which is that it's sporadically failing to provide hot water. This is something that happened a few weeks back, but it seemed to go back to normal, but in the past couple of days it has happened again each day. We have a conventional setup with the following components:
Boiler: Vaillant Ecotec Plus 815
Programmer: Potterton EP2002 (pre-dates boiler)
Room stat: Danfoss Randall TP7001 (programmable)
Cylinder stat: Honeywell L641A
Diverter: Drayton Mid-Position Actuator MA1
The programmer has CH set to 'On' so that the room stat can take care of timings. The HW is set to 'Timed' and is on for something like 40 or 50 minutes in the morning and again in the afternoon, which is normally enough for our needs.
We've now had a couple of mornings where no hot water was available, and this evening there was none left after washing up, which is not usual. The programmer has an 'Ext'(end) function which I set to +1 hour just to get some hot water available again, but nothing happened. Well, the HW light illuminated on the programmer, but there was no 'click' and the boiler didn't kick in. I tried unseating the cylinder stat and turning it right up, but that made no difference. The diverter was positioned at H because the heating had been on earlier. I wondered if it might be stuck, but if I cut the power, it goes back to W. On the programmer, I moved the HW slider between On, Once, Timed and Off, and this made no difference. However, when I moved the CH slider to Off and then back to On, the boiler kicked in to heat the water (no demand from room stat and diverter moved to W).
One other thing I noticed yesterday was that if I tried to get the CH and HW on simultaneously by turning up the room and cylinder stats, it seemed to satisfy or the other demand, but not both. E.g. if it was heating the water and I turned up the room stat, the latter showed a flame (heating demand) on the screen but nothing seemed to happen, and then it eventually seemed to give up (flame disappeared). I'm fairly sure the converse also applied - i.e. when CH was active, trying to get HW didn't work. I have yet to see the diverter at position M.
Does anyone have a feel for what the problem is here? The diverter valve seems able to switch position, but could it still be at fault, or is it more likely to be the programmer (which is a bit ancient after all, and the switches have felt a bit iffy for a while)?
Any help much appreciated, as waking up to no hot water in deepest February is not a fun game.
Boiler: Vaillant Ecotec Plus 815
Programmer: Potterton EP2002 (pre-dates boiler)
Room stat: Danfoss Randall TP7001 (programmable)
Cylinder stat: Honeywell L641A
Diverter: Drayton Mid-Position Actuator MA1
The programmer has CH set to 'On' so that the room stat can take care of timings. The HW is set to 'Timed' and is on for something like 40 or 50 minutes in the morning and again in the afternoon, which is normally enough for our needs.
We've now had a couple of mornings where no hot water was available, and this evening there was none left after washing up, which is not usual. The programmer has an 'Ext'(end) function which I set to +1 hour just to get some hot water available again, but nothing happened. Well, the HW light illuminated on the programmer, but there was no 'click' and the boiler didn't kick in. I tried unseating the cylinder stat and turning it right up, but that made no difference. The diverter was positioned at H because the heating had been on earlier. I wondered if it might be stuck, but if I cut the power, it goes back to W. On the programmer, I moved the HW slider between On, Once, Timed and Off, and this made no difference. However, when I moved the CH slider to Off and then back to On, the boiler kicked in to heat the water (no demand from room stat and diverter moved to W).
One other thing I noticed yesterday was that if I tried to get the CH and HW on simultaneously by turning up the room and cylinder stats, it seemed to satisfy or the other demand, but not both. E.g. if it was heating the water and I turned up the room stat, the latter showed a flame (heating demand) on the screen but nothing seemed to happen, and then it eventually seemed to give up (flame disappeared). I'm fairly sure the converse also applied - i.e. when CH was active, trying to get HW didn't work. I have yet to see the diverter at position M.
Does anyone have a feel for what the problem is here? The diverter valve seems able to switch position, but could it still be at fault, or is it more likely to be the programmer (which is a bit ancient after all, and the switches have felt a bit iffy for a while)?
Any help much appreciated, as waking up to no hot water in deepest February is not a fun game.