Hi All, hoping somebody could give me some pointers with this problem. Sorry if any of the details below are not relevant, but I figure it best to describe in full what I have tried and noted.
Glowworm Ultracom 24hxi condensing boiler in airing cupboard with HW cylinder
Drayton LP722 control unit
Honeywell 3 way MV
Honeywell cylinder thermostat
Initially, I noticed a couple of downstairs rads were not heating very well recently. Having looked around this forum I decided the system needed balancing. I followed the instructions found in another thread and turned the locks off on the rads, turning them back on a quarter turn each. All upstairs rads continued to work as expected, still not a lot of heat from the rads downstairs.
I noticed that the hot water at the taps was extremely hot and thought maybe the cylinder thermostat was at fault. I don't hear any clicking sound when increasing or decreasing the temp setting on the cylinder.
However, I also discovered that the water was being pumped to both the HW and CH system simultaneously, even if I turned the HW off. This is how it has been for the past week or so. With the HW set to OFF, when the CH is on, the rads heat up ( still a bit dicky in a couple downstairs ) but very hot water is still being sent to the cylinder. All pipes from the 3 way motorised valve are hot constantly.
The MV slider (?) for auto/manual is loose and flappy with no resistance at all. I have just switched off all power to the house and opened the MV. With no power, the slider DOES have resistance and can be pushed to auto or locked to manual. With the power back on it goes loose again. Possibly perfectly normal, I have no idea!
After restoring power to the house I decided to see what would happen if I reversed things on the control unit so that the CH was OFF the HW was on. Cold water then ran through all pipes out of the MV. I have just checked again and the pipes are now hot, but the boiler has not started and the display for the boiler is showing 38c.
So...
With the HW off and CH on, both the rads and water cylinder are heated. HW is extremely hot and seemingly uncontrollable by the cylinder thermostat.
With the CH off and the HW on, cold water was initially running through the MV but this is now hot water, despite the boiler sitting quietly minding it's own business.
I just can't get straight in my mind what may need looking at and in what order. I was going to pop out and get a new honeywell MV, but not sure if I need the motorised section alone or the whole assembly. I thought the floppy lever indicated a fault, but was then surprised when it was stiff without power. This is all sounding like fifty shades of plumbing now!
Any help very gratefully received.
All the best,
Lee.
Update
With the HW on I increased the cylinder thermostat way up, beyond 80c, and the pump and boiler started up AND the MV lever has resistance...can be pushed to the right to manual and moves itself back over to the left.
Glowworm Ultracom 24hxi condensing boiler in airing cupboard with HW cylinder
Drayton LP722 control unit
Honeywell 3 way MV
Honeywell cylinder thermostat
Initially, I noticed a couple of downstairs rads were not heating very well recently. Having looked around this forum I decided the system needed balancing. I followed the instructions found in another thread and turned the locks off on the rads, turning them back on a quarter turn each. All upstairs rads continued to work as expected, still not a lot of heat from the rads downstairs.
I noticed that the hot water at the taps was extremely hot and thought maybe the cylinder thermostat was at fault. I don't hear any clicking sound when increasing or decreasing the temp setting on the cylinder.
However, I also discovered that the water was being pumped to both the HW and CH system simultaneously, even if I turned the HW off. This is how it has been for the past week or so. With the HW set to OFF, when the CH is on, the rads heat up ( still a bit dicky in a couple downstairs ) but very hot water is still being sent to the cylinder. All pipes from the 3 way motorised valve are hot constantly.
The MV slider (?) for auto/manual is loose and flappy with no resistance at all. I have just switched off all power to the house and opened the MV. With no power, the slider DOES have resistance and can be pushed to auto or locked to manual. With the power back on it goes loose again. Possibly perfectly normal, I have no idea!
After restoring power to the house I decided to see what would happen if I reversed things on the control unit so that the CH was OFF the HW was on. Cold water then ran through all pipes out of the MV. I have just checked again and the pipes are now hot, but the boiler has not started and the display for the boiler is showing 38c.
So...
With the HW off and CH on, both the rads and water cylinder are heated. HW is extremely hot and seemingly uncontrollable by the cylinder thermostat.
With the CH off and the HW on, cold water was initially running through the MV but this is now hot water, despite the boiler sitting quietly minding it's own business.
I just can't get straight in my mind what may need looking at and in what order. I was going to pop out and get a new honeywell MV, but not sure if I need the motorised section alone or the whole assembly. I thought the floppy lever indicated a fault, but was then surprised when it was stiff without power. This is all sounding like fifty shades of plumbing now!
Any help very gratefully received.
All the best,
Lee.
Update
With the HW on I increased the cylinder thermostat way up, beyond 80c, and the pump and boiler started up AND the MV lever has resistance...can be pushed to the right to manual and moves itself back over to the left.