Any ideas? Unreliable heating.

[garyevans]

Got closer. Yes arrow on right is downwards. View attachment 80051

All inlet valves downstairs are scorching hot. All rads have been bled. First 3 rads on system downstairs are warm but there 4 after that are not.

 

[John.g]

Very strange allright, presume not something daft like the pump valves not opened fully, they look like gate valves so should be ~ 3 or 4 full turns from fully shut to fully open. There arn't too many things left, the pump was probably changed out without drain or partial system drain down, possible sludge build up but unlikely except the F&E tank was full of crap and drained down into the system. (if system drained)

The possibility of a faulty UPS3 still exists but if so unlikely that air would continue to build up, are you still venting air, you say all rads have been bled?.

CP1 at 3M should not cause any problems and is required for most systems of your size, my system runs at 3.5/3.6M with the (Wilo) pump set to a PP setting of 4.6M.

 

[garyevans]

Very strange allright, presume not something daft like the pump valves not opened fully, they look like gate valves so should be ~ 3 or 4 full turns from fully shut to fully open. There arn't too many things left, the pump was probably changed out without drain or partial system drain down, possible sludge build up but unlikely except the F&E tank was full of crap and drained down into the system. (if system drained)

The possibility of a faulty UPS3 still exists but if so unlikely that air would continue to build up, are you still venting air, you say all rads have been bled?.

CP1 at 3M should not cause any problems and is required for most systems of your size, my system runs at 3.5/3.6M with the (Wilo) pump set to a PP setting of 4.6M.

What does venting air mean?

 

[garyevans]

What does venting air mean?

John, should the gate valve directly under the pump be fully open? The middle of the three you can see in the photo I uploaded yesterday.

 

[John.g]

What does venting air mean?

Opening the vent screws and getting rid of any air in the rads. (Bleeding the rads)

John, should the gate valve directly under the pump be fully open? The middle of the three you can see in the photo I uploaded yesterday.

Not sure about the one with the red handwheel (you would have to trace it but let it be just now whatever its opening is).

The two brass valves, immediately above and below the pump MUST be fully open, get a adjustable spanner or even a pliers and try shutting first, if they are open then you should get 3 to 4 turns to shut, then immediately reopen, ie they must be ~ 3 to 4 full turns open from fully shut.

 

[garyevans]

Opening the vent screws and getting rid of any air in the rads. (Bleeding the rads)

Not sure about the one with the red handwheel (you would have to trace it but let it be just now whatever its opening is).

The two brass valves, immediately above and below the pump MUST be fully open, get a adjustable spanner or even a pliers and try shutting first, if they are open then you should get 3 to 4 turns to shut, then immediately reopen, ie they must be ~ 3 to 4 full turns open from fully shut.

Cheers. In work now so will try again when I get home late afternoon.

 

[garyevans]

Cheers. In work now so will try again when I get home late afternoon.

That middle pipe seems to go into the bottom of the immersion heater.

 

[garyevans]

Opening the vent screws and getting rid of any air in the rads. (Bleeding the rads)

Not sure about the one with the red handwheel (you would have to trace it but let it be just now whatever its opening is).

The two brass valves, immediately above and below the pump MUST be fully open, get a adjustable spanner or even a pliers and try shutting first, if they are open then you should get 3 to 4 turns to shut, then immediately reopen, ie they must be ~ 3 to 4 full turns open from fully shut.

Yes, all rads are bled - doing it all the time. No air in them.
The way I got the CP2 to work on Sunday (bleed rads, turn on HW, run HW, turn off HW, turn on CH, when upstairs rads get hot, switch them off and pump heat downstairs) is failing on the last part with CP1 as only 3 or 4 of the 7 rads downstairs get the heat - should I switch all off apart from last one and rebalance the rads?

 

[John.g]

When you bled the rads on Sunday, how much water did you bleed off each?

If no air in them then pointless venting, except that you are getting some heat in them by actually bleeding off a few litres of water which means no circulation or circ pump defective, CP2 at 4.5M even with all rads open (no balancing) should circulate plenty of water to get all/most quite hot, you have another problem IMO.
When you come home and if you find that the pump valves are fully open (and probably are) then may have to check the circ pump.

That middle pipe seems to go into the bottom of the immersion heater.

probably the cold water supply to your HW cylinder.

 

[garyevans]

If no air in them then pointless venting, except that you are getting some heat in them by actually bleeding off a few litres of water which means no circulation or circ pump defective, CP2 at 4.5M even with all rads open (no balancing) should circulate plenty of water to get all/most quite hot, you have another problem IMO.
When you come home and if you find that the pump valves are fully open (and probably are) then may have to check the circ pump.



probably the cold water supply to your HW cylinder.

Thanks John. I have bled the rads but not emptied them per se - when you say 'no circulation or corc pump defective' what else could cause the 'no circulation'? The weird thing is that on Sunday after I changed to CP2 all rads were hot, same Monday but then Monday night the downstairs rads went cold. So that must be an airlock? But there is no air in rads! Given that we have had heat i would guess the pump valves are fully open.