Air lock i think

[Johntheo5]

OK thanks, you can cool down now, if the watts didn't fall below 26/30W for a few seconds before you re opened the outlet valve then its possibly a 45W pump, (it should have fallen to 20W if a 35W pump) and the circ flow is very low at ~ 2.5/3.0LPM, just about enough for 3 rads or so, can you, if you are up to it, change the pump mode to CP2, this is a 4.5M constant pressure mode, and then put HW only on, you may have to turn up the cylinder stat temporarily, note the power W, again. You can then let it on this mode when the CH is scheduled back on, turn off the HW if not scheduled off, if you don't feel inclined to do this, just wait until the CH is on again and then change the setting to CP2 and note the power.

 

[scotthud]

im out at present so will change it to CP2 mode when i get home (schedule will have kicked in by then) what is the difference between CP mode and I II III as, as far as i can remember since the pump was changed during a service, its always been on III mode

 

[Johntheo5]

The pump will circulate 87% of the flowrate in CP2 mode (4.5M) vs CSIII (6.0M), The main reason for changing to CP2 is to determine for sure whether you have a 35W or a 45W pump, if it is a 45W pump then the circulation rate is only ~ 2.0LPM at 36W, if its a 35W pump then the circulation rate is ~ 10.0LPM and we can look for the problem elsewhere.

When you do change to CP2 and have noted the power, shut the outlet valve again, wait another 4 or 5 secs after the power has stopped falling and then reopen the valve. If the power falls to 14W then its a 35W pump, if it only falls to 22W then its a 45W pump, when you shut the valve on CSIII, the power should have fallen to 20W if a 35W pump but it didn't.
You can then return to CSIII if you wish.

If you look at the writing on the black part of the pump body you might see the power in watts, something like 4w 35w or 6w 45w

 

[scotthud]

With valve open

With valve closed

All radiators now on and "appear" to be working as they should - touch wood, fingers crossed and all that

 

[Ray1000]

Well Done

 

[Johntheo5]

View attachment 340057

With valve open
View attachment 340058

With valve closed

View attachment 340059

All radiators now on and "appear" to be working as they should - touch wood, fingers crossed and all that

Yes, confirmed on all counts, a 45W pump.

However, unfortunately this only corresponds to a flowrate of 0.2m3/hr, 3.3LPM which seems unlelievably low for what?, 6 or 7 rads, however, the proof of the pudding is that all the rads are hot, I would expect a very big dT of at least 20/25C.

It will/would be interesting to see the pump power when running with HW only or/and HW&CH.

45W Pump.

 

[scotthud]

Yes, confirmed on all counts, a 45W pump.

However, unfortunately this only corresponds to a flowrate of 0.2m3/hr, 3.3LPM which seems unlelievably low for what?, 6 or 7 rads, however, the proof of the pudding is that all the rads are hot, I would expect a very big dT of at least 20/25C.

It will/would be interesting to see the pump power when running with HW only or/and HW&CH.

45W Pump.

Those images where with both HW & CH on, we have 8 rads downstairs and 6 upstairs, all are hot to touch now.
Ive lived in the house since new (95/96) and only had one pump failure, ? never really had issues apart from needing to bleed the radiators and obviously to flush the one that caused all of this lol.

 

[Johntheo5]

What is the make/model of the boiler?

 

[scotthud]

What is the make/model of the boiler?

erm its ancient lol been in since hte house was built,

 

[scotthud]

So i really just want to say a massive thank you to everyone who took time out of their lives to help me with the issue, i feel ive learnt a lot about the system in the house and even at my age feel a lot more confident to tackle any similar issues in the future.

No doubt ill be on here asking for advice if any further issues occur, knowing that their are people on here who not only have the experience/knowledge but the time to give advice and to try and help others. Its really appreciated.

 

[Johntheo5]

This might be of interest to someone with the same pump, these numbers are from a system with 12 rads.