Dreaded air in upstairs radiators and heating is off

[Johntheo5]

Many thanks again for your very useful suggestions. Presently not at home but will be back around mid day. Pump was on 4.0 and PV setting. It shows the power setting but I don't think flow. Was also set on dynamic setting but turned this off.

If you mean a PP setting?? of 4.0M then this shouldn't cause problems, or was/is it set to CP 4.0M, see below.
The pump (as you probably know) apart from C1,C2&C3 modes, will flash the set head pressure for a few seconds and then display the power, W,
I have mine set to PP (proportional pressure) at 4.6M which gives a actual head of ~ 3.6M with all the (10 rad) TRVs open and ~ 2.7M when they throttle down, the second photo shows a CP (constant pressure) setting of 4.0M., For info, C1=constant curve 2M, C2=constant curve ~ 3.8M & C3=constant curve 6M.
You could try a CP setting starting at say 2.5M, if no air problems then but if rads a bit slow to heat up, you can gradually increase the SP incrementally in 0.1M steps to get the optimum setting.

Another bit of information which could negate potential blockage. Have tried the magnet test on all pipes in that area and no pull detected. I did this test 10 years ago and had several areas to replace

I have a 50 year old open vented system with some rads over 40 years old, never gave/gives any sort of air ingress problems because of the way it was installed over 50 years ago with a true combined vent& cold feed, I have seen VCP systems converted to my type which cured the problem despite havin a perfectly clean VCP system

 

[nairb999]

Pump was set at 4.0. Changed to 2.6 to see if that helps

 

[Johntheo5]

You wont pump much at that PP? setting of 2.6M which isn't giving a head of much more than 1.5M or so and 9W will pump practically nothing even at that 2.6M PP setting. What was the power at 4.0M SP??, whatever its shownig then turn the setting knob clockwise, the pump curve line should be straight horizontally, until you get the same power output as you had on PP 4.0M, you can then see what the actual head is, if its down around or less than 3.0M then you you almost certainly have a problem somewhere IMO.

 

[nairb999]

If I set at PV

 

[nairb999]

If I set at PC

 

[Johntheo5]

Ok set it to say 2.5M now.

 

[nairb999]

2.5

 

[Johntheo5]

Thats more like it, ~ 0.7m3/hr, 11.7LPM, how many rads is that circulating through? (if HW cylinder, ensure coil zone (motorized) valve closed).
You certainly shouldn't be getting any air problems with that head so get rid of any remaining air and then see how it goes, you can allways increase the head later.

 

[nairb999]

Will do much appreciated

 

[Johntheo5]

Based on the above, then when running on the PP (PV) setting then the flow should have been ~ 0.78m3/hr @ a 3.2M & ~ 20W.

 

[nairb999]

The expansion tank is approximately 2m above the pump. The water level in the expansion tank is 2inches above feed pipe. Does that help diagnosis?

 

[Johntheo5]

No harm to have it a bit higher, say maybe 6" above the feed pipe while allowing enough room for the expansion vol when the system heats up which even if your system is 100 litres will still only be ~ 2 litres or so.

 

[nairb999]

I have a few things to go at now thanks to Johntheo. If still have air ingress I could look at joint feed/vent as per your layout. Looks a very simple switch

 

[fixitflav]

Pump was set at 4.0. Changed to 2.6 to see if that helps

Something funny going on here. Those attachments appear to relate to your financial dealings.

 

[nairb999]

Many thx for pointing that out. Hopefully deleted now