TRVs not fully open at maximum?

[MrTherm]

mrbrunes,

Your link to the Calleffi pdf file shows how to reset the valve head. Perhaps you overlooked it yet it is easy to follow.

Put blade in valve head slot to reveal lower rim, hold the rim and turn the valve all the way to reset. Most Calleffi heads have similar setting adjustment.

You should hear the water flowing through the valve at some stage of the resetting.

This youtube clip may help...

good luck.

 

[mrbrunes]

Thanks, as I said before I found the temp fixing/limiting procedure in the PDF but this has not been done on the valves, otherwise they would not be able to be set at V.

Answers to D_Hailsham's Qs:

Yes the bodies may not match the heads, but IMO it's unlikely given that swapping heads from upstairs shows the same issues, as does using a Honeywell head.
The downstairs TRVs appear to be the same as upstairs.
I'll take a pic of the body next time.
I'll take an exact room temp reading next time, but I'd have been sweating if it was anything over 24C!
It's a sealed system of 8 rads with a Intergas Combi Compact HRE 28/24 boiler.
I've done a very rough balancing without taking pipe temps, although it took a while to discover that the rads were not fully open with the TRV head present!

 

[D_Hailsham]

If the valve is not fully open when set to max (V) (assuming the room is not extremely hot), the pin projecting from the body must be too long, which implies the head is incompatible with the body.

I'm not sure what taking the temperature will achieve.

Balancing should always be done with TRV heads removed.

You wondered if a lack of system pressure would affect the downstairs rads. The static pressure (as shown on the boiler's pressure gauge) would have no effect. If the dynamic pressure (produced by the pump) was too high a TRV may be noisy. In any case a TRV does not depend on the water pressure to open; this is controlled by springs. The only way pressure could have an effect is if there were insufficient pressure drop between flow and return connections - specifically the T connections from the main flow and return pipes. If this is too low, the water flow through the rad will be insufficient. This can be caused by an incorrectly balanced system.

However, this does not explain why the TRV is shut when it should be open.

 

[mrbrunes]

Some pics of the bodies of two TRVs in case it helps:


Will have to check the balancing properly next time.

 

[D_Hailsham]

That's definitely a Caleffi body; you can see the logo on the left pic.

Just wondering if it's an old body with an incompatible head for a newer body.

 

[MrTherm]

Some Caleffi valves have a threaded insert adapter (spacer) that fits over the white valve nut, inspect the good working valves to compare and check if these are missing otherwise without them the pin will be always pushed down and water flow shut off.