@toodles 

Ah, that makes sense. Your using the TRV body to augment a lockshield that has poor flow control.

I think I've been lucky in that the two bedroom radiators both have TRVs which control the room temperature fairly consistently around 17.5° when set just above '2'.

Not all LSVs are created equally and that will affect how much flow the respective TRV has to deal with. 

@singlespeed I had better explain how my radiators are set up:

As per MCS advice, all emitters have a TRV fitted (along with a LSV on t’other end with the TRV fully open by means of removal of the head and use of decorator’s caps for neatness. All balancing was carried out using the LSV’s so the flow rate is constant. I have achieved a good balance in all rooms; our requirement is for 22.5 degrees C 24/7 in all rooms except the bathroom which has been set to achieve ~ 25-26 degrees. This took some time to finesse after the initial setting up but  ~4 years on is still working fine. If I do adjust the required comfort level on the Homely controller, the various rooms stay ‘in step’ without any problems. Perhaps I should mention that we rarely shut internal doors so we are effectively ‘open plan’. I appreciate that 22.5 is higher than some would like but age and health conditions have dictated this to be our comfort level.

As to the LSV’s authority merits, I am not sure but, having achieved the balance required by time and patience, the system seems very stable. Regards, Toodles.

@andrewj

Posted by: @andrewj

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I currently have it set to keep the house at 22c (runs off a thermostat if you recall) with a setback to 21c 23:00 to 03:30.  Hot water runs 02:30 to 03:30.  I have the house set to warm back to 22c at 03:30 because I’m on an overnight tariff of 6.6p until 05:30 so it make sense to do “heavy lifting” before the peak period starts and it pulls on my battery.

I used to have a similar strategy but with a set back of 2c from 21c to 19c in an attempt to keep the running costs down (did not have a battery at the time ). It would set back at 9pm and start ramping up the temperature at 3-30am while still in the cheap overnight period. The problem was it took over 12 hours to recover back to 21c (especially on really cold days) where it remained for approximately 3 hours while we watched TV and then it would start the whole cycle again.

I concluded it did not save anything and may have even cost more setting back for 6 hours. I just leave the HP running 24/7 now, keeping the downstairs at a constant 22c and control the bedroom temperature with a smart TRV. The heat from downstairs helps to stop the upstairs temperature from dropping too much.

Having a battery does help a lot and I find the HP is within the battery's power budget now its running constantly.

@technogeek agreed.  I’ve stopped the setback since that post and just leave it at 22c.  I’ve dropped the warm weather end of the curve down to 31c and it is still maintaining temperature although it isn’t particularly cold right now.  It did get down to 8c last night mind and my Govee thermostat is showing that internal temperature is maintained.  Still working on the tuning and I’d like to get to the point where it is running constantly rather than on hysteresis.

Posted by: @andrewj

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If it was taking 18 hours to recover from 19c to 22c I definitely would care

Much longer than that here. The heating isn't even on.