Help with choosing TRVs

Just a quick question regarding the IMI valves.

If setting the flow restrictor in the trv head, do you still need it to balance the rad, or just open the lockshield wide open
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I found the lock shield valve setting was very important specially if the TRV fitted on return, as to make of TRV can't see it matters as all the heads that came with them are in a draw not fitted, as first thing was to change head to a programmable head.

With the expensive programmable heat it shows both target and current temperature, so I set the lock shield valve by first turning off completely then with central heating running opening bit at a time until supply pipe warm. Then I monitored the target and current over a few days, if target over current after 2 hours running I would open lock shield a little, and if target under current close the lock shield a little.

What I found was the radiator at full temperature stores too much heat, so even when the TRV closes the radiator is still heating the room, and even a programmable TRV takes time to close, so before the TRV can close the radiator is stinking hot unless the lock shield is adjusted, by slowing down the speed at which the radiator heats up, it gives chance for the TRV to do its job.

Also of course although while the central heating is running each TRV can open or close a little to adjust flow, once the heating switches off, all TRV heads will open, so on switching on again the water takes easiest route, so some radiator near to boiler will get hot first, and before room has warmed up it will allow hot water back to the boiler, so the boiler will modulate, i.e. turn down its output, so instead of the whole house warming up together, it will warm up room at a time. OK I will admit in my house with oil fired central heating boiler the boiler does not modulate so likely it would not matter that much if the lock shields were wide open, as my boiler only controls output temperature, and with micro bore pipe sizes tend to ensure each radiator does get its fair share, but with 15mm pipes and gas modulating boiler the setting of the lock shield valve is very important.

Some TRV valves are a combined TRV and lock shield valve, in which case what @muggles says is valid you don't set two lock shield valves, just one, as to what the setting of the combined TRV and lock shield valve does to pin travel I do not know, with one programmable valve I use it does not tell you if pin travel is within the heads range, oddly that is the expensive type, the other give fault codes, F3 too small and F2 too large, so if you get a F3 code with the cheap eQ-3 valve then you would need to open the combined TRV and lock shield valve and use the one on other side of radiator.

I considered the TRV was rather poor controlling room temperature, but the house I did live in had a problem with bay windows and the sun making the room temperature far too high when combined with heat from radiators, so I tried programmable heads, once the lock shield was set, they worked very well, with target temperature of 20°C before fitting electronic programmable heats room could hit 32°C after fitting and adjusting 24°C sun still caused an over shoot but very much reduced, also fitted in 3 other rooms, and once adjusted they were within 1°C of target, what was a surprise was on deciding to sell the house the old wax heads were put back, and we brought the programmable heads with us, but did not alter the lock shield valve settings, and found the rooms were still reasonably well controlled with old was heads, on the make we were using between 2 and 3 was 20°C.

The Energenie heads in old house never seemed to make radiators fully cold, they were not hot, but did not feel warm or cold to touch, but in the new house our eQ-3 heads do make radiator fully cold when the boiler is running and room warm enough, as to if this was the valve bases, or the heads hard to say, all bases were changed when we moved into this house.

From what I have read, the Drayton Wiser TRV heads seem to be best, it seems these heads are smart in that they work out when they need to close for the room to reach target without over shooting, however they are expensive, I would not recommend the Energenie I have, as you have very little control without the phone or PC, the default is eco 16°C and comfort 21°C which is to my mind too low and too high, so have to use PC to set a schedule, the much cheaper Eqiva eQ-3 allows the user to set the eco and comfort temperatures, and although we have the bluetooth version (£15 each) I rarely use the phone to set them, I simply turn dial or press eco/comfort button when entering a room where running at eco temperature. Non bluetooth seen at less than £10 each.

All my electronic TRV heads exercise the TRV once a week, so sticking valves is no longer a problem, we still have a wall thermostat set to same schedule as TRV head in the hall, but it is the TRV's in my house that control room temperature, the wall thermostat turns boiler off over night and when we go out, it has geofencing and occupancy detection so don't need to touch it.

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