Still having control problems with central heating using eTRV's.

[ericmark]

Idea was cool at night warm up in the day, but simply not working. The problem is getting hot water to the rooms in the morning, the valves open OK, but there is simply no hot water flowing from boiler.

So boiler control is a time switch and a wall thermostat in the hall, the hall had no TRV fitted until yesterday when I fitted one to try and stabilise hall temperature. So last night the wall thermostat set to 17°C the remote thermometer sitting on the thermostat was showing between 17 and 17.3 degrees, the hall radiator was tepid, 6 am central heating turns off, and 7 am back on again at the same time as the eTRV's change temperature, idea was turning the heating off and on at these times would ensure boiler was running when the temperature changed, it did not work.

So went down to check what was running and both uncontrolled towel rails and the controlled radiators were just tepid. Outside temperature dropped to 6°C now 9:50 am at 10°C. So raised temperature on the thermostat to 18°C remote thermometer sitting on the thermostat is showing a gradual raise in temperature. I can hear the boiler cycling on and off, upstairs over temperature 22°C in my bedroom radiator cold. The radiators down stairs are warming up by 10 am the hall radiator and towel rails are hot, but not at full temperature. The two radiators with eTRV are now at full temperature.

However both eTRV's showing 17°C the camera in living room also showing 17°C and the baby alarm in the bedroom with eTRV is showing 21°C although on the wall with the hall radiator on the other side of it. The thermometer is showing hall climbing now 10:10 showing 17.7°C so very shortly with thermostat set to 18°C the boiler will cut out.

It would seem allowing the rooms to cool to 15°C over night was going too far, it simply can't warm up again, tomorrow with hall set at 18°C it is still going to be a problem simply as boiler is not running, so it would seem 17°C to 19°C night and day temperatures are about the maximum differential I can set with a hope of it warming up in the morning. Seems rather pointless having eTRV's fitted? Unless the thermostat is also programmable and can alter temperature at the same time.

I have reset temperatures and off times for another run tomorrow, set minimum to 17°C on the two eTRV's and increased the off time before the change to 19°C but to be frank 2°C is hardly going to make any difference to comfort or energy used, so in real terms they have been a waste of money. And this is with outside temperature at 6°C at night.

I can see they may work upstairs, the bedrooms and landing upstairs seem to get a lot hotter than downstairs, the only house I have had where upstairs did not get too hot used hot air central heating not water, and the ducts must have leaked as it cost an arm and a leg to run.

Odd as I have been writing this, hall temperature went up to 17.8°C then dropped again to 17.5°C boiler still running. May be a delay in the standard TRV turning off? Seems just too many variables, from lock shield valve to TRV to thermostat will I ever get it right?

 

[ericmark]

Well at long last working OK, wish I had never started, found a number of things wrong.
1) The eTRV had not been set up correctly on living room radiator, removed batteries, replaced batteries, waited for orange LED, pressed button and it then turned off radiator as it should.
2) The hall lock shield valve was opened too far, closed and re-opened little bit at a time, and now hall radiator takes longer to get warm and bedroom radiator warms up quicker.
3) Used the wireless programmable thermostat in kitchen set to 20°C from 6 am to 8 am this keeps boiler running in the morning while the two rooms warm up.
Also set the stops on hall thermostat so can't be set too high, if we want a boost then kitchen thermostat will auto return to off 5 times a day, so can't forget. So the two rooms cool down at night and heat back up again ready for when carers arrive at 8 am. However since to get the rooms to heat up in the two hours it needs the heating completely off two hours before to allow hall to cool down, one needs to know 4 hours in advance of any temperature increase, so forget any idea of delaying heating or bringing heating forward with your phone, it simply would not work. So in hind sight and that's always easy, it did not need eTRV that can be altered from the phone, those where you program them directly on the unit would have worked just as well. Originally I had intended to turn down the heating when mother was in day care, now I am just leaving it alone, it works so not touching again.

 

[Dan Robinson]

The hall lock shield valve was opened too far, closed and re-opened little bit at a time, and now hall radiator takes longer to get warm and bedroom radiator warms up quicker.

Weren't you cock-sure that there was no problem with this in the plumbing forum? .

 

[ericmark]

Weren't you cock-sure that there was no problem with this in the plumbing forum? .

Yes I made a mistake, I was sure 6 months ago I had set all the lock shield valves, however the knob is on the valve, so what I think happened is, it was the valve other side of radiator that was being used as the lock shield valve, which in last few days was replaced with a TRV, so until the valve was replaced with the TRV is was set correctly, I forget to shut down the valve after fitting the TRV to other side.

In hind sight, and easy in hind sight I should have either fitted the Honeywell EvoHome, or gone the other way and fitted a self contained eTRV, the MiHome was picked because I also wanted a remote control socket with timer, and it said MiHome would work with Nest.

I was considering getting Nest, but now I realise totally useless trying to alter temperatures in this house by phone. My own house is a completely different concept, it heats up and cools down fast, within minutes of Myson stopping you feel the cold, and within minutes of it starting you feel warm. But mothers house is so slow changing temperature. From 17°C to 19°C takes 2 hours, actually set to 16°C but it never actually got that low, and up to 20°C but never got that high. Since no decimal point it could be 16.5°C to 19.5°C.

The baby alarm in mothers bedroom shows 21°C in the day and 18°C at night I expect due to that radiator being in the bay window, reverse in the living room radiator on inside wall, and camera in bay window shows larger difference to the valve. 2°C between camera and radiator could also mean one is not accurate, but more likely where they are in the room.

 

[SimonH2]

Idea was cool at night warm up in the day, but simply not working. The problem is ...

All that, to me, can be condensed down to "doesn't work properly if you don't link the TRVs to boiler demand". "All it needs" is a boiler interface that will fire the boiler when any of the TRVs demand heat and it'll all work.

 

[ericmark]

Hind sight is good, should have used EvoHome and it would likely have worked first time. In theory the TRV is interfaced with the boiler as it controls the return temperature of the water which in turn controls the boiler output, I think it is all now working reasonably well after fitting the TRV to the hall radiator, but at the moment I am not using the central heating, until we get to November I am unlikely to know if it works OK or not. I do hear the eTRV working, and I do ask myself why when the room has been over the temperature set all day long, the valve should work other than weekly exercise. The current exceeds target temperature all day long, so why do I hear the motor run?