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Any recommendations for smart TRVs possibly compatible with MEL Cloud?

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by JamesPa 2 years ago
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 TRBob
(@trbob)
Trusted Member Member
Joined: 4 years ago
Posts: 61
Topic starter 14/10/2024 10:03 am   [#1767]

2.5 years into our ASHP. We have our Mitsubishi wireless thermostat in the lounge set at 19 degrees, we found that at night it was getting too warm in the bedrooms, I tried altering the thermostatic valves but it's not ideal, it seems like you get to an all or nothing point with them and I had a couple that were clicking on and off regularly and being a nuisance. We have 2 young kids that are not great sleepers, so getting a good nights sleep without external factors like room temperature is a challenge.

In the end I set up a timer so that at 9pm the temp goes to 17.5 degrees and then 3:45am 18.5 and 5:30 19 degrees (we're on Octopus Cosy), this mostly works ok, but really I'd like to leave the thermostat at 19 degrees all of the time and have much more precise control of the bedroom temperatures.


Mitsubishi Ecodan 8.5kW
4.4kW Solar PV
5.2 kWh Battery Storage
1983 build, 300mm loft insulation, cavity wall insulation (beads)


   
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Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3052
14/10/2024 1:51 pm  

@trbob The control of heat output from each radiator or emitter is best set using the lockshield valve rather than using a TRV; the TRV should be thought of as a limiter that ensure the room doesn’t go above your desired maximum due to things like solar gain or perhaps a number of people all in one room causing a temperature rise. By the sound of things, your radiators have not been balanced. By all means the TRV may be employed as this ‘limiter’ once the radiators have been balanced. May I suggest that you may care to read my article on the subject:

https://renewableheatinghub.co.uk/how-to-balance-radiators-the-role-of-the-lockshield-valve

Regards, Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
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 TRBob
(@trbob)
Trusted Member Member
Joined: 4 years ago
Posts: 61
Topic starter 31/10/2024 1:44 pm  

Thank you @toodles , I ordered a temperature probe with two clamps and it's taken a while to arrive, I just need some time when the kids are out now so I can get on with it. I've done some research and a lot of sources mention having a 12 degree drop across the radiator, does this apply to ASHP systems as well or are we looking for less of a drop given that our flow temp is much lower than a gas boiler system?


Mitsubishi Ecodan 8.5kW
4.4kW Solar PV
5.2 kWh Battery Storage
1983 build, 300mm loft insulation, cavity wall insulation (beads)


   
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Toodles
 Toodles
(@toodles)
Famed Member Contributor
Joined: 4 years ago
Posts: 3052
31/10/2024 2:13 pm  

@trbob 5 degrees is the aim - though some of mine only manage 4 or so, all works well though for all that. Toodles.


Toodles, heats his home with cold draughts and cooks food with magnets.


   
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 TRBob
(@trbob)
Trusted Member Member
Joined: 4 years ago
Posts: 61
Topic starter 31/10/2024 2:21 pm  

@toodles Thank you


Mitsubishi Ecodan 8.5kW
4.4kW Solar PV
5.2 kWh Battery Storage
1983 build, 300mm loft insulation, cavity wall insulation (beads)


   
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JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 4 years ago
Posts: 5616
31/10/2024 9:32 pm  

Adiathermal are developing smart TRVs specifically designed for heat pumps, with an integrated control circuit that controls the flow temperature.  I don think they support Mitsubishi yet (but worth asking). 

Until they (or someone else) do support your system, smart TRVs are best avoided for heat pump systems or confined to a small minority of rooms.  Instead balance all or at least the majority of rads (including all the main living areas) using the lockshields as @toodles says, adjust the weather compensation curve down as far as you can so the house is comfortable, leave it largely alone.  

Recently some installers seem to have adopted a slightly modified approach (for larger houses) of having the main living rooms open (ie controlled on solely lockshields/WC) and using TRVs in the bedrooms only.  I can see (but don't know by personal experience) that this could be sensible for some houses.

If you have a 12C temperature drop across the rads then the water flow rate is too low, either because the rad is turned down or because the water pump isnt set high enough, or because some installer has installed a bypass to ensure you get poor performance but they don't get call outs.


4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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