TRV as a Zone Valve....any reason why not?

[Ydraiggoch]

Hi,

I have been building my own Home Automation system and have now managed to get what is essentially a DIY 'Hive' system up and running.

My house has 2 zones at the moment made up by using Honeywell type Zone Valves.

I'm planning on making more zones for my downstairs rooms to improve efficiencies in the heating system. The main reason for this is that in my Kitchen I have a Wood Stove. When this is on, the kitchen is hot and yet, because the stat for the boiler is in the living room where its colder, the heating still comes on in the kitchen. It's probably worth noting that I have a standard Radiator & a kickplate heater in here. The Radiator has a TRV already, but it never seems to cut the heat to the radiator.

My plan is to use a TRV valve body and attach a mains powered actuator (the type you use for underfloor heating) to control the flow to the heating. Rather than this being attached to the radiator, I will install it inline with the 15mm copper pipe going to the kitchen (under the floor). The actuator will be fed from a relay and controlled by my qutomation system. I'll install a wireless stat in the kitchen which will be used to monitor the temp of the room. So when the room goes below a certain temp it the valve will open and the boiler will fire.

I'm confident that the logic will work, but don't have much experience with the valves. So hoping someone could advise if they could be used in this way?

If all goes to plan, I would look to extend this idea to other rooms too.

Many Thanks

 

[kidgreen61]

It would be far simpler to just change the kitchen TRV for one that works.

 

[Ydraiggoch]

@kidgreen61 You're right, this would be a simple option. However, I've never been convinced over the accuracy of a TRV, especially when the sensor is next to the radiator. Controlling the radiators from a thermostat within the room is more accurate in my opinion, plus the Kick plate heater does not have a TRV, so doesn't regulate on room temperature.

 

[oldbutnotdead]

The theory is reasonable (not sure about the efficiency logic but there ya go). Drayton have beaten you to it (along with others) with WiFi TRVs that effectively turn every radiator into a zone.
But a project is a project...you'll need a fair bit of force from your actuator to push and hold the pin down, i'd suggest using an inline TRV (or just leave the TRV body on the rad and attach your device to it).

 

[Ydraiggoch]

Hi Oldbutnotdead Thanks for the response.

I looked at the 'smart TRVs' but figured that they were quite expensive for what they are. Also the main reason for not choosing them is that I can't fit one to the kick plate heater.

My plan is to use an inline TRV body (as you suggest) with an under floor heating actuator like this;

This will be installed on the common supply 15mm pipe which feeds both the radiator & the kickplate heater.

I still need to test it on an inline TRV to see if its strong enough for the valve...so fingers crossed!

I guess my main concern was whether the valve restriction in the common feed would have a negative affect on the Radiators?

 

[Madrab]

Carefully what you are zoning off, your wood stove is classed as an uncontrollable heat source, as such it will always need a heat sink, therefore there will always have to be at least one reasonably sized radiator that is always on, you just need to keep that it mind.

That being said cant see any reason why you couldn't use a TRV with an actuator and control that via a thermostat

 

[Ydraiggoch]

Hi Madrab,

Apologies, I dont understand what you mean? Why would I need a radiator that is always on?

As it happens when the heating kicks in downstairs, I will always have heat going to the downstairs W/C which doesn't have any thermostatic control. Not sure if this is what you mean?

 

[oldbutnotdead]

As @Madrab, there must be a heatloss radiator permanently connected in the primary gravity circuit of the uncontrolled heat source (the woodburner) -iirc it has to be 10% of the energy output to water of the source. This to prevent excessive boiling in the system.
Back to the trv- you can get single radiators up to about 6kw controlled by 1 TRV so you should be fine

 

[Madrab]

Ah wait, apols, your CH system is fed by a boiler, not the wood stove in the kitchen .... Misread the OP methinks ...

 

[vulcancontinental]

Hi Oldbutnotdead Thanks for the response.

I looked at the 'smart TRVs' but figured that they were quite expensive for what they are. Also the main reason for not choosing them is that I can't fit one to the kick plate heater.

My plan is to use an inline TRV body (as you suggest) with an under floor heating actuator like this;

View attachment 236933

This will be installed on the common supply 15mm pipe which feeds both the radiator & the kickplate heater.

I still need to test it on an inline TRV to see if its strong enough for the valve...so fingers crossed!

I guess my main concern was whether the valve restriction in the common feed would have a negative affect on the Radiators?

If you wanted to control a kick space heater with a smart TRV do so but bind it to a wall stat as the reference point.