Controller or smart plug to control a towel heater circuit

[Adsibob]

We have a multizone water based system is an UFH system. The only heating which is not UFH are two towel rails, one in each of two adjacent bathrooms.

Our plumber has set up a separate zone for just these two towel heaters with its own zone valve. 

Today the electrician asked me how I want to activate that valve. Each towel heater has its own thermostatic valve anyway, but this zone valve will stop us sending hot water down the pipes to those two bathrooms during the majority of the time we are not using them. He made two suggestions:

1. As we are already having Phillips Hue to control a couple of lights, we could just get a phillips hue smart plug and plug the zone valve into that. I think the fact we are going to have a Phillips Hue system already is a red herring because I think the smart plug works independently from that system, and just relies on a bluetooth connection to your phone and the free Hue app. We should then be able to programme the plug to a routine through the app - I assume this is possible?
2. Buy a wireless zone controller that enables us to programme it.

 

Another requirement is that we need to be able to control this from the first floor, whereas the zone valve is on the ground floor (albeit more or less directly under one of the two adjacent bathrooms, so not particularly far away; maybe 4m from one towel heater and 7m from the other. But it would be nice to be able to be within range of a wirelessly controlled controller anywhere in the house and I'm not sure bluetooth (which is the way the Phillips Hue works) will have enough range.

 

Option 1 seems simple and easy, but is that how a zone valve really works: when it gets power it opens and when it doesn't get power it closes? 

Option 2 seems overkill. The cheapest smart controllers I can find are about £70 and that is because they all have thermostats at the heart of them. We don't need a thermostat, just a controller.

[ProDave]

You are over complicating it.  It is just like any other 2 zone heating system.  Just use a 3 channel programmer, one for the UFH one for the radiators and one for the DHW and wire it as any other S plan system.

[tonyshouse]

Timer plug or smart plug, 

[JohnMo]

Stick in an electric element and have its own thermostatic controller.  Something like a Termo One.

 

Then you don't need to fire up the central heating in the summer to just heat/dry some towels.

[Temp]

Wet UFH and two towel rails fed from a thermal store.  

 

The towel rads are on a basic time clock but we also put a pipe stat on the return pipe. The latter just stops the pump to the towel rads running all the time and stops our thermal store being stirred more than necessary. 

 

 

[Adsibob]

1 hour ago, ProDave said:

You are over complicating it.  It is just like any other 2 zone heating system.  Just use a 3 channel programmer, one for the UFH one for the radiators and one for the DHW and wire it as any other S plan system.

So we don’t have any need for a controller for the UFH because we are using the Tado system; each zone is controlled by its own tado thermostat (which is smart and programmable). 
 

[Adsibob]

1 hour ago, tonyshouse said:

Timer plug or smart plug, 

I remembered that I had an old Kasa TP smart plug that works over wifi. I found it and rigged it up to my bedside table light to see if it works okay. It works well and even has a towel heater (well radiator) icon in the app I can assign to this plug.

 So I guess we will use this. 

[JohnMo]

How thick is you screed and how well insulated are you?

[ProDave]

9 hours ago, Adsibob said:

So we don’t have any need for a controller for the UFH because we are using the Tado system; each zone is controlled by its own tado thermostat (which is smart and programmable). 
 

But you will need a controller.  The way UFH works is if one zone calls for heat from it's thermostat, then the manifold pump starts, it calls for heat from the boiler and just the actuators for that zone that needs heating are energised.

 

I am not familliar with this Tado system but I hope it does all that, and if it is that clever can it not cope with one more valve for the towel rails?

[Adsibob]

5 hours ago, JohnMo said:

How thick is you screed and how well insulated are you?

It’s a 1930s semi with no cavity. We have upgraded the insulation throughout by installing a concrete slab in the subfloor, topped by 100mm of PIR and then 75mm to 80mm of screed. All the external of the house has had kingspan  EWI added to it, but not too thick as the original features of the house didn’t allow for it. All windows are brand new double glazed thermally broken aluminium, and some of the veluxes are triple glazed.

We have put a tonne of wood fibre insulation into the roof and also installed MVHR with lots of air tightness measures.

 So it is certainly not passive, but warm enough.

 Why do you ask?

[Adsibob]

4 hours ago, ProDave said:

But you will need a controller.  The way UFH works is if one zone calls for heat from it's thermostat, then the manifold pump starts, it calls for heat from the boiler and just the actuators for that zone that needs heating are energised.

 

I am not familliar with this Tado system but I hope it does all that, and if it is that clever can it not cope with one more valve for the towel rails?

I thought the manifold has different loops on it, and each loop can be controlled by its own thermostat. We have 4 manifolds but about 11 zones because some manifold cover two to four zones.

[Temp]

38 minutes ago, Adsibob said:

I thought the manifold has different loops on it, and each loop can be controlled by its own thermostat. We have 4 manifolds but about 11 zones because some manifold cover two to four zones.

 

You might be able to connect each stat to its respective actuator(s) but the wiring centre normally also performs a logical OR on all the stats to control the manifold pump and in some cases the Boiler Enable (BE) signal.

 

Edit: I don't think its possible to perform the OR function just using wire without getting feedback from one stat to all the others. It needs relays or logic gates or similar which is what the wiring centre does.  Might be possible if the stats have two isolated outputs? One for the actuator and one that can be wired OR?

Edited February 5, 2022 by Temp

[JohnMo]

1 hour ago, Adsibob said:

Why do you ask?

 

Not sure if you have purchased the controllers/ thermostats, but you will find the reaction time of the slab very slow and once heated, slowly gives heat to the house. We have around 100mm screed and ended up taking all the smart stuff out, as it couldn't react in the right time frame. 

 

Now have a thermostat in the hall that can call for heat, and one in each bedroom, they cannot call for heat, but can stop it earlier than the rest of the house, so the bedrooms are cooler.

 

Boiler kicks in for a few hours once a day to charge the slab, even though same heat is set on the thermostat all the time (24/7).

 

Thermostat is set to 19 degs at moment, will drop to 18.5, as slab is in the heating phase and overshoot to 19.5, if the sun comes out, the evening temps can be around 20 to 21 degs.

[Adsibob]

Yeah, I’m not expecting much responsiveness on the ground floor, but on the upper floors the floor coverings are much thinner so should be fairly responsive. I have used quite thick pipes 16mm diameter, in the screed, so hope that will help a bit. On the ground floor, I suspect we will just run it from 3am to 7am and then from 3pm to 9pm. Until I live in it I won’t know, but one of the features of the Tado is the ability to monitor air temperature and humidity and graph it, so you have historic data capture to understand how the running time of the heating corresponds to the room temperature. After a few days, the Tado can use machine learning to work out when to call for heat to achieve your desired temperature at the times that are ore-programmed. It is a really Smart system that has other features that we will use apart from just the basic thermostat.

[speedyplumer]

Maybe this product can you use.

https://elegant-radiators.co.uk/products/optimum-digital-fused-spur-timer-wall-controller

[Nickfromwales]

Towel rads on a digital timer fused spur? Simple and cheap. Does it actually need to be any more complex? 
If so, a Shelly controller off WiFi would do it.

May need a contactor if one device is to control both rads.