4 Zone CH controller

[RichD1]

Our house has three floors and has 18 radiators. I'd like to split the house into four zones to cut down on heating costs. All the rads have TRV's but I'd like the ability to only have the heating on in areas which we are using. Buying something like a Wiser or Evohome with wireless valves is just too expensive to fit all the rads and these units can't support that many. I was hoping I would find a 'smart' solution but so far I haven't found one. I was hoping that there were wireless electro actuator valves for an UFH 4 port manifold that I could use but it looks like I will have to revert to the old 2 port valves.

I'd prefer a smart solution on your smartphone rather than a traditional electromechanical controller.

Any ideas on a solution?

 

[ericmark]

Do you have an opentherm or a modulating boiler, as this changes what is good, although it will still work.

A programmable TRV head can cost as little as £15 at least that's what I paid in 2019 for bluetooth heads, but linked to a wall thermostat the cost jumps, around £45 each, so select coolest rooms for linked, and non linked for rest.

EPH do zone valves which link, and can work with opentherm, but in the main zone valves are open or closed, but TRV's gradually open and close.

It is down to the boilers method of gaining latent heat, if it can, so methods used with gas and oil are not the same.

 

[RichD1]

The boiler is a modulating Vaillant but no OpenTherm.

I've been thinking about whether I could use a wifi mains relay driving each zone valve on and off.

 

[oldbutnotdead]

Wiser will run 16 zones/63 devices- yes it's pricey but gives you completely granular control.
I've got a few of these Relay cards, the app is ok but slow to load, however you can link to Alexa (and probably others), if you link the Wiser gear to Alexa you can then have a more or less integrated solution.

 

[RichD1]

Thanks, I didn't realise Wiser could manage so many zones and devices. Do you know whether Wiser wifi TRV's can control the boiler?

Those relay cards could be interesting especially with the use of Alexa.

 

[oldbutnotdead]

Yeah. The Wiser hub (you have to have one) replaces your existing controller and connects to the boiler (either by Opentherm or just a standard make/break pair). When one or more WiFi TRVs calls for heat it calls to the hub which then fires up the boiler, when all TRVs are satisfied the hub then shuts the boiler down.
If you do a total WiFi install you don't really need zone valves- if (for instance) only 1 rad is calling for heat there will only be circulation to/from that rad.
If you have tanked hot water you'd need a motorised valve and cylinder stat on that (don't think there is a Wiser WiFi cylinder stat).
Integrating the relay card with Wiser is doable but gets complex. Last time I looked the Wiser TRVs and hub don't expose much data outside the app- ON and OFF commands via Alexa would work but you'd need IFTTT or similar to manage 'in a heating period, all TRVs are satisfied in this zone so close this zone valve' situations.

 

[Mister Banks]

Yeah. The Wiser hub (you have to have one) replaces your existing controller and connects to the boiler (either by Opentherm or just a standard make/break pair). When one or more WiFi TRVs calls for heat it calls to the hub which then fires up the boiler, when all TRVs are satisfied the hub then shuts the boiler down.
If you do a total WiFi install you don't really need zone valves- if (for instance) only 1 rad is calling for heat there will only be circulation to/from that rad.
If you have tanked hot water you'd need a motorised valve and cylinder stat on that (don't think there is a Wiser WiFi cylinder stat).
Integrating the relay card with Wiser is doable but gets complex. Last time I looked the Wiser TRVs and hub don't expose much data outside the app- ON and OFF commands via Alexa would work but you'd need IFTTT or similar to manage 'in a heating period, all TRVs are satisfied in this zone so close this zone valve' situations.

Sounds very inefficient to have the boiler fire up for one radiator. Can this be overridden?

 

[ianmcd]

Sounds very inefficient to have the boiler fire up for one radiator. Can this be overridden?

Well how are you going to heat the radiator then ?

 

[RichD1]

Sounds very inefficient to have the boiler fire up for one radiator. Can this be overridden?

Surely a modulating boiler will take care of this.

 

[jeff the gasman]

Surely a modulating boiler will take care of this.

Depends on the boiler and it’s minimum modulation.
Cycling can occur and flue temperature rise to kill any efficiency benefits of a condenser.

 

[Mister Banks]

Well how are you going to heat the radiator then ?

But you’re firing up the boiler for one radiator because one room asks for heat when the rest of the property is up to temp. Seems like a waste of energy.

 

[oldbutnotdead]

But you’re firing up the boiler for one radiator because one room asks for heat when the rest of the property is up to temp. Seems like a waste of energy.

In principle you are correct. Especially if the one rad calling for heat is a small (800w) or so. However, the wasted energy cost (not really wasted, most of it will stay in the house just not exactly where you wanted it) will be much less than the savings made by only heating rooms you are using when you are using them
Yes you can achieve the same results by wandering round the house shutting rads off (or setting TRVs to tickover) manually - where modern controls score is with variable occupancy- both rooms and times. I work fairly random hours- if I swap from normal to nights it takes me about 30 seconds to swap the house programme over. If I'm going to get home earlier (or later) than planned I can do all that from my phone wherever I happen to be.

 

[ianmcd]

But you’re firing up the boiler for one radiator because one room asks for heat when the rest of the property is up to temp. Seems like a waste of energy.

well the heat has to come from somewhere