Smart Thermostat and Smart TRV installation advice

[Lower]

Your question was "can the Smart TRV's override the thermostat and turn on the heating by themselves?".

If the roomstat & smart TRV are in the same room then "no" is the correct answer. If they are in different rooms, the TRV is not overriding the thermostat as they control separate areas and either can independently turn on the heating.

Ahh. Differences in terminology then. I meant if a smart TRV was in a different room to the roomstat, could the smart TRV still get the boiler to fire even if the roomstat was satisfied. EG roomstat is in hall. Hall has reached set temperature but a room with a Smart TRV is below set temperature. Can the smart TRV still get the boiler to fire even though the roomstat in the hall has already turned off the boiler?

 

[ian1182]

Ahh. Differences in terminology then. I meant if a smart TRV was in a different room to the roomstat, could the smart TRV still get the boiler to fire even if the roomstat was satisfied. EG roomstat is in hall. Hall has reached set temperature but a room with a Smart TRV is below set temperature. Can the smart TRV still get the boiler to fire even though the roomstat in the hall has already turned off the boiler?

Yes, they are independent. In that case the boiler would remain running as at least one area has not yet reached its setpoint temperature. As each room cools they can independently fire up the boiler.

We need to be careful what is meant by a room in this discussion. In the Wiser system a room is a name for a controlled area. The Wiser system has no understanding of the physical plumbing of the heating system. You could in theory have a lounge containing a roomstat and iTRV. If you assign the roomstat to "room1" and the iTRV to "room2" as far Wiser is concerned that's two separate areas to manage. In this case either could fire the boiler even though they reside in the same physical room. However if the roomstat & iTRV are assigned to the same room in the Wiser system, then the roomstat exclusively controls when the boiler comes on or off.

Taken to the next stage, if you have your lounge, dining room and hall assigned to common "room" in Wiser. Then fit the roomstat in the lounge and smart TRV's to the radiators in dining room & hall. You have a single managed area controlled by the roomstat with neither the dining room or hall able to call for heat.

It's even possible to run the Wiser system using only smart TRV's with no roomstats.

 

[Mister Banks]

Yes, they are independent. In that case the boiler would remain running as at least one area has not yet reached its setpoint temperature. As each room cools they can independently fire up the boiler.

We need to be careful what is meant by a room in this discussion. In the Wiser system a room is a name for a controlled area. The Wiser system has no understanding of the physical plumbing of the heating system. You could in theory have a lounge containing a roomstat and iTRV. If you assign the roomstat to "room1" and the iTRV to "room2" as far Wiser is concerned that's two separate areas to manage. In this case either could fire the boiler even though they reside in the same physical room. However if the roomstat & iTRV are assigned to the same room in the Wiser system, then the roomstat exclusively controls when the boiler comes on or off.

Taken to the next stage, if you have your lounge, dining room and hall assigned to common "room" in Wiser. Then fit the roomstat in the lounge and smart TRV's to the radiators in dining room & hall. You have a single managed area controlled by the roomstat with neither the dining room or hall able to call for heat.

It's even possible to run the Wiser system using only smart TRV's with no roomstats.

That’s a very good point regarding rooms and zones, it would be better if the Wiser app called the different areas a zone rather than a room.

I have two lounges which are separated by double doors and I keep thinking about grouping the two rooms as one creating a single zone.

 

[joboro]

You should not fit a smart TRV in the bathroom/en-suite as the electrics can be affected by the damp atmosphere. A regular dumb TRV is OK for either. That said, I don't have any TRV on the bathroom/en-suite radiators as these are my bypass devices.

If your aim is accuracy of temperature, the roomstat should go into that room as the smart TRV's use an alogrithm to estimate. The TRV sits within a few inches of the heat source and hence makes a "guess" on the ambient room temp. In the Home Assistant thread I previously linked there has been some discusion on the accuracy of the TRV's and the belief that a roomstat works better. Unfortunately a roomstat is twice the cost of a TRV (£80 vs £40).

On the general points. Do you have dumb TRV's on all your existing radiators?, if not get a heating engineer to add them. The cost of the actual dumb TRV is modest in comparison to the fitting cost. As you have invested in Drayton easiest is to just get some RT212 or TRV4's. You then have a base for fitting a smart TRV.

On the installation, start simple and work upwards. I would install just the Hub & roomstat to begin with, then add smart TRV's one by one in the zones you feel need independent control. I'd hold off getting another iTRV until you need it.

Thanks. Yes we currently have regular TRVs on all the radiators apart from the bathroom. Maybe when I put the smart TRVs on the other radiators I could just move the dumb TRVs to the bathroom radiators?

 

[joboro]

As an aside, I'm just about to install. Does anyone know if my Main EcoElite boiler supports communication module interface? I can't find an industry standard wallplate to wire the hub in that way so I'm hoping so! Might make the wiring a bit trickier though!

 

[ian1182]

Thanks. Yes we currently have regular TRVs on all the radiators apart from the bathroom. Maybe when I put the smart TRVs on the other radiators I could just move the dumb TRVs to the bathroom radiators?

If the radiator does not have a TRV today, it's a job for a heating engineer (or skilled DIYer). You may need to drain down the CH system. There are some Youtube videos on the process but it's not something I'd feel confident to do. A job for the summer or just leave as is with no TRV.

 

[joboro]

If the radiator does not have a TRV today, it's a job for a heating engineer (or skilled DIYer). You may need to drain down the CH system. There are some Youtube videos on the process but it's not something I'd feel confident to do. A job for the summer or just leave as is with no TRV.

Thanks. I'm confident on the plumbing side of things but not the electrical wiring side of things having just looked at the multizone hub!

 

[Mister Banks]

What are you using at the moment as a programmer and room thermostat?

 

[ian1182]

As an aside, I'm just about to install. Does anyone know if my Main EcoElite boiler supports communication module interface? I can't find an industry standard wallplate to wire the hub in that way so I'm hoping so! Might make the wiring a bit trickier though!

How is central heating side controlled today. Do you have an integrated timer? Is the current room thermostat wired or wireless?

In principle the switching side of the Wiser hub is wired to the external thermostat connection in the boiler with the Wiser power input coming from the same source that feeds the boiler. Any pictures of current programmer and thermostat would assist.

 

[joboro]

What are you using at the moment as a programmer and room thermostat?

At the moment I just have a wired thermostat. No programmer though.

 

[joboro]

How is central heating side controlled today. Do you have an integrated timer? Is the current room thermostat wired or wireless?

Just a wired non programmable room thermostat. The boiler has a simple dial timer on it.

 

[ian1182]

Just a wired non programmable room thermostat. The boiler has a simple dial timer on it.

Depending on how the room thermostat is wired it could be fairly simple. If you can get a picture of the wiring at the thermostat. The keypoint is does it have 2 or 3 cores into the roomstat. If it's 3 the Wiser Hub might just be able to go in the same place as the existing roomstat. However its probably better to locate it next to the boiler.

 

[ian1182]

Just a wired non programmable room thermostat. The boiler has a simple dial timer on it.

The dial timer is in effect the programmer.

Looking at similar threads, the approach seems to be setting the integral timer to permanently on and then use the external thermostat connection to switch the central heating on/off.

If I have read correctly there should be a control box cover at the left hand side of the fold down panel on the boiler. Under the cover would be the Live, Neutral and Earth connections to power the boiler plus a connection for an external thermostat and/or programmer. The external connection should be labelled 1 & 2. More than likely the 1 & 2 connection currently goes to your wired thermostat but that's something you should verify

 

[joboro]

Below are some pics.
Pic 1 is in the boiler. The 2 core wire coming in at the top left is going to the current room thermostat.
Pic 3 shows the current thermostat which has the 2 core wire going to it.
Pic 4 is the back of the Wiser hub

 

[joboro]

Depending on how the room thermostat is wired it could be fairly simple. If you can get a picture of the wiring at the thermostat. The keypoint is does it have 2 or 3 cores into the roomstat. If it's 3 the Wiser Hub might just be able to go in the same place as the existing roomstat. However its probably better to locate it next to the boiler.

Only 2 wires at the current thermostat unfortunately. Please see the pics below (pic 1 the top left 2 core is the ones going to the current room stat. How am I best to wire it in in this case?