New install. Not sure of setup.

hotrads

Hi,
Considering moving to Tado x. I have several questions please.

I currently have 1 wired thermostat (heatmiser) downstairs This controls underfloor heating in one big room.

This is the easy one. Replace with 1 tado x wired thermostat.

The bit I’m not sure about is upstairs.
There are two floors.
Lower floor has another wired thermostat on the landing + 1 rad.
Bedroom 1 and 2 also have rads.
Upper floor, 2 more rads in two more bedrooms.

So… 4 rad thermostats for bedrooms and wired thermostat for landing? (Meaning rad thermostat not required for landing)

So in total, 2 wired thermostats and 4 radiator thermostats? (Don’t need a hub as I will be using Eero routers)

My second question…

If bedroom 4 is cold but the landing is toasty.
Will bedroom 4 rad, still switch on and heat the room, independently of the thermostat on the upstairs landing? I’m guessing not. Is there anyway I could achieve this? (If it’s a sensible thing to do?)

Thank you.

policywonk

Need to know.
1. Somewhere near the boiler - you need to track the pipes leaving the boiler, just after the primary pump, there are motorised zone valves, at least two, one located close to the manifold for UFH, another controlled by that wired thermostat. How many do you have?
2. Do you have a hot water cylinder or is you boiler a combi? In have what exact model of boiler do you have?
If you want to remove the wired thermostat and insert smart Trv heads you'll have to modify things to replace the motorised valve handling the central heating with an automatic bypass valve.
Come back with the answers and we can proceed from there.

hotrads

Thanks for the reply!
1. Have taken some pics. Can I upload them anywhere? (Or DM you?) Looks very complicated. Starting to think this maybe beyond my abilities 🫤
2. Yes. Cylinder, not combi. Vitodens 100-W
Thanks again.

hotrads

Used an old insta account!
Pics here:
https://www.instagram.com/share/BAcGD6vbCp

policywonk

Hi. Easiest way to post photos are from a desktop, using a recent Mac or Win browser, not a mobile phone. At the bottom of the post it will allow you to add a pic. You wont see that from a phone.

By the way your plumber and electrician were very, very neat!

From the pics, it seems that you have at least two zone valves. They look like this:

One is placed just under the boiler and runs from the output feed from the boiler to the underfloor heating manifold. Another is right next to your cylinder (it has a white motor cover) and decides when your cylinder is to receive heat. The thermostat for the cylinder, and the cables for those two motorised zone valves, all heat to somewhere on the left of the boiler - outside the pictures, you've put on instagram.

This suggests you have whats called an S PLUS PLAN. To understand what this means, look at this website: Central Heating Controls and Zoning - DIYWiki and scroll down to the part which describes the plumbing for the S PLUS PLAN, and also describes the wiring for the S Plan. Normally the convention is in an S PLUS Plan:

• One two port zone valve for the radiators
• One two port zone valve for the underfloor heating
• One two port zone valve for the HW cylinder

The ones in bold you've photographed. The one thats missing, connected to your landing thermostat, is the one we need to locate - if it exists.

To help you understand things a little more:

• Trace the black wire from the UFH zone valve, then the grey one from the cylinder, and the white one from the boiler.
• The should all head into a small plastic box, about 9" x 5", hung on the wall, next to the pressure vessel. That box is called a wiring centre. It likely handles all the logic for your home, with a small part delegated to the UFH manifold's wiring centre.
• Now, apart from power going into that wiring centre ( another cable - which I couldnt quite see), there should be yet another cable from that box heading towards where the thermostat is placed. Along the way it should also engage the third zone valve.

Another approach: to go the landing's thermostat and see if you can work out where and how it enters the area where the boiler is present. If there isnt another zone valve along the way, it is possible that the thermostat downstairs actually directly controls all heating and that it is somehow wired directly onto the boiler.

• That's unlikely because your plumber and electrician were meticulous and I dont believe they'd have taken such a silly step.

We still have to locate where the original programmer for the home is situated. It may be somewhere near that missing third zone valve. Its location may help.

If you want to convert all radiators to Smart TRV heads, it is important to find out if there is another zone valve, and if it is there, have a heating engineer come in, remove the zone valve supplying the rads, insert a bypass valve, and remove the wiring for that zone valve from the wiring centre. They have to prove it can all still work before you fit the Tado bits.

When is the Vitodens meant to be serviced? Those engineers could be asked to make the changes.

Anyway, come back…

hotrads

Thank you.

At least things look like they have been done properly!

Had a quick look round for another zone valve. No Joy.

The only other area with pipes and wires is under the stairs (please see pic)

Boiler does need servicing, will look to get install bundled up.

Cheers

policywonk

@hotrads Make no mistake, this is a complex and well organised system. Am really impressed with the team that implemented the UFH, cylinder and boiler. Now this is interesting. It seems that you have at least three UFH manifolds in your home. It begs questions.

1. Is the central heating radiator loop on a seperate zone, with its own zone valve?
2. Are all the UFH manifolds driven by another zone valve?
3. Do the UFH manifolds have dedicated wired stats to trigger their use?
4. Would the boiler benefit from having a divertor valve?

These questions, if your engineer can answer them, or if you have time to study, would determine how best to improve whats there. Ideally:

• Fit smart TRV heads
• Fit a wireless receiver to replace the programming interface
• Fit wired thermostats with each UFH zone valve, to ensure they dont waste heat.
• Remove the zone valve handling the radiators (if it exists) - and ensure that an automatic bypass valve is present.
• Consider running this boiler in Opentherm mode - which may mean that you'll have to change the cylinder thermostat for an Opentherm sensor.

The engineer may identify that there is already an automatic bypass valve fitted with the 100-W. It depends on what options were included. So, I'd suggest you ask them to survey the property and give you a quote to make the changes. Some of those bits you can handle yourself- and we can help.

There's another user on this forum who seems to know this boiler quite well. @Montage would you be open to chipping in here?

hotrads

Nothing like more info late into the diagnosis 🫤
There are in fact 2 thermostats on the ground floor. For some reason there is one in the downstairs loo. Tiny room that’s perfectly well heated with its thermostat permanently switched off. I forget it’s there…

policywonk

Isnt it fun learning about a home?😅

@hotrads how comfortable are you handling diagnosis of wiring? That wiring centre, to the left of your pressure vessel contains the primary wiring for your house's heating system. Gave you a link earlier, identifying what you should find in that wiring centre for a home with ONE two port valve for HW, and ONE two port valve for CH. You seem two have at least one more handling at least ONE UFH manifold. We need to find the rest, if there are more. It is necessary to:

1. Locate the outbound heat pipe from the boiler (I believe it is the one which has one of your two port valves coming off at a right angle).
2. Then look for other two port valves. They should be on the ground floor. One or two may be near the other (I think there are two more, looking at your photos) UFH manifolds.

A cheeky but valid way of getting this resolved with almost no cost, is to call whoever does your servicing, ask them to visit to give you a quote to make changes:

1. First priority is so that all the radiators are controlled with smart Tado TRVs. Ask them to make sure there is an automatic bypass valve in place and remove any RADIATOR designated two port zone valves.
2. Second priority is to check to see if that thermostat in the toilet is actually wired to anything.
3. Third priority is to check how the UFH manifolds are triggered to call for heat, and pump their fluid- are there relays, or valves triggering pumps, which supply pressure for each of the UFH manifolds, other than that one Heatmiser UFH wiring centre?
4. Fourth, is to ask them if they have experience of migrating the wiring of the Vitodens from Relay switching mode to Opentherm mode and using Tado controls for that purpose? It may also involve changing your HW cylinder thermostat to operate in Opentherm mode.

If they are willing to come over, give you a quote you'll have a basis. If they have questions, come here or talk to Tado Pre-Sales support, and you should get help. Come back if you need help.

Is this a valid path for you? The alternative is to study the wiring centre (not the Heatmiser, the other one), photograph it and use a multimeter to check the wiring. Takes longer, we go back and forth about 4 times, but it will take you to where you need to go.