Central heating puzzle

[Lisahood]

Hello! Wondering if someone can help, Google doesn’t seem to understand my question…

I have 2 upstairs radiators (combi boiler) on smart TRV’s which don’t get hot when valves are open. The TRV’s work fine, and I can hear them call for the boiler correctly but the rad’s stay cold.

HOWEVER…

When I turn my downstairs radiator on (also TRV) everything - one downstairs, 2 upstairs and the bypass rad in the bathroom - all heats up perfectly well.

I’ve been through all the smart TRV settings and smart thermostat settings and it all seems fine (and, crucially, nothing has changed since last winter when it all worked perfectly).

Has anyone come across this before? Thank you for any help in advance!

 

[CountryFan]

Is it smart TRVs or zonal Heating (eg 2 thermostats?)

 

[Mister Banks]

Hello! Wondering if someone can help, Google doesn’t seem to understand my question…

I have 2 upstairs radiators (combi boiler) on smart TRV’s which don’t get hot when valves are open. The TRV’s work fine, and I can hear them call for the boiler correctly but the rad’s stay cold.

HOWEVER…

When I turn my downstairs radiator on (also TRV) everything - one downstairs, 2 upstairs and the bypass rad in the bathroom - all heats up perfectly well.

I’ve been through all the smart TRV settings and smart thermostat settings and it all seems fine (and, crucially, nothing has changed since last winter when it all worked perfectly).

Has anyone come across this before? Thank you for any help in advance!

What make of smart TRV are they?

 

[Lisahood]

Is it smart TRVs or zonal Heating (eg 2 thermostats?)

It’s smart TRV’s with one thermostat downstairs. So the upstairs rads with smart TRV’s call for the boiler independently, the downstairs rad uses the smart thermostat to call for the boiler.

 

[Lisahood]

What make of smart TRV are they?

Tado v3+

 

[CountryFan]

Tado v3+

Pretty sure that’s a smart thermostat. TRVs don’t bring boilers on and off, controls do.

 

[Lisahood]

Pretty sure that’s a smart thermostat. TRVs don’t bring boilers on and off, controls do.

Sorry, yes you’re absolutely right. The upstairs TRV’s are talking to the smart thermostat to ask it to call for the boiler. All the rads in the house use the same zone controller/thermostat to call for the boiler. The upstairs rads use the TRV’s to measure temperature, the downstairs rad uses the smart thermostat to measure temperature.

 

[CountryFan]

Ok, so when you want just upstairs on, you call for heat using the Tado V3+ thermostat and then rely on TRVs but turn downstairs TRVs off?

 

[Lisahood]

Ok, so when you want just upstairs on, you call for heat using the Tado V3+ thermostat and then rely on TRVs but turn downstairs TRVs off?

Yes exactly, the downstairs rad can stay off or on with its own TRV.
It’s just that the upstairs ones stay cold unless the downstairs one is also on.

But last winter it was fine, so I know it CAN work, I’ve just run out of ideas!

 

[CountryFan]

Definitely only the one thermostat? We had a recent poster that claimed this and then realised it was zoned heating. Could it be batteries on the trv head, or are these normal?

 

[Mister Banks]

So you have a Tado "smart" heating system, are all the TRV's Tado as well? If they are then any Tado TRV should be able to turn on the boiler but if the 2 TRV's upsatairs are normal TRV's then they wont turn the boiler on.

 

[Lisahood]

Definitely only the one thermostat? We had a recent poster that claimed this and then realised it was zoned heating. Could it be batteries on the trv head, or are these normal?

Just one thermostat. I installed it myself. Batteries on TRV’s are all fine. The TRV’s are opening and closing the valves on the rads when I ask them to, and calling for the boiler correctly.
I have a feeling my issue is a plumbing one, not a smart system one, because when I swap my smart TRV around the issue stays with the upstairs rads and doesn’t move with the TRV.

 

[Lisahood]

So you have a Tado "smart" heating system, are all the TRV's Tado as well? If they are then any Tado TRV should be able to turn on the boiler but if the 2 TRV's upsatairs are normal TRV's then they wont turn the boiler on.

The whole system is Tado. 2 x smart TRV’s upstairs, 1 x smart TRV downstairs, all speaking to the same zone controller. Bathroom rad has no TRV and is acting as a bypass rad so it heats up any time the boiler is called for.

 

[CountryFan]

Just one thermostat. I installed it myself. Batteries on TRV’s are all fine. The TRV’s are opening and closing the valves on the rads when I ask them to, and calling for the boiler correctly.
I have a feeling my issue is a plumbing one, not a smart system one, because when I swap my smart TRV around the issue stays with the upstairs rads and doesn’t move with the TRV.

My apologies, I’ve just read up on these and it seems the TRVs can control the boiler, but via the smart controller/thermostat. So I’m guessing maybe it’s to do with the smart controller?

 

[Lisahood]

My apologies, I’ve just read up on these and it seems the TRVs can control the boiler, but via the smart controller/thermostat. So I’m guessing maybe it’s to do with the smart controller?

Yeah, it does sound like that might be the case. Thank you for looking into it.
What’s strange is that the upstairs TRV’s are clearly speaking to the zone controller because when I open the valves I can hear the boiler fire up.
Do you think it could be anything to do with the downstairs rad needing to be on to push the hot water through the system enough to heat the upstairs rad? I suspected the system needed balancing but it’s odd that they do get nice and hot as soon as the downstairs rad is on.