Installed Tado Smart valves - now our tower rail is leaking...

[stek2011]

Hi folks,

I spent some time over last week installing our Tado kit onto our central heating.

We have a Baxi 830 boiler with 11 standard radiators and one towel radiator in the bathroom.
All had TRVs when installed except the towel rad.
The whole system - boiler, pipework and rads are new and were installed during Nov/December.

I've now replaced all but one (waiting on a replacement from Tado) of the existing tops of the TRVs with tado valves and we have the system working nicely.
Except - our towel rad was gushing hot rusty brown water from the top near the bleed valve. We turned that rad off for the moment.

As it is the only one not with a TRV is it possible the pressure is too high for it when the tado-controlled rads aren't requesting heat?
Or more likely it's just a coincidence it's failed a few days after the Tado upgrade?

Any pointers are appreciated.

If it's useful this is the towel radiator:

Ultraheat Eco Rail Radiator 500 x 1175 x 30 mm | Costco UK

The Ultraheat Eco Rail is a contemporary styled radiator with plenty of room to warm your towels. The high quality of the Eco Rail construction is coupled with an unbeatable combination of style and practicality, making it the perfect addition to bathrooms of any design. Features: Pipe Centres...

www.costco.co.uk

Thanks,
Steve

 

[ericmark]

I have tried to look up the boiler, and don't see a built in by-pass valve. The standard way for modulating boilers to work is as each TRV closes the by-pass valve opens so the hot water is returned to boiler without cooling and the boiler reduces output. Once at minimum then starts switching on/off.

However that would be with a on/off thermostat, your boiler however is I think OpenTherm enabled, and Tado also works with OpenTherm so the TRV tells Tado how much heat is required, and Tado tells the boiler what output is required, I don't know if the pump is variable speed, or if when using OpenTherm a by-pass valve is required.

 

[Mister Banks]

I have tried to look up the boiler, and don't see a built in by-pass valve. The standard way for modulating boilers to work is as each TRV closes the by-pass valve opens so the hot water is returned to boiler without cooling and the boiler reduces output. Once at minimum then starts switching on/off.

However that would be with a on/off thermostat, your boiler however is I think OpenTherm enabled, and Tado also works with OpenTherm so the TRV tells Tado how much heat is required, and Tado tells the boiler what output is required, I don't know if the pump is variable speed, or if when using OpenTherm a by-pass valve is required.

The UK version of Tado doesn’t support Opentherm, you need the EU version. Tado have said they will reintroduce OT support but I don’t know when.

 

[ericmark]

The UK version of Tado doesn’t support Opentherm, you need the EU version. Tado have said they will reintroduce OT support but I don’t know when.

Thank you, I did look at Tado, but getting info on how their system worked was like getting blood from a stone, the other manufactures were far more open, however still made a mistake, I got Nest claimed to work with Energenie Mihome, but it doesn't.

My mothers house had two by-pass valves, one built into the boiler, and an external one, it would seem the installer had not realised one was built into the boiler, they also made other errors, like connecting a power shower to mains water.

I looked at the boiler manual for Baxi 830 boiler, but as an electrician I could not see a built in by-pass valve, it time gone by it was common I know not to fit a TRV to towel rails, and to use one instead of a by-pass valve, I personally can't see how this works, as time is important.

With a by-pass valve near the boiler as the TRV's close the valve opens sending hot water back to the boiler causing the boiler to modulate (turn down) or initiate the mark/space ratio (turning off/on) sequence, having a towel rail instead would delay this process due to the length of piping, and would mean the boilers built in anti-cycle software may not work as intended.

I only talked about OpenTherm as this removes the boilers built in control using return water temperature and uses the system built into the thermostat/hub, and I am not really sure how this controls the boiler, I know today we have variable speed pumps, which may remove the need for a by-pass valve.

 

[stek2011]

Quite right - i had to buy the older version of the extension kit to get my OpenTherm support. So I do have OpenTherm.