Configuration advice for legacy boiler

Neil_P8l

I have a gravity-fed Potterton Suprema 60 boiler configured in a Y-plan. I recently replaced the Honeywell (water and heating) timer after it broke with a Tado Wireless Receiver and Smart TRV valves in all the bedrooms, lounge and dining room. Some rooms, like the downstairs toilet and conservatory radiators, still have the old TRVs installed. I have a few weird problems, and I need advice on configuring the system to stop these mistakes.

Problem: When the heating is supposed to be off during the day, all the rooms with Tado TRVs have the rads switched off, but in the rooms with the old TRVs, the rads are hot, meaning the heating is on when it shouldn't be. Why is this? My boiler isn't capable of modulating the temperature due to its age.

Tado Support told me that I needed to put Smart TRVs on all the radiators for this work, which doesn't make sense since the legacy TRVs cant call for heat, which makes me think one of the devices is turning the boiler on and I don't know which device it is.

Does anyone have any ideas?

wateroakley

@Neil_P8l Welcome.

Unexpected heating. Looking at the rads with dumb TRvs unexpectedly heating when they should not normally be heating, the problem points to four possibilities. The first three relate to the operation of a mid-position (Y-Plan) valve, which can do strange and unexpected things.

Possibilities:

• Incorrect wiring
• Incorrect wireless receiver configuration
• Faulty mid-position (Y-plan) valve.
• Lack of a bypass

Question/thoughts

• Is this a new install or a new problem?
• I'll post below the instructions to check the wireless receiver setting.
• Faulty mid-position valves can do wierd things
• Boiler pump over-run, without a bypass, 'could' exhibit as your rads with dumb TRVs heating

When this happens:

• Is the boiler 'ON'?
• Is the CH light illuminated? Yes or No?
• Is the HW light illuminated? Yes or No?

If the the lights are OFF and the boiler is ON, it's either a wiring problem or a faulty valve.

If the HW is ON and the rads are heating, it's either wiring problem or a faulty valve.

If the lights are OFF, the boiler is OFF, I'd start to think of boiler over-run and the bypass.

Boiler bypass. Your boiler manual says it must have a bypass on the pipework (that allows heat to circulate and dissipate when the boiler stops heating). That could be an automatic bypass on the pipework or a radiator without a TRV. Motorised TRVs (like Tado) will be more of an issue than old dumb TRVs. You should not fit TRVs on all your rads unless you know the answer to the bypass question.

Wireless reeiver configuration.

Neil_P8l

Hi wateroakley

Thanks for the advice I rechecked everything as advised and I now believe this is caused by the boiler over-run moving it to the dumb rads to dissipate the excess heat since a lot of the rads are now closed. I dont recollect it doing it previously with the Honeywell but that time it was pumped to all radiators which were open unlike now.