Hot water tank firing but heating and water off

[Paul Moreton]

We have a brand new house with a tank system and boiler. I had nest installed to control water and heating.
Sometimes when the water and heating times off the tank keeps on doing something.
I have to either reset the nest or turn the power off to the boiler for a bit to reset it.
Is this a nest issue or a valve issue?

 

[Deleted member 120897]

Could be a fault on the nest giving out a switched live to the valve, or a sticking valve/switch.

Did it work correctly before the Nest was fitted?

You say brand new, how old is brand new? (I still call mine new, but it’s approaching 12 years old).

 

[mikerotherby]

This is a similar problem that I have, the system is about 2 years old Unvented, Nest with Baxi, and a Y system.

I have Smart meters, and can see the use of gas, while the heating is off and no call for hot water.

I have found the boiler firing up late evening 11 pm and cannot find why, it works fine to supply demand when required,

My current solution is to switch boiler off, (if I find it rouge firing) on the front of the boiler, this then allows pump to continue working to clear not required heat from the boiler, turn back on next morning and boiler fires up at normal @9am.

Has anyone met this with a Nest system?

 

[ShaunCorbs]

Yes nest has an anti legionella cycle stays on for about an hour

 

[Deleted member 120897]

Could be the 24v link if applicable has been left in.

 

[Ziggie]

Baxi switches on if no comms from thermostat for a few hours. Safety feature

 

[mikerotherby]

Thank for that, I will check out and post back my findings. Been away a few days so will be a week or so before I post any more, Thanks

 

[Ziggie]

This is the quote from manual

5.9 Emergency Mode (Fig. 20)
1. If communication is lost between the Transmitter and Receiver for longer than 1 hour the unit will go into continuous heating mode to ensure that the property will not be without heating.
2.This will continue until communication is re-established (see Section 7.2).
3.When in this mode the heating can be turned OFF & ON if required by operating the button on the Receiver:-
Heating ON = Receiver LED ON Heating OFF = Receiver LED OFF

 

[mikerotherby]

This is the quote from manual

5.9 Emergency Mode (Fig. 20)
1. If communication is lost between the Transmitter and Receiver for longer than 1 hour the unit will go into continuous heating mode to ensure that the property will not be without heating.
2.This will continue until communication is re-established (see Section 7.2).
3.When in this mode the heating can be turned OFF & ON if required by operating the button on the Receiver:-
Heating ON = Receiver LED ON Heating OFF = Receiver LED OFF

have you a link to manual, save hunting about, thanks

 

[Ziggie]

have you a link to manual, save hunting about, thanks

Hard copy I’m afraid but you probably replaced receiver when you installed Nest.
Included this in case the receiver was left in place !

 

[Alessandro]

This is a similar problem that I have, the system is about 2 years old Unvented, Nest with Baxi, and a Y system.

I have Smart meters, and can see the use of gas, while the heating is off and no call for hot water.

I have found the boiler firing up late evening 11 pm and cannot find why, it works fine to supply demand when required,

My current solution is to switch boiler off, (if I find it rouge firing) on the front of the boiler, this then allows pump to continue working to clear not required heat from the boiler, turn back on next morning and boiler fires up at normal @9am.

Has anyone met this with a Nest system?

I am currently having the same problem - the boiler engineer saying that it is a problem with Nest miscommunicating with the water boiler valves which then sends the wrong input to the boiler. ie boilers fires up for 1 min as Nest thinks we need a top up but only lasts for 30sec. Boiler /water tank/valves all good heating valve is good only have issue with the hot water side. Did you manage to find a solution? Thinking of calling a Nest installer Thanks for your help!

 

[mikerotherby]

Hard copy I’m afraid but you probably replaced receiver when you installed Nest.
Included this in case the receiver was left in place !

Hard copy I’m afraid but you probably replaced receiver when you installed Nest.
Included this in case the receiver was left in place !

 

[mikerotherby]

Thanks all for the help, it is the bio function so sorted