Tank thermostat demanding boiler for HW but off on programmer

jonnydeppiwish!

Okay so I’ve had a new unvented cylinder fitted to a 2 year old ideal heat only boiler. I then had a new Nest thermostat added as the previous occupant threw out the thermostat when they cleared the property post probate.

I have set the program for 2 hours HW morning and evening. The boiler, however, is coming on and off every min or so. The HW valve switch is open. The only time it shuts is if I turn the tank thermostats to below the current tank temperature.

Any ideas? I have the engineer coming again on Friday but just looking for simple fixes if there is one.

Thanks in advance!

FreeBear

Might need a new thermostat/sensor on the tank.

A couple of comments on the wiring - There is a stray, unterminated blue wire (bottom left). Without knowing if it is live or not, it should be made safe either with a Wago block or in a spare terminal.

In the same box, you have an earth wire that appears to be going to terminal No.3. Sleeved with a bit of brown tubing. The other end of the cable (going to the Nest receiver ?) doesn't have the brown sleeve - This is wrong on many levels. An earth wire is always earth, and should never be used to carry live current ! Who ever did that needs a physical reminder of his/her wrongdoing.

Hopefully, your heating engineer will recognise the faults and rectify them.

Albermarle

Probably not relevant to the issue, but having the HW on for 4 hours a days is a lot, unless you really use a lot.
We have the same set up and for two showers and one bath a day, it is on for 45 mins in total.
If it was from stone cold it would be longer, but these tanks are very well insulated so keep some heat in, especially if you are heating it up every day.

FreeBear

Albermarle said:

Probably not relevant to the issue, but having the HW on for 4 hours a days is a lot, unless you really use a lot.

But if there is a (working) thermostat on the tank, the boiler may only run for ~5mins to make up for any overnight heat loss.

ThisIsWeird

jonnydeppiwish! said:

Okay so I’ve had a new unvented cylinder fitted to a 2 year old ideal heat only boiler. I then had a new Nest thermostat added as the previous occupant threw out the thermostat when they cleared the property post probate.

I have set the program for 2 hours HW morning and evening. The boiler, however, is coming on and off every min or so. The HW valve switch is open. The only time it shuts is if I turn the tank thermostats to below the current tank temperature.

Any ideas? I have the engineer coming again on Friday but just looking for simple fixes if there is one.

Thanks in advance!

This new cylinder has just been fitted? If so, leave it to the guy to sort :-)
Fair chance he's wired the new cylinder's stat up wrong.

jonnydeppiwish!

Thanks for all your responses so far. I’ve not wired this in or changed anything but trying to work out what’s what made my head spin!
I know the nest has a legionella setting so I’ve turned that off as well.
the most annoying thing is that the heating keeps coming on, with pipes all around the house warming up 🤦 

jonnydeppiwish!

FreeBear said:

Might need a new thermostat/sensor on the tank.

A couple of comments on the wiring - There is a stray, unterminated blue wire (bottom left). Without knowing if it is live or not, it should be made safe either with a Wago block or in a spare terminal.

In the same box, you have an earth wire that appears to be going to terminal No.3. Sleeved with a bit of brown tubing. The other end of the cable (going to the Nest receiver ?) doesn't have the brown sleeve - This is wrong on many levels. An earth wire is always earth, and should never be used to carry live current ! Who ever did that needs a physical reminder of his/her wrongdoing.

Hopefully, your heating engineer will recognise the faults and rectify them.

The blue is dead - will add a wago on to confirm. The earth confused me in the nest but I’m assuming it’s being used as a common - as you say, it should also have a brown sleeve on it.

ThisIsWeird

jonnydeppiwish! said:

Thanks for all your responses so far. I’ve not wired this in or changed anything but trying to work out what’s what made my head spin!
I know the nest has a legionella setting so I’ve turned that off as well.
the most annoying thing is that the heating keeps coming on, with pipes all around the house warming up 🤦 

Did all this begin with the new cylinder?

FreeBear

jonnydeppiwish! said:

FreeBear said:

Might need a new thermostat/sensor on the tank.

A couple of comments on the wiring - There is a stray, unterminated blue wire (bottom left). Without knowing if it is live or not, it should be made safe either with a Wago block or in a spare terminal.

In the same box, you have an earth wire that appears to be going to terminal No.3. Sleeved with a bit of brown tubing. The other end of the cable (going to the Nest receiver ?) doesn't have the brown sleeve - This is wrong on many levels. An earth wire is always earth, and should never be used to carry live current ! Who ever did that needs a physical reminder of his/her wrongdoing.

Hopefully, your heating engineer will recognise the faults and rectify them.

The blue is dead - will add a wago on to confirm. The earth confused me in the nest but I’m assuming it’s being used as a common - as you say, it should also have a brown sleeve on it.

You misunderstood me. An earth should never be repurposed to be live, ever.

If you need a multicore cable, and don't have enough cores, go out and buy some that does. My local electrical wholesalers will cut multicore to length, and if push comes to shove, I can get it online. For example, YY 2 to 50 core.

jonnydeppiwish!

ThisIsWeird said:

jonnydeppiwish! said:

Thanks for all your responses so far. I’ve not wired this in or changed anything but trying to work out what’s what made my head spin!
I know the nest has a legionella setting so I’ve turned that off as well.
the most annoying thing is that the heating keeps coming on, with pipes all around the house warming up 🤦 

Did all this begin with the new cylinder?

Yes, I believe so. But we never had the last cyclinder working as we hadn’t moved in and the gas/elec was all off

jonnydeppiwish!

FreeBear said:

jonnydeppiwish! said:

FreeBear said:

Might need a new thermostat/sensor on the tank.

A couple of comments on the wiring - There is a stray, unterminated blue wire (bottom left). Without knowing if it is live or not, it should be made safe either with a Wago block or in a spare terminal.

In the same box, you have an earth wire that appears to be going to terminal No.3. Sleeved with a bit of brown tubing. The other end of the cable (going to the Nest receiver ?) doesn't have the brown sleeve - This is wrong on many levels. An earth wire is always earth, and should never be used to carry live current ! Who ever did that needs a physical reminder of his/her wrongdoing.

Hopefully, your heating engineer will recognise the faults and rectify them.

The blue is dead - will add a wago on to confirm. The earth confused me in the nest but I’m assuming it’s being used as a common - as you say, it should also have a brown sleeve on it.

You misunderstood me. An earth should never be repurposed to be live, ever.

If you need a multicore cable, and don't have enough cores, go out and buy some that does. My local electrical wholesalers will cut multicore to length, and if push comes to shove, I can get it online. For example, YY 2 to 50 core.

Thanks - I’ll let the heating engineer know when they come