Hot water pump running remains on for entire hot water schedule even if up to temp on cylinder therm

[drthompson]

I found a topic started already with my current issue, but it hadn't been answered and was subsequently closed.  I have copy and pasted the query again:

I have recently had a nest learning thermostat (3rd gen) installed. My heating system is a conventional (also known as heat only) one and has a separate hot water tank.

When I set up the thermostat, I selected the system heating option. Everything works fine other that a slight issue with the hot water.

When the hot water is called for by the thermostat, the boiler heats up the water and the circulating pump in the airing cupboard powers on. Eventually the boiler stops heating the water as the thermostat on the hot water tank says it is satisfied, however the pump continues to run for the remainder of the hot water schedule, it doesn't power off.

It doesn't do this with the central heating however, once the central heating is up to temp and hot water is off, the boiler stops heating and the pump powers off after a brief overun period. I have turned bacteria protection off and this doesn't seem to change anything.

Is it normal for the pump to continue running throughout the hot water schedule???

[Biggs]

I think I kind of have this problem too.

I've a Worcester combo boiler and can hear the water being pumped around intermittently when the heating is off. I've tried turning the green leaf off, in case eco mode is causing it, but in spite of turning everything including safety temperature off, it's still doing it. The green light is on the receiver by the boiler. 

Frustrating.

[DragosC]

Hi there @drthompson and @Biggs,

Thanks for letting me know and I'm sorry for the inconveniences the product has caused. Could you tell me please when did the situation start occurring first and when was the thermostat installed? 

Also, I'll need to know what are youre Home&Away assist settings for the thermostat, it might be determined by that. 
 

[Biggs]

Mine was,wired the wrong way around and has been switched now, so is working. Look at the wiring again, support will talk you through it.

[Robbiedobbie]

Thank you. I don't think that is the issue. It seems to come on at unscheduled times. It was on for around an hour today when there was no schedule set. More hassle than its worth tbh 

[DragosC]

Hi there. I'm just following up on our last message. Do you still need our help? Keep us posted. 
 

[AlexD]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community. Thanks, AlexD.

[drthompson]

Installed a week ago and always done it. Home and away are on - on at home, away is set to off after 48 hrs. I wonder if the pump timings stick to the schedule set, whilst the cylinder thermostat can override this and stop the boiler from activating for the entire schedule when up to temp.

[DragosC]

Thanks. We can check if the Heat Link is doing its job properly with a multimeter. Do you have one at hand? 

[drthompson]

I do not. I can see if I can get hold of a multimeter at some point in the next few days. I can see if the installer would be able to check though, if you could give me some instructions on what to do. This is likely not going to happen for a few days tho. 

[DragosC]

Sure, no worries. I've sent you an email with the instructions. Let me know when it's done please. 

[AlexD]

Hi, I wanted to check in. Did you get the email from my colleague? 

[drthompson]

I did thanks. It will take me some time to get someone to do what you have asked.

[AlexD]

Of course, no worries. Just keep us posted as soon as you are able. 

[Vladut]

Hi there, just checking in with you. Did you have the chance to check the steps as advised in the email from my colleague? Keep me posted.

[drthompson]

Not yet please stop posting. I know that I have to reply or else you will close the topic. I am still waiting for someone to come test the wiring and will respond when I can

[Vladut]

No worries, so sorry for any inconvenience. Let me know once you have updates.

[AndaD]

Hi there @drthompson, I wanted to let you know that this thread is still open, in case you need our help. Don't hesitate to reach back. 

[Vladut]

Hi there, as you haven't replied I'm gonna go and close this thread. If you need anything else please feel free to open a new one. Have a great day ahead!

[drthompson]

Read above comments and please do not close thread until I am ready to 

[Robbiedobbie]

I think I have a similar issue. The hot water pump is running when the hot water is not scheduled. Plumber believes it is the nest. Seems to happen at certain times.

[DragosC]

Hi there all.

Thanks for reaching out. We have checked on your other threads as well. 

@drthompson, Thanks for the explanation. It is very helpful. We'd like to clarify a few things before. Could you tell us please what does it say on the Bacteria prevention feature in the thermostat when you access it? "Enable" or "Disable"? Also, we'd like to take a look at the wiring to make sure everything's fine in there, please send us a clear picture of the Heat Link's wiring to see where does each wire go. IMPORTANT!!! Please make sure to turn off the power to the Heat Link when removing the case. You mentioned before you have a system boiler with thermostatic hot water control, right? 

@Robbiedobbie, please make sure that the Bacteria prevention feature is off and let us know afterwards.