Vokera Linea 24 - Running when turned off

[Dazzh]

Hi All,

Looking for your help once again please.
Vokera Linea 24 combi. Switched over to hot water only as it’s summer.
I’ve recently noticed the pump appears to be running even though there is no demand for HW.
If I turn the water off via the switch the pump continues to run. The only way to turn it off is via the fused spur.
This appears to reset it for a short time and it will then kick in again later in the day.
Any suggestions as to where to check.
As ever thanks again for any help or advice.

 

[ianmcd]

Move the control knob to the off position (middle setting) does the led display still show or does it go blank ?

 

[Dazzh]

Hi Ian, the display will turn off but something is still running. Sounds like the pump. There is no ignition/flame.
Only switching it off via the fused spur stops it.

 

[dilalio]

Thermistor problem?
Pump overrun is being activated and sending live to the pump?
@vulcancontinental ?

 

[Dazzh]

Thanks @ianmcd and @dilalio for your replies.
I would say thats its probably worse in the morning when the boiler has not been used overnight.
It does sound like pump overrun.
I see there are 2 thermistors one at the heat exchanger and the other at the domestic water heat exchanger. The thermistors are cheap is it worthwhile just replacing both to see what happens?

 

[ianmcd]

are you sure it is the pump that is running, these boilers have a fan overun, but not a pump over run, if it is actually the fan that is continuosly running change the primary NTC if it is actually the pump then probably PCB, nothing legally to stop you removing the outer casing yourself on this boiler to see which is running

 

[dilalio]

are you sure it is the pump that is running, these boilers have a fan overun, but not a pump over run, if it is actually the fan that is continuosly running change the primary NTC if it is actually the pump then probably PCB, nothing legally to stop you removing the outer casing yourself on this boiler to see which is running

Wasn't sure if it had an overrun mate.
That's why I put a "?" at end of my comments

 

[ianmcd]

I see there are 2 thermistors one at the heat exchanger and the other at the domestic water heat exchanger. The thermistors are cheap is it worthwhile just replacing both to see what happens?

If you have to change one I always change both for as you say they are not expensive, but a little tip the DHW thermistor has a little witches hat covering it, make sure you fit that back over properly, your boiler also has a DHW pre-heat function which might be the cause, easy enough to find out, hold the DHW outlet pipe when set to DHW only and ask someone to open a hot tap, if the pipe gets hot instantly, then the pre-heat mode is activated , if not it isnt , this can be disabled but is done on the pcb, unlike modern boilers where you can do in the controls facia

 

[Dazzh]

Thanks @ianmcd.
I've not taken the case off but the next time it happens I will, but from the outside it definitely sound like the pump and not the fan.
Which one is the primary NTC, Heat Exchanger or Hot water Heat Exchanger?

 

[ianmcd]

Primary is the main heat exchanger thermistor, when removing the case there are two screw pointing upwards on the controls facia, they wont fall out but you need to undo them to get the control panel to drop, do that and you will have access to the pump and that will tell you if it is indeed the pump that is running

 

[Dazzh]

No problem @dilalio, I'm always grateful that someone takes the time to reply.

 

[dilalio]

No problem @dilalio, I'm always grateful that someone takes the time to reply.

Think I was on the money with a thermistor though

Also, I was aiming that at @ianmcd, we converse a lot on here

 

[ianmcd]

where is the boiler located is it on a ground floor ?

 

[Dazzh]

Hi @ianmcd, yes its on the fround floor.
You came out to my house in Stewarton, Ayrshire a few times when I was having issues, but that was many years ago when you were in Lanarkshire I believe.

 

[ianmcd]

Hi @ianmcd, yes its on the fround floor.
You came out to my house in Stewarton, Ayrshire a few times when I was having issues, but that was many years ago when you were in Lanarkshire I believe.

yes mate I remember now, when it does the noise just feel the flue outlet and if you can feel the air moving it is obviously the fan, I still work lanarkshire , just moved house to Livingston, good to hear from you again and glad the old girl is still chugging away