Vokera 15 vhe Boiler

[mattgriff88]

Hi

I have a Vokera 15 vhe boiler and all has been running well for the last 6 months since moving in up until a few weeks a go.

Boiler throws up a flashing 79 code.
Try restarting the boiler straight away but I have to wait 10 minutes for it to cool down before it works.

I reset the boiler after 10 mins and all works well until the end of the next day when the heating switches off and the boiler temperature climbs to around 90 on the display and then throws up this code again.

Have to wait for it to cool down before resetting.

My boiler was set at a temperature of 70c but after having this problem I turned it down to 65c but still the same problem.

Turned it down to 60c same problem

Turned it down to 55c Same problem

Turned it down to 53c works fine and have done for a couple of weeks.

Turned it back up to 60c problem starts again.

Problem is having it on 53c seems to take forever to heat the house up to a reasonable temperature.

I can put it on 70c but don't want to reset the boiler every night once the heating turns off.

Any suggestions before I call a professional.

Not looking to fix myself but rather have a better understanding before getting ripped off for something it's not.

 

[John.g]

Is there a ABV (automatic by pass valve ) installed.

 

[mattgriff88]

Is there a ABV (automatic by pass valve ) installed.

No idea to be honest.

 

[John.g]

That boiler may be a heat only boiler with a external circ pump, this might be installed in your hot press or close to the boiler, you may also have a mid position 3 port valve or a number of two port (motorised) zone valves, if you have the mid position valve, no need for the ABV, if a number of two port valves, the ABV, if installed, will be close to and between the pump and these two port valves.

Below, you have a ABV, a two port valve & a three port mid position valve.

 

[mattgriff88]

Thanks for your help. I have these.

 

[mattgriff88]

Thanks for your help. I have these.

And this.

 

[John.g]

That's your man (ABV), can you start up the boiler and then take a photo of the LEDs on the pump front.

 

[mattgriff88]

That's your man (ABV), can you start up the boiler and then take a photo of the LEDs on the pump front.

 

[John.g]

The pump is running at max setting, CC3 which is > 6M so the setting on the ABV, 0.4?, 4M, should be quite adequate to to allow the ABV to open when the boiler/burner trips on shutting the HW and CH zone valves, the pump then, if wired correctly should run on (overrun) for ~ 3 minutes to cool down the boiler heat exchanger.

Can you feel the pipes on either side of the ABV with boiler running, are both sides hot?, then switch off CH & HW and see if the pump runs on for a few minutes and check if (ABV) pipes are now hot (if not previously).

How many rads have you got?.

 

[mattgriff88]

The pump is running at max setting, CC3 which is > 6M so the setting on the ABV, 0.4?, 4M, should be quite adequate to to allow the ABV to open when the boiler/burner trips on shutting the HW and CH zone valves, the pump then, if wired correctly should run on (overrun) for ~ 3 minutes to cool down the boiler heat exchanger.

Can you feel the pipes on either side of the ABV with boiler running, are both sides hot?, then switch off CH & HW and see if the pump runs on for a few minutes and check if (ABV) pipes are now hot (if not previously).

How many rads have you got?.

14 rads.

I will run a test tomorrow when the boiler is on for the heating in the evening. I will come back with my findings.

Thanks for your help.

 

[John.g]

You can check the pump overrun any time (maybe first) just start the boiler on either HW or CH, then shut it down after a few minutes and see if pump runs on for a few minutes, if not, that should be addressed.

 

[mattgriff88]

You can check the pump overrun any time (maybe first) just start the boiler on either HW or CH, then shut it down after a few minutes and see if pump runs on for a few minutes, if not, that should be addressed.

Hi,

Heating has been on for 2hrs.
Rooms have hit temperature and the heating has now switched off.

Both pipes either side of the ABV are hot
Pump cut straight off with heating.

 

[mattgriff88]

Hi,

Heating has been on for 2hrs.
Rooms have hit temperature and the heating has now switched off.

Both pipes either side of the ABV are hot
Pump cut straight off with heating.

Temp on boiler was at 61 when it cut off and its now on 82 and still climbing.

 

[mattgriff88]

Temp on boiler was at 61 when it cut off and its now on 82 and still climbing.

Up to 87 and then threw code 79.

 

[John.g]

Pump is probably wired incorrectly Matt, it should be wired directly from the boiler which should supply the overrun period, it's probably wired fom the zone valves auxiliary contacts that tell the boiler to fire when any one zone valve is open.

 

[mattgriff88]

Pump is probably wired incorrectly Matt, it should be wired directly from the boiler which should supply the overrun period, it's probably wired fom the zone valves auxiliary contacts that tell the boiler to fire when any one zone valve is open.

Ok thanks for your help.
Big/costly job to put right or easy fix?

 

[John.g]

Probably a few hours work but check first that your boiler has the overrun.

 

[mattgriff88]

Probably a few hours work but check first that your boiler has the overrun.

Hi Mate,

So I'm having a bit of trouble getting somone to do this job.
I have tried getting a couple of quotes over the weekend but none seems interested in actually running the cable.
The boiler is downstairs in the kitchen and the pump is up stairs in the bathroom. (Opposite ends of the house) probably not worth their time.

I have measured up and I'm looking at around 20m of cable.

I might have a go at running the cable myself and then getting a sparky in to connect up.

What size cable should I be buying?
1mm 3 core good enough?
Would it need to be heat resistant cable or anything special?

Thanks

 

[Basher]

I have measured up and I'm looking at around 20m of cable.

Assuming permanent live mains is available where the pump is, there is a 'radio' link option that could avoid the hassle of having to run a cable. Here's an example - it costs about £100, so you might prefer hard wiring!

MAINSLINK 5KM WIRELESS MAINS TO MAINS 230VAC LINK

MAINSLINK is a plug and play solution to replace a switched live cable. When 230Vac “LIVE” is input to the transmitter; the receiver provides a 230Vac “LIVE” switched output at its screw terminals. When a cable run is awkward or expensive to achieve, the MAINSLINK can be used, saving time and...

www.rfsolutions.co.uk

 

[mattgriff88]

Assuming permanent live mains is available where the pump is, there is a 'radio' link option that could avoid the hassle of having to run a cable. Here's an example - it costs about £100, so you might prefer hard wiring!

MAINSLINK 5KM WIRELESS MAINS TO MAINS 230VAC LINK

MAINSLINK is a plug and play solution to replace a switched live cable. When 230Vac “LIVE” is input to the transmitter; the receiver provides a 230Vac “LIVE” switched output at its screw terminals. When a cable run is awkward or expensive to achieve, the MAINSLINK can be used, saving time and...

www.rfsolutions.co.uk

Thanks for posting this.

looks like a much better solution.
👍

 

[ShaunCorbs]

Why not just install an overrun / timer relay on the pump so when it looses switch live it runs the pump for 10 mins etc

Eg

AC 230V 16A 1SPDT Multifunction Timer Relay On Off Time Delay Relay for Home | eBay

Output: 16A 1SPDT. 1 function of latching relay ( I ). There might be a bit of color distortions due to different computer resolutions.

www.ebay.co.uk

 

[mattgriff88]

Just want to say thanks to @John.g @Basher problem has now been sorted.

John was spot on with the pump not using the overrun function due to it being wired up incorrectly.

Bought one of these for £59.99 Mains Switch RF Pump Overrun Switch MAINSSWITCH01 - https://www.plumbarena.co.uk/product/mains-switch-rf-pump-overrun-switch-mainsswitch01/?gad_source=1

Had it fitted today and all now is running well.

Thanks again!

 

[Activate Trade Training]

It sounds like your Vokera boiler is overheating when set above 53°C, leading to the error code. This could be due to a faulty thermostat, circulation issues, or a blockage in the system causing restricted flow. Before calling a professional, check if the radiators are evenly heating and if there's any noise indicating a pump or flow problem. Understanding these symptoms can help diagnose the issue more accurately and prevent unnecessary repairs.

 

[Basher]

It sounds like your Vokera boiler is overheating when set above 53°C, leading to the error code. This could be due to a faulty thermostat, circulation issues, or a blockage in the system causing restricted flow. Before calling a professional, check if the radiators are evenly heating and if there's any noise indicating a pump or flow problem. Understanding these symptoms can help diagnose the issue more accurately and prevent unnecessary repairs.

This response doesn't make any sense, as the issue has been identified and resolved. Are you a Bot?

Edit: Seems likely since "Activate Trade Training" use website developers, who are, to quote:

Combining Creative Marketing with Cutting-Edge AI​