Vokera Linea Max cycling endlessly

Hi all! I hope there’s someone out there who can solve this mystery.

I first noticed an issue a few days ago, because even in the hot weather, the radiators were getting warm.

In either DHW or DHW+heating (makes no difference):

Internal circulating pump runs constantly during which:

- Boiler rests for 70s approx

- Runs for 15s approx

- Display reads temp which goes from 58/59 (resting) to 74 (during the 15s it’s heating).

This repeats endlessly

———-

Hot water demand instantly starts boiler, which then reads DHW temp (as it should) and hot water is as it should be.

When DHW demand stops, boiler stops firing and returns to monitor heating water temp (as it should) but to endless cycling as above

The radiators get warm (not hot but constantly warm).

Calling for heat from thermostat seems to make no difference to the cycling and the boiler still doesn’t run for longer than 15 seconds - unlike what it would be doing if it was trying to heat up the radiators.

Divertor valve motor is constantly energised with 240v (water to DHW circuit) throughout any of the above.

I’ve already had a leaking filling valve replaced, together with a new expansion vessel and thermistor, so obviously I’ve thrown a bit of money at this thing. I just want to know if the new faults are something that’s also fixable, or whether I should just go for a new boiler. It’s quite a large house. Any replies appreciated!

@vulcancontinental is your man for this

Yes it is fixable.

This is all positive! Any pointers as to what I should be looking for? Happy to look at any electronics / sensors etc.

first thing to do is disconnect all external controls and see if it still does it.

Good idea. Will try that.

Prior to disconnecting the external controls, fired it up this morning, and all sorts of strange noises. Banging and intermittent whooshing from the pump. I have a horrible feeling this thing is just about to die spectacularly so I think I may well just have it replaced.

Thinking of the Worcester Bosch 550 – I have a Nest thermostat already. Fortunately we have another boiler upstairs which operates separately, so not without hot water.

Cheers - good alternative boiler suggestions always welcome if there’s a better one for similar money than the 550.

Your boiler needs a proper service
Have yet had a need to replace this model
Uncomplicated boiler easily fixed, if you know what you are doing.
Not end user fixable as will need seals etc a good service engineer would have on hand

Hi DP. What I’ll do is get the plumber who did the expansion vessel / thermistor / filling valve to come back and have a look. A new boiler would be a lot of money so if it’s fixable it’s a question of what would be cost-effective.

Cheers

The store is not getting up to temperature, hence boiler keeps firing
That is why I said proper service and diagnostics
If your plumber ( read heating 'engineer') is clued up on this boiler, he will know what to do. If not, he will be recommending a new boiler