Vokera compact 28 hot water isn't fluctuating cold and hot

[Inverness]

went to see about a problem. I've never dealt with these kind of boilers. I'm new to it so be gentle..
Any advice what the issue could be? Blocked flow ?

 

[ShaunCorbs]

Hot water is fluctuating ???

If so check the temps at the plat heating side if there not moving much I would be looking at plate

Unless the boiler isn't staying fired then could be flow switch

 

[Inverness]

When hot tap is turned on it goes hot then cold. I was thinking might be the primary thermistor??

 

[ShaunCorbs]

does the boiler flash on and off?

 

[Inverness]

Green light is on when it's producing hot water then after a few seconds the light goes red, then green again.

 

[ShaunCorbs]

sounds like it cant get the heat away

heating ok?

 

[Inverness]

I checked the expansion vessel was fine and I topped up the pressure as it was at zero.
What might it be?

 

[ShaunCorbs]

could be a few things but i think dirty plate or system (hex)

if its doing the same in heating then its the hex

 

[Inverness]

Also I went to that other job today. It was one 40 cdi Worcester heat only boiler 35mm gas pipe.
Max ratio 0.0007 min ration 0.0001
Ppm less than 100.
I did a gas rate imperial meter timed for one relvoution of a turn.i used my phone app.

 

[Inverness]

This boiler doesn't have a plate heat exchanger. It old style.

 

[ShaunCorbs]

This boiler doesn't have a plate heat exchanger. It old style.

so twin heat exchanger

 

[Inverness]

I think so.. plumbase have the manual vokera compact 28.

 

[Inverness]

What would you recommend Shaun ? With your knowledge and experience.

 

[sammathias]

Does it cut out when heating is on?

 

[AMGasServices]

Id probably say check and replace the thermistors, burner pressures.

If that’s doesn't sort it I’d be looking at PCB.

 

[Inverness]

More information.
The boiler cuts out when the heating comes on too. Vokera compact 28

 

[ShaunCorbs]

check pump and water quality also main hex

 

[Inverness]

Ok but when your working for estate agent you not have long to view the job to then put an quote in to get the job, so you think it could be the pump or main heat exchanger?

 

[Inverness]

What will do to the heat exchanger is there anything I should be looking for?

 

[ShaunCorbs]

Ok but when your working for estate agent you not have long to view the job to then put an quote in to get the job, so you think it could be the pump or main heat exchanger?

your the gas engy tell them you want more time

 

[AMGasServices]

Check the flexible flow and return pipes they may be full of muck.

How long would you say it stays on for ?

 

[Darren Jackson]

De-scale the rolled lead hex, swap out the 2 thermistors & the high limt stat, clean the flow restrictor. And set the HW litre per min throttle to Mi's. Then reset the max & min gas rates to factory settings.