Biasi 28s hot water problem

[DTG plumbing]

Got a boiler causing head ache. Its a biasi RIva
28s. Hot water fires for about 5seconds then shuts down.
Heating is working
changed temperature probes
and checked plate heat exchanger,
Could be possibly divertor valve or pcb?
Any help is much apreciated guys 🙂

 

[Doodlebug]

Got a boiler causing head ache. Its a biasi RIva
28s. Hot water fires for about 5seconds then shuts down.
Heating is working
changed temperature probes
and checked plate heat exchanger,
Could be possibly divertor valve or pcb?
Any help is much apreciated guys 🙂

When you say you have checked the plate heat exchanger, what exactly do you mean? What checks have you done. What's the temperature difference across it?


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[DTG plumbing]

It's cold across it mate. Doesn't get chance to even heat the water up!

 

[diamondgas]

Boiler work fine on heating?

 

[DTG plumbing]

Yes mate

 

[diamondgas]

Best to check pump flow switch is lifting enough to start the sequence of events 🙂 Could be that it isn't! May be switch mechanism is stretched? Flow's restricted ... ?

 

[DTG plumbing]

Flow seems ok mate. And pump runs fine on hheating so should be ok or hot watert
thanks for help so far

 

[diamondgas]

Flow seems ok mate. And pump runs fine on hheating so should be ok or hot watert
thanks for help so far

Worth checking anyhoo's IMO ... Never assume in my humble opinion but check! I've had a good few problems with them in the past on the ideal mini, they have a poorly designed return manifold, Does the pump runs but the fan doesn't ?

 

[DTG plumbing]

Yeh your right mate. Well yeah the fan runs and the burner ignites but tthen shuts down after about 5 seconds 🙁

 

[Doodlebug]

Will more than likely be temperature probe.
This may help in ruling the sensor out.
Biasi Riva 28s NTC sensor part number - 164026
Aprox temp - 15c expected resistance reading - 15k
Approx temp - 82c expected resistance reading - 1.5k

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[diamondgas]

I'd be looking at both flow switched to be honest, pump and hot water ... They may be one of them dodgy? If the fan's kicking in then that would leave pump switch less likely but not ruled out. Best check their op resistance. Could be dirty?

 

[GrahamM]

Dodgy APS is also worth checking. Had them prove and work on CH with no problems, but kicking off on HW.

 

[Doodlebug]

This may help....



Legend.....

Br = brown
B = blue
Bk = black
W = white
R = red
Gy = grey
Y = yellow
G/y = green/yellow

* - direct connection with the ignition and flame control device.



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