Biasi boiler- weird behaviour

[David937]

Hi there,

Boiler: Biasi 24S/28S

My Uncle is having a weird problem with his Biasi combi boiler.

The heating comes on when not asked for, it is not when the hot water is used but just randomly at any time.

The CH knob is set to minimum.

An engineer has looked at and said there is no problem.

Any ideas of the problem?

 

[clf-gas]

How is the heating timed. by integral clock/programmer or independent programmer

 

[David937]

Integral mechanical timeclock.

Replaced in winter as the other one broke.

 

[mehran]

there could be a number of things that could cause this.

1,frost protection kicking in(not sure if this boiler has it tho) cause by faulty ntc

2,water leaking in to the dhw micro switch which is shorting it out and making the boiler run.

3, faulty clock

needs a engineer that knows his stuff, which is sadly is lacking

 

[clf-gas]

Integral mechanical timeclock.

Replaced in winter as the other one broke.

Argh! now then that was one of my thoughts as the integral is known to malfunction.

Could still be the clock or the room thermostat if fitted.

Outside chance the PCB, though for some reason I doubt it

Agile is far better than me with these, am sure he will of come across this before.

 

[David937]

Thanks for the replies so far guys.

Now for the question you all hate....how much can he expect to pay to get it repaired?

 

[Agile]

Leaking gland at DHW flow switch causing conduction through the circuit making the boiler think there is a demand for DHW.

To fix, the gas valve needs to be removed so it needs a qualified engineer! We charge £127 which includes the new gland and switch.

Tony

 

[David937]

Leaking gland at DHW flow switch causing conduction through the circuit making the boiler think there is a demand for DHW.

I presume you mean "making the boiler think there is a demand for CH"?

To fix, the gas valve needs to be removed so it needs a qualified engineer! We charge £127 which includes the new gland and switch.

Tony

Thank you very much.

 

[Agile]

Leaking gland at DHW flow switch causing conduction through the circuit making the boiler think there is a demand for DHW.

I presume you mean "making the boiler think there is a demand for CH"?


Thank you very much.

No not at all!

If the DHW switch is made then the boiler thinks there is a demand for DHW !!!

Tony

 

[clf-gas]

If the DHW switch is made then the boiler thinks there is a demand for DHW !!!

Tony

This bit I understand Tony, BUT!!!!!

How is it affecting the OPs boiler in the heating mode

Would you not agree it could be due to the faulty batch of clocks
Could it be a faulty NTC kicking in frost protection.
Could it be a PCB fault.

I know without either of us being at said boiler whilst fault occurs, that a true diagnosis is almolst impossible, but, what sort of issues can cause this.


PS. Not a dig, purely engineer to engineer question

 

[glasgowgas]

If the DHW switch is made then the boiler thinks there is a demand for DHW !!!

Tony

This bit I understand Tony, BUT!!!!!

How is it affecting the OPs boiler in the heating mode

Would you not agree it could be due to the faulty batch of clocks
Could it be a faulty NTC kicking in frost protection.
Could it be a PCB fault.

I know without either of us being at said boiler whilst fault occurs, that a true diagnosis is almolst impossible, but, what sort of issues can cause this.


PS. Not a dig, purely engineer to engineer question

View media item 12518

 

[Agile]

If the DHW switch is made then the boiler thinks there is a demand for DHW !!!

Tony

This bit I understand Tony, BUT!!!!!

How is it affecting the OPs boiler in the heating mode

Would you not agree it could be due to the faulty batch of clocks
Could it be a faulty NTC kicking in frost protection.
Could it be a PCB fault.

The boiler is operating in DHW mode and NOT in CH mode!

The temperature is controled by the DHW control knob.

Practically those clocks either work or dont!

A faulty high resistance NTC would also cause the CH and DHW to overheat.

Practically speaking those PCBs dont fault like that.

Engineer/engineer discussion is better in the CC !

Tony

 

[clf-gas]

Hi there,

Boiler: Biasi 24S/28S

My Uncle is having a weird problem with his Biasi combi boiler.

The heating comes on when not asked for, it is not when the hot water is used but just randomly at any time.

The CH knob is set to minimum.

An engineer has looked at and said there is no problem.

Any ideas of the problem?

I must be missing something then as Im sure the op is saying heating

GG, I hope your implying I am the one in the blue Mankini .

 

[clf-gas]

OH!!

By the way, I do agree some things are better discussed in th CC, though this aint one of them

 

[Agile]

I must be missing something then as Im sure the op is saying heating

GG, I hope your implying I am the one in the blue Mankini .

You are missing something!

If there is no water flow on the DHW circuit then the diverter valve is resting in the CH position and the heat produced by the boiler to satisfy the ( false ) DHW demand is then routed to the CH circuit.

I did not even know those things were called mankinis.

Tony