Baxi 105 E strange problem?

[bbaxi]

Hi!
Ok here I go Baxi 105 E [Not the instant or HE]
HW diaphragm leaking replaced! Checked all pressures/electrical. Everything ok for a few hours, then >first the pressure rose to 3bar on the CH dropped that to 1bar after changing the pressure relief valve> everything fine for a few days and now no CH. But!
This is really baffling me lift the CH pressure switch nothing happens it is calling for heat? Lift the HW pressure switch CH comes on? Set the HW only on the control knob turn the HW tap on and the CH comes on with the HW No HW Preference. Put the control to CH/HW> CH no work no flashing lights nothing, turn the HW tap on and both CH/HW back on?
My first diagnosis is the PCB. Anyone had this problem here who can help?

 

[Slugbabydotcom]

As always, I could be wrong because I cant see it but I would be suspecting a dodgy diverter and a dodgy programmer going by what you said

 

[bbaxi]

As always, I could be wrong because I cant see it but I would be suspecting a dodgy diverter and a dodgy programmer going by what you said

Mmm... now forgot to say The PCB had water on it at the first visit?

 

[ChrisR]

The PCB had water on it

Probably bust then, that's what they do.

 

[bbaxi]

The PCB had water on it

Probably bust then, that's what they do.

Yes probably! I am still puzelled with this though

Lift the HW pressure switch CH comes on? Set the HW only on the control knob turn the HW tap on and the CH comes on with the HW No HW Preference.

As Slugbabydotcom suggested it very well could be the diverter? as for the programmer I have linked that so have ruled that out.
So Thursday I will change the PCB. In the meantime I will keep looking here in case something else springs to mind

 

[ChrisR]

NOt odd really. If you lift the HW pressure switch it thinks there's a HW demand so the boiler would light. Because the DV hasn't moved, as the hw isn't on, the ch gets hot.

This is really baffling me lift the CH pressure switch nothing happens

It isn't a ch switch it's a pump-on detecting switch.

Check you have a call for heat in the boiler with a meter.

 

[bbaxi]

NOt odd really. If you lift the HW pressure switch it thinks there's a HW demand so the boiler would light. Because the DV hasn't moved, as the hw isn't on, the ch gets hot.

This is really baffling me lift the CH pressure switch nothing happens

It isn't a ch switch it's a pump-on detecting switch.

Check you have a call for heat in the boiler with a meter.

Yes have done that Thats what makes me think PCB. As that would make a boiler do such odd things. Like with the old grey cells

I am a retired PC engineer a PCB is as a MOBO is on a computer bloody strange

 

[baxpoti]

You didn't put the micro switches back on the wrong plungers?

Red on top. Green on front.

 

[bbaxi]

You didn't put the micro switches back on the wrong plungers?

Red on top. Green on front.

No they are on correct did one at a time Red top x2 green bottom x2

 

[baxpoti]

No they are on correct did one at a time Red top x2 green bottom x2

You do mean green on the front?

 

[bbaxi]

No they are on correct did one at a time Red top x2 green bottom x2

You do mean green on the front?

Yes as they came off they went back on

 

[Agile]

No they are on correct did one at a time Red top x2 green bottom x2

You do mean green on the front?

Yes as they came off they went back on

Assuming anything is correct so blindly is a recipe for disaster!

 

[bbaxi]

No they are on correct did one at a time Red top x2 green bottom x2

You do mean green on the front?

Yes as they came off they went back on

Assuming anything is correct so blindly is a recipe for disaster!

In nature, nothing is ever right. Therefore, if everything is going right... something is wrong.

 

[bbaxi]

Problem solved replaced PCB+Pressure relief valve