Baxi 105e - DHW but no CH

[baxpoti]

Tried that already, as per my original post, in order to elimate the timer as being the problem.

Does the pump not running up suggest something electrical to you, i.e. the PCB, microswitch or a sensor?

Yes that's why I'm trying to work out if there is actually a demand for C/H

Have you left the link in place between 1 and 2?

Is there a built in timer? Back in a few hours

 

[eversohappy]

If you need parts for your boiler ring a guy called steve on 01227 478899 he keeps most bits in stock and sends it by carrier next day. he is really helpfull and very reasonably priced.

 

[electronman]

Thanks eversohappy, will make a note of the number.

Baxpoti,

I have jumpered the pins on the PCB that the internal timer used to be connected to, and have also linked terminals 1 and 2 on the terminal block, and still no demand for CH.

Incidentally, I popped home at lunchtime and checked both microswitches on the Diverter valve assembly, and they checked out fine for continuity when pressed manually. I also measured resistance of CH and DHW flow temp sensors and they both measure around 6K ohms (cold), so I assume they are ok.

Could you please explain why both microswitches would be operated whilst there is a demand for DHW, but only the primary one is operated when a demand for CH is made? When there is no demand for DHW, neither of the microswitches are being activated, i.e. neither spindle is being pushed forward at all.

I will pick up a new PCB on the way home from work tonight if necessary, so any more thoughts would be appreciated before I take the plunge and do this.

The pump runs as soon as I turn a hot sink tap on, and then stops when I turn the tap off, but still nothing happens when a demand for CH is made.

I have tried upping the system pressure to around 1.25 bar and still nothing.

Hope you can help me fix this, as it's driving me mad.

Incidentally, I've already had the diverter valve manifold assembly replaced in the last couple of months as that was leaking.

Thanks,
Electronman.

 

[electronman]

I've also noticed that by turning selector switch to reset position and holding there for a few seconds, the boiler doesn't reset itself. Does the reset only usually operate if one of the neons has been flashing, or should it be possible to reset at any time?

 

[electronman]

Hi Folks!

I took the plunge and purchased and fitted a new PCB and all now works fine!

Many thanks for all your help.

Electronman.