Baxi 105 e continuous burner

[Thoggy]

Hi all been to a call out today and can't figure out what is going on with this baxi 105e, if you turn it on to hot water mode the burner kicks in without the tap being run, slowly increases pressure the prv releases.
Turn it to ch and dhw mode the same thing happens, now if I turn the tap on it eases the pressure at the mb it was at and also same with heating! Any one any ideas. Many thanks Martyn.

 

[diamondgas]

Sounds like a call for hot water when it's not requested! First thoughts maybe a sticking hot water spindle or microswitch?

 

[Billy Bob Bob]

as steve or a burst hot water pipe easy way to prove it,isolate the cold to the combi if it stops firing you have a burst pipe

 

[diamondgas]

as steve or a burst hot water pipe easy way to prove it,isolate the cold to the combi if it stops firing you have a burst pipe

Yeh had that one in the past under a concrete floor ... custard thought the extension had UFH Good one Mate!

 

[Thoggy]

Cheers for replies. I tried to micro switch on the diverter valve pressed it in manually and it went to heating mode and eased the pressure of, would the hot water light not come on the boiler as in when you put the hot tap on the tap symbol goes green when it is just turned onto dhw on the dial but no tap running?

 

[Destroyer2813]

Sounds like you also have a expansion vessel issue with the pressure suddenly increasing and the prv going off

 

[Thoggy]

Do you think 2 separate issues or both from same fault?

 

[diamondgas]

Cheers for replies. I tried to micro switch on the diverter valve pressed it in manually and it went to heating mode and eased the pressure of, would the hot water light not come on the boiler as in when you put the hot tap on the tap symbol goes green when it is just turned onto dhw on the dial but no tap running?

You've lost me Thoggy! What version of Baxi 105? What microswitch went to heating mode pressed in what exactly? :willy_nilly:

 

[Thoggy]

Sorry it's a baxi instant 105 he I think, I'm going back tomorrow it was last thing tonight and had to get back but thought I'd check with you guys what you thought. I tried to see if the diverter was somehow sticking but it was ok, I'm more on the install side and only just learning about breakdowns so I'm not 100% on everything. If I can't fix it will get the heat team out does anyone know what they charge?

 

[diamondgas]

Sorry it's a baxi instant 105 he I think, I'm going back tomorrow it was last thing tonight and had to get back but thought I'd check with you guys what you thought. I tried to see if the diverter was somehow sticking but it was ok, I'm more on the install side and only just learning about breakdowns so I'm not 100% on everything. If I can't fix it will get the heat team out does anyone know what they charge?

Makes such a difference when you know the appliance Thoggy . There's either no problem at all or you need to know how to check the hot water sensor IMHO AND as previously said by gas man .. you have a hot water pipe running you're not aware of

 

[Billy Bob Bob]

sounds like no issue with the boiler as its a instant its topping up the store sounds like the EV has failed the EV is part of the store,this is why its increasing in pressure

 

[buckley plumb]

Cheers for replies. I tried to micro switch on the diverter valve pressed it in manually and it went to heating mode and eased the pressure of, would the hot water light not come on the boiler as in when you put the hot tap on the tap symbol goes green when it is just turned onto dhw on the dial but no tap running?

what do you mean when you say eased the pressure.is the pressure gauge constantly going up and then the prv opening without the boiler on ? if so could it be a split plate heat exch

 

[Thoggy]

No it goes up when you just turn the dial from the 0 position to dhw or ch/dhw but when you actually turn a tap or call for heat the pressure stops goin up.

 

[Thoggy]

Been back to this boiler today and it works normal which makes the whole situation stranger, thoughts anyone? I've left it and told Cust that it will prob happen again but until then see how you go on!

 

[diamondgas]

Been back to this boiler today and it works normal which makes the whole situation stranger, thoughts anyone? I've left it and told Cust that it will prob happen again but until then see how you go on!

Was at an '105 Instant' today with exact same symptoms. Unable to get heating on via controls and the preheat turned off, burner on and off! Found hot water diaphragm spindle stuck. Replaced diaphragm and 'stuffin box' job done!

I'd be looking closely at the hot water diaphragm spindle myself Thoggy