Baxi 80 HE runs then locks out.

[armyash]

I tagged a long on a job today for the above boiler. Engineer i was with thought the problem was just on HW. tap/shower running, temperature fluctuates a lot and boiler can go to lock out. I said to customer does it happen on CH she said she hasn't tested so i put CH on also and after 5 or so minutes it went to lock out. Sounds like there is a lot of air going around the boiler.

Right, parts changed so far: Flow sensor, gas valve, plate heat ex, electrode leads and PCB.

What would you be looking at? AAV or maybe pump?

Thanks

 

[gasmanrob]

Flue seal.

The blue one (originally red i think depending on age) the one off the top of the causation box.

 

[gasmanrob]

Or burner door seal for that matter

 

[gasmanrob]

Unless we're talking the later mid combi 80 he then perhaps heavy corrosion in the cylindrical secondary circulator top right of the combustion chamber.

I may be getting my models mixed up its been a few months since I've touched one

 

[gasmanrob]

But all above is only for lock out my bad didn't read the post properly

 

[armyash]

There did appear to be a slight flame lift. Guy I was with has called Transco out saying governor needs looking at as he was not happy with pressures at the gas valve.

It was a fairly old looking boiler.

 

[gasmanrob]

Multi parts visits always require the basics checking first that often get over looked.

Flow rate, gas rate, BP if possible and combustion readings if all are as per MI then start looking at components.

Temperature fluctuations in hw will also require more then one outlet checking as it could be back flow or faulty blending valve or mixer.

Temp fluctuations also need the resistance checking on NTC sensors if you haven't got them ring technical baxi tech are mustard for those.

Also by pass setting (if adjustable) as if the system is poor quality water content the path of least resistance is always the bypass which will prematurely modulate the burner.

Gritty div valves or worn DHW pressure differentials also leave the back door open on heating circuits and by passes. Fire up from stone cold on hw only and keep your hand on ch flow pipe monitor for heat increase.

 

[gasmanrob]

There did appear to be a slight flame lift. Guy I was with has called Transco out saying governor needs looking at as he was not happy with pressures at the gas valve.

It was a fairly old looking boiler.

Was it the square ally heat ex same as the solo he?

Any idea on the working pressure at the meter and again at p1 on appliance gas valve that'll indicate if it's a regulator fault or gas pipe work under sized.

Flame lift also indicates to faulty seal. But again if it's the square type check the burner. The felt ones should all be replaced regardless of condition and the ceramic ones used to split on the metal at the rear as it met the ceramic.

 

[armyash]

Multi parts visits always require the basics checking first that often get over looked.

Flow rate, gas rate, BP if possible and combustion readings if all are as per MI then start looking at components.

Temperature fluctuations in hw will also require more then one outlet checking as it could be back flow or faulty blending valve or mixer.

Temp fluctuations also need the resistance checking on NTC sensors if you haven't got them ring technical baxi tech are mustard for those.

Also by pass setting (if adjustable) as if the system is poor quality water content the path of least resistance is always the bypass which will prematurely modulate the burner.

Gritty div valves or worn DHW pressure differentials also leave the back door open on heating circuits and by passes. Fire up from stone cold on hw only and keep your hand on ch flow pipe monitor for heat increase.

I think we will be going back so plenty of stuff there to check. thanks

 

[gasmanrob]

Equally if you can hear air get it out. Those flow switches can be precious, especially when pipe work goes up and over the boiler

 

[GrahamM]

This guy a BG engineer you with?
That the old combi instant thing?
Check pump. If guy BG should have limpet which does work quite well to tell if pump ok. Otherwise screwdriver method.
Check thermistors.
Otherwise maybe blockage?

 

[armyash]

Was it the square ally heat ex same as the solo he?

Any idea on the working pressure at the meter and again at p1 on appliance gas valve that'll indicate if it's a regulator fault or gas pipe work under sized.

Flame lift also indicates to faulty seal. But again if it's the square type check the burner. The felt ones should all be replaced regardless of condition and the ceramic ones used to split on the metal at the rear as it met the ceramic.

To be honest I didn't look too closely. It was his job and being new I didn't want to step on any toes. Just trying to find possible solutions so if i go back again with someone i can make a few suggestions.

 

[gasmanrob]

To be honest I didn't look too closely. It was his job and being new I didn't want to step on any toes. Just trying to find possible solutions so if i go back again with someone i can make a few suggestions.

Never be afraid to speak up. We are all guilty of over looking the simplest of stuff.

 

[gasmanrob]

This guy a BG engineer you with?
That the old combi instant thing?
Check pump. If guy BG should have limpet which does work quite well to tell if pump ok. Otherwise screwdriver method.
Check thermistors.
Otherwise maybe blockage?

I used to love that! Like a little lie detector that was.

 

[Billy Bob Bob]

80 HE IS A BARCELONA WITH COMBI GUTS,not worth repairing IMHO,utter junk,if it was a baxi 80 e or 80 he eco then yes,worth sorting

 

[gasmanrob]

I remember the Barcelona had those awful float switches that were forever getting bogged down with magnetite.

Oh crap I'm getting palpitations thinking about the Phex replacement

 

[Billy Bob Bob]

I remember the Barcelona had those awful float switches that were forever getting bogged down with magnetite.

Oh crap I'm getting palpitations thinking about the Phex replacement

phex is a right pig on those

 

[gasmanrob]

Id still take one over a high flow any day!