baxi duo tec he a 24 gets to temp on boiler then wont fire up again unless reset

[julesverne]

Hi guys

Any help on this would be appreciated just off to look at it now. Any tips to look for

Thanks in advance

 

[diamondgas]

Room stat reached temp? :lol: Unless you know of any codes you're just guessing mate I guess?

 

[julesverne]

More info now im at boiler the motor actuator on diverter does not diverter after the hot water has been turned and off it does divert back to hot . No errors given tried another actuator still same

 

[julesverne]

After the demand for hot has finished there is 240 volts on pins 5 & 7 instead of 5&6 which shoukd be back to central heating.

 

[julesverne]

On terminal block x3

 

[zeebeedee]

Seen similar on isar, display stayed on d for hw divertor didn't move. New actuator sorted it.

 

[REDSAW]

take actuator off and manually depress diverter pin, does that solve it?

 

[julesverne]

Actuator fine traced it back to magnet sticki g in hall effect sensor

 

[zeebeedee]

Actuator fine traced it back to magnet sticki g in hall effect sensor

Good work

 

[zeebeedee]

Actuator fine traced it back to magnet sticki g in hall effect sensor

Did the red light not stay lit on the sensor?

 

[buckley plumb]

I thought hw light would be on if magnet stuck

 

[julesverne]

possibly not the magnet itself then but def the hall effect sensor. no red light on after hot water demand so it took me a little longer to trace it back to that. luckily cust had manual so i check voltages on specific pins.

 

[REDSAW]

possibly not the magnet itself then but def the hall effect sensor. no red light on after hot water demand so it took me a little longer to trace it back to that. luckily cust had manual so i check voltages on specific pins.

thats cheating lol

 

[arran197]

I've come across this once before and Baxi tech said pub or actuator. Can you confirm it was definitely the Hall effect sensor as I didn't go back to finish the job I went to.

 

[julesverne]

i will let you know monday but 99% sure its that

 

[diamondgas]

It certainly makes sense... Did you notice whether the hot water demand light stayed on?

 

[buckley plumb]

After the demand for hot has finished there is 240 volts on pins 5 & 7 instead of 5&6 which shoukd be back to central heating.

is this with a central heating demand if no demand I think diverter reverts to hw

 

[julesverne]

Light never stayed but actuator was still giving 240 v to hot water demand not ch demand after demand for hot water ceased.

 

[buckley plumb]

got you still giving 240 v to hw pins on diverter - even though boiler was set for heating makes sense

 

[arran197]

I didn't suspect the hall effect sensor because the light was off.

 

[julesverne]

I didn't suspect the hall effect sensor because the light was off.

same here but im sure as hell it is anyway will know for sure on monday

 

[julesverne]

well i feel an idiot went back tonight fitted a new hall sensor still the same problem so to recap what i have done so far.

demand for hot water
red light on sensor comes on
demand for hot water finshes red light comes off
check terminal block x3 and 240 v is still showing demand for hot water and is not reverting back to central heating. no errors codes reset doesnt work on the boiler
but turning the boiler off and back on again does reset the boiler and actuator goes back to central heating and pins on terminal block now showing 240v for ch demand.
my initial thoughts of hall sensor are ill founded now pointing towards pcb .

unless you guys can point me in another direction all help appreciated.

 

[Ermintrude]

Ooh sounds like some sort of voltage spike or latching? Did u clean out the sensor or just replace bit that clips on.

Could try and discharge pcb, disconnect all leads and turn DHW and ch temp up and down few times. Can sometimes remove gremlins / charge on pcb which leads to small issues. Is boiler supply 100% good earth and neutral?

 

[julesverne]

i replaced with a new sensor and plastic housing.

as far as i know its a good earth but i didnt test it at the time.

 

[arran197]

It's either the momo actuator or the pcb. Get an actuator, they're cheap and try it. If it doesn't cure it then stick a PCB on. If you ring Baxi they say the same, so custard can't argue too much!

 

[zeebeedee]

Pcb surely! Does it do it when you isolate cold to boiler?

 

[zeebeedee]

Or as I previously said actuator, seems similar to isar fault

 

[julesverne]

swapped actuator as i had a spare one and no difference so that why i am leaning towards to the pcb. just got a pcb for £40.00 quid off fleabay brand new so at that price i'll take a risk on it.

 

[arran197]

This is only the second I've heard of/seen this on a Duo Tec, so uncommon. I think it's more likely to be the PCB as surely it switches the demand over and moves the actuator, pump, fan, etc. I don't think the actuator actually has that much of a baring on the actions of the boiler. It follows rather than leads. I think so anyway! Ha ha!

 

[julesverne]

these bloody finicky faults do my head in. but i believe in the end it will make me a better engineer