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  #1   Report Post  
Stephen Clark
 
Posts: n/a
Default Baxi WM 38/3 RS

I have a problem with my central heating boiler, a Baxi WM 38/3 RS. After
the burners have been lit for 20 minutes they turn off and the pilot light
is out. I can immediately re-light the pilot but if I start the boiler
again, the pilot goes out and the burners do not start. If I light the pilot
and leave it for 10-15 minutes, the burners will fire up again but only for
the 20 minute period. Looking at the fault guide it say that a cause of
nuisance shut downs is a dirty or loose thermocouple connection; defective
thermocouple or a defective power unit. I'm unwilling to do any diy on a gas
appliance so have spoken to a plumber (BUT I have checked that the
thermocouple is not loose). Over the 'phone he has suggested the boiler is
near its end of life (its 12 years old) and that the fault is probably with
the gas value which will cost £150+ and labour cost to replace. Is this
reasonable in the opinion of the members of this group?

Thanks for any contributions.





  #2   Report Post  
Ed Sirett
 
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Default Baxi WM 38/3 RS

On Thu, 20 Nov 2003 19:14:20 +0000, Stephen Clark wrote:

I have a problem with my central heating boiler, a Baxi WM 38/3 RS. After
the burners have been lit for 20 minutes they turn off and the pilot light
is out. I can immediately re-light the pilot but if I start the boiler
again, the pilot goes out and the burners do not start. If I light the pilot
and leave it for 10-15 minutes, the burners will fire up again but only for
the 20 minute period. Looking at the fault guide it say that a cause of
nuisance shut downs is a dirty or loose thermocouple connection; defective
thermocouple or a defective power unit. I'm unwilling to do any diy on a gas
appliance so have spoken to a plumber (BUT I have checked that the
thermocouple is not loose). Over the 'phone he has suggested the boiler is
near its end of life (its 12 years old) and that the fault is probably with
the gas value which will cost £150+ and labour cost to replace. Is this
reasonable in the opinion of the members of this group?

Thanks for any contributions.


I'm not familair with this model but I strongly suspect that there may be
an overheating fault. Which might simply be that the over-heat thermostat
has become faulty and open at too low a temp.

From you description it sounds like a boiler with a permanent pilot.

The gas valve is probably the _least_ likely part to fail, the valve is
also likely to cost sub 100 including VAT (although Baxi are quite
expensive for spares).
HTH

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html


  #3   Report Post  
Christian McArdle
 
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Default Baxi WM 38/3 RS

and that the fault is probably with the gas value which will cost
£150+ and labour cost to replace.


I'd replace the thermocouple first and then see if it fixes it. A
thermocouple is about 3 quid and is usually fitted very easily. I don't
specifically about the Baxi. It is fail safe. If you don't fit it right, the
boiler won't light.

I wouldn't replace the gas valve on it. It'd be like putting a new engine
into an 'A' reg car.

Christian.


  #4   Report Post  
BillP
 
Posts: n/a
Default Baxi WM 38/3 RS


"Stephen Clark" wrote in message
...
I have a problem with my central heating boiler, a Baxi WM 38/3 RS. After
the burners have been lit for 20 minutes they turn off and the pilot light
is out. I can immediately re-light the pilot but if I start the boiler
again, the pilot goes out and the burners do not start. If I light the

pilot
and leave it for 10-15 minutes, the burners will fire up again but only

for
the 20 minute period. Looking at the fault guide it say that a cause of
nuisance shut downs is a dirty or loose thermocouple connection; defective
thermocouple or a defective power unit. I'm unwilling to do any diy on a

gas
appliance so have spoken to a plumber (BUT I have checked that the
thermocouple is not loose). Over the 'phone he has suggested the boiler is
near its end of life (its 12 years old) and that the fault is probably

with
the gas value which will cost £150+ and labour cost to replace. Is this
reasonable in the opinion of the members of this group?

Thanks for any contributions.




Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years service
this boilers given I've needed to replace the thermocouple three times, and
the symptom you describe is typical. The gas valve solenoid failed once and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light was
ok but the main burner didn't light. The WM381 has no overheat. The internal
circuit is shown in the manual and consists only of boiler thermostat and
gas valve.

Replace the thermocouple first, it's a straight forward job and you won't be
disturbing any gas joints.

Good luck

Bill


  #5   Report Post  
Mark Dumbrill
 
Posts: n/a
Default Baxi WM 38/3 RS

"Christian McArdle" wrote in message
. net...
and that the fault is probably with the gas value which will cost
£150+ and labour cost to replace.


I'd replace the thermocouple first and then see if it fixes it. A
thermocouple is about 3 quid and is usually fitted very easily. I don't
specifically about the Baxi. It is fail safe. If you don't fit it right,

the
boiler won't light.

I wouldn't replace the gas valve on it. It'd be like putting a new engine
into an 'A' reg car.



A gas valve for this boiler cost me £70 three months ago.

Mark




  #6   Report Post  
Stephen Clark
 
Posts: n/a
Default Baxi WM 38/3 RS

"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat and
gas valve.

Replace the thermocouple first, it's a straight forward job and you won't

be
disturbing any gas joints.

Good luck

Bill

The plumber has just been and had a look at my boiler. Listening to the
value he say that it is "constantly" clicking making him think the value is
faulty. Anyway he did not do anything because its not really something he
likes doing (he didn't charge me for this visit!) and recommends I call
around plumbers in the Yellow Pages for someone who would have the spare and
replace the value (today's plumber ws recommended by a friend). BUT first I
will follow the suggestion of members on the group to replace the
thermocouple. It looks easy - just:

1) unscrew the current one at both ends;
2) insert the new one;
3) tighted the bolts.

Is there a guide on what I might need to look out for? For instance is it
just sufficient to ensure the boiler is "switched-off" (ie no electricity)
or do I need to do more (no gas).


  #7   Report Post  
IMM
 
Posts: n/a
Default Baxi WM 38/3 RS


"Stephen Clark" wrote in message
...
"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years

service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat

and
gas valve.

Replace the thermocouple first, it's a straight forward job and you

won't
be
disturbing any gas joints.

Good luck

Bill

The plumber has just been and had a look at my boiler. Listening to the
value he say that it is "constantly" clicking making him think the value

is
faulty. Anyway he did not do anything because its not really something he
likes doing (he didn't charge me for this visit!) and recommends I call
around plumbers in the Yellow Pages for someone who would have the spare

and
replace the value (today's plumber ws recommended by a friend). BUT first

I
will follow the suggestion of members on the group to replace the
thermocouple. It looks easy - just:

1) unscrew the current one at both ends;
2) insert the new one;
3) tighted the bolts.

Is there a guide on what I might need to look out for? For instance is it
just sufficient to ensure the boiler is "switched-off" (ie no electricity)
or do I need to do more (no gas).


Don't go to a plumber!!!!! Go to a heating engineer. No wonder he didn't
have a clue. If the company say heating and plumbing avoid them. Go for
heating only.


---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.542 / Virus Database: 336 - Release Date: 18/11/2003


  #8   Report Post  
Ed Sirett
 
Posts: n/a
Default Baxi WM 38/3 RS

On Sat, 22 Nov 2003 17:55:44 +0000, Stephen Clark wrote:

"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat and
gas valve.

Replace the thermocouple first, it's a straight forward job and you won't

be
disturbing any gas joints.

Good luck

Bill

The plumber has just been and had a look at my boiler. Listening to the
value he say that it is "constantly" clicking making him think the value is
faulty. Anyway he did not do anything because its not really something he
likes doing (he didn't charge me for this visit!) and recommends I call
around plumbers in the Yellow Pages for someone who would have the spare and
replace the value (today's plumber ws recommended by a friend). BUT first I
will follow the suggestion of members on the group to replace the
thermocouple. It looks easy - just:

1) unscrew the current one at both ends;
2) insert the new one;
3) tighted the bolts.

I think it is unlikely that the thermocouple is up the spout. Much more
likely given these symptoms is a loose connection on the electrics to the
gas vavle. Also the themrostat contacts can get 'jumpy' with age and that
could easily cause the clicking. These contacts are essentially a
microswitch with all the usual problem that such switches sometimes have.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html


  #9   Report Post  
Stephen Clark
 
Posts: n/a
Default Baxi WM 38/3 RS

"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat and
gas valve.

Replace the thermocouple first, it's a straight forward job and you won't

be
disturbing any gas joints.

Good luck

Bill

I've just had a look at the end of the thermocouple and it looks badly
corroded. I visited a DIY store and got a Universal Thermocouple. It does
not exactly match the existing one for length etc so I'm no sure which
adaptors to use to fix it correctly. Since it's a fail safe component - I
imagine that I can't do any harm by trying various combinations.



  #10   Report Post  
Ed Sirett
 
Posts: n/a
Default Baxi WM 38/3 RS

On Sun, 23 Nov 2003 13:55:22 +0000, Stephen Clark wrote:

"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat and
gas valve.

Replace the thermocouple first, it's a straight forward job and you won't

be
disturbing any gas joints.

Good luck

Bill

I've just had a look at the end of the thermocouple and it looks badly
corroded. I visited a DIY store and got a Universal Thermocouple. It does
not exactly match the existing one for length etc so I'm no sure which
adaptors to use to fix it correctly. Since it's a fail safe component - I
imagine that I can't do any harm by trying various combinations.


The hot end it is only necessary to make sure it is held securely in
place, with about the last 10mm in the flame.
The connection to the gas valve is usually quite fiddly but is likely to
be only one of a couple of the nuts.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html




  #11   Report Post  
Christian McArdle
 
Posts: n/a
Default Baxi WM 38/3 RS

A gas valve for this boiler cost me £70 three months ago.

But the OP will need someone to fit it. This may cost a lot of money.

Christian.


  #12   Report Post  
Stephen Clark
 
Posts: n/a
Default Baxi WM 38/3 RS


"Ed Sirett" wrote in message
news
On Sun, 23 Nov 2003 13:55:22 +0000, Stephen Clark wrote:

"BillP" wrote in message
...


Hi Stephen,

I've got a Baxi WM381. I'd definitely go for the thermocouple first,
universal thermocouple kit will do the job. Over the 20 odd years

service
this boilers given I've needed to replace the thermocouple three times,

and
the symptom you describe is typical. The gas valve solenoid failed once

and
had to buy the complete valve assembly, about £75 + vat three years

ago,
this gave a different fault to what you are describing, the pilot light

was
ok but the main burner didn't light. The WM381 has no overheat. The

internal
circuit is shown in the manual and consists only of boiler thermostat

and
gas valve.

Replace the thermocouple first, it's a straight forward job and you

won't
be
disturbing any gas joints.

Good luck

Bill

I've just had a look at the end of the thermocouple and it looks badly
corroded. I visited a DIY store and got a Universal Thermocouple. It

does
not exactly match the existing one for length etc so I'm no sure which
adaptors to use to fix it correctly. Since it's a fail safe component -

I
imagine that I can't do any harm by trying various combinations.


The hot end it is only necessary to make sure it is held securely in
place, with about the last 10mm in the flame.
The connection to the gas valve is usually quite fiddly but is likely to
be only one of a couple of the nuts.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

Yea, I fitted the Universal thermocouple device yesterday. The connection to
the value WAS fiddly, it took 20 minutes. So far the burners are quite
stable. Hopefully all is OK. Thanks to this group for giving the the courage
to replace the thermocouple - you've saved me a packet. Perhaps if you ever
have a meeting in Leeds I'll buy you all a drink? (o:



  #13   Report Post  
Junior Member
 
Posts: 1
Default

Quote:
Originally Posted by Stephen Clark
I have a problem with my central heating boiler, a Baxi WM 38/3 RS. After
the burners have been lit for 20 minutes they turn off and the pilot light
is out. I can immediately re-light the pilot but if I start the boiler
again, the pilot goes out and the burners do not start. If I light the pilot
and leave it for 10-15 minutes, the burners will fire up again but only for
the 20 minute period.
I have a similar problem, but one that follows a strange series of event before xmas:

1) begining of december, Heating goes down. I investigate and discover an apparently faulty motor in my Y valve. While looking at the valve, I notice that the controlling circuit looks like it has burnt at some point in its life... I replace the motor, test the circuit, which still seems to work, but I can't fire the boiler with the room thermostat. I look at the thermostat to find a short in the live wire. The thermostat is too old to see if that short has caused the circuit to arc, but replacing the thermostat fixes the fault.

2) Everything work fine for 2 weeks, until I go away for xmas. I come back to find the circuit breaker for the CH circuit down! I stupidly just try to switch it on again (it was after all midnight after a 7 hour journey!) and it trips again, with a big falsh (that woke me up!). In the morning, I open the Y-valve control box again, look at the controlling circuit, clean it up a bit, check the connections, put everything back on, and switch the circuit back on. Surprise, that seems to work...

3) A day later, boiler has been running continuously and all I have are lukewarm radiators and water :-( The pipes coming from my boiler are not very warm either. I borrow an electric radiator and put my room thermostat to the minimum, so that whatever little heat I get goes to the water circuit.

4) Boilers goes down overnight... I start it again.

5) Room is getting cold, I put the thermost to max again: boiler goes down! I start it again, but it will only work in the water position... I leave the thermostat to the minimum position.

6) Boilers goes down overnight... I switch the pilot light back on, but any attempt to draw heat for the water switches everything off!

So here the question: am I being very unlucky, or is there a possibility for one problem to cause the other ones?
I will have a go at changing the thermocouple, but I can't see how this is linked to the other problems. I have talked to a CH engineer to replace the Y valve with a new one (with removable head), but I don't see how that would fix the boiler problem...

Any help appreciated.

Cheers

PS: the boiler is a Baxi WM 38/3 RS, the Y-valve a landis & staefa MAV-322
  #14   Report Post  
Posted to uk.d-i-y
external usenet poster
 
Posts: 1
Default Baxi WM 38/3 RS

replying to Franck, salamander 45 wrote:
my baxi wm 381 rs is nearing 36 years,to me it's the rolls-royce of
boilers.this thing is serviced every year and it still performing
brilliant.part's renewed over this period o time, the burner filament in
2011,the pilot & ignition + casing gasket in 2015,total cost
approx,£196.still running spot on as of 2018.im with eon and always in credit
wi gas & electric.. soo the moral o this story is,if u own an appliance like
the above and its serviced regular,it beats any new fandangled combi or
similiar hand's down.the baxi wm 381 rs has 4 main parts,these where the best
quality built...

--
for full context, visit https://www.homeownershub.com/uk-diy...-rs-31402-.htm


  #15   Report Post  
Posted to uk.d-i-y
external usenet poster
 
Posts: 1
Default Baxi WM 38/3 RS

My Baxi 381rs has been in my home for 38 years . I've only replaced pump 3 times and 3 thermocouples in that time. I will need to replace it as the heat exchanger is starting to leak. I will be sorry to see it go as parts are hard to come by now. I will replace it with another baxi boiler.

--
For full context, visit https://www.homeownershub.com/uk-diy...-rs-31402-.htm



  #16   Report Post  
Posted to uk.d-i-y
external usenet poster
 
Posts: 6,213
Default Baxi WM 38/3 RS

On 01/12/2020 22:45, Frank wrote:
My Baxi 381rs has been in my home for 38 years . I've only replaced pump
3 times and 3 thermocouples in that time. I will need to replace it as
the heat exchanger is starting to leak. I will be sorry to see it go as
parts are hard to come by now. I will replace it with another baxi boiler.


How much did you spend on insulation over that 38 years (and no, I
don't mean double glazing) ?.

The replacement won't last 38 years :-(.

Get one with a 7 year warranty.
  #17   Report Post  
Posted to uk.d-i-y
external usenet poster
 
Posts: 4,120
Default Baxi WM 38/3 RS

On 02/12/2020 12:26, Andrew wrote:
On 01/12/2020 22:45, Frank wrote:
My Baxi 381rs has been in my home for 38 years . I've only replaced
pump 3 times and 3 thermocouples in that time. I will need to replace
it as the heat exchanger is starting to leak. I will be sorry to see
it go as parts are hard to come by now. I will replace it with another
baxi boiler.


How much did you spend on insulation over that 38 years (and no, I
don't mean double glazing) ?.

The replacement won't last 38 years :-(.


Indeed. 38 years ago, Baxi made some of the best boilers available. Now
they don't.

Get one with a 7 year warranty.


I've just replaced my 30-year-old Baxi Solo with a Vaillant with 10 year
warranty, and would recommend the OP to do the same - or maybe a
Worcester Bosch.
--
Cheers,
Roger
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