Problems with Baxi Baharma 100

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micky p

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i went to repair one yesterday and today. i have currently replaced the DHW flow switch as it was definitely faulty and now it is working fine in that area. But I have now discovered that every now and again the boiler will go to lockout (flame failure lights up). I suspect it is overheating and the water gets pretty hot. I have a few ideas what might be causing it like primary heat exchanger sludged up or blocked up but i took a sample of the CH water and it was as clean as drinking water. So maybe it isn't sludged up.
The reason why i am posting is i want to know if any of you guys and gals have had any dealings with this boiler and maybe point me in the right direction. Many thanks
 
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Moz said:
faulty overheat themostat .....:)
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well maybe but i can hear the boiler starting to kettle then it goes onto low flame but im sure it shouldn't start to kettle (hiss like a kettle) at all. It is only everynow and again it goes to lockout. i might be barking up the wrong tree with it overheating thats why im asking on hear. Like you said tho its a possiblity.
 
micky p
I assume you have run through the M/I fault diagnostic tests ? ;)
 
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Moz said:
micky p
I assume you have run through the M/I fault diagnostic tests ? ;)
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i have but it doesn't help. they are only any use if the boiler is totally broken down and with it firing up and running ok then every now and agin it will go to lock out. No answer in the book im afriad.
 
doitall said:
Pump being lazy at startup. :rolleyes:
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I did wonder if the pump was lazy but i thought well the primary flow switch would drop out if that was the case. Have you had this problem with one before DIA
 
The system flow switch is much more likely to stick than the DHW flow switch because it picks up magnetic dirt.

None of the many things said above would definately point to that though.

There is a gauze filter built into the return somewhere.

A Magnaclean would be a big advantage to anyone with this aweful boiler.

Tony
 
Agile said:
The system flow switch is much more likely to stick than the DHW flow switch because it picks up magnetic dirt.

None of the many things said above would definately point to that though.

There is a gauze filter built into the return somewhere.

A Magnaclean would be a big advantage to anyone with this aweful boiler.

Tony
Click to expand...

I took a sample of the Ch water and i could not belive how clear it was. So i'm ruling out sludge being the problem.
 
Some people are easily fooled !!!

It is likely to be clear because all the magnetic sludge is trapped by the magnetic element of the flow switch!

Whilst I cannot guarantee the flow SW is the only or main fault in your case, its the most common cause of malfunction on that model!

Tony
 
Agile said:
Some people are easily fooled !!!

It is likely to be clear because all the magnetic sludge is trapped by the magnetic element of the flow switch!

Whilst I cannot guarantee the flow SW is the only or main fault in your case, its the most common cause of malfunction on that model!

Tony
Click to expand...

ok if i get called back to it i shall remove the flow switch for peace of mind. All i have done regarding the primary flow swtich is test the continuity and when the pump runs the switch makes. So the switch looks to be working fine. according to the Sequence of operation in the manual if the primary flow switch drops out then it will not go to lock out. I think according to the manual the only way it will go to lock out is if flame rectification fails or if the boiler overheats. So really im down to 2 possible faults. Its either failing to light every now and again or overheating (which the boiler does get quite hot even with thermostats turned down and also it sounds to kettle a bit).
 
Mickey p, while I would have to double check the boiler, I suspect the flow switch comprises a shaft with a collar on it that moves up and down with water flow. The collar is a magnet and shaft houses a reed switch. Reed switch comprises a glass tube with a metal wire inserted each end. Tube ends are sealed. Air within is inert. Wire ends are flat, gold plated (for low resistance) and close together. When a magnet is placed at the center of the glas tube (where the teo wires overlap), the ends come in contact completing the switch circuit.

The metal rods over time become magnetised and do not release when magnet is no longer in proximity.

You will find when the boiler fails to start, if you thump the boiler case, the fault goes away.

Excuse any grammer errors, have typed on the run.
 
DP said:
Mickey p, while I would have to double check the boiler, I suspect the flow switch comprises a shaft with a collar on it that moves up and down with water flow. The collar is a magnet and shaft houses a reed switch. Reed switch comprises a glass tube with a metal wire inserted each end. Tube ends are sealed. Air within is inert. Wire ends are flat, gold plated (for low resistance) and close together. When a magnet is placed at the center of the glas tube (where the teo wires overlap), the ends come in contact completing the switch circuit.

The metal rods over time become magnetised and do not release when magnet is no longer in proximity.

You will find when the boiler fails to start, if you thump the boiler case, the fault goes away.

Excuse any grammer errors, have typed on the run.
Click to expand...

i know rougly how these flow switches work but thumping the boiler won't make it work i am sure about his. when the fault occurs i have to maually press the reset switch. This is the only way it will start to work again. I unplugged the lead (broke resistance) from the flow switch whilst the boiler was running and it never locked out. So this tells me this is not the problem.

I replaced the DHW flow switch because it was reading several Mega ohms regardless if the magnet was fully up or down. So this sounds like that was the problem with DHW flow switch. but that particular fault is now sorted. Its the locking out im scrating my head at a little.
 
You have not made it clear to me if the kettling is on CH or DHW or both !

Clearly it should not kettle ever.

If its only on CH then clean the return filter as its probably blocked.

If it fails to light and then goes to lockout then this can be due to a sticking gas valve. Not likely to be your problem but the seals can be easily cleaned on each of the three solenoids.

My best bet is pump if kettling on both CH and DHW.

Return filter if on CH only!

Tony
 
Agile said:
You have not made it clear to me if the kettling is on CH or DHW or both !

Clearly it should not kettle ever.

If its only on CH then clean the return filter as its probably blocked.

If it fails to light and then goes to lockout then this can be due to a sticking gas valve. Not likely to be your problem but the seals can be easily cleaned on each of the three solenoids.

My best bet is pump if kettling on both CH and DHW.

Return filter if on CH only!

Tony
Click to expand...

Are you not getting mixed up with the Baxi Genesis with the gas valve sticking. This one doesn't have 3 solenoids. It looks like the pump or blockage then by the sounds of it.
 
D

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