Nice pic pattern part lmao
Vaillant Thermocompact diagnosis
- Thread starter bertiebooth
- Start date
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What's pattern part?
Bypass
Call it what you like, but the bypass valve came in a Vaillant box and was bought at Parts Center.
Thanks for those figures Andygasman10.
If my understanding is correct, the NTC thermistor is used (along with the user control knob setting) by the temperature control PCB to modulate the flame/output.
The on/off flow thermostat, lower down, is a backstop in case the control circuit fails, and is therefore in series with the gas valve operator. And even though this overheat thermostat never fails in the closed circuit state
roll there's a second overheat detector, operated by a capillary tube, that operates only when superheated water is banging out of the heat exchanger.
And since neither of the overheat mechanisms is acting, the conclusion is that some of the water in the heat exchanger is superheating because there is a constriction or blockage.
Well I'll buy into most of that, and I'll start with the previously planned replacement of the main PCB, part number 130331.
Thanks for those figures Andygasman10.
If my understanding is correct, the NTC thermistor is used (along with the user control knob setting) by the temperature control PCB to modulate the flame/output.
The on/off flow thermostat, lower down, is a backstop in case the control circuit fails, and is therefore in series with the gas valve operator. And even though this overheat thermostat never fails in the closed circuit state
roll there's a second overheat detector, operated by a capillary tube, that operates only when superheated water is banging out of the heat exchanger.And since neither of the overheat mechanisms is acting, the conclusion is that some of the water in the heat exchanger is superheating because there is a constriction or blockage.
Well I'll buy into most of that, and I'll start with the previously planned replacement of the main PCB, part number 130331.
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Ur quite good mate probably the most arrogant i have seen but wrong part number that's the one for a combi it will do the job tho leave the heating switch on continuous u should have got the 130330 Lol but hey that's Vaillant technical help for u!!
the proper part is about a third cheaper
130330 is actually what I've ordered - I just wanted to see your reaction
If my understanding is correct, the NTC thermistor is used (along with the user control knob setting) by the temperature control PCB to modulate the flame/output.
The on/off flow thermostat, lower down, is a backstop in case the control circuit fails, and is therefore in series with the gas valve operator. And even though this overheat thermostat never fails in the closed circuit state
Correct.
I doubt either of these machanisms have failed though, it's probably just not getting hot enough to trip them. Pretty difficult to test without accuratly measuring the temperature. I don't think they're expensive (i've never had to buy either of them) if you decided to change them anyway.
Also, please be patient with us guys on here. Wether advice is right or wrong it's still people taking time out to help for free.
Andy
Impatient? I don't think I am.
Nor am I ungrateful - I've been thanking people left right and centre.
But in return, as well as the free advice, I've received 'free' abuse, in the form of sarcasm and personal comments.
Nor am I ungrateful - I've been thanking people left right and centre.
But in return, as well as the free advice, I've received 'free' abuse, in the form of sarcasm and personal comments.
I think almost ever other thread ends like this ha! I'm not really sure why.
Oh well....
Oh well....
This isn't the end - I'll be reporting back with the results of any changes I make.
Since my thanks seem to have fallen on deaf ears, the least I can do to repay the site is document this experience for other non-experts to read.
Since my thanks seem to have fallen on deaf ears, the least I can do to repay the site is document this experience for other non-experts to read.
Oh no, your thanks are well recieved.
I'll watch out for the results of your diagnosis.
I'll watch out for the results of your diagnosis.
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my two penneth worth...
130330 is what you obviously need, and thats being sorted.
NTC sensor and overheat stats: VERY low on the list of problems, but never the less can be defective. In the case of the NTC, if it failed, it would go open circuit (99/100) so the boiler would not modulate and would operate the 97C stat causing the boiler to lock out. The Main H/Ex overheat is a back up as you mentioned and is there to cut the electric supply should the PD valve or gas valve stick open.
Usually though the capillary stat and the safety switch (97C) become defective by operating well below their rating. Non of this is happening in your case so don't waste your time!
More than likely is that: 1. Your main heat exchanger is partially blocked with system ****e (about the right age of boiler). It will need replacing. Part No. 061836. 2. The gas valve has not been checked and set correctly on servicing. This gas valve has a tenancy to drift upwards in pressure supplied to the burner, I've seen them sometimes 100% and over overgassed. This will cause scaling and subsequent kettling from your heat exchanger. These pressures can only be checked and set by a RGI.
I have got a graph of NTC resistance to temperature in a very large and in depth folder from Germany as I'm sure Bunnyman has too but you really don't need it!
On the subject of Bunnyman, he was working for Vaillant before this model was launched, so he should know!
Hope you get your problem sorted.
The831Bunny
130330 is what you obviously need, and thats being sorted.
NTC sensor and overheat stats: VERY low on the list of problems, but never the less can be defective. In the case of the NTC, if it failed, it would go open circuit (99/100) so the boiler would not modulate and would operate the 97C stat causing the boiler to lock out. The Main H/Ex overheat is a back up as you mentioned and is there to cut the electric supply should the PD valve or gas valve stick open.
Usually though the capillary stat and the safety switch (97C) become defective by operating well below their rating. Non of this is happening in your case so don't waste your time!
More than likely is that: 1. Your main heat exchanger is partially blocked with system ****e (about the right age of boiler). It will need replacing. Part No. 061836. 2. The gas valve has not been checked and set correctly on servicing. This gas valve has a tenancy to drift upwards in pressure supplied to the burner, I've seen them sometimes 100% and over overgassed. This will cause scaling and subsequent kettling from your heat exchanger. These pressures can only be checked and set by a RGI.
I have got a graph of NTC resistance to temperature in a very large and in depth folder from Germany as I'm sure Bunnyman has too
but you really don't need it!On the subject of Bunnyman, he was working for Vaillant before this model was launched, so he should know!
Hope you get your problem sorted.
The831Bunny
Thanks to everyone who contributed on this topic, especially Andygasman10 and The831Bunny, who each took time to address the questions in the opening post.
To those people who thought that I wanted to fault-find the unnecessary firing problem - thanks, but I had already diagnosed that problem with confirmation from Vaillant Technical Support. You might have a poor opinion of my technical ability to do that, or theirs, or both, but the reality is that we got it right and the problem is fixed.
To those people who thought it was a bypass problem - you were right. The 'new' autobypass valve was sufficiently blocked (with magnetite crust from an earlier era in the life of the system) to obstruct the flow almost completely. It now has another new autobypass valve, and is a happy and very quiet boiler.
To those people who think that boiler fault diagnosis is best achieved by assuming that parts that rarely fail, cannot fail, I wish you luck, because you'll need it.
This is a good site, but the bickering amongst long-term members reduces the quality of the experience of using it.
To those people who thought that I wanted to fault-find the unnecessary firing problem - thanks, but I had already diagnosed that problem with confirmation from Vaillant Technical Support. You might have a poor opinion of my technical ability to do that, or theirs, or both, but the reality is that we got it right and the problem is fixed.
To those people who thought it was a bypass problem - you were right. The 'new' autobypass valve was sufficiently blocked (with magnetite crust from an earlier era in the life of the system) to obstruct the flow almost completely. It now has another new autobypass valve, and is a happy and very quiet boiler.
To those people who think that boiler fault diagnosis is best achieved by assuming that parts that rarely fail, cannot fail, I wish you luck, because you'll need it.
This is a good site, but the bickering amongst long-term members reduces the quality of the experience of using it.
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