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Webasto thermo top C acting randomly and shutting itself off


JerryDu33

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Hi, 

 

We have a Webasto Thermo Top C we use for heating and hot water. It always worked well but since some times two odd things happen I can't explain:

 - after a while (generally > 1.5h) it shuts itself off. It does not crash but shuts off properly after the cut out routine. It only happen sometimes.

 - it used to ramp up in revs from standby mode to the full operation smoothly, but now it makes sudden jumps. And when it is in full operation, it does not sustain the speed but tends to "oscillate" around it, making waves and giving the impression it tries to reach a speed but can't. Oddly, this is worse when we're on shore power and the battery charger is on (and consequently the voltage is high).

 

I checked similar issues I could find on the forum. Here for example, they say that "They will shut down if there is air in the system they cut out if there is no water going through the system", and that Webasto heaters are sensitive to voltage. I regularly check there is no air in the heating system and that the header tank is full. All radiators are getting sufficiently hot, what confirms there isn't massively air in the system. As far as I could verify, the shut off was not due to low voltage. Each time the heater turned itself off, the voltage was >12.2. The heater is not particularly noisy and does not produce fumes. The water and the radiators are hot as desired and the fuel pump ticks regularly as normal. There is no suspicious odour getting out of the heater or dripping of any sort. Just this funny behaviour...

 

A similar issue has been posted here but so far nobody replied.
 

I suspect the following possible root causes:

 - we've been using the Webasto quite intensively those last times without servicing it. I called some mechanics to service it but so far never got somebody to come and do the job. I guess these machines can get dirty inside and may require a bit of cleaning. I'd thought I'll get a servicing kit (like this gasket set here) and open it by myself (as described here for example) but I'm not sure what exactly I would need to do to clean it once I opened it.

 - faulty voltage or temperature sensors?

 

Any idea where the issues come from and what I should do?

 

Thanks for your advice!

 

@NMEA I heard you're the Webasto expert of the community ?

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6 hours ago, JerryDu33 said:

Hi, 

 

 - it used to ramp up in revs from standby mode to the full operation smoothly, but now it makes sudden jumps. And when it is in full operation, it does not sustain the speed but tends to "oscillate" around it, making waves and giving the impression it tries to reach a speed but can't. Oddly, this is worse when we're on shore power and the battery charger is on (and consequently the voltage is high).

 

Could this be the battery charger cutting in and out because the batteries are failing? 12.2v is nothing on a 12v battery bank, they are well below fully charged.

I would suspect the battery voltage is low and that they are now sulfated and incapable of supplying the required current over a long period.

You symptoms are the same as low battery voltage ones. How old are they?

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10 hours ago, JerryDu33 said:

Hi, 

 

We have a Webasto Thermo Top C we use for heating and hot water. It always worked well but since some times two odd things happen I can't explain:

 - after a while (generally > 1.5h) it shuts itself off. It does not crash but shuts off properly after the cut out routine. It only happen sometimes.

 - it used to ramp up in revs from standby mode to the full operation smoothly, but now it makes sudden jumps. And when it is in full operation, it does not sustain the speed but tends to "oscillate" around it, making waves and giving the impression it tries to reach a speed but can't. Oddly, this is worse when we're on shore power and the battery charger is on (and consequently the voltage is high).

 

I checked similar issues I could find on the forum. Here for example, they say that "They will shut down if there is air in the system they cut out if there is no water going through the system", and that Webasto heaters are sensitive to voltage. I regularly check there is no air in the heating system and that the header tank is full. All radiators are getting sufficiently hot, what confirms there isn't massively air in the system. As far as I could verify, the shut off was not due to low voltage. Each time the heater turned itself off, the voltage was >12.2. The heater is not particularly noisy and does not produce fumes. The water and the radiators are hot as desired and the fuel pump ticks regularly as normal. There is no suspicious odour getting out of the heater or dripping of any sort. Just this funny behaviour...

 

A similar issue has been posted here but so far nobody replied.
 

I suspect the following possible root causes:

 - we've been using the Webasto quite intensively those last times without servicing it. I called some mechanics to service it but so far never got somebody to come and do the job. I guess these machines can get dirty inside and may require a bit of cleaning. I'd thought I'll get a servicing kit (like this gasket set here) and open it by myself (as described here for example) but I'm not sure what exactly I would need to do to clean it once I opened it.

 - faulty voltage or temperature sensors?

 

Any idea where the issues come from and what I should do?

 

Thanks for your advice!

 

@NMEA I heard you're the Webasto expert of the community ?

NMEA is the Webasto expert but been very quiet on this forum since MTB had a go at him.

 

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If your batteries really are 12.2 volts (only 50% charged) with the battery charger 'on', then your battery charger is probably not working.

 

If the 12.2v is under load (heater trying to ignite) then the batteries are 'shot' and unable to support the required current, you may be trying to run the heater directly form the battery charger with no assistance from the batteries ?

 

What charger do you have ?

How old are the batteries ?

How many / what size batteries ?

Have you tried a capacity check on the batteries ?

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  • 2 years later...

My Webasto cook top is doing the same thing. Installed in 2019. The cooktop has done it when my voltage is at 13.9. Have heard it is wind blowing in the exhaust or something with the fuel( bad). I thought it was happening after I moved the vehicle (traveling) but it has done it after the stove has been on in the same location. I have started putting the controller down to the lowest setting when I start it and it has be doing good about 10 starts w/ out shutting off.. But I think it is only a matter of time. I took the stove apart and looked at the glow plug and it was clean.

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6 hours ago, escalante joe said:

My Webasto cook top is doing the same thing. Installed in 2019. The cooktop has done it when my voltage is at 13.9. Have heard it is wind blowing in the exhaust or something with the fuel( bad). I thought it was happening after I moved the vehicle (traveling) but it has done it after the stove has been on in the same location. I have started putting the controller down to the lowest setting when I start it and it has be doing good about 10 starts w/ out shutting off.. But I think it is only a matter of time. I took the stove apart and looked at the glow plug and it was clean.

Its the voltage at the appliance whilst it is starting that is important. Standing voltage on the battery without the load is irrelevant.

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