Thermo top c

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Garyw6123

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Hi
I'm new to this forum, hope somebody can help.
My thermo top c is playing up, it starts up no trouble runs for about an hour then just stops all of a sudden, the rads get hot n pump seems to be circulating okay, I recently fit a new burner tube the old one was really coked up but this has made no difference.
HELP

thanks
 
Welcome to the forum
Hope you get some good advice-
Does the heater just stop but can be restarted easily? If so, I would try to ascertain the temp of the water as it returns to the thermotop after having circulated around the rads. If return water is above a critical temp (see in manual) the thermotop shuts down to prevent damaage.
Can you use more rads or cool them or introduce a supply of fresh 'cooled' water on the imput side to see if it keeps running for more than the hour?
By feel there should be a noticable difference in temp for the flow and return sides of the circuit. Also by changing the burner and making the heater work better it will be getting the water hotter quicker and perhaps even on low setting producing more heat then the rads can dissipate
 
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Hi Dave

Thanks for the reply, I had it in mind it might be high temp cut out prob,the fuel pumps stops and the heater just cuts out then the fan kicks in presumably to cool it down, I don't have the means to check the heat of the water but the first rad does get quite hot more so than the others can the temperature sensor be replaced, it does start up again straight away again tho I do leave it a while before I try it, then it just does the same tho it doesn't run as long probably cos the water is still warm
 
Ensure that the valves on both ends of the rads are fully open, this will allow more water to circulate through the rads and lower the temperature of the water being returned to the thermotop.
 
All the valves are fully open, I did manage to bleed some air out I'm wondering if it could have an air lock somewhere I'll try bleeding the system again but I'll leave it while tomorrow dancing on ice is on soon lol, thanks for your help
 
Sounds like a non marine heater to me, it is behaving just as it should if so.

Just in case it is a marine version, how many rads, are they parallel or series? and of what size? is the calorifier linked to it?
 
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Hi Dave

It's a webasto thermo top c we have had it on board from new for years and this is the first time we have had a problem like this, after about an hours run time it shuts down completely and you have to manually start it again, it fires up ok it runs full load then just stops it doesn't even go on to tick over mode so I guess I do have a problem but not sure what
 
Hi Dave

Sorry only read half your thread, we have a single 22m ring with 15m tees to the rads, we have four 600x900 single with fins and one 600x900 double and it does go through calorifier, four years we've had it.
Any help would be appreciated
 
OK, we'll assume it's a marine version then, the vehicle ones cut out after about an hour by default. Unfortunately if it is a temperature sensor fault they are not replacable on the TTC, the components on the TTC are not available in the same way as the AT range even the glowpin is not a seperate part. The best way to diagnose any faults on a TTC is with the Thermo Test software but you could start by flushing the system with a proprietry product and opening every valve you can wide, it will mean rebalancing the system afterwards. If the heater is operating correctly it should fire up on its own again if you leave it alone. Did you remove the top cover from the heat exchanger when you serviced it?
 
I did flush the system out but just via a hose pipe but I did flush it both ways and left it running for a while, once the heater stops it won't start again on its own, when it does stop it doesn't cycle down it just stops abruptly, the fuels pump stops then almost immediately after the burner cuts out then the fan cuts in to cool it down, I've left it for over an hour and it doesn't start up on its own
 
Heating Operation
When the coolant reaches temperature the heater switches to the energy saving part load operation. A rise in coolant
temperature above the upper threshold causes the heater to enter a control idle period. The circulation pump and the
operation indicator light remain on during control idle. After cool-down of the coolant, the heater resumes full load
operation. Another rise in coolant temperature above the upper threshold causes the heater to enter the control idle
period again. A drop in the coolant temperature during part load operation due to an increased demand in heat will
cause the heater to switch to full load operation

When the heater shuts down is the circulation pump still running?
 
That sounds like a controlled shutdown after either an overheat or the coolant has reached temperature, if it were the latter it should kick in again after a short time. So it is reasonable to assume that it thinks its overheating, the positioning of sensors is critical on these heaters and they should never be disturbed. All the air must be removed from the system as even a small bubble in the exchanger close to the sensor can cause false readings, a good way to get all the air from the exchanger is to start it up and quickly remove the outlet hose and replace it, be prepared for some spillage, this often removes the air if indeed there is any trapped.
 
Hi Bert

When the heater starts up it goes into full load mode but cuts out before it gets to part load or idle so I'm guessing it is over heating for some reason but can't find the problem as yet
 
Hi Dave

I'll give that a try, what do you recommend to use to flush the system out as I haven't top up with any antifreeze since refitting the heater
 
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