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Truma Heater 3002 - 12v Fan Function


geoffl
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Hi - Can anyone help.

I am mystified as to why this unit is designed so that the 12v fan continues to run after the heating has reached the desired temperature. In other words why doesn't the fan switch off as soon as the heating element is switched off. As it is the result is that it reaches a stage where all that is being pushed out of the vents is cold air until the thermostat picks up again. If you set the thermostat higher to try and overcome this then you end up being roasted.

Since the fire is designed to run as a radiating fire without the fan on then can anyone suggest a way of fitting a separate thermostat to the fan so that it will cut the fan off at approximately the same temperature as the fire. Would there be any safety issues? I can't think of any. This problem is particularly noticeable in winter conditions.

Thanks for any help

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Hi - Can anyone help.

I am mystified as to why this unit is designed so that the 12v fan continues to run after the heating has reached the desired temperature. In other words why doesn't the fan switch off as soon as the heating element is switched off. As it is the result is that it reaches a stage where all that is being pushed out of the vents is cold air until the thermostat picks up again. If you set the thermostat higher to try and overcome this then you end up being roasted.

Since the fire is designed to run as a radiating fire without the fan on then can anyone suggest a way of fitting a separate thermostat to the fan so that it will cut the fan off at approximately the same temperature as the fire. Would there be any safety issues? I can't think of any. This problem is particularly noticeable in winter conditions.

Thanks for any help

A good point you raise, yes it is quite annoying, I have wired a relay in on mine so that when 240v from the thermostat is sent to the element, the 12v fan via the relay gets power, when the thermostat cuts out the fan stops too.

 

Steve

 

 

 

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If you set the fan to the automatic position, i. e. selector to the right, then the fan will slow down to an inaudible level when the heating cuts out.

Brian

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Thanks for your interest Brian, I have tried this but even the small amount of air produces a very unpleasant draught when it starts to run cold and then you have what seems to be a long period when you have to waite for the thermostat to kick in again, the elements then have to slowly heat up which takes even longer with the air being blown round the system. The only way I have overcome this problem is to put the themostat up to max and simply keep turning down when it becomes too hot - not really the best or convenient of solutions.

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Thanks for your interest Brian, I have tried this but even the small amount of air produces a very unpleasant draught when it starts to run cold and then you have what seems to be a long period when you have to waite for the thermostat to kick in again, the elements then have to slowly heat up which takes even longer with the air being blown round the system. The only way I have overcome this problem is to put the themostat up to max and simply keep turning down when it becomes too hot - not really the best or convenient of solutions.

We have found the same, but our solution is to ignore the blown air and use the fire as a convector, and once the van is warm enough to turn the output level down, it is surprising how warm the 500 setting will keep an already warm van if you do not try to use the blown air.

Bill

 

Growing old is compulsory, growing up is not.

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Thanks for this and I will try out but in the winter I think it will leave feet feeling cold!!

 

Surprisingly not.

Bill

 

Growing old is compulsory, growing up is not.

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Hi - Can anyone help.

I am mystified as to why this unit is designed so that the 12v fan continues to run after the heating has reached the desired temperature. In other words why doesn't the fan switch off as soon as the heating element is switched off. As it is the result is that it reaches a stage where all that is being pushed out of the vents is cold air until the thermostat picks up again. If you set the thermostat higher to try and overcome this then you end up being roasted.

Since the fire is designed to run as a radiating fire without the fan on then can anyone suggest a way of fitting a separate thermostat to the fan so that it will cut the fan off at approximately the same temperature as the fire. Would there be any safety issues? I can't think of any. This problem is particularly noticeable in winter conditions.

Thanks for any help

 

The problem is not that the fan continues to run after the element has switched off but that the heating element is not switching on soon enough. This is usually because the thermostat (located in the control panel) is attached to the units above the heater (usually the wardrobe). This acts as a heatsink, takes ages to cool down and so results in the 'van getting cold. We had this problem. The solution is to fit a remote thermostat (attached to the gas thermostat at the base of the heater) and use the fan on 'Auto'. We leave it on low overnight and it does not disturb our sleep.

 

The thermostat can be obtained from Gary at Arc Systems (info@arcsystems. biz) at half the price of a Truma one.

 

We fitted one to ours and it transformed the heating.

 

Hope this helps.

 

Mike

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Thanks for this input Mike, but believe it or not I have already fitted a remote sensor and whilst under normal conditions this did help I have found that in particularly cold winter conditions I still have a problem. I have fitted the sensor at the coldest point in the van but I think the problem is that the operation of the thermostat is no different to that in a domestic fan heater in that when it switches the heater off it takes an age for the thermostat to re-set itself to make contact again and start up the heater. It can be bad enough with a domestic fan heater being off for a period when it is very cold but when cold air is also being pushed round the van as with the Truma then it soon becomes unpleasantly chilly. My best solution I am convinced is to get it set up so that the fan switches off at the same time as suggested by Granpa Steve.

Thanks again for your help

Geoff

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Thanks for this input Mike, but believe it or not I have already fitted a remote sensor and whilst under normal conditions this did help I have found that in particularly cold winter conditions I still have a problem. I have fitted the sensor at the coldest point in the van but I think the problem is that the operation of the thermostat is no different to that in a domestic fan heater in that when it switches the heater off it takes an age for the thermostat to re-set itself to make contact again and start up the heater. It can be bad enough with a domestic fan heater being off for a period when it is very cold but when cold air is also being pushed round the van as with the Truma then it soon becomes unpleasantly chilly. My best solution I am convinced is to get it set up so that the fan switches off at the same time as suggested by Granpa Steve.

Thanks again for your help

Geoff

 

Try moving the thermostat to the correct position, first.

 

Mike

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Well I assume it's not one of mine then?

 

The trouble with the new Truma thermostat is they wrap it in a blanket of rubber! looks really neat but this insulates the stat and you end up with the same problem as when it was in the switch in the wardrobe.

Depends though on which stat you have, Truma have made two now, the new short leaded one that copies mine and the original now discontinued 3m long one?

 

As Mike says though, it will alway work much better attached to the gas thermostat

Edited by Arc Systems

gary1s.gif

 

Arc Systems are specialist Carver caravan product repairers, committed to providing a comprehensive service as well as spare parts for these popular heaters.

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Thanks Mike and Arc, The sensor wire was I believe approx 3 mtr long but I extended this by a reasonable length so as to get it to the other side of the van to the coldest point. I appreciate that legthening the wire might have altered the resistance though this has not affected the operation of the thermostat in any obvious way. It does seem to be the lack of sensitivity of the thermostat, as with those fitted to domestic fan heaters, that seems to create the inefficiency.

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In truth the resistance of extra wire length will be constant so can if anything only change the position of the dial slightly in relation to the temperature you desire.

Do though check the remotes Jack plug is fully home in it's socket, otherwise both sensors could be connected and cause havoc with temperature control!

 

The point is though, cool air from floor level is drawn into the base of the heater, this is the point the temperature needs monitoring and not some perceived cold spot which is open to possible adverse influence in anyone of a number of ways.

 

A faulty relay on the main control board is also possibly the reason for inadequate overall heating on electric, all things being correct and apart from the coldest of weather, the Ultraheat should work admirably.

gary1s.gif

 

Arc Systems are specialist Carver caravan product repairers, committed to providing a comprehensive service as well as spare parts for these popular heaters.

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