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TOPIC: Truma S3002 electric heating not working

Truma S3002 electric heating not working 2 months 1 week ago #465457

  • ecliptic
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To the problem.

I cannot get the heater to blow hot air using the electricity mode - the elements do not heat up.
The control unit is side-by-side with the hot water controller and that controller works. This might help eliminate a question of local overheating causing problems.
I removed the control wire from the fan speed selector on the top of the heater front panel and on re-inserting found the green light had come to life in the heating control unit. Perhaps an oxidised contact cleared? But still no heat.
Checking the question of power, I turned on the Ultraheat switch (240v) - yes, fuse is OK, and checked the voltage on the heater side of the box behind the heater. 240v from both black wires to earth, nothing else.

I am now seriously pondering the thermostat question.
Removing the composite material cover from the back of the fan I discover what has to be a thermostat, This fits thru a hole into the fan housing. Now, is it a max temp cut-out or a temperature sensing unit. Have photo but cannot see how to attach to this post. The lack of apparent connection to the box at the rear base of the heater lends weight to it being a max-cutout sensor.
Video on the Internet showed the fix was to remove the gas fire and replace thermostats. There is nothing showing re thermostats in any exploded schematic diagrams of the heater, and I do not see a thermostat on any wiring diagram, so perhaps this one is the culprit. However, disconnecting the 240v for a period did not change the situation.
The wiring from the ultraheat wattage and heat control goes to the control box close to the floor at the rear of the heater. If there is another thermostat then it must be inside the heater box cover and yes, I would need to remove the gas fire to access.

Because the van was not built here, local support is nil from dealers and such.
Truma EU referred my request for assistance back to their local Aust. agents who declined to assist -" heater not registered within Australia".

Your thoughts are encouraged, please.

Some folk will tell me, here in Australia, that I made a mistake taking a UK van back to Australia. My 2004 Lunar Quasar 525 has better quality fittings and finish compared to the local varieties and towing 1050Kg is easier than 3000kg. Just finished replacing the front floor section and will prepare a booklet regarding the process.
1998 petrol Pajero GLS LWB, 2004 Lunar Quasar 525 Van, 1 springer, 1 choc lab
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Truma S3002 electric heating not working 2 months 1 week ago #465467

  • Damian-Moderator
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Have a read of this from over 9 years ago:
It very often is the thermostat or rather it's situated in the control switch where it is then directly affected by heat from the fire or another heat source.

However, it maybe the man control board is at fault, these use three simple relays to switch the elements on and off, contacts bun out over time and prevent the elements working.

A quick check with fan off, is to switch the heater too 1000w and number 9 on the dial, now feel the heat coming directly from the fire.

Switch too 2000w and you should now get a large increase in heat, if not the at least the 2kw relay is not switching on.

If though all seems ok then fitting a remote sensor will usually sort out the system, you can get one of those directly from me at less cost than anyone else sells them! and mine work better than anyone else's?! www.arcsystems.biz

Other reasons for poor performance is how your using it and or how it's installed, below is my take on how to get the best from it;

The Ultraheat's wattage settings are there so you can make use of low amperage hookups, 500W for 6A, 1000W for 10A and 2000W for 16A hookups, their not there to adjust the temperature of the van.

The Ultraheat is thermostatically controlled, therefore the wattage used will simply mean the fire is heating for shorter or longer periods. Where the problems arise then is if the temperature control is not working correctly, this is often due to the heat from the elements directly affecting the sensor itself, it's within the control switch. This means the heat brings the temperature sensor up to that set on the dial and the elements switch off, you and the vans are still cold but the sensors toasty and takes forever to cool before switching the fire back on!!

Due to this and particularly overnight, it's become something of an urban myth to set it at 500w or 1000w, this or that number on the dial and fan speed setting. In truth what's happening is the available heat is not capable of reaching the set temperature so never switches off, it's a useful work around but not how it should work.

The real solution is to fit a 'remote' temperature sensor and attach it to the gas fires sensor, if a remote is already fitted, it to will usually react better if moved to this location.

Setting the fan on manual speed means the fan runs at this speed regardless of the amount of heat being produced, I would suggest manual fan is only for use without heat for cooling in summer, if infact it has a use?!

Setting the fan to 'A'utomatic allows the heat produced to control the fan speed 'up' to the speed set on the dial, you can then, keep this set maximum low and therefore quiet over night perhaps

Automatic means the fan will run slowly initially and speed up as the air passing through gets warmer, doing it this way allows heat and fan to be switched on together and doing away with waiting xx minutes as often suggested.

I would suggest as a start and during the day, the wattage selected is as high as the hook up allows and then fan speed set to maximum on Automatic.

This provides the maximum heat if required and the fans speed will respond to change in temperature, ie, fast when heat cycle is on and slow when heat is off.

After that you can fine tune to suit your own needs

Other heating problems concern the control board, the elements are switched on and off by relays and the contacts burn out, particularly the two 1kw relays. If this happens you may think you have it set to 2kw but only one element is working, finally perhaps leaving you with just 500w working when both 2kw and1kw settings no longer work.

(Note, relays will still be heard to 'click' but unless you have heat, their not working)

The 12v for control also comes from this board and the transformer sometimes packs up, apart from no heat, you will lose the green light in the switch if this happens

Lastly and also if no heat is forth coming, there are two safety thermostats, one at least of these has a habit of self destruction which stops all heating on electric! If the lower 125C thermostat trips, it automatically resets when it cools. However, the 175C limit stat is a 'self hold' and cannot reset once tripped until the mains supply to the heater is switched off, once mains supply is off, it will then cool and reset automatically.

The control switch itself seems generally reliable but the odd one does fail.

The numbers on the dial represent roughly 4degs and 9 is 32degs or thereabouts, this in theory makes 6 or 7 'normal' but it's what feels comfortable that matters not the number.

Another problem not caused by the heater itself is long runs of un-insulated blown air pipe running outside under the floor, insulating this will improve matters considerable.

Everything installed and working as it should, there is no good reason why the electric heating should not work very well and keep an even temperature to suit your needs.

However, it must be remembered the van needs to be warmed through thoroughly, not just the air, before the heating is turned down. While the vans cold it will constantly drag heat from the air and this in turn needs constant topping up or the van will always feel 'draughty'. It's most useful then while particularly cold to use gas as well for the first couple of hours, also, if the heating is off during the day to turn it back on at the first sign of a chill.
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Truma S3002 electric heating not working 2 months 1 week ago #465468

  • Damian-Moderator
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In addition to the above information, you need to treat the heating system as three separate units which work entirely on their own or in combination.
The gas heater is one part, the electric heating is the second and the fan unit is third.
Each will work on their own or in combination with the fan.

If when the fan is selected (which works entirely on 12v DC) it runs then there is nothing wrong with it.
As for the electric heater unit, it has two cutouts mounted on the control box behind the gas fire, a lower limit cutout and a higher limit cutout.
Both are known weak points and if going as far as replacing them, then it is sensible to replace both at the same time.

Have a look here at temperature control and limit : www.leisureshopdirect.com/gas/caravan-ga...y-heater-spare-parts
However, access to the control box usually means taking out the gas fire which in turn involves breaking gas joints and breaking the flue seal.
It is highly important that on reassembly a new flue seal is fitted and that all gas joints are tested for soundness and pressure tested.

It should also be noted that the thermostat for the electric heating is part of the control switch , which if mounted near the fire, or above the fridge, it can be fooled into thinking what the temperature is as the back side of the control switch is in a cavity which is heated and does not cool down as quickly as the main van.
The answer to rectify this is to fit a remote thermostat if one is not already fitted.
If one is fitted it will be usually attached to the gas fire sensor bulb at the front base of the gas fire just behind the front cover.
Last Edit: 2 months 1 week ago by Damian-Moderator.
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Truma S3002 electric heating not working 2 months 1 week ago #465469

  • ProfJohnL
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I understand from your posting and your status this is a 2004 Caravan.

Have you only just acquired this caravan?

Has the electric heating worked for you previously?

Was it sold you as working, if so you may have some redress against the seller if you purchased it in the UK even if you bought it to export. Our Consumer rights act does not require the buyer to be resident in the UK. only that the contract and transaction took place in the UK. Whether its worth trying a long distance complaint is a decision for you.

There are some common failure modes that Damian has explained. As for obtaining spares, I am surprised that Truma's Australian agent is reluctant, but perhaps that becasue of local liability laws on such things.

If its only thermal switches you need, I pretty sure you would be able to order them from a UK or EU seller.

I concur with Damaian that contacting Gary art Arcsystems would be good step.
Unless I use quotes, All advice and opinions given are my own and are given in good faith. Never act on anything you read on a forum unless you can validate and verify its source and content.
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Truma S3002 electric heating not working 2 months 1 week ago #465484

  • EH52ARH
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Ah the old Grey Cells are reviving,.
Nothing bad meant ! Thanks for digging in.

Thats why this Forum is so helpful..
Sir Were-Rabbit
Sante Fe 2014, tugging a Coachman 560 VIP. 2013.
Rural Milton Keynes
Last Edit: 2 months 1 week ago by EH52ARH.
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