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truma combi - air circulation motor replacement


spoons66

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Hi

 

I have purchased a replacement air circulation motor for my truma combi boiler. I've removed the two screws (through the holes in the fan) but can't figure out how to remove the motor spindle from the fan assembly.

 

Looks like there's possible a grub screw that needs unscrewing but due to where the boiler is located, I've been unable to see or determine how to release the spindle.

 

Anyone know how to release the motor from the fan?

 

Thanks

 

spoons66

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Welcome to the Out&AboutLive forums.

 

When you mention a “truma combi boiler” do you mean the current type - that Truma does actually call a “Combi” and lies on its side as shown in the first image attached below, or the earlier combination air/water heater that Truma call a “Trumatic-C” but many motorhome owners refer to as a ‘combi’?

 

This 2010 MHFacts enquiry asked about replacing the fan on a Trumatic C-6002EH appliance (which the forum thread refers to as a ‘combi’!).

 

https://forums.motorhomefacts.com/182-electrical/72767-truma-combi-boiler.html

 

I’m assuming that the ‘fan’ being asked about thee was the air recirculation fan (not the gas-burner combustion fan) and - if that’s correct - it sounds like the fan is a press-fit on the motor’s spindle with (possibly) a locking compound used too.

 

Regarding current “Combi” heaters, I THINK the air circulation unit is sold as a complete ‘kit’ that comprises the motor with the fan already attached to it, and that the motor alone cannot be purchased.

 

You could try asking the Truma(UK) technicians by phone or email

 

https://www.truma.com/uk/en/service/customer-service

 

 

 

2142892820_TrumaCOMBI.jpg.09a9f505758a9b66b44f34ddbbfe6788.jpg

1329706003_TrumaTrumatic-C.jpg.d0cb9e823346350a7fc1798af16bbae6.jpg

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Hi Derek

 

Many thanks for your swift reply.

 

My Truma Combi is indeed the new version (as seen in your first image) - the 6E (but I think all the new versions share the same air recirculation fan and motor.

I have bought the motor separately from the fan (both are readily available).

 

The fan is behind the larger grille shown bottom right on your image and the motor is behind that, below the electrics/motherboard.

 

Where the motor spindle joins the fan centre, there's what looks like a grub screw housing on both sides but only one of these is open ended - looks to have a screw thread inside. I'm reluctant to try allen keys etc without first knowing the correct size in case I damage any screw head if present.

 

Motor:

 

Truma_Motor_34020_61300.jpg.c1a887cd76f6b02a7210223ba99ce6a0.jpg

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Hi, Looking at your motor picture you can see that the spindle has a flat surface and that this is always used to secure the fan with a grub screw to steady the fan and ensure it will always rotate with the spindle if the screw would ever come loose. Just ensure whichever Allan key you use that it is a tight fit.
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I’m with Ninian on this one. The use of a grub screw to secure a lightweight fan to a spindle is not unusual. Find the Allen key with a snug fit. Then try the next size up, if it doesn't fit then the previous key was the correct size. If you want a belt and braces approach then when reassembling add the tiniest dab of thread lock to the grub screw when reassembling, that way you won't feel the need to accidently over tighten. Only one grub screw should be required.
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The screw that holds the fan-wheel on to the fan-motor’s shaft is evidently available as a separate item (Truma Parat Number 10020-41000) and was used for Trumatic-C appliances as well as the later Combi heaters. It’s advertised here

 

https://www.ebay.ie/itm/Truma-10020-41000-Gewindestift-AM4X4-/223599061384

 

and described in Truma Spare Parts listings as "Set screw ISO 4029 M4x4-45H”

 

This description apparently means that - for tightening the set-screw - a 2mm allen-key would be required.

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Thanks Derek

 

Was indeed a 2mm (or 5/64") allen key. Motor now replaced and heating up and running again :)

 

Was a little tricky accessing the motor/fan housing due to the boiler's location under seating.

 

Tips:

1. take plenty of photos of the PCB, connections and fan housing (including rotating to show the 2 screws through the holes)

2. Use a magnetic screwdriver to remove/refit the 2 screws through the fan housing into the motor

3. When retightening the grub screw with 2mm allen key, ensure motor spindle is flush with fan housing hole (not poking out as this will make it too tight and won't run smoothly)

4. use one end of tweezers under the white plastic connector in order to remove the motor wire connector from the pcb (I found it easier to remove the PCB (disconnecting all other connectors first)

5. a small mirror and/or headtorch may be useful to help see some areas of the boiler

 

The reason for replacing the motor was due to seeing several occurrences of error code E89H on my Combi 6E. This prevented the heating from firing up which at this time of year, is a major problem!

 

I found a very useful video that suggested carbon build up and recommended a gentle tap on the metal fan housing and this worked for me on three separate occasions:

 

I was hoping a vacuum out and replacement motor brushes would cure the problem but the motor does not have replaceable brushes.

So ordered and replaced the whole motor and I now have a toasty van once again :)

 

Thanks again for all your help.

 

spoons66

 

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