Roof aircon install - 240v supply

[Dan_A]

I'm thinking about installing a roof aircon unit in a standard 400 x 400 opening. The installation seems straightforward, the only challenge being the 240v supply. There's a nearby socket with Wago quick connections behind, so I can easily spur a connection from this using a Wago 3-way connector, but the tricky part is then routing to the roof opening.

I believe the usual method is routing through the roof insulation, using copper pipe to create the route before feeding through the cable. This seems do-able, but also a bit tricky to get right first time, i.e. get the route straight so it can be picked up with a hole drilled in a nearby cupboard ceiling.

Another option is to go upwards through the roof, along the roof in trunking, then back down into the cupboard near the socket using cable glands for entry/exit. This seems much easier/predictable, but I'm not sure whether it's OK to route a 240v cable along the roof exterior?

 

[Richard n Ann]

When I fitted the toilet ceiling fan I managed to get it through the roof insulation, there was a channel in it. Certainly look at that option first, you'll be able to decide what looks the best way when you get the hole out.
I also used a cheap camera probe thing... Can't remember what they're called... Hospitals use them anyway they plug into your phone and are about £8 on ebay

ENDOSCOPE!

 

[Dan_A]

When I fitted the toilet ceiling fan I managed to get it through the roof insulation, there was a channel in it. Certainly look at that option first, you'll be able to decide what looks the best way when you get the hole out.
I also used a cheap camera probe thing... Can't remember what they're called... Hospitals use them anyway they plug into your phone and are about £8 on ebay

ENDOSCOPE!

Thanks - there aren't any channels, just the solid foam core of the PUAL roof panel. It should be fairly easy to work through this with a copper pipe, but the channel will need to be about 50cm long to reach the cupboard, so the worry is getting it straight and knowing where to drill up to access it once it's done.

 

[Itsmcb]

Thanks - there aren't any channels, just the solid foam core of the PUAL roof panel. It should be fairly easy to work through this with a copper pipe, but the channel will need to be about 50cm long to reach the cupboard, so the worry is getting it straight and knowing where to drill up to access it once it's done.

If it's not an aluminium roof you could use a little metal detector tool usually used to locate pipes and cables in house walls to guide/locate the copper pipe

 

[Googlebot]

If you heat the end of the copper pipe it goes through like a knife through butter.

I used 10 mm and it’s actually quite easy to keep it straight as you push it through. Once the end gets cold and you have to push, just reheat.

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[Dan_A]

If it's not an aluminium roof you could use a little metal detector tool usually used to locate pipes and cables in house walls to guide/locate the copper pipe

Good idea, but yes, the panels are aluminium/foam sandwich.

If you heat the end of the copper pipe it goes through like a knife through butter.

I used 10 mm and it’s actually quite easy to keep it straight as you push it through. Once the end gets cold and you have to push, just reheat.

That's a great tip, thanks!

If I can keep the pipe straight it should be simple to drill up into the channel inside the cupboard.

 

[Dan_A]

To round off this thread, I can report that the installation was successful. It was reasonably straightforward in the end, although the insulation in the roof panel is quite sturdy, so boring a cable tunnel with copper pipe (heated or otherwise) doesn't really work. You would need a 3ft drill bit or some other tool to do this, so I decided to go for external cable routing.

I used arctic grade electrical cable as used in high quality EHU cables, rated to -25c, and routed this through a short tunnel in the insulation and out to the roof via a cable gland. This was sealed with sikaflex in the hole and under the cable gland, then silicone around the cable egress. The cable is routed through mini-trunking, then down into a cupboard via a double gland alongside the satellite TV cable. Inside the van, the cable is routed behind cupboards to a rear wall where I was able to tee into the mains supply using Wago Winsta connectors, making for a neat connection with no soldering or cutting of existing cables.

The Truma aircon unit is quite big and heavy, so I hired a lifting platform to get it onto the roof before sealing with Hodgsons Seamseal CV and the Truma sealing plate. It was then a 30 minute job to clamp the unit from the inside, install the air diffuser and connect the electrical terminals.

Overall quite a satisfying job to complete, and the unit works great.

 

[pappajohn]

And the noise will drive you nuts and you'll stop using it.

 

[Dan_A]

And the noise will drive you nuts and you'll stop using it.

Having used a portable aircon in my previous van, which is louder than the Truma, I can say that the noise is no issue whatsoever during the day and a chilled van is a very nice thing to have. In the evening, having the van cooled off / dehumidified before bedtime followed by using a fan through the night works great in warm weather. In stinking hot/humid weather, the aircon noise is tolerable, and certainly preferable to a sweaty sleepless night.

 

[Richard n Ann]

Noise doesn't bother me either I can hear the fridge fan occasionally come on but even the coolbox doesn't bother me

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