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DaftOldGit



Member Since: 20 Sep 2015
Location: London
Posts: 52

United Kingdom 
warm air ducting for roof tent
I've just invested in a roof-tent ready for a trip through Scandinavia in February.

I need to plumb in a hot air heater that i shall fit in the 110. I've been advised by the manufacturer that, due to the low air temperature, i'll need to route two 76mm tubes into the tent for flow and return so that the air is recirculated (I'm anticipating -30C or below).

I want to keep the tubes short short and have as little external exposure as possible.

I'm thinking:
Maybe fit the heater close to the roof of the 110 and cut a hole in the roof of the vehicle and in the floor of the tent, fit a big enough rigid duct to pass the two flexible tubes through. This can stay in place throughout the trip, but when I get home and remove the tent, I want to be able to remove the duct and blank it of with screw cap.

Has anyone done anything similar?

Or can anyone suggest suitable fittings to achieve this?

Many thanks
Post #579752 22nd Nov 2016 9:16pm
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Mdm



Member Since: 11 Sep 2013
Location: Sunny Lancashire
Posts: 1625

United Kingdom 
ive seen this done a few different ways

the easiest is to mount the heater on a wheel arch and this keeps the fuel feeds short and lowers the risk of freezing fuel plus it can be used to heat the vehicle during the day

also roof mounted in the tent (at the rear in a box) but this had fuel line issues and was to noisy for the occupier when cold.

you can buy insulated ducting which will help keep the air temp up as well
Post #579758 22nd Nov 2016 9:22pm
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Inigo



Member Since: 13 Nov 2011
Location: Kent
Posts: 617

United Kingdom 2012 Defender 110 Puma 2.2 USW Orkney Grey
I've been clambering about in my loft fitting Ubink insulated ducting recently. Rigid foam stuff down to 125mm, quite easy to work with.

I'm also midway through a project to fit an Airtop heater to my trailer tent. Not planning for such extreme temperature as yours, but I have used Superflex Calor high temperature (and slightly insulated) flexible hose. I was concerned at the possible high temperatures at the outlet from the heater melting other hose. I have externally insulated it (Webasto offer sleeves of insulation) and am going to add a fibreglass cowl to protect the flexible hose as it comes out of the base of the trailer.
Post #579767 22nd Nov 2016 9:48pm
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dantastic



Member Since: 04 May 2010
Location: London
Posts: 367

United Kingdom 
Something like this?
https://www.devon4x4.com/static/workshop/w...ng-system/

Take loads of photos, something I've been interested in for a while.
Post #579803 23rd Nov 2016 7:58am
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bpman



Member Since: 21 May 2008
Location: Oslo
Posts: 8069

2008 Defender 110 Puma 2.4 SVX Station Wagon Santorini Black
^^ that was exactly what I was going to suggest. I did Nordkapp in 2013, I had a Maggi, a webasto thermotop block heater and a webasto built into a aluminium box fitted to the roof rack, I used some 90mm flexible brake ducting from merlin motor sport to pipe the air into the tent, took minutes to warm up.

I fitted an extended exhaust to the heater so that the fumes did not enter the tent.
Post #579807 23rd Nov 2016 8:08am
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Mdm



Member Since: 11 Sep 2013
Location: Sunny Lancashire
Posts: 1625

United Kingdom 
yep thats one built to d44 usual high standards
Post #579808 23rd Nov 2016 8:12am
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Cupboard



Member Since: 21 Mar 2014
Location: Suffolk
Posts: 2971

United Kingdom 2011 Defender 110 Puma 2.4 HT Corris Grey
If you used a Thermotop (or equivalent water heater) then you could run the much smaller water pipes in to the tent.
Post #579870 23rd Nov 2016 4:26pm
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DaftOldGit



Member Since: 20 Sep 2015
Location: London
Posts: 52

United Kingdom 
The heater that i've bought needs 76mm ducting and is fuelled by propane. I chose this because I didn't want to be dependant upon diesel. I figured that if I had a fuel problem and was stranded in an Arctic wilderness, i'd still be able to avoid frostbite for a few days.

I saw the Devon solution, but it had quite a long length of duct exposed to the cold outside. Also it would mean connecting and disconnecting the ducting each time you open up the tent.
I've found some 110mm tank connectors (made by Kockney Koi for fish ponds!). I'm planning to fit a 110mm one in the roof and a 82mm one into the base of the tent so that they fit concentrically. Then the 76mm flexible duct can be passed straight through.
I'll fit a 110mm access screw cap onto the roof one so that when i take the tent off the roof and store it, i'll screw the cap on and then the motor will be fine.

The next project will probably be to make some kind of shallow but wide duct inside the tent to run beneath the mattress and up at the end of the tent, then i can leave it connected throughout the journey. Another idea might be a false metal floor with the hot air passing everywhere beneath it and just have multiple small vents poking up all around the edges.

Next, I have gas pipe questions which I'll put in a separate thread.
Post #584099 11th Dec 2016 1:02pm
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walfy



Member Since: 29 Aug 2007
Location: Frome
Posts: 2661

 
Looking at the D44 version. It's a nice well put together option. But why not take the airpipe in through the flap that is 1/2 way along the tent. I know thats where I intend to bring my hose in. No drilling into the RTT, then have a remote to turn it on. No need for a control box and associated wiring going into the tent. Unless that is what the owner specified?? 110 D250 SE HT
110 USW SOLD
RRE HSE Dynamic Gone, wife killed it
VOLVO XC60 R Dynamic with some toys

Polaris RZR 900XP SOLD
Post #584215 11th Dec 2016 7:58pm
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DaftOldGit



Member Since: 20 Sep 2015
Location: London
Posts: 52

United Kingdom 
bpman wrote:
^^ that was exactly what I was going to suggest. I did Nordkapp in 2013, I had a Maggi, a webasto thermotop block heater and a webasto built into a aluminium box fitted to the roof rack, I used some 90mm flexible brake ducting from merlin motor sport to pipe the air into the tent, took minutes to warm up.

I fitted an extended exhaust to the heater so that the fumes did not enter the tent.


Thanks bpman. Mounting the heater in a rooftop enclosure might be the answer. It'll save space inside the motor and I'll be able to keep the ducts short.

You say it took minutes to warm the tent. Did you have to keep the heater running, or was it just a few minutes every so often? I need to try to estimate how much propane to take as Norway use different bottles.
Post #584395 12th Dec 2016 11:06am
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DaftOldGit



Member Since: 20 Sep 2015
Location: London
Posts: 52

United Kingdom 
I wonder if i should have just got one of these heated underblankets instead!
http://cozywinters.com/shop/ew-rvhmp.html
Post #584699 13th Dec 2016 10:16am
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bpman



Member Since: 21 May 2008
Location: Oslo
Posts: 8069

2008 Defender 110 Puma 2.4 SVX Station Wagon Santorini Black
I tried a couple of 12v blankets, they really are not strong enough for the arctic (even imported a USA truck driver blanket) like the one in your link

The roofrack mounted air heater, I kept it on for dressing and undressing but also have reindeer skins and -40c sleeping bags so worked perfectly.. I still have lots of kit left over from my trip(s)

If you are in a tdci you won't need an additional air heater inside the vehicle because the tdci heater is so good. we actually wore tee-shirts and body warmers during the day inthe truck. But you will need the breather heater modification, d44 sell them and I'll be selling mine when it's removed.
Post #587910 27th Dec 2016 8:23am
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