A little job before winter

Feb 23, 2018
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We have the Truma blown-air heating in our caravan, which has performed really well during cold-weather touring; however, the washroom at the rear never gets warm - with the pipe-run to the washroom being the longest and also being routed outside and underneath the van, it is not surprising. It seems that loads of other people have lagged the external pipe, so I thought I'd have a go.

Before: The factory "insulated" pipe.

I purchased some pipe insulation in the form of Armaflex 80mmID x 13mm Wall - This came as a 2 metre length which was perfect, with no wastage. There is a thicker option, but i'm glad I got the thinner walled version, as the pipe was routed close to the chassis rail, so required some massaging to fully encompass the pipe. Another wrinkle was the grey water drain pipes, which ran parallel - I unscrewed the mounting to allow some flex whilst i worked.

Pipes in the way.

I purchased some 200mm x 4.8mm zip ties for securing the insulation but they were too short. Luckily I had just enough to double-zip them, so I burnt through all 50 purchased for the job, plus some more I had in the garage. Buy 450mm+ if you want to do this yourself.

Overall the job is not perfect, but has insulated over 95% of the pipe so I hope tto have at least some warm air getting to the washroom!

Finished job
Loads of zip ties
 
Nov 11, 2009
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JTQ said:
The original black tubing is the Truma's external insulated sleeve, over the actual duct tube. So there was some insulation there initially, but every bit helps so the extra should make things better to some extent.
Have you "tested" yet how effective your rework has been?

]https://www.leisureshopdirect.com/gas/caravan-gas-fires/truma-fires/spare-parts-for-truma-blown-air-heating/insulating-ducting-for-blown-air-system-2m-length
https://www.leisureshopdirect.com/g...ducting-for-blown-air-system-2m-length[/quote
At least Truma have now got around to insulating the ducting. I did the same as CA on. Bailey. It made a noticeable difference too. Suspect CAs insulation was cheaper than Thule too.
 

JTQ

May 7, 2005
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I think Truma have for long had their insulated shield option, I suspect if it was not fitted, that would be more down to the mindset of the particular van builder. Our last blown air 2002 van, a Hymer, had the sleeve fitted, even so it will be the last one we will buy with blown air..
 
Nov 11, 2009
17,560
4,831
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JTQ said:
I think Truma have for long had their insulated shield option, I suspect if it was not fitted, that would be more down to the mindset of the particular van builder. Our last blown air 2002 van, a Hymer, had the sleeve fitted, even so it will be the last one we will buy with blown air..

I like blown air as one major benefit is the graceful degradation mode that even when all goes wrong you can still have heat as long as you have gas. Also upkeep is simpler and less expensive than Alde, and Combi puts too many eggs in one basket. Plus we’ve always been comfortable with blown air in our caravans. Call me old fashioned but time spent in a closed environment not knowing where I was convinced me that system redundancy is a big advantage when the world goes pear shaped.
 

JTQ

May 7, 2005
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Not convinced any "blown air" heating system has blown air without some electrical power to blow it?

The older Carver, and the Trums "S" units gave convection so you could keep warm locally without any electricity, but these types of unit seem all to have disappeared with most UK vans.

I agree that functionally that was a plus, but they dictated the van's layout and that together with provisions needed to avoid heat damage, has effectively seen their adoption in new builds be dropped here, in all but small vans.
 
Nov 11, 2009
17,560
4,831
50,935
JTQ said:
Not convinced any "blown air" heating system has blown air without some electrical power to blow it?

The older Carver, and the Trums "S" units gave convection so you could keep warm locally without any electricity, but these types of unit seem all to have disappeared with most UK vans.

I agree that functionally that was a plus, but they dictated the van's layout and that together with provisions needed to avoid heat damage, has effectively seen their adoption in new builds be dropped here, in all but small vans.

I didn’t say you could have blown without electric but you can have heat via gas even when the fan is without power. Remember the “good old days” -:( my Truma gives heat from electric or gas so in that respect it’s similar to the old units you mention.
 
Nov 16, 2015
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We have the Truma Combie, Which works welll, the morning Heating comes on very well although a bit noisey, and the back bathroom warms up well , "Winter time" as the dog covers the front air vents. I Had thought about the same mod, but realised it was double covered anyway. . Lets see if there is an improvement..
 
Feb 23, 2018
889
66
4,935
JTQ said:
The original black tubing is the Truma's external insulated sleeve, over the actual duct tube. So there was some insulation there initially, but every bit helps so the extra should make things better to some extent.
Have you "tested" yet how effective your rework has been?

]https://www.leisureshopdirect.com/gas/caravan-gas-fires/truma-fires/spare-parts-for-truma-blown-air-heating/insulating-ducting-for-blown-air-system-2m-length
https://www.leisureshopdirect.com/g...ducting-for-blown-air-system-2m-length[/quote
To me it feels almost the same as the interior ducting, just slightly more robust - the website shows how thin the walls are.

Sadly I did not have the chance to test the efficacy of my mod. I was making the best of the dry ground and weather we had on Saturday to get it lagged; I need to test it on a colder day.
 

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