Insulating Webasto Heater Duct Pipe - what to use?

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Matt341

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Hi All,

Reading the other thread about diesel heater outlet temperature reminded me of a job that I intended to do over the Winter and never got round to. Rather than hijack that thread I thought it better to start another.

I have searched the forum and there are lots of threads on a similar subject but there doesn't seem to be a definite answer.

Over the Winter I found our Webasto heater to be fairly efficient at heating the aft cabin, saloon and heads but the forward cabin ended up with a barely mild amount of air out of the outlet. Closing the outlet in the aft cabin made no difference apart from increasing the amount of cold air blown out of the bow cabin outlet. There is a long length of ducting that runs through locker space which is loosing a fair amount of heat before reaching the outlets in the cabin, the heater is located behind the aft cockpit locker so it probably has around 9 meters of duct before it reaches the bow cabin outlet.

With a wet and windy bank holiday forecast I plan to sort this out so want to find out the best product to use. I have seen Thermawrap insulation mentioned a few times in similar threads and Screwfix seem to offer it at reasonable prices but reading the product information indicates an operating temperature up to 70 degrees c which i'm sure is lower than the Webasto temperature.

Thanks
Matt.
 
Matt341 said:
Hi All,

I have searched the forum and there are lots of threads on a similar subject but there doesn't seem to be a definite answer.
Thanks
Matt.
Click to expand...

Yes there is, Webasto Thermoduct insulation it's Thinsulate so takes up little space, doesn't absorb moisture, has an abrasion resistant cover and is easy to retrofit if you buy the unstitched version, identical to the Eber stuff Elessar aluded to, it is in 750 cm lengths to make installation easy but the cost puts many off.
 
From my experience the foil backed bubble wrap is little or no better than standard bubble wrap.
Bubble wrap is OK in itself (cheap and easy to obtain) but you need several layers.

My best suggestion is the latest in packaging materials, polyethylene foam like this
http://www.custompac.co.uk/Foam-Packaging/Foam-Packaging-Sheets

I haven't checked out the costs but I'm sure it'll be a whole lot cheaper than the Eber or Webasto stuff.
 
Trundlebug said:
From my experience the foil backed bubble wrap is little or no better than standard bubble wrap.
Bubble wrap is OK in itself (cheap and easy to obtain) but you need several layers.

My best suggestion is the latest in packaging materials, polyethylene foam like this
http://www.custompac.co.uk/Foam-Packaging/Foam-Packaging-Sheets

I haven't checked out the costs but I'm sure it'll be a whole lot cheaper than the Eber or Webasto stuff.
Click to expand...

I don't see any operating temperatures there but I doubt it meets the required level. I shouldn't really, but you can buy a 1m x 1.5m sheet of thinsulate for less than the price of a single 750cm length of Thermoduct or Eber stuff, just the same and rated to 120 degrees for 20000 hours.
http://www.3mdirect.co.uk/3m-thinsulate-acoustic-thermal-insulation-au4020-6-60-1m-x-1524m-1.html
 
Last edited:
David2452 said:
I don't see any operating temperatures there but I doubt it meets the required level. I shouldn't really, but you can buy a 1m x 1.5m sheet of thinsulate for less than the price of a single 750cm length of Thermoduct or Eber stuff, just the same and rated to 120 degrees for 20000 hours.
Click to expand...

?

David2452 said:
A dry system air temperature is considerably higher that of a matrix based one,[ - - 8<- - ]the air distribution components of a dry system should be rated at 140 degrees.
Click to expand...
 
Thanks for the replies,

I had a look at the heater duct pipe last weekend and it was more awkward than I anticipated. As it was factory fitted it seems to be fixed inside part of a conduit which also holds the bulk of the wiring and plumbing throughout the boat so attempting to insulate the duct is going to prove near impossible. The Wickes insulation could be a posibility for insulating it where it goes through the lockers and isn't fitted to the conduit but will this make enough of a difference to the output heat?!
 
We have 4m of pipe work on our ST2000 webber. The difference before insulation was warm but not hot air which you could hold your hand in front of. After fitting the expensive stuff the air was too hot to hold your hand in front of the vent for more than a few seconds, so ever bit helps. Don't insulate the first 6 inches as the heat warms the heater up too much. Had to chop a bit off ours after reading about it on here somewhere.

Pete
 
Pete7 said:
Don't insulate the first 6 inches as the heat warms the heater up too much. Had to chop a bit off ours after reading about it on here somewhere.

Pete
Click to expand...

Absolutely no reason not to fully insulate right up to the cowl, I always do, have never had to remove any except in one case where the back pressure was on the limit due to the extreme length of the duct.
 
Last edited:
Is there any reason not to use something like armaflex? It's cheap and you can order larger bore sizes from plumbers merchants.

I think it's about £9 for 2m

A plumber friend has used this and the outside of the insulation is cool to the touch. Must be working well!

I'm considering replacing my tatty bubble wrap with it.
 
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