Club 80-90 Forums

Just had a PM about this so thought I'd kick off a more comprehensive pre-winter lagging thread so we can collectively throw in some ideas.

For Aircooled T25s, which can lose a lot of heat before it even reaches the front, basically you lag the heating system in the same way you would insulate cold water pipes in the winter. If you bear in mind that a good deal of heat is being lost to the air underneath, that should give you some idea of what needs lagging. Some years ago I came across some jackets on a beetle that covered the heat exchangers and these worked really well in the winter but never seen any since. I should think any boiler/plumbers merchants (possibly a big DIY store) would stock insulation that would cope with hot heat exchangers and you could bind this around the exchangers with suitable wire. Certainly the main hot air channel that runs underneath could (and should) be lagged with some kind of glass fibre pipe wrap or even the aluminium bubble wrap you can use for interiors.

Above all, lag your panels and floor. This is particularly true of watercooled vehicles. The difference that insulation made to mine was astonishing and turned a relatively chilly camper into a fairly snug igloo as well as reducing noise. In the Summer it has the opposite effect, making the interior a little cooler although a baking roof, is a baking roof

This is also a good time to swap out the anti-freeze if it hasn't been done in a few years (reminds self to do this job.....)

Hi Cov, I'm in the process of fitting foil backed glass-fibre into my bus before I fit my newly recovered panels. Regarding the air-cooled heat exchangers and pipework... I'm a plumber and it occurred to me that the lagging/ insulation that is used in boiler houses would be ideal. It comes already split and also with aliminium straps to hold itself inplace. It's easy to cut and shape to curves by mitre. A question for you though....where I have no vapour membrane i.e sliding doors and rear panels, would it be advisable to fit one or leave uncovered? Rob

Refit the membrane. It stops the doorcards from warping (well, thats the theory). Yes, I had a feeling there would be some material suitable for the heat exchangers, thanks for that. Crucially this about doing these jobs in advance of the freezing temperatures when the last place you want to go is underneath.

The other thing than can bite you is not dealing with a leaking windscreen surround as its at this time of year when incoming water can make driving one most unpleasant. I did mine over a year ago and it made such a difference without soggy front mats which just make winter driving ten times worse and contributes to mist on the inside. Nothing worse than scraping ice on both sides of the glass.

the lagging you would need would be a neoprene. this is what they wrap solar hw piping in. the normal grey stuff would just melt. mine just let in an oil smell when i open em up as a reckon a previous owner had a bit of a blow up and the exchangers got oily. i just wear a coat.

I'm sure the slider and tailgates are not supposed to get ingress (if the seals are good) however the membrane is needed on the cab doors as water gets down the scrapers, 1/4 light bar and through a drain hole in the 1/4 light seal.

Also check your quarterlight bar for rusting just below where it disappears into the door as eventually the mounting will corrode away. The prices for this obsolete part seem to be constantly rising.

the heat exchanger jackets are no longer available as the seller retired many years ago he was from manchester and advertised regurlarly in vw motoring

That would make sense. Still, easy enough to make up I guess.

I lagged my warm air pipe (Aircooled bus) with the thermowrap stuff andcable ties under the bus and also used the ally tubing to sleeve the pipe from above the fuel tank upto the point where it comes into the cab.

With regard to insulation, the basic principle is that some materials resist passage of heat or reflect radiant heat. Metal is a very good conductor of heat therefore a poor insulant. Also our vans are quite draughty and let lots of cold air in through door gaps, fridge vents etc.

The best type of insulation to use is debateable and depends on the application.

For insulating the body of the van there are 3 choices – foil, wool or rigid boards.

The shiny foil stuff works by reflecting/ not emitting radiant energy. I'm not sure how much heat radiates at ambient temperatures and I am a bit dubious about the benefits.

It should always work best when next to an empty cavity provided that the air in that cavity is kept still. So if using it make sure at least one shiny surface is facing a clear cavity of 20mm+; i.e. don't install it and then cover it with wool type insulation or panels.

Air is a poor conductor of heat (if kept still) and therefore a good insulant. Mineral Wool type insulation (like the stuff in your loft) works by keeping air still. The thicker it is the better the insulation.

If there are gaps in the insulation it won’t work properly, so for insulating awkwardly shaped areas Mineral Wool insulation would be best in my view as it is cheap, easy to cut and fit around odd shapes.

It's also non-combustible and gives sound deadening benefits. Look under the engine cover for an example.

Can be a bit dusty and itchy though (more so with rock wool than glass wool I’d say) so wear some gloves when fitting, seal it in and try not to get it all over your internal panels, carpets, bed etc.

It would be best to choose mineral wool with a water repellant additive like the stuff they use for insulating brick walls (Google 'DriTherm') as when/ if moisture forms somewhere it shouldn’t get wet through which would also spoil the insulation value.

The lower the thermal conductivity, the better the insulation value for a given thickness.

There are rigid board type insulations which have a very low thermal conductivity but these are hard to shape and fit inside panels. Gaps and holes will mean that the insulation is a waste of time, effort and money. They might be good for insulating the floor of the van though where you could use a thin insulation in one complete layer. (Google ‘Celotex’ or 'Tile Backer' or 'Underfloor Heating Insulation')

For heating and ventilation systems, insulation formed into circular sections, flat sheets or bespoke covers could be the way to go.
Mineral wool can also be bought in the form of pipe sections from an insulation specialist, (Google 'SIG Insulation' or 'Encon') which could be useful for insulating pipes and ductwork.

A better choice might be foam stuff in sheets or pipe sections (Google 'Armacell') for this as it is flexible but a bit pricey I think.

For heat exchangers etc. there are companies around who make bespoke valve covers for industrial purposes. These are generally full of insulation and come with lace up ties or velcro meaning they can be fitted and removed for maintenence etc. when needed. (Google 'valve covers' or 'thermal covers'). If given an example of the size and shape I reckon they could easily and reasonably cheaply knock up a bespoke cover.

As for moisture and condensation, warm air carries a lot of moisture but it drops that moisture when it cools sufficiently or hits a cold surface (the 'dew point') and because you are insulating the external surface of the van this will be kept colder than before. Breathing and LPG heating systems produce a lot of water vapour.

The rule is that there needs to be a vapour control layer to prevent moisture ingress as much as possible and somewhere for moisture to escape when it inevitably finds a way in.

The VCL must be on the warm side of the insulation.

That will mean without a VCL on the warm side of the insulation a lot of moisture will be deposited on the inside of the external panels potentially leading to corrosion. Anyone looked behind their fridge?

Even with a VCL some moisture will still form I reckon because there are loads of holes in panels where moisture laden air can get in and loads of metal passing through the insulation creating cold spots.

It would be wise to ensure all drain holes are unblocked, there is no bare metal visible and preferably a good coating of waxoyl/ dinitrol type stuff for protection.

Hope that helps someone

Well written Skippymoss. Much appreciated.

Thanks skippymoss
Has anyone tried the stuff that's made from recycled plastic bottles, I'm presuming this wouldn't go soggy like rockwool if it got wet??

I think you're right - it probably wouldn't get too damaged by moisture.
Against would be;
- Don't think it would help much with sound deadening
- Thermal conductivity is relatively high - no better than normal loft insulation which is OK but you can only fit so much in a panel
- I wouldn't like to see what it did to my van in a fire...at best, panels full of melted plastic!

Well written Skippy moss earned your self a wiki entry!

skippymoss wrote:I think you're right - it probably wouldn't get too damaged by moisture.
Against would be;
- Don't think it would help much with sound deadening
- Thermal conductivity is relatively high - no better than normal loft insulation which is OK but you can only fit so much in a panel
- I wouldn't like to see what it did to my van in a fire...at best, panels full of melted plastic!

Thanks skippymoss
If I'm to use foil bubble wrap, would it be okay to get the stuff that's only insulated on one side and face it inwards. Presuming that double foil would only be effective to keep cooler in summer? Insulating is my next job and I wan't to get it right

Hacksawbob wrote:Well written Skippy moss earned your self a wiki entry!

Agree. I'll wait until we've exhausted this thread and then I'll plonk the core info in the WIKI