cylinder insulation effectiveness diminishing

[bludger]

I'm intending to have my direct hot water cylinder replaced. A firm called Gledhill use a rockwool insulation around their cylinders and state that the normal type of sprayed on foam insulation can lose a fair amount of its insulating capacity very quickly.

Any know if this is true or may just be a sales pitch?

 

[D_Hailsham]

I remember reading this somewhere, but can't remember where.

Where's the bloodhound gone when you need it?

 

[Steve]

I have a 20 year old cylinder with sprayed on insulation and it can keep water hot enough for a shower for 8 hours (provided its heated to 80 degrees first, with a faulty 3 way valve lol)

 

[bludger]

Steve,

My hot water cylinder is an old copper one with only a drape and tie over insulating cover. It will still give a decent shower after 12 hours, depending on the other demands on the hot water of course. It's heated on economy seven electric and we never boost the temperature in the day.

So maybe your sprayed on insulation has lost most of its function.

 

[someonelse]

My original cylinder was copper to which I added the old fashioned red drape-over and tie insulation pads. Then I added another set. Worked V well.

Two years ago I replaced the cylinder with a modern sprayed on insulation cylinder, but kept the tie on pads and addd those on as well.

I now heat the hot water every 4 days. Day one water is boiling so shower needs mixing with cold. Day 2 a touch of cold needed. Day 3 I shower using hot tap only. Day 4 turn on hot water again.

Now that's insulation!

 

[twgas]

Gledhill are now using spray on foam, they just put a plastic cover on it.

 

[bludger]

twgas,

I'm glad to told me that. thanks.

 

[jono_h]

I have a Gledhill with the mineral wool insulation / plastic cover. It was so effective that my Wife used to complain that nothing would dry in the airing cupboard!

Unfortunately one of my connections sprang a leak and I had to cut it all off to find it - it's now got a normal jacket on which seems nearly as good.

 

[JohnD]

I believe that these hard plastic insulating foams (also Kingspan and similar) with the very fine holes, have some special gas in the bubbles when they are manufactured, and this makes them better insulators than fibreglass or expanded polystyrene. Over years this gas diffuses out and is replaced with air, so they are not as good as when new. However, they are still as good as expanded polystyrene, and still better than the same thickness of fibreglass.

So they story you were given is not accurate. old foam is still a good insulator, but not as good as new foam. Don't cut it off as it is well-fitted with no gaps, thin spots or seams like a jacket might have.

My cylinder is foam-coated, but I had a couple of red jackets that I had used on the old cylinder, and I put them on top. I also insulated all the pipes with Climaflex which is stiff plastic foam and very effective. I too find that the airing cupboard is now cold, except in winter when the pump is from driving the heating circuit. I don't mind as this means I am not wasting energy and keeps my summer gas bill very low.

 

[D_Hailsham]

See Insulation Deterioration

So it will depend on how the polyurethane insulation is made.

 

[bludger]

Thanks for your replies and link. It seems that I might as well trust the manufacturer to put the right sort of foam on his products. I'd have no way of testing whatever was said had been used.

I certainly will keep my old red insulating jacket and add that to the new cylinder as well.

If my airing cupboard get too cold I'll install a little tubular greenhouse heater in it. They are cheap and cost little to run.

Happy Christmas to all