Removing the foam insulation on a copper hot water tank.

  Diemmess 10:51 AM 24 Jan 12

A redundant 40 gallon tank given to me for the sheet copper, has foam insulation.

No problems cutting and using the metal for various things as in the past, but this is the first tank where I have to shift its insulated covering.

I think the bulk of cover is polystyrene foam, but some adhesive holds this to the cylinder.

I think a blow torch would make a mess of treacly blackened foam unless most of it is chiselled off first.

I could use cellulose thinners on the last adhesive layer when the foam has been scraped off, but that would also be expensive and messy and may not attack the adhesive. I haven't tried anything yet, awaiting pearls of wisdom from members.

Has anyone tried (and succeeded) in cleaning back to the metal?

  spuds 11:07 AM 24 Jan 12

I find a Stanley knife and scraper works fine. Cut the foam off in cubes, then lever and scrape off the blocks. Anything left behind, can be removed with a insulation foam remover or a blowtorch, scraper etc. Remember to use protective gear, in case of mishaps?.

Some people might light a fire, then throw the item on it (don't forget to remove any bungs, or you might have a ticking timebomb), the same applies to electric cables and sleeving removal, but this can cause a right old stink and black clouds in the neighbourhood?.

  spuds 11:11 AM 24 Jan 12

Perhaps also worth mentioning, that the old uninsulated copper tanks were much thicker than the now used insulated copper tanks, and as such have less value in content or use.

  frybluff 13:44 PM 24 Jan 12

Burning not recommended, fumes toxic (not deadly, in open air, but not exactly healthy). Not real alternative to chop and scrape.

  Graham* 15:33 PM 24 Jan 12

A scrap recycler may take the tank as is. They will have the experience to deal with it.

  onthelimit1 18:51 PM 24 Jan 12

Local scrap dealer (Oswestry) took my large insulated tank. It weighed 38kg (copper heat exchanger inside) and he paid me 80 quid for it. He will no doubt make a good profit, and I get something towards the cost of a new one.

  Diemmess 17:08 PM 26 Jan 12

Thank you all.

The job had to wait until this afternoon, but as you said the foam can be stripped quite easily with a suitable scraper.

I have a venerable one bought about 1958. It is springy and could be pushed under the insulation already sliced with a Stanley knife, and forced off. Underneath there was no sign of more than a lacquered surface.

This must be the thinnest walled cylinder I ever handled. I could lift it with one puny arm, and at as guess it weighed no more that 10-15Kg. Even so, since I never had any intention to sell for scrap and only wanted it for dabbling in coppersmith type DIY, it 'cuts the mustard.'

The weather became so foul I left cutting up the cylinder until tomorrow.

  Forum Editor 17:37 PM 26 Jan 12

"This must be the thinnest walled cylinder I ever handled."

They don't need to have thick walls - they have thicker tops and bottoms, and the construction provides enough strength for purpose.

  onthelimit1 18:37 PM 26 Jan 12

'They don't need to have thick walls'

Does make you wonder, though, when you think of the torque we sometimes have to apply to a joint to stop a weep.

  Forum Editor 18:58 PM 26 Jan 12


There's usually a reinforcing flange on the inside face of the cylinder behind the primary coil connection bosses, and behind the cold water feed boss. The DHW connection boss is on the top of the cylinder, where the metal is thicker.

You can still wreck the cylinder if you overdo the torque on the side connectors, so go easy.

  frybluff 19:06 PM 26 Jan 12

One general word of WARNING. When dealing with very old solid insulation, BE ABSOLUTELY CERTAIN it is not ASBESTOS. It hasn't been used for insulation for 30 years or more, and even before that, rarely used in domestic systems, but...... If in any doubt, leave well alone!!!


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