Could increased tank insulation cause condensation?

Question from ‘Cornishyokel’,via email:
I have an insulated fortic tank which I have increased the insulation by adding a tank jacket, could the jacket cause condensation between the foam on the tank and the additional jacket?

The reason I am asking is because there is slight dampness on the jacket which is very slowly dripping and causing a damp patch on the ceiling.

Answer from Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group:
I would be surprised if the insulation jacket is creating condensation to occur between the foam insulation of the cylinder and the new jacket.

I expect this would be possible if you have covered the lid of the Fortic tank with the new jacket as the cold water within the tank could be warmed by the cylinder below.

I would suggest you inspect the cylinder for any possible pipework or even cylinder leaks and if so, remove the insulation jacket from the cold water tank of the Fortic and only insulate the same areas as the existing foam insulation.