I've looked at the HeatraeSadia and Gledhill sites and, so far as I can see, the vented Megalife HE, Stainless Lite Vented and Envirofoam Stainless Vented all require pumped circuits and are unsuitable for gravity systems.
Hi , I have found one suitable for your system . it is made by gledhill and is called stainless lite triple coil, which has 3 coiks , onevof whichcan be used for gravity systems http://www.gledhill.net/page/107/Stainless-Lite-Triple-Coil.htm Copy and paste this into your browser
Many thanks. Your suggestion would have been perfect, except that the triple coil model is 2M in height and I only have 1.8M max height availability ! All the other Gledhill vented, indirect SS cylinders need a pumped circuit. You don't know of a slightly smaller alternative to the Gledhill IND300-STC do you ?
Combi not suitable - V large (listed) property (this hot water supply problem applies to one wing only !). No mains gas - in rural wilds !
Have found a Joule Cyclone triple coil with appropriate dimensions but cannot find a UK stockist. Have you experience with this (Irish) manufacturer?
Alternatively, Newark Cylinders do build to customer requirements, but their expertise has always been in copper not SS - your experience ?
Have now received a satisfactory quote from Newark for a bespoke indirect vented Duplex cylinder with large bore gravity coil in 316 marine grade stainless steel. That should solve the problem.
That's great ,all the best with it, Kind Regards