CH Setup Query

With a gravity HW system there is no need for a bypass. However when you replace the boiler the new one may or may not require some permanent path for water to circulate.

The idea of not having a TRV on one rad is that you have a room stat in that location, which provides a boiler interlock by switching the whole lot off when satisfied. This is only any use if the boiler interlock *also* applies to the DHW system. To achieve this with a gravity system, you need a cylinder stat and a motorised valve rather than a thermostatic valve.

All new systems have to have a boiler interlock to stop the boiler from cycling and wasting energy when all external demands are satisfied.

Unless you want to totally revamp your system - and go fully pumped - you can get somewhere close to half-way decent by converting it to a C-Plan system [See

Having said that, you really need to get rid of the primatic cylinder and replace it with a standard indirect cylinder and separate DHW and heating system header tanks. Then at least you'll be able to put corrosion inhibitor into the central heating.

.... and you also would benefit from a more effecient hot water system.

Mark

Not so easy where I live in a tenement block of flats .The tanks would need to be in the communal loft two floors above me so I'll make do with what I've got . I dont pay any more for either gas or leccy regardless of how much I use .

Stuart