On 5 Oct, 01:26, "cj" wrote:
Hi
You say the house is a 60's build IIR the backboilers in these houses was
(as you say) behind a coal fire with a flue diverter in the chimney to suck
heat around it when the fire was lit.
This type of system was a direct system with the same water in the hot
cylinder being routed through the back boiler .(memories of dad yelling Turn
on the Bl*&^y hot water quick before the bedroom fills with steam).
When central heating was fitted one way to heat the existing tank was to
remove the immersion heater and replace it with a heat exchanger coil which
the new gas boiler heated.
Another was to replace the existing cylinder with an indirect unit and
disconnect the back boiler totally leaving the boiler behind the fire empty.
It may be worth checking your cylinder to verify the system.

HTH
CJ.

The above has a point. However I think if it had been disconnected
you would have become aware of it.
(a) Your water in the cylinder wouldn't get hot when you lit a fire.
(b) The firebacke boilers had no drain point you would have heard the
rumble of boilng water in the boiler after a while when you lit a
fire if it had been disconnected.
After a few hours the boiler would have melted /burned through/
sagged./ when it boiled dry.

There used to be an alternative way of dealing with the cyinder's lack
of heat exchanger. That was to install a " sidewinder" heat exchanger,
a dodgy device with mechanical joints.
Bloody hell, they still make them!
http://www.trademate.co.uk/ProductEx.../yorkshire.pdf
page nine.
These were very popular back in the sixties/seventies. They worked
quite well but sometimes leaked.