no separate controls on gravity hw system

[wally5460]

Hi, can anybody offer me some advice, i have a fairly old gas boiler with gravity hot water and pumped central heating, the problem i have is that i have no separate control for the HW and CH, when using the central heating the water in the hw cylinder is constantly heating up making it dangerousley hot! it has a cylinder stat that someone diconnected as it would switch the boiler off when temp was reached and therefore the CH would be off also. It has been suggested to me to create some sort of bypass circuit in the gravity HW pipework (after the vent) and use a motorised valve to divert to this circuit when the cylinder has reached required temp. Does this sound reasonable? and if so would this circuit also need a vent pipe going into the f&e tank to allow for the expansion of the heated water in the pipes?
Bit of a long one but any ideas or alternative solutions would be much appreciated!

Thanks

 

[wnjswozo]

i would bite bullet the system youve got must cost a fortune to run,the cost invovled in trying to alter it to try and make it more effic/controlable,put it towards new boiler upgrade,you would probably be eligable for scrappage scheme

 

[macplumb]

If you want to spend money get a combi.
For less money upgrade system to a Y plan.
To spend no money check if there are gate valves on the flow to the hw/ch these can be ajusted to isolate one side or the other. Have a good look because sometimes the wheels get removed.

 

[wally5460]

Thanks for the replys, the boiler i question is at my inlaws house and they are adament that they dont want a combi???? im thinking of suggesting the 3 port mid position route as they already have suitable controls ie cylinder stat, room stat, programmer and wiring centre. is it ok to join the old gravity pipework into the pumped pipework via the mid position valve on the supply and then join the return from the HW cylinder to the CH return pipework? if so would you cap off the old redundant gravity pipework left coming from boiler or would you join them to still allow water circulation?

I hope this all makes sense

thanks

 

[macplumb]

Use the old primaries. Cap off other side.