Using the solar coil on a twin coil hot water tank for solid fuel rayburn back boiler?

[theflyingpig]

these 'solar cylinders from Gledhill claim to have "dedicated high performance solar coils" .... I'm not sure how they differ from regular twin coil cylinders, but I'm wondering if there is any reason I couldn't run the back boiler from Rayburn through the lower coil?

anyone got any insight here?

thanks!

 

[Johntheo5]

Depends on what type of back boiler, if its solid fuel (uncontrolled heating) then the coil must be something like 28mm?? or something like that and smooth walled as the water must circulate by convection, a corrugated coil of any diameter will not convection circulate.
If the Rayburn is oil/gas fired then the solar coil should be OK but don't know what "dedicated high performance solar coils" means, a 1M2 coil would be considered normal for a solar coil, at least mine is. Can you post a link to the cylinder.

 

[old duffer]

The issue I would have is in controlling the overheating of the tank from an uncontrolled supply. The tank won't explode or anything as drastic but it could become noisy as it bubbles with boiling water. The simple answer to that is of course run the hot tap.

 

[jeff the gasman]

You could use a dunsley neutraliser and run a controlled circuit from there. Heatsink also required.
Feed and expansion from neutraliser to galvanised f and e tank with a copper overflow.

 

[Exedon]

We have used a number of Gledhill twin coil cylinders mostly with bottom coil for oil fired aga cookers.
You gave to specify when ordering that the bottom coil is for gravity circulation.

 

[theflyingpig]

Thanks for all input. I'm unsure as to best path forward and found a cheap cylinder do thought that might show me the way....

Currently have vented cylinder with two coils, one for a solid fuel Rayburn and the other am oil boiler...

Moving to an unvented system, still with an oil boiler (albiet a new one)... Want to keep the Rayburn though it would only get occasional winter use (appreciate that circuit must remain vented), but also have the perfect facing and pitched roof for solar...

Can't decide if I should go 100% pv with the solar, or a couple of solar thermal collectors too... And, if so, which cylinder to handle three inputs....

 

[Johntheo5]

Don't think a unvenred cylinder can be used with a vented solid fuel appliance?

 

[Terrywookfit]

A Thermal store is the norm for a uncontrolled heat source