hot water from aga

[copperman]

advice needed.I want to use twin coil unvented cyl for dhw.Top coil supply. from boiler bottom from oil fired aga.Iknow that unvented not allowed uncontrolled heat source but could i fit diverter valve to gravity from aga ,controlled by cyl temp stat,that would divert to towel rail heat sink at say,50 degs c

 

[oilman]

No. Best thing to do is to take the boiler out of the Aga and have it as a cooker only. Water heating is around 80 deg C, cooking is around 300 deg C. To achieve these two together is an inefficient compromise.

 

[PDrawmer]

I very little about the merits of your proposed installation, except that if you are planning any safety systems, you should also consider the fail-safe implications of your proposal. If anything fails, what state will your safety system be in? For example if the diverter valve failed - would you know before an overheat happened?

Regarding the Aga, after many years and living in 5 houses with various Aga configurations of oil, gas, solid fuel, with and without boilers; I fully agree with oilman, if you want to use the Aga for cooking, then forget the water heating. Because the Aga works with heat as opposed to temp, it is very poor at recovering, and the effect of a cool boiler tank, will be to absorb heat from the whole Aga, and the cooking will suffer. This is very annoying, since you can't 'turn it up a bit'.