Re-use brew controller in fermentation chamber

[walther]

I am experimenting with adding a radiator like this to my brew system, in order to control the temperature in the fermentation chamber:


My brew system (Grainfather) already has a heating element, temperature control and a pump. By connecting the pump to the radiator, I can adjust the temperature on the Grainfather, and circultate it through the radiator.



I haven't got a fancy fermentation chamber to my FastFerment, only a simple sleeping bag, but initial tests seem to work fine. Here the thermostat is set at 32C:



At the moment I can raise the temperature of 20L(5gal), 2K/h, but expectedly, this rate will decrease.

 

[govner1]

I’d be concerned about a potential fire hazard or melting of the wall of your Fast Ferm given the proximity to the heat source.

 

[walther]

Thanks for the reply,

The water I am circulating is only 32C/90F, so that should be safe.
(if the there is a leak in the system, there is however a danger of the Grainfather boiling dry).

 

[walther]

Temperature response curve for 20L (~5 gal), with the Grainfather thermostat at 32C (~90F):

 

[Picotto]

What's the outside temperature? Can you keep temperature of 20c in this setup?

 

[walther]

What's the outside temperature? Can you keep temperature of 20c in this setup?

Yes, that is no problem.
In the heating up phase, as shown in the graph, the temperature should be higher in the Grainfather, than the target temperature, as it approaches asymptotically.
When at target temperature, the Grainfather should only be a few degrees above target, but I'll need to experiment a bit more with this. It depends on the insulation of the chamber.
The ambient temperature was 14C/57F in the experiment.

Thank you for the reply,