Heater tray not thermostatically controlled?

BenderRodriguez

Hi,

I got my heater tray delivered on Friday so thank you for quick postage. It's this model:

http://home-brew-online.myshopify.com/products/25l-fermenting-vessel-heater-tray

I have noticed that it can get extremely hot. Instruction attached to the package says that it is thermostatically controlled and that power light should turn off once it reaches optimal temperature. As an experiment I placed my fermentation bin with 2 gallons of water on it (some ales I brew make only 2 gallons) and tray got really warm. When left standing on its own it for 15-20 minutes it gets so hot that I can't hold my hand on it for more than few seconds and yet it doesn't switch itself off.

I know it's been designed for 5 gallons of homebrew but I would expect it to turn itself off when it gets too warm which doesn't seem to be the case. Is this how it's meant to work or perhaps mine is just faulty?

Thank you

BenderRodriguez

I just noticed I didn't select appropriate forum Category, sorry for that!

HBO_Staff

The trays can get very hot, we have some more information from the manufacturers which we will copy and paste here for you, it gives better details on the way they work and other useful info relating to the temperature;

Measuring the temperature between the tray and vessel would not be particularly effective, as other factors such as the ambient conditions will have an effect on the liquid temperature.  The position of the vessel is also important, as a constant cold draught near a door will have an effect, or if it is close to a radiator.  Also, there are significant thermal losses between the tray surface and the underside of the brewing vessel, and the wall of the vessel also acts as a thermal barrier.  The internal thermostat is actually set to approximately 55 deg C to achieve the correct surface temperature, which would shock most customers! 

 

The base temperature of the vessel will not necessarily correspond to the liquid temperature in the brew either, as convection currents will cause the warmer layer at the bottom to rise giving a fairly even temperature gradient throughout.

 

Although the trays have an internal thermostat, this is not the primary means of temperature control, as the power output (wattage) of then different models has been arrived at to ensure that the thermostat rarely operates under normal domestic ambient temperatures.  These would normally be in the region of 15-18 deg C, with the tray designed to give a 9 deg increase resulting in liquid temperatures of 24-27 deg, well within the acceptable fermentation range.

 

Our instructions state that in temperatures above 25 deg C the heater should be switched off (such as if the vessel was in direct sunlight), and that regular temperature checks should be carried out to ensure that the temperature of the brew is as desired.

BenderRodriguez

Thank you, I was just a bit worried to leave it when I go to work in case whole thing melts.

My kitchen gets about 15'C with heating off so this should do the job.

HBO_Staff

It is surprising how hot they need to get in order to transfer the heat into the liquid, your room temperature is ideal, and the good news is we have never had a report of a single heater overheating or having a problem like that!