Which Thermostat Takes Control?

[nurglespuss]

Hi Again,

Last question!

I bought a Fluval edge aquarium heater (built in thermostat, set to 26'C or 4'C above room ambient), its non adjustable.

So I wonder can I use an external thermostat to adjust it?

like this one:

Hydor Hydroset Analogue Thermostat

If i ran the heater through this thermostat, would it take control, or, would the heater keep trying to turn itself on, and the external keep turning it off?

thanks guys, I'm in the mists on this one!

 

[OldMan47]

I suppose you could power a heater through a separate thermostat like that, but it a very expensive solution to a simple problem. It costs more than a heater with a built in adjustable temperature control would cost.

 

[Geoff-]

the edge will always heat up to 26C and turn off. an external thermostat will only let you LOWER the temperature, not raise it. Eg an external could turn it off early at 24C, but it will get higher than 26C because the inbuilt one will always shut off.

simple answer is buy a decent heater! no point skimping on them.

 

[nurglespuss]

Cheers both.


Yeah I just want it to sit at 18'C no higher.

I'll give it a whirl and see how it goes (test it on a bucket first), Unless there are other heaters out there of the same design, that are adjustable?

 

[Miles_hot]

the edge will always heat up to 26C and turn off. an external thermostat will only let you LOWER the temperature, not raise it. Eg an external could turn it off early at 24C, but it will get higher than 26C because the inbuilt one will always shut off.

simple answer is buy a decent heater! no point skimping on them.

I would expect that the Hydor heater would only allow you to heat the tank to more than 26 not lower the temp as:
- below 26 the internal heater would trigger causing the temp to ris
- above 26 the internal heater would be doing nothing but the Hydor could continue to heat.

I would think that if you want to maintain 18 you will have to not use the internal heater and use some external instead?

Miles

 

[nurglespuss]

Hi there

Thanks.

Yes thats the idea, the hydor is an external control unit (which is set to allow the water to be heated to 18'C), the fluval edge heater, though pre-set will be controlled by the external thermostat.

I'm ordering one next week

 

[Geoff-]

Miles the Hydor is a thermostat, not a heater!

If it was a heater then what you describe is true.

 

[OldMan47]

If you are connecting a heater through a separate thermostat, the highest temperature you will ever see is whichever of the two settings is lower. If the thermostat is set high enough, the heater setting will control temperature and the thermostat will be out of the way. If the thermostat is set lower, the heater will lose power before reaching its setting.

 

[Miles_hot]

Miles the Hydor is a thermostat, not a heater!

If it was a heater then what you describe is true.

duh!

 

[nurglespuss]

thanks for all your help guys

I finally ordered the external thermostat today .

Will also be useful when I get a larger aquarium in my next place, as I want to give a heating cable a twirl (always been afraid to try one!)