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Posted by pausto on March 10, 2005, 9:09 pm
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"David C. Stone" wrote:
>
> Most of the heaters I've seen cycle on and off at a rate determined by
> the "temperature" setting of the control. If ambient temperature
> changes by a couple of degrees, the result is a corresponding change
> in water temperature since the thermostat is still adding the same
> amount of heat.
>
> I would be interested to see if your "Won Brothers Pro Heat II" actually
> had a temperature controller rather than a cycling heater in it. The
> former would actually measure the water temperature and adjust the
> on/off cycling rate to maintain constant temperature. If any one knows
> of a system that does this, I could really use one for my 120 gal. lab.
> tank - the room temperature is normally pretty constant, but if the
> outside temperature changes dramatically overnight, it can vary by as
> much as 6 F, and I have to go adjust the thermostat.
>
> Speaking of which, it's time for my daily tank check...
I think any heater where the sensor is located remotely from
the heating element, is going to give a more stable tank temp
regardless of reasonable fluctuations of the surrounding room
temperature. At least *some* (all?) of the Won Bros. "Pro Heat"
units are set up this way. I have never tried one, but a friend
of mine has one, and he says he likes its performance.
You might also want to check out the "Ranco ETC-11xxxx-xxx"
series temperature controllers. I had recognized this unit as
being used in some pre wired aquarium heater packages. I
purchased just the controller at a local air-conditioning supply
house, for about $50us. You have to cut an extension cord in half
to wire through the contacts (and for power to the controller),
then plug whatever heaters you want into it. The controlers come
in combinations of 1 or 2 stage, heating and/or cooling, 120 or
240volt.
The single stage heating unit that I have will handle 15 amps
of resistive load @ 120volts. I have this unit controlling two
150w EBO's in the sump, with the sensor located in the syphon
overflow box. The unit cycles on at 78.1 deg, and off at 78.6 deg
(though the controller adjusts and displays in whole degrees
only). The tank cycles on add off at these exact same
temperatures whether the room temp is 74 deg, or all the way down
to 57 deg in the winter.
The only way the fish can tell what time of year it is, is by
how warmly I am dressed.
Paul
Yes, I watch TV wearing a hat and scarf in the winter.
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> Most of the heaters I've seen cycle on and off at a rate determined by
> the "temperature" setting of the control. If ambient temperature
> changes by a couple of degrees, the result is a corresponding change
> in water temperature since the thermostat is still adding the same
> amount of heat.
>
> I would be interested to see if your "Won Brothers Pro Heat II" actually
> had a temperature controller rather than a cycling heater in it. The
> former would actually measure the water temperature and adjust the
> on/off cycling rate to maintain constant temperature. If any one knows
> of a system that does this, I could really use one for my 120 gal. lab.
> tank - the room temperature is normally pretty constant, but if the
> outside temperature changes dramatically overnight, it can vary by as
> much as 6 F, and I have to go adjust the thermostat.
>
> Speaking of which, it's time for my daily tank check...