3" and 11" Flex on same T-stat??

[ivylea77]

I've seen reference to this in one other post yet nothing conclusive was determined.

So can you safely put a 3" and 11" piece of flexwatt onto the SAME thermostat? How does the temps differ if at all?

[casperca]

I was wondering the same thing! I hope someone has some answers.

[jglass38]

The temps will differ. 3" is 10 watts/ft and 11" is 20 watts/ft . Unless you had a dual output tstat (which would actually act like 2 thermostats), you will need to attach the probe to either the 3" or 11". If you attach it to the 3" and set your stat to 94 it will be higher on the 11" and if you attach it to the 11", then the 3" will be lower.

[ivylea77]

Well its good to know you won't be blowing anything up
It would be interesting to see if anyone has ever "tested" the difference in degrees.

[Flagg]

Yes they can be used on the same thermostat, as long as you aren't trying to get the same temps on both pieces.

The setup in question was described in another thread in order to have both a warm side of 94 and a cool side of 84 both run off different pieces of flexwatt. The cooler side also has a dimmer on it to keep the temp down lower than the warm side.

There is no reason why this wouldn't work, as long as the temps are adjusted properly. My current BP tub is set up this way, though I used 2 pieces of 4" flexwatt.

Basically as long as you are monitoring the temps of both and are not trying for them to both be the same temp, yes it will work.

[ivylea77]

Yes they can be used on the same thermostat, as long as you aren't trying to get the same temps on both pieces.

This is the key and seems that it would only work if you were not trying to establish the same temps.

I hope this clarifies for others if they expect that 11" and 3" flex will heat to equal temps hooked up to the same t-stat.

Setups differ and obvioulsy people can manage their setups in differnt ways

[chimpkin]

I have tested this for a rack I built. I used a Ranco T-stat, 2-3-foot strips of 3" flex-watt and 4-1 foot sections of 11" flex-watt. I simply taped the probe to the 3" inch piece and set the thermostat for 90. What I discovered is that the 3" tape heats up much faster than the 11". Plus the 11" never gets quite to the temp of the 3". I have my 3" tape at 90 while the 11" tape only gets up to around 84-85.

Another discovery: I may be a little out of my league here but follow me. The "Thermal Mass" of the tub takes much longer to heat up on the 11" tape because the 3" tape heats up so much faster that the thermostat shuts off.

Basically the 3" will get the tub up to temperature in an hour, the 11" may take several.