2 racks, 1 t-stat

[kid_mustango02]

I've got 2 of the 32q racks from RBI and a Helix t-stat. It seems one rack won't get as warm as the other. About a 4 degree difference. One rack will be at around 91 and the other is around 87. I'm using Accurites for thermometers.

Can I put a dimmer in line between the warmer rack and t-stat, and turn the t-stat up to bring the colder rack's temp up?

Or does anyone have an idea why they aren't heating the same. The 2 racks are identical...

[waltah!]

I have the same racks.If they are on top of each other the top one will be warmer. I keep my room temps up to about 80-82 and it works out okay. The bottom tub is about 2 degrees less than the top. If you have a temp gun I would check temps with it. I've found that many thermomters can show a drastic difference in the exact same spot. If they were raised and next to each other than they should stay the same. Mine are back heat, so not sure if yours is belly heat.

[kid_mustango02]

Mine is belly heat. I have them setting side by side so maybe if I put the colder one on top I could get them closer to the same temp? I'll give it a try...

[Mike Schultz]

If one is closer to the door/window or under an air vent or something that could cause a problem.

[Argentra]

Positioning counts for a lot. If one is closer to the 'inside' of the room and the other is nearer a door, window, or vent, then that one will be cooler. Also, if there are any outside walls in the mix, that affects things as well.

I have a rack and a separate tub (on a stand) next to it. The stand is closer to the room door and the large window, and the rack is in the warmest corner of the room. Naturally, the solo tub is about 2-3 degrees cooler than the rack temps, which also vary from bottom to top.
Soon, I'll have another identical rack beside the first and all 8 enclosures will be on one Herpstat (6 tubs 3 in each rack and 2 tanks one on top of each rack). Hopefully the differences won't be too big, but you have to expect variations of some sort.

[kid_mustango02]

yea I have a temp gun too, just to let ya know. It's reading similar to the accurite.

[FIREball]

Seems like good temps to me even with the difference, I wouldnt worry about it.

[waltah!]

Seems like good temps to me even with the difference, I wouldnt worry about it.

I was actually thinking the same thing. Maybe kick the Helix up a degree or so to get the cooler one up to 88-89. The warmer one should still be at a good acceptable temp.

[simplechamp]

How are the heating pads/flex-watt for each rack connected together, or to the thermostat? (In regard to series, parallel, or combination)

If they are connected in series the current will be the same through each and the heat output should be the same.

BUT if they are in parallel there is a chance of the current differing in each rack due to slightly differing resistances in the heat mats/ flex-watt. This could cause the heating elements in each rack to output a slightly different amount of heat like you are describing.

if the two racks are connected in parallel it might be worth measuring the total resistance of each heating system with an ohmmeter to see if they are the same or different. If they are in series this probably isn't the problem.

[kid_mustango02]

How are the heating pads/flex-watt for each rack connected together, or to the thermostat? (In regard to series, parallel, or combination)

If they are connected in series the current will be the same through each and the heat output should be the same.

BUT if they are in parallel there is a chance of the current differing in each rack due to slightly differing resistances in the heat mats/ flex-watt. This could cause the heating elements in each rack to output a slightly different amount of heat like you are describing.

if the two racks are connected in parallel it might be worth measuring the total resistance of each heating system with an ohmmeter to see if they are the same or different. If they are in series this probably isn't the problem.

I checked the resistance of both strips of flexwatt at the plug. The warmer one is .201, the colder is .227. I'm not too familiar with electronics but to me it doesn't seem like the little difference is resistance should make the temps differ that much. Or I may be wrong and the two differ a lot?

I know some of you say the temps are fine, but I feel like the two racks should be closer considering they are identical. Maybe there's a bad connection at the soldering point? If so, I'm afraid it might cause problems down the road....