Uneven Flexwatt temps (?)

Hello,

I have 7 12" long 4" Flexwatt each wired with a plug. They are all plugged into a power strip. Each piece reads a different temp with a temp probe (compared to the other pieces), and has various temps within each piece when using a temp gun. I understand that there may be reflection when using a temp gun but the whole strip is inconsistent with temps.

I do not want to start re-wiring etc if I do not have to. Are these temp fluctuations normal?

Thanks

Jim

Are you sure they are rated for the same wattage? I know they make 11 watts a foot 3" and 6 watts a foot 3" but I'm not sure if they make multiple types of 4". I don't have that problem and I know all of mine is the same wattage per foot and I bought them all from the same place. If you find out whats causing it let me know. Good luck.

Plus it would be good to know how they are wired. Who wired the pieces? Are they soldered or connected with clips? Are the cut ends protected with electrical tape?

Sorry for leaving out this info:

I got all of the pieces at the same time from Rich at Reptile Basics. They are all individually wired with a plug using clips and Rich did the wiring. I actually have a total of 12 pieces split between 2 power strips.

I do not have any of the ends taped, at the same time I do have each piece foil taped to the shelving I am using.
Would/could this be causing "shorts"?
Could each socket of the power strip be putting out different wattage?

I know I am reaching but just do not understand why this is happening.

Thanks

Jim

Yes, you can be getting shorts from the uncovered ends. Before taping the heat tape down to the shelves you should cover the cut ends with electrical tape. I had a friend who had temp fluctuations and we put a multimeter on the aluminum tape on his flexwatt and noticed a small charge. After adding the electrical tape it helped his temps. :salute:

Also, he could sometimes feel "tingles" when touching certain areas.

One more thing, LOL. Sometimes the clip connections can loosen up over time, wouldn't hurt to double check they're tight.

Thanks!

I will work on all that and see if it helps . . .

Jim

I actually spoke to Rich at Reptile Basics about this yesterday. Flexwatt is made by the same people that make the Zoomed and other pet store type UTH's. It's a printed circuit board type heater and sometimes the ink is thicker in spots. It gets hotter in those spots and cooler in the "thin" areas.

He said you get more consistent temps in a cloth type UTH like his Ultratherm Heat Pads but there will always be variances in the UTH area.

He also said that the temps vary based on the room temp if you don't use a t-stat. It's more of a problem if the room gets too hot because the UTH will get hotter if there's nothing adjusting it.

Hope that helps.
JohnNJ

Well that really would pose some challenges! At this time I have both power strips on separate dimmers. (I know . . .) The room is heated to 80-81 and seems to stay in that range.

I am going to be converting the wire shelves I use into a rack system (more enclosed) and I have a Herpstat ND that I will be using once I do this. My concern is that if each Flexwatt strip will have fluctuation in temps, how can I properly use a T-stat and regulate temps for the whole rack?

How big are the fluxuations? I would suspect they would be pretty close (ie within a degree or so). If you want to get technical you could use a digital multimeter and set it for resistance. make sure the heat tape is not plugged into the AC and measure each side of your plug. The lower the resistance the hotter it would get I would suspect. You should be able to see how far off each piece is to the other. I suppose if your building a rack you could take your hotter pieces and put them in your lower levels. Since heat rises usually the lower levels are cooler. (See.. its not a problem. Its a feature!)

Anyone who has seen my posts know I am not a fan of the infrared temp guns. If you want to really test them grab a couple of $5 digital thermometers from walmart that have probes on a wire. Tape the probes together and leave them in the ambient air for 15 minutes. Then check the displays. They will be off from each other normally (maybe even by couple of degrees) just mark down how much their difference is and label the thermometers so you know which is which. The use them to measure your heat tape. This way you can take two readings at the same time and as long as you add in your calibration difference that you wrote down previously you can tell if they are truely running at difference temps and by how much.

Dion Brewington
Owner, Spyder Robotics

Quote:

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Originally Posted by spyderrobotics

How big are the fluxuations? I would suspect they would be pretty close (ie within a degree or so). If you want to get technical you could use a digital multimeter and set it for resistance. make sure the heat tape is not plugged into the AC and measure each side of your plug. The lower the resistance the hotter it would get I would suspect. You should be able to see how far off each piece is to the other. I suppose if your building a rack you could take your hotter pieces and put them in your lower levels. Since heat rises usually the lower levels are cooler. (See.. its not a problem. Its a feature!)

Anyone who has seen my posts know I am not a fan of the infrared temp guns. If you want to really test them grab a couple of $5 digital thermometers from walmart that have probes on a wire. Tape the probes together and leave them in the ambient air for 15 minutes. Then check the displays. They will be off from each other normally (maybe even by couple of degrees) just mark down how much their difference is and label the thermometers so you know which is which. The use them to measure your heat tape. This way you can take two readings at the same time and as long as you add in your calibration difference that you wrote down previously you can tell if they are truely running at difference temps and by how much.

Dion Brewington
Owner, Spyder Robotics

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Listen to the man, he builds one of the top Thermostats in the industry for a living! On topic: I just use those accurite digital wireless humidity/temp readers. Just stick the sensor inside the tub on the hot spot wait a half hour or so for temps to adjust and boom great reading without the hassle of a temp gun. The tingling could simply be because the cord isn't grounded and generally has no impact on fluctuation.

i never reallychecked alonge the temp but I do find there are sometimes a slight warmer spot in some areas. I figure this was a given based on the material that used .. but it neve been more than a degree or 3 in my cases..