Rack Inconsistensies Continued

Hi,

Couple of probably pointless observations - the top shelf has less flexwatt in it than the others when you take the bit going down the side into consideration?

You could probably get some foam board insulation to sit the rack on - it shouldn't be in contact with the flexwatt so I don't think there is any fire risk.


dr del

Seen this problem before and what I found is that the probe or the tstat is the problem. Try moving the probe to different levels and different places on the heat tape. This is the main reason me and my friends no longer use herpstats at all, as we haven't seen the issue with any other brand of tstats.

That is a great notion DrDel I had not thought of that.

I was thinking the same thing..top shelf has no side heat tape and the bottom shelf has nothing in it..

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Originally Posted by kitedemon

That is a great notion DrDel I had not thought of that.

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The seller contacted me earlier, saying the following: 1) I didnt have substrate in any of the tubs so the first step was getting substrate into the top tubs and seeing if the temps went up. And they did, Im getting 89-92 on the hot spot now on one of the top bins, 79-80 on cool side. 2) I am missing the bottom two tubs because they broke on delivery. The seller thinks that the missing two tubs might be the reason: the cool air flowing through the bottom shelf is cooling the heat tape, making it work harder than normal, and its creating inconsistent temps.

Once I get the two missing tubs in there, and put substrate in all of my tubs, then I can re-assess to see how it really works. Im quite happy that I got the top shelf to go to 92 already, so thats definitely an improvement. Thanks for all the input guys!

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Originally Posted by meeistom

Seen this problem before and what I found is that the probe or the tstat is the problem. Try moving the probe to different levels and different places on the heat tape. This is the main reason me and my friends no longer use herpstats at all, as we haven't seen the issue with any other brand of tstats.

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I think I am missing something. The original post shows the top shelf cooler than the lower shelves. How could this be a problem with the thermostat or the probe? The Herpstat ND thats in the posted picture is a single output thermostat. It doesn't have the ability give preferential treatment to one shelf. In fact typically on racks the top shelf is the hottest because heat rises.

With that in mind it appears to be a issue with the flex watt. I have seen many cases where one piece of flex watt doesn't output the exact amount of heat of another or further down the strip its cooler. Flexwatt is basically like a large resistor. And just like resistors their is a manufacturing tolerance.

I've always been a believer of the flexwatt independantly wired in parallel for each level. If its one piece snaked from the bottom to the top then it has more of a possibility of voltage drop at the top lowering temps.


meeistom: When you had a problem did you contact us? I answer all the emails and I happy to help anyone experiencing a problem with our product. If you have a moment shoot me an email at the sales@spyderrobotics.com and let me know any feedback you have.

Dion Brewington
Owner, Spyder Robotics

The top shelf is not 'insulated' and requires more heat tape. The middle shelves are 'insulated' by the heated upper and lower shelves. I see this a lot with back heat. I would supplement with extra heat tape at the top or put the top shelf as an isolated unit with a separate probe.

Sorry, by 'insulated' I mean the surrounding shelves are assisting in keeping the others warm. For the lack of a better word.

I am having this same exact issue with my racks as well. I have two different racks from two different companies. They sit side by side and have their own thermostats (Zilla 1500watts). Both racks have between 3-7 degree difference from top drawer and second to top drawer. The remaining lower drawers are all within 2 degrees of each other.

The bigger 32qt Tub Rack/5 lvl high/1 Tub per shelf is wired with 4" belly flexwatt heat tape snaked from top to bottom with power connected at the bottom. Thermostat probe is on Bottom shelf and taped to heat tape with al. tape.

The smaller 14qt Tub Rack/5 lvl high/2 Tubs per shelf is wired with 3" belly flexwatt heat tape snaked from the bottom to the top with the power connected at the top. Thermostat probe is on 2nd shelf from top taped to heat tape with al. tape.

The top drawers on both rack systems are significantly cooler than the drawers beneath. I am beginning to think its due to a lack of insulation for the top drawer since there is no drawer above it helping retain the heat.

Apparently the way the tape is snaked isn't causing the problem since each system is snaked opposite and having the same issues. Also, I doubt the heat tape is malfunctioning since its happening to both racks.

P.S. when I shoot the temp gun on the prob I am getting a proper read out as to what the thermostat is set to. Also, I've made sure the AC vent is facing away and practically closed off.

I am going to blanket the top of racks and see if this helps retain some of the heat....