Rack Inconsistensies Continued

So, still having problems with my rack. Only got the one lesser in there, but shes in a tub with optimal conditions. Her rack has 90-95 on hot spot, 79-81 in cool side, its a 12 quart tub with aspen bedding, one hide and one water dish.

The temps Im achieving inside the tubs are: (all of them have 79-81 cool side)

Top shelf: 87-88 hot spot
2nd shelf: 91-95
3rd shelf: 91-95
4rth shelf: no tubs yet, broken on shipment

The temps of the flexwatt are:
Top shelf: 92-96
2nd shelf: 96-102
3rd shelf: 96-102
Bottom shelf: 92-95

What the heck is going on?? I have used accurate ways of taking temps including my Flukers thermometer, a few probe thermometers and my IR gun (which gave me similar readings as my other thermometers). I am using a oil filled heater regulated by a Ranco, set at 80 F.

I feel like my flexwatt might be dysfunctional, but I have no idea. If it was not working properly, wouldnt it not heat up at all? The flexwatt is snaked all the way through so the only solution would be to get the seller to send me some new flexwatt to run through myself. I can't increase the temps on the thermostat anymore without risking over-heating the second and third shelves so i have no clue what to do! I thought when I bought an expensive rack like this it would be plug and play but so many problems have arised :( Thanks for reading

And I dont know if it makes a difference, but after reading Kitedemon's recent post on here, I have my herpstat probe foil taped on top of the flexwatt, on the second shelf. By foil taped I mean a big piece of foil tape that covers the entire probe. I didnt want ambient temps affecting it which is why I did it like that. Should I change it to electrical tape/whats the best way to secure the herpstat probe onto the heat tape? Thanks again

Guessing here but is the flexwatt wired from the bottom to the top? if it is the line loss may account for this variation some is unavoidable usually it is a balancing act between top and bottom it is odd however usually the top is the hottest and bottom coolest. I have my flexwatt all running off a single wire so rather than one piece running into the next they are all wired off a central lead of wire. I have fairly contestant temps on the flexwatt I however do not heat the room so I have secondary and back up heat sources too that changes my situation from the norm quite a lot.

"Do not use aluminum tape to secure the probes. This will cause false readings and poor regulation."

from the herpstat 4 manual last page. http://spyderrobotics.com/products/herpstat4_manual.pdf

I found that I got better readings when I switched I also lay down al. tape first I believe it helps transfer heat from a larger area to the probe evening out some of the variations in the flexwatt. (2 inch strip across the 'stripes' in the flexwatt) I cover the whole thing with eletrical tape and al. tape over that. (eletrical tape doesn't stick as well) I found it brought the set point to 95 and that delivers 89-93 bottom to top on my rack. I feel better not having the herpstat set too far away from a 'safe temp' my fail safe is set to 99.

Quote:

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Originally Posted by kitedemon

Guessing here but is the flexwatt wired from the bottom to the top? if it is the line loss may account for this variation some is unavoidable usually it is a balancing act between top and bottom it is odd however usually the top is the hottest and bottom coolest. I have my flexwatt all running off a single wire so rather than one piece running into the next they are all wired off a central lead of wire. I have fairly contestant temps on the flexwatt I however do not heat the room so I have secondary and back up heat sources too that changes my situation from the norm quite a lot.

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This whole issue is boggling my head right now, Ive contacted the seller to see what he thinks and if his customers have encountered this before. I just want to know if its something wrong with what Im doing on my end or if its the actual setup of the rack.

The flexwatt is snaked from bottom to top, with the wires coming out the back of the top shelf. There are actually small slits on the sides where I could re-wire the flexwatt so that I have a seperate strip on each shelf, but that would be a little annoying considering I suck at putting things together and the reason I paid a whole paycheck for this rack is so I wouldnt have to put in extra time to deal with this stuff. Heres a few pictures of the whole setup

Room:
http://img849.imageshack.us/img849/5153/dsc00444j.jpg
http://img17.imageshack.us/img17/9383/dsc00445m.jpg

Top Shelf:
http://img64.imageshack.us/img64/6721/dsc00446nj.jpg

Second Shelf, with herpstat probe:
http://img267.imageshack.us/img267/1277/dsc00447y.jpg

Bottom Shelf:
http://img696.imageshack.us/img696/6307/dsc00449a.jpg

Thanks Kitedemon.. So if I am understanding correctly, the probe placement should be from bottom to top: Flexwatt - Big piece of aluminum tape - Herpstat probe - small piece of electrical tape - Foil tape?

basically that is what I use.

Foil tape - probe electrical tape covering both tape and probe and foil tape covering electrical tape.

Your flexwatt makes an s through the rack? The electrical plug is on the top of the flexwatt? if that is the case my thought is not valid the bottom would then be the end of the line. Also a single un cut flexwatt strip should be more or less even.

That is very odd to me heat rises the flexwatt might loose some power over distance but if the start is the top that isn't it either. Stumped. My rack is also PVCx and my warmest is the top. It is odd. The pic of the top shelf failed to load could you re post it?

Sorry it just appeared...

Ok I have a thought... It is a bit of a band aid but if it works...

The top flex watt seems to be set deeper than the other one you posted. Is it??

If that is the case that could be the issue heat dissipates quickly in air you might try adding a spacer under it to raise it up some. make sure the spacer will take the heat I personally would use pvc but I have some laying around a thin bit of plexy might work just make sure it won't get too hot and cause a fire.

Quote:

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Originally Posted by kitedemon

Ok I have a thought... It is a bit of a band aid but if it works...

The top flex watt seems to be set deeper than the other one you posted. Is it??

If that is the case that could be the issue heat dissipates quickly in air you might try adding a spacer under it to raise it up some. make sure the spacer will take the heat I personally would use pvc but I have some laying around a thin bit of plexy might work just make sure it won't get too hot and cause a fire.

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The guy who made the rack for me uses the same plans (owns the rights) to RBI racks. They are not made by Rich at RBI, but are of the same design.

The top flexwatt is at the same depth as all of the other shelves, Im really stumped lol. I'll wait till I hear from the seller and I'll update you on what he says.

Thanks for trying to help Kitedmon I appreciate it

Sorry it wasn't more useful. proping up the top strip might solve the problem but it is a guess, not knowing the exact cause would make me crazy (er) A second thought perhaps you will indulge me place a towel on the top of the rack and see if that changes the temps in the top shelf.

Quote:

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Originally Posted by kitedemon

Sorry it wasn't more useful. proping up the top strip might solve the problem but it is a guess, not knowing the exact cause would make me crazy (er) A second thought perhaps you will indulge me place a towel on the top of the rack and see if that changes the temps in the top shelf.

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Took your advice with the towel, we'll see how it goes.

I also added some aspen into one of the top tubs. It was reading 87-89 hot spot, and after 30 min with the little bit of aspen in there, the temps are now 92 at some points! but still around 88 on most of the hot side. The tub next to it, also on the top shelf, has no aspen inside, and is still reading 87-88, so maybe the aspen is helping keep the heat a bit better?

The towel might help too, but how would I insulate the bottom shelf? Put a towel under the entire rack? Would the towels be a fire hazard? I dont have a failsafe t-stat at the moment like you suggested to me in the past.

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..

Quote:

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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!

Quote:

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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....