Hey guys i have a little bit of a problem,

I built 3 racks each rack has 6 compartments and holds obviously 6 tubs one on top of the other. I used Melamine, and recessd my 4 inch heat tape 1/8 of an inch down and thumb tacked it down and it all sits perfectly recessd the tubs go right over top of the tape no problems. Each rack has its own thirteen foot piece of 4 inch heat tape which i weaved from level to level. I bought a new herpstat 4 and each rack gets a probe i placed the probe inside of the top tub directly on top of the tape (hot spot). Set my thermostat to 88 and it reaches that temperature perfectly within 10 minutes. I plugged it in and here is where the problem lies. About an hour later i went through my tubs and all were temperatures between 95-101! The display on the thermostate says that its reaching 88 perfectly.

Anyone have any idea's why my tubs are getting so hot. Each level of the rack is identical, with the tape recessed. Im completely stumped on why my lower levels are hotter then my setpoint. IF anything it should be the other way around.

If anyone can give information on why this is happening it would be appreciated!

THanks guys!

Is your thermostat kicking off? Usually the thermometers have a way to set a range so that once the probe hits a certain temp. it kicks off, then comes back on once the probe falls to another set point. Could it just be as simple as having the herpstat set wrong?
How did you get the reading of 95-105? If the temp probe is reading 88 when it is actually 105, then the temp probe has to be faulty.

Not sure. What thermometer are you using to measure the 95-101 degree temps? Are you sure that is accurate? Is there some air circulation.
Mine usually is the opposite. I have the temp set a few degrees higher to get the temp in tub that I want.
Are you using the proportional heat? Do you have a night drop set on it?
I didn't realize I had the night drop set at first and my clock was not correct and my temps were flucuated during the day.

Until you figure it out, just set your temp at 78-80.

Im using a PE2 to measure the temperature!

I don't set my hermostat to a few degrees higher because the top tub of each rack i leave empty and have the probe taped down directly on the hot spot inside the tub. Its literally in the tub directly overtop of the heat tape.

I thought it could be a bad probe but all 3 of them??? Also i took them and held them in my hand and under my arm and they went up and down in temp and appeared to be in good working order.

I have it all turned off right now, i just have my room temp set to 85 for today, when i get home from work i plan on going through everything, making sure the probe is not slightly lifted up or anything and double check to make sure its directly over the hot spots on each rack and try it again.

I will also reset my herpstat and set all the settings from the beginning!!

The wood is insulating the tubs. I bet if you put some holes in the sides of the tubs they wouldnt get that hot.

Try setting the thermostat 5 degrees cooler and see what happens.

I would take the probe out of the tubs.
I put my probes on top of the heat source. (aluminum tape works great)
Try the side next to the tub.

Your Herpastat is a proportional thermostat.
It doesn't go on and off. It turns it's self up and down.

I would bet your probe just isn't reading your heat tape, but is reading the air above it.

Am I misunderstanding or are you saying that your temp probe is reading 88 in the exact same spot your PE2 is reading 105? If that's the case, it shouldn't matter where the probe is, it's defective, right?
Also if the wood was insulating the tubs, then the thermostat should turn itself down accordingly (I didn't realize that one didn't go off and on). Or is the herpstat incapable of going all the way off if it needs to? That seems like it would be a design flaw.

I would take the probe out of the tubs.
I put my probes on top of the heat source. (aluminum tape works great)
Try the side next to the tub.

Your Herpastat is a proportional thermostat.
It doesn't go on and off. It turns it's self up and down.

I would bet your probe just isn't reading your heat tape, but is reading the air above it.


Hes not using a Herpstat he is using a RBI VE-100 which is an on-off thermostat. THat model doesnt have the proportional or pulse mode(s).

Hey guys i have a little bit of a problem,

I built 3 racks each rack has 6 compartments and holds obviously 6 tubs one on top of the other. I used Melamine, and recessd my 4 inch heat tape 1/8 of an inch down and thumb tacked it down and it all sits perfectly recessd the tubs go right over top of the tape no problems. Each rack has its own thirteen foot piece of 4 inch heat tape which i weaved from level to level. I bought a new herpstat 4 and each rack gets a probe i placed the probe inside of the top tub directly on top of the tape (hot spot). Set my thermostat to 88 and it reaches that temperature perfectly within 10 minutes. I plugged it in and here is where the problem lies. About an hour later i went through my tubs and all were temperatures between 95-101! The display on the thermostate says that its reaching 88 perfectly.

Anyone have any idea's why my tubs are getting so hot. Each level of the rack is identical, with the tape recessed. Im completely stumped on why my lower levels are hotter then my setpoint. IF anything it should be the other way around.

If anyone can give information on why this is happening it would be appreciated!

THanks guys!

Hes not using a Herpstat he is using a RBI VE-100 which is an on-off thermostat. THat model doesnt have the proportional or pulse mode(s).

http://spyderrobotics.com/products/herpstat4_manual.pdf
Thank you for choosing the Herpstat 4 digital proportional thermostat. This product
offers the following features:
• Four output proportional heating constantly monitors and adjusts amount of heat necessary to
maintain a target temperature (usable range from 40°F to 150°F or 4°C to 65°C).

tape the probe to the tape....

Sorry my mistake. I misread his second post and thought It read VE. Again sorry.

I agree with Buckskin and BigDog, the probe needs to be on the tape. I route a groove under my heat tape, but taping the probe to the heat tape works too. You will probably have to adjust your sensor matching (SM) in the Herpstat 4 once you get everything to settle down. Mine is usually off by about 3 to 4 degrees when I measure the temp inside the tub.

Hes not using a Herpstat he is using a RBI VE-100 which is an on-off thermostat. THat model doesnt have the proportional or pulse mode(s).

I am using a herpstat, its the new herpstat its called the herpstat 4, i got it because it can run 4 racks by itself, has a night time drop built in and most importantly Spyder Robotics added a new safety feature where if anything goes wrong, mechanically, probe malfunction, temp over 110 degree it automatically shuts off all power.

I double checked everything last night and reset the machine and reset my temps and programs and it seems to be right on the money. Im very pleased, im home for the next 2 days so i can keep an eye on it.

Thank you to everyone who replyed, this is a very inviting forum and people are always trying to help each other, much appreciated! Thank you!