Flex Watt Mfg says NO to foil/aluminum tape

[stevek123]

Lots of us use it.

I spoke to the Mfg today and the fellow there said you are asking for trouble if you use it. Ever get shocked? He said that's why. He cautioned to not use it even to secure the flex watt sides, and to forget about using it under or on top of the heat tape. He recommends using plain old duck tape.

So I'm curious as to what "others" here use under their flexwatt tape, to secure the sides of their flexwatt tape, and on top of the flexwatt tape (if anything).

Want to reflect as much heat upwards toward your tubs?.....The Mfg says using a foil tape on the bottom creats a "heat sink" and actually draws heat downward to be absorbed to whatever the tape is attached to. He recommended using a sheet of rigid insulation (like blueboard) that is made not to absorb heat.

[RobNJ]

I use duct tape to keep mine in place.

[stevek123]

Robert any issues with it wearing out from the tubs going over it?
Do you cover the top of the tape with it?
Have you ever tried to remove it from the tape and is it a sticky mess?

Thanks for the reply.

[Snake-Queen]

I am also interested in the answer to the stickiness of the duck tape and the durability of it. I am going to be adding racks to my building (when it is done) and will need to secure the flex watt.

[MrBig]

I prefer Kevlar tape, its used in manufacturing and is extremely slippery. Doesn't leave sticky residue, and has nice hold.

[Double B Reptiles]

The foil shouldn't matter as long as you arent touching the leads of the tape, or have it over the top of the middle part of the tape (where the conductors are). If it is touching the leads, you would essentially be creating a giant electrical conductor. You might as well stick your fingers into a light socket lol. As long as your connectors are well insulated and you watch the friction over the top of the heat tape, you shouldnt have a problem with the foil tape being used to hold your flex watt in place.

sources: 5 years experience as an electronics technician and am going for my Bachelors in electronic engineering.

[Snake-Queen]

I prefer Kevlar tape, its used in manufacturing and is extremely slippery. Doesn't leave sticky residue, and has nice hold.
Available at Lowes? Home Depot?


The foil shouldn't matter as long as you arent touching the leads of the tape, or have it over the top of the middle part of the tape (where the conductors are). If it is touching the leads, you would essentially be creating a giant electrical conductor. You might as well stick your fingers into a light socket lol. As long as your connectors are well insulated and you watch the friction over the top of the heat tape, you shouldnt have a problem with the foil tape being used to hold your flex watt in place.

sources: 5 years experience as an electronics technician and am going for my Bachelors in electronic engineering.

Would it create a heat pocket though?

[Double B Reptiles]

Available at Lowes? Home Depot?




Would it create a heat pocket though?

Melissa, I am not exactly sure what you mean by a heat pocket? If you arent touching the conductors (anywhere from the metal lines on the outside, to the black lines on the inside), there is no way that the heat is going to transfer from the heat tape to the foil tape. I think what the guys at flex watt are trying to say is that when you put foil tape on the bottom, you will essentially be creating a heat sink, which is used to dissipate heat. You don't exactly want to be focusing all of the heat on the bottom of the heat tape right? You want it on the top, where your tub is. Putting foil on top of your heat tape could be beneficial because you would get better heat transfer to your tubs, however it could be a potential danger if you cause a bunch of friction and rub the heat tape down to the conductors. It would turn your heat tape and foil tape into one giant electrical conductor, if any part of the foil tape was touching the conductor of the heat tape, that is. If you keep the foil tape on the outside, and touching plastic only, you wouldnt have any issues. Then use electrical tape to insulate the connectors and tape the ends down. Can you please explain what you mean by heat pocket though?

[Snake-Queen]

Wouldn't using foil tape, create hotter spots where the tape is? When I think of foil, I think of cooking... shiny side reflect heat back and dull side absorbs the heat and diffuses it.

I know it sounds kind of stupid, but I have never used heat tape, most of my snake enclosures have radiant heat panels & I use basking lights for my dragons. Please bear with me. :D

[Double B Reptiles]

Wouldn't using foil tape, create hotter spots where the tape is? When I think of foil, I think of cooking... shiny side reflect heat back and dull side absorbs the heat and diffuses it.

I know it sounds kind of stupid, but I have never used heat tape, most of my snake enclosures have radiant heat panels & I use basking lights for my dragons. Please bear with me. :D

No you are fine, don't worry :thumbsup:. If you arent touching the conductor of the heat tape with the foil tape, it would be next to impossible for the heat to transfer in the foil tape, except for the radiated heat that comes off from the tape, which wouldnt be much. The main type of heat that you are trying to get out of heat tape is conductive heat, which is why you have the heat tape touching the tubs in a rack system. If the foil tape is not directly touching the conductors on the heat tape, there will be little to no conductive heat transfer, which would mean that you couldn't create hot spots. Is some of the foil tape going to be affected by the radiated heat off of the tape, yes. Is it going to be in temperature spikes of 10+ degrees, no. You may have a spike of somewhere around a couple of degrees. If you touch the plastic edges of flex watt, you will notice it doesnt get anywhere near as warm as the center conductors. This is because metal is an excellent conductor of heat, and plastic is relatively poor at conducting heat. Hence why we insulate houses with fiber glass and styrafoam. Generally speaking, if it is a poor electrical conductor, it is a poor heat conductor. Vice versa. Good heat conductor, good electrical conductor.

[Double B Reptiles]

Radiant heat panels are fairly different from heat tape in that aspect. They use radiated heat, rather than conductive heat if I am not mistaken, hence the name radiant heat panel. Then there is heat convection, which is what many of us use for our incubators when we install DC fans to spread the air around. Head dispersal by flow of liquids (air included) is convection.

[RobNJ]

Robert any issues with it wearing out from the tubs going over it?
Do you cover the top of the tape with it?
Have you ever tried to remove it from the tape and is it a sticky mess?

Thanks for the reply.

The heat I use duct tape on is back heat, so no issue with wear. I did cover the top of the tape with it, no problem there. I have not tried to remove it, but I'm sure when I do it will be a sticky mess...though the sticky mess should be easy to clean off melamine when the time comes.

[stevek123]

Mike do you put the kevlar tape on the bottom of the flex watt and over the top, or just to hold the flexwatt down on the sides?

[Snake-Queen]

Thanks!

No you are fine, don't worry :thumbsup:. If you arent touching the conductor of the heat tape with the foil tape, it would be next to impossible for the heat to transfer in the foil tape, except for the radiated heat that comes off from the tape, which wouldnt be much. The main type of heat that you are trying to get out of heat tape is conductive heat, which is why you have the heat tape touching the tubs in a rack system. If the foil tape is not directly touching the conductors on the heat tape, there will be little to no conductive heat transfer, which would mean that you couldn't create hot spots. Is some of the foil tape going to be affected by the radiated heat off of the tape, yes. Is it going to be in temperature spikes of 10+ degrees, no. You may have a spike of somewhere around a couple of degrees. If you touch the plastic edges of flex watt, you will notice it doesnt get anywhere near as warm as the center conductors. This is because metal is an excellent conductor of heat, and plastic is relatively poor at conducting heat. Hence why we insulate houses with fiber glass and styrafoam. Generally speaking, if it is a poor electrical conductor, it is a poor heat conductor. Vice versa. Good heat conductor, good electrical conductor.

[Focal]

My tubs slide across flexwatt and aluminum tape every day. It hasn't worn in the last couple years and only produces a light lead colored dust that easily wipes away. This dust does not appear to come from wear. Aluminum tape doesn't leave a residue behind when removed and is more dependable with temperature fluctuations. Duct tape will decay over time and dry out unfortunately, which is weird because its the worst thing to use on ducts.

If you install your flexwatt correctly, you will not be shocked. Everytime you use a piece of heat tape, there are four connections you have to seal, two for the wires and the two on the opposite end where you cut it.

[Focal]

So I'm curious as to what "others" here use under their flexwatt tape, to secure the sides of their flexwatt tape, and on top of the flexwatt tape (if anything).

Want to reflect as much heat upwards toward your tubs?.....The Mfg says using a foil tape on the bottom creats a "heat sink" and actually draws heat downward to be absorbed to whatever the tape is attached to. He recommended using a sheet of rigid insulation (like blueboard) that is made not to absorb heat.

Missed this part, the only thing under my flexwatt is melamine. The fact that heat rises and often takes a path of least resistance, it rises just fine.

I use the aluminum tape on the three sides that do not have the wires. It's just my theory, but I think letting it breathe will reduce hot spots and help the heat rise rather than heat the shelf. When it's taped flat against a surface, it can't help but to directly transfer the heat below, at least to some extent. Allowing a vent on one side seems to keep the shelf cooler.

Nothing goes on top of the heat tape. With proper periodic inspections, it should be fine a long time with tubs rubbing on it. I examine mine once a month.

[hhmoore]

*Off topic - duct tape is a name that was adopted over time...the original name of the product was duck tape. Today, you can find products labeled either way.

If we're going to go with what the manufacturer says (I've just been waiting for a chance to point this out, lol, but haven't wanted to start a new thread to do it) Calorique heat tapes should not be placed vertically (think back heat). That bit of info is listed somewhere on their website - the warning about foil tape is there, as well - I think it was in the section about floor warming.

[Gloryhound]

I've previously used Aluminum tape on flex watt. I just made sure the cut ends were electrically insulated before covering them. I was never shocked by my flex Watt.

Here is a question: What is the difference between a layer of aluminum tape on the flex-watt compared with it being glued to Galvanized steel panels like the heating elements in professional rack systems like Freedom Breeder and ARS.

[Focal]

One other thing I have done, which has signifigantly increased the heat in the tubs on a back heat setup, is made an aluminum frame for 4" heat tape (5"x48"x1") and taped the heat tape to one side and bought 1" thick insulation board. I cut and packed this into the frame I built and sealed with aluminum tape. This was great for redirecting the heat towards the tub.

[stevek123]

So Nick, you're flexwatt is sandwiched between aluminum and insulation board?

[MrBig]

Steve, I only use the kevlar tape on top of the Flexwatt. I don't place anything under the heat tape, don't see anything to be gained by more tape underneath.

[stevek123]

Hi Mike, The comment was addressed to Nick.

Kevlar Tape is not an easy thing to find in Vermont.

[MrBig]

Mike do you put the kevlar tape on the bottom of the flex watt and over the top, or just to hold the flexwatt down on the sides?

It was in response to this. I don't think it's easy to get anywhere. I ordered mine from Grainger.

[Matt2979]

I've always use foil tape to secure all of my Flex Watt heat tape, and never had an issue. Of course I insulate the connectors on one end, and the other end I use electrical tape to ensure there is no exposed wiring where I cut the heat tape (even the tiniest exposed hot wire would electrify foil tape). Once I'm sure it's all insulated, foil tape goes on to secure it to my rack.

[RonzRoyalz]

Ain't flexwatt tape covered with a sheet of plastic on both sides? That's why we have to scratch the plastic off the section that we solder to. So if it's completely covered in plastic and you tape up both ends with electrical tape, throw some duct tape on the bottom of homemade HD racks and cover the top with foil tape. What can go wrong? Right now mine has foil on both top and bottom, but am putting painters tape on the bottom and try foil just on the edges to see if my humming goes away. But still it's completely covered in plastic so why would it humm with the foil tape. I'm using their pinch connectors by the way. My soldering sucks. And I used to be a cert. welder in the Navy.

[Matt2979]

Ain't flexwatt tape covered with a sheet of plastic on both sides?

It is covered in plastic; however, when you cut it to the desired length, you expose the very edge. This is what I cover with electrical tape, just to make sure it does not come in contact with the foil/aluminum tape.

[AbsoluteApril]

I use Aluminum/foil tape but only on the edge of the sides to secure it in place (not over the flex, just the very clear edge). I run heat up the back on racks, I don't put anything on the other side. I didn't think we could use duct tape.

[Snake-Queen]

So basically, the message was for "idiots", like the warning on McDs coffee... caution HOT.
:rolleyes_

[Focal]

So Nick, you're flexwatt is sandwiched between aluminum and insulation board?

Sorta. Imagine a picture frame, but made out of aluminum, and the heat tape is the picture. The insulation is like the little carboard that holds the picture to the front of the frame. I'll try to snap some pictures tonight.

[edf01]

I use duct tape. I do eventually have to re tape the flexwat down with new pieces. Yes, it does leave some sticky residue- but I just put the tape back over that spot. Some tubs don't pull out so easily if the tape becomes dislodged, and yes, its a pain in the butt, but re-taping it usually fixes it. Its usually just a problem for the slots that are a smidge tight ( my racks went through a few moves). But other then that- it works. I try to just tape the edges...

[R. Eventide]

No you are fine, don't worry :thumbsup:. If you arent touching the conductor of the heat tape with the foil tape, it would be next to impossible for the heat to transfer in the foil tape, except for the radiated heat that comes off from the tape, which wouldnt be much. The main type of heat that you are trying to get out of heat tape is conductive heat, which is why you have the heat tape touching the tubs in a rack system. If the foil tape is not directly touching the conductors on the heat tape, there will be little to no conductive heat transfer, which would mean that you couldn't create hot spots. Is some of the foil tape going to be affected by the radiated heat off of the tape, yes. Is it going to be in temperature spikes of 10+ degrees, no. You may have a spike of somewhere around a couple of degrees. If you touch the plastic edges of flex watt, you will notice it doesnt get anywhere near as warm as the center conductors. This is because metal is an excellent conductor of heat, and plastic is relatively poor at conducting heat. Hence why we insulate houses with fiber glass and styrafoam. Generally speaking, if it is a poor electrical conductor, it is a poor heat conductor. Vice versa. Good heat conductor, good electrical conductor.

:iagree: This. Aluminum tape is conductive, so if putting aluminum tape on the heat tape shocks you, wouldn't the heat tape by itself shock you too? ;)

The fact that heat rises and often takes a path of least resistance, it rises just fine.

Incorrect. Hot air rises. Heat moves from areas of higher temperature to areas of lower temperature.

---

The main problems with heat tape are (1) what others have already mentioned about covering the conductive ends after cutting it and (2) to be sure that the tape can "breathe"--i.e., it isn't set up in a way that causes excessive heat buildup (the tape can't dissipate excess heat).

For example, I have metal racks with heat tape completely covered in foil tape. Foil tape is a conductor, which is the reason why it's good to use on heat tape. You want to heat the bin, not just the tape! (Isn't duct tape more of an insulator, by the way?) The metal shelves are not solid, and there's a gap between the bottom of one shelf and the lid of the tub underneath. This allows several pathways (tub, shelf, air) for any excess heat to dissipate.

EDIT: The reason I put aluminum tape on top of the heat tape is to decrease the chance of damaging the Flexwatt itself (damaged heat tape is a fire hazard). If any damage occurs, it will happen to the aluminum tape first, making damage easy to see and easy to repair.

---

Radiant heat panels (and ceramic heat emitters) emit infrared light (IR). This is different from heat tape, which is used to transfer heat (kinetic energy of the molecules) from one object to another through conduction. (Though, the heat tape--well, everything in the setup, including you!--also emits IR.) Brendan probably said it better, though. :)

[MrBig]

Krystal, I have to disagree. Metal Duct tape works by keeping heat/cold from passing through the tape and reflects heat/cold away with the reflective side. So you are actually causing more heat build up by completely covering the tape. As to the breathing, you said Heat moves from areas of higher temperature to areas of lower temperature, so if the tub is cooler the the surroundings this is where the heat will transfer to. You shouldn't get heat "buildup" as your thermo should regulate it that it stays within the target temp.

[Double B Reptiles]

:iagree: This. Aluminum tape is conductive, so if putting aluminum tape on the heat tape shocks you, wouldn't the heat tape by itself shock you too? ;)



Incorrect. Hot air rises. Heat moves from areas of higher temperature to areas of lower temperature.

---

The main problems with heat tape are (1) what others have already mentioned about covering the conductive ends after cutting it and (2) to be sure that the tape can "breathe"--i.e., it isn't set up in a way that causes excessive heat buildup (the tape can't dissipate excess heat).

For example, I have metal racks with heat tape completely covered in foil tape. Foil tape is a conductor, which is the reason why it's good to use on heat tape. You want to heat the bin, not just the tape! (Isn't duct tape more of an insulator, by the way?) The metal shelves are not solid, and there's a gap between the bottom of one shelf and the lid of the tub underneath. This allows several pathways (tub, shelf, air) for any excess heat to dissipate.

EDIT: The reason I put aluminum tape on top of the heat tape is to decrease the chance of damaging the Flexwatt itself (damaged heat tape is a fire hazard). If any damage occurs, it will happen to the aluminum tape first, making damage easy to see and easy to repair.

---

Radiant heat panels (and ceramic heat emitters) emit infrared light (IR). This is different from heat tape, which is used to transfer heat (kinetic energy of the molecules) from one object to another through conduction. (Though, the heat tape--well, everything in the setup, including you!--also emits IR.) Brendan probably said it better, though. :)

Yes exactly the aluminum tape is a conductor. Not an insulator. The duct tape is a non-metal synthetic material, therefore it is an insulator. Duct tape would actually create a hot spot, as well as be a fire hazard, and also keep a lot of the heat from getting to your tubs. That goes for the kevlar as well, as kevlar is also a synthetic non metal material. You have to think of physics in this case, as you are working with heat and electricity. If you have no concept of physics, in this case you would be working blindly. Not trying to be rude or anything, but it is the truth. If you just use the duct tape to hold the plastic edges, that is fine, but otherwise it is potentially dangerous and could cause a fire if it covers the black heating elements when a thermostat fails. Aluminum tape cannot be set on fire (at least by standards of just being plugged into the wall, and also doesnt create hot spots, reflect heat, or cause any of the previously mentioned issues that duct tape or any non conductive material tape. Just make sure you dont

[stevek123]

Brendan, Here's the number for The flex watt mfg (800 922-9276) they are in MA.
Ask for Jim he's one of the teck guys there. You seem to be a Physics guru of sorts so it would be a good conversation. Jim suggested using duct tape (top and bottom), and strongly advises against using aluminum tape at all and I think he said using aluminum tape WOULD cause hot spots. If it's not too much trouble I'd like to see a post here, and I'm sure others would also, on the outcome of your conversation.

If I understand your comment correctly using an under laying base of rigid blue board insulation would trap heat and be dangerous. Jim recommended it under the tape to help direct heat upwards. I was planning to do this on my next build, as well as use a underlying layer of heat resistant poly tape on top of it.

[R. Eventide]

Krystal, I have to disagree. Metal Duct tape works by keeping heat/cold from passing through the tape and reflects heat/cold away with the reflective side. So you are actually causing more heat build up by completely covering the tape. As to the breathing, you said Heat moves from areas of higher temperature to areas of lower temperature, so if the tub is cooler the the surroundings this is where the heat will transfer to. You shouldn't get heat "buildup" as your thermo should regulate it that it stays within the target temp.

"Metal duct tape"? I can't say I've ever heard of that. Doesn't mean it doesn't exist, of course, but I was not referring to any type of metal duct tape in my post.

If metal duct tape works by keeping heat/cold from passing through, then it's an insulator. (Aluminum tape is metallic--it is a conductor--and it is most definitely not a type of duct tape.) Shiny material reflecting light (it doesn't reflect "heat," in the colloquial use of the term) has pretty much nothing to do with what we're talking about here. Shiny surfaces reflect both visible light and IR, but that has nothing to do with a heat source underneath it. Actually, dark material radiates heat (IR) faster than lighter material. (EDIT: Nifty useless facts! This is why telescope domes are white or shiny. When observing, we want the air around the telescope to be as still as possible so as not to distort our images. A dark dome would radiate the heat it built up during the day like crazy, causing a crapton of turbulence just beyond the telescope itself! Not good! This is also why we temperature-regulate large telescope mirrors as well: we want the temp of the mirror to be the same as the temp of the air directly above it. End nifty useless facts!)

Whether the heat from the tape transfers more quickly to the tub or the shelf depends on what material the tub and shelf are made of. If the shelf is made of a material that conducts heat better than the tub, then more of the heat will be lost to the shelf. Though, if you're using an enclosed rack unit with the heat in the back, this will help heat up both that shelf and the one below it (since the shelf is warming), so technically, you're not "losing" or wasting the heat.

Thermostats can only regulate the temperature where the probe is placed. If the probe is placed at one end of a span of heat tape, one can still get hot spots. The heat tape is basically a big resistor, so a heat buildup at one end of the tape will not spread equally throughout the length of the tape. That hotter section will remain hot, unbeknownst to the probe at the other end.

[CornNut]

What was the concern with a vertical installation? I currently use 11" heat tape in a back heat configuration (stapled by the edges to osb). I want to replace the tape and am trying to think of a material to attach it to and possibly sandwich it between that would be:

1. non electrically conductive
2. non flamable
3. good heat conductor
4. good heat sink
5. rigid, durable, and portable

I have lots (like 9 inches) of insulation behind the back of the shelves and about 35 square feet to cover. The heat tape will not be under all the area but I would like a material that would spread the heat out and have some capacity to store heat in case of a power outage. I also need to be able to take the heat system out and move it without damage as I periodically break this snake room down and move it.

Was thinking of maybe sandwiching the heat tape between two layers of melamine even though it's relatively expensive, very heavy, and I'm thinking not entirely fireproof in spite of all the nitrogen. Is there some sort of large format (at least 4' X 2') tile or tile backer board product that would also conduct and store heat well and not be totally fragile (I've pretty much excluded glass for that reason)?

[MrBig]

You can only enhance the chances of creating hotspots by completely covering the heat tape in metallic duct tape. This is sold for the purpose of sealing joints in metal ductwork, hence me calling it metal duct tape.

[R. Eventide]

What was the concern with a vertical installation?

I don't know. I was wondering about that too. Electricity/resistance doesn't care what orientation it's in....

As for the rest, I don't know what materials to use off the top of my head. You should be able to find heat capacity, conductance, etc. for most synthetic material online, I would think. It'll probably just take some research on different kinds of material to see what would be best. Maybe make up a spreadsheet with properties and pros/cons of different things--should make it easier to compare.

You can only enhance the chances of creating hotspots by completely covering the heat tape in metallic duct tape. This is sold for the purpose of sealing joints in metal ductwork, hence me calling it metal duct tape.

Okay, I will ask again: What is this metallic duct tape? You say it's used for metal ductwork, but this tells me absolutely nothing about the tape itself. Is it actually metal or is it just shiny? What else is it made of? What kind of ductwork is it for? From my limited experience with ductwork, most ductwork I've seen is for transporting air, so there's no reason why tape for sealing ductwork joints would need to actually be made of metal (unless there's no other way to make it blend in with the ductwork itself).

Also, I repeat: What does metallic duct tape have to do with this thread? No one here has mentioned using metallic duct tape, as far as I remember. We're talking about normal duct tape, Al tape, and some type of kevlar tape.

EDIT: Wait, are you referring to Al tape as "metal duct tape," for some strange reason?

[stevek123]

I have seen a "metallic" duct tape and the standard grey duct tape in hardware stores. Both made by the Duck tape mfg. I never bought the "metallic" duct tape, and so I can't say it's really metallic like the aluminum foil tape or not. It does exist though.

[MrBig]

It is the only tape allowed by universal building code, to be used to seal duct work from leaks. It is reinforced with fibers like grey duct tape. Like alluminum tape it does have a slight insulating factor, as well as being an electrical conductor. Alluminum tape is simply the cheap version of the tape I'm referring to. Being a certified HVAC/R contractor, I'm well aware of how heat transfers, and the materials we are discussing. That being said, I used metallic tape over just the clear edges of flexwatt, I have since replaced it with the kevlar because of profile, ease of sliding, and durability. Given that I only cover a 1/4" of the clear plastic on the ends, I am not in anyway concerned about Kevlar being an insulator. I also cover all cut ends with electrical tape to avoid any issues.

As to why you need metal tape for ductwork, there are numerous reasons. First is that you loose significant amount of airflow and velocity and efficeincy when you don't seal joints. Second universal building code requires the use of it. Third, metal tape does not dry out and deteriorate at anywhere near the rate of grey or alluminum duct tape. I do not know the exact metals used to make said tape, only that it is significantly stronger then either of the other options. Blending in is of no concern when making or sealing ductwork, keeping hot/cool air in the ductwork until it reaches the desired location is the one and only reason for using tape or mastic to seal joints. It is used to seal all types of duct, from sheet metal, to duct board, to spiral. Hope this answers any questions you have, and again i reccommend that you don't cover your complete heating surface as you are only asking for trouble in doing so with no real advantage.

[Focal]

So Nick, you're flexwatt is sandwiched between aluminum and insulation board?

A little late on this, but this is what it looks like:

http://img.photobucket.com/albums/v93/focalx/9cbe971d.jpg

http://img.photobucket.com/albums/v93/focalx/ff676a81.jpg

[stevek123]

Nick, what kind of insulation board/material is between the heat tape and foil tape on the back? This set-up is similar to what the mfg. suggested to me. Blue board on the underside of the heat tape to keep the heat from being absorbed on the side away from the tubs.

[R. Eventide]

It is the only tape allowed by universal building code, to be used to seal duct work from leaks. It is reinforced with fibers like grey duct tape. Like alluminum tape it does have a slight insulating factor, as well as being an electrical conductor. Alluminum tape is simply the cheap version of the tape I'm referring to. Being a certified HVAC/R contractor, I'm well aware of how heat transfers, and the materials we are discussing. That being said, I used metallic tape over just the clear edges of flexwatt, I have since replaced it with the kevlar because of profile, ease of sliding, and durability. Given that I only cover a 1/4" of the clear plastic on the ends, I am not in anyway concerned about Kevlar being an insulator. I also cover all cut ends with electrical tape to avoid any issues.

Ah, I see! Nifty.

Yeah, I don't see a problem with kevlar tape if you're only covering the edges.

As to why you need metal tape for ductwork, there are numerous reasons. First is that you loose significant amount of airflow and velocity and efficeincy when you don't seal joints. Second universal building code requires the use of it. Third, metal tape does not dry out and deteriorate at anywhere near the rate of grey or alluminum duct tape. I do not know the exact metals used to make said tape, only that it is significantly stronger then either of the other options. Blending in is of no concern when making or sealing ductwork, keeping hot/cool air in the ductwork until it reaches the desired location is the one and only reason for using tape or mastic to seal joints. It is used to seal all types of duct, from sheet metal, to duct board, to spiral. Hope this answers any questions you have, and again i reccommend that you don't cover your complete heating surface as you are only asking for trouble in doing so with no real advantage.

First reason: That's why one tapes the ducts, not a reason for using a specific type of tape.

But yep, that does answer some of the questions I have! Thanks!

I still disagree on covering the heat tape with Al tape, but...well...we may never agree on that. :) Given the tape's high conductance, there is no physical reason I can think of as to why covering Flexwatt with it would create hot spots or similar heating problems. (Do you have a reason as to why you think it's a problem?)

Plus, there are definitely real advantages: it protects the heat tape from damage. Flexwatt is protected by the plastic covering, but I don't know how long it lasts when sliding tubs over it constantly. (And until someone does a rub test, that will remain unknown.) With that in mind, I prefer to add extra protection. Perhaps it is unnecessary, but I would rather the Flexwatt have extra protection than not enough.

[CornNut]

In my incubator I sandwich a 12" section of 11" heat tape between two large ceramic tiles. My thinking is that they are such good heat conductors that they even the heat out and prevent hot spots and of course do a great job of holding the tape in place. Also, there is some heat sink characteristic keeping my incubator a little warmer after a quick check on the eggs. I just can't think of any such material for the back of my rack though.

[Focal]

Nick, what kind of insulation board/material is between the heat tape and foil tape on the back? This set-up is similar to what the mfg. suggested to me. Blue board on the underside of the heat tape to keep the heat from being absorbed on the side away from the tubs.

I'm not sure what type, but it's the kind you can cut and build boxes out of. It's yellow on one side, about an inch thick, and silver/aluminum tape-looking on the other side. It comes in a 4'x8' sheet I believe. It was left over from running some duct work in my house. I think we got it at home depot.

(And until someone does a rub test, that will remain unknown.)

I have helped local members change out their heat tape on expired racks. Depending on the setup, it will rub and wear, short and burn. The two and only instances that I have seen it rub, is on certain manufactured racks that have 3" heat tape zig-zaging left to right (then right to left) through all the shelves. The pre-made slots for the heat tape were about a 1/4" short and caused the center of the tape to bow upwards. I really wish I took pics, but yes, if it's not laid flat, it will rub through.

[RonzRoyalz]

In my incubator I sandwich a 12" section of 11" heat tape between two large ceramic tiles. My thinking is that they are such good heat conductors that they even the heat out and prevent hot spots and of course do a great job of holding the tape in place. Also, there is some heat sink characteristic keeping my incubator a little warmer after a quick check on the eggs. I just can't think of any such material for the back of my rack though.

Randy, can I see a couple pic's of your incubator setup? I just got a mini fridge and am gonna start gutting it today. Ron

[MrBig]

Krystal, thermal and electrical conductance are 2 very differant things. The AL tape has high electrical conductance, but not so much on thermal conductance. It will eventually heat to the temp of the material it is attached to, but not at the same rate as the material. This coupled with the fact that you most likely overlap it to some degree, can cause hot spots as some areas heat faster and hotter then other areas. If you run the tape so it is completely flat (or better yet recessed) then rubbing can be kept to a minimum. I would never cover the whole sheet, but if it's been working for you then good luck with it. As to why Uniform Building Code requires a specific type of tape, well it performs and lasts better then the other available options.
Nick the board you are reffering to is actually called duct board. It comes in varying thicknesses and has a high R-value. You place the foil side against the back of the heat tape?
Randy, other then simple mass to keep temps up (I prefer water bottles) I can't think of any benefit to using ceramic tiles. To me it's simply a larger load for your heating element. The only material I could think of that would be similiar would be Hardeebacker. It's a 1/" to 1/2" tile backing board, but I think that Nick's idea of duct board would be better.

[Focal]

Nick the board you are reffering to is actually called duct board. It comes in varying thicknesses and has a high R-value. You place the foil side against the back of the heat tape?

No, I put the raw material against the heat tape and the foil towards the rear. I did this because when we made the ducting box, we folded it so the foil was on the outside so I just kept that idea.

[stevek123]

I have two of those older racks where the heat tape bows upwards and rubs against the tubs. And from the constant rubbing its not a matter of "if the tape will fail, but when".

So what are my alternatives? Aluminum tape, plastic tape or duct tape over the flexwatt? Laying a thin sheet of vinyl on the top of the shelf over the flexwatt? Other? Thousands of these racks were sold and are in use out there.

[R. Eventide]

Krystal, thermal and electrical conductance are 2 very differant things. The AL tape has high electrical conductance, but not so much on thermal conductance. This coupled with the fact that you most likely overlap it to some degree, can cause hot spots as some areas heat faster and hotter then other areas.

I have been mostly referring to thermal conductance, not electrical conductance, since we're talking about heat, and Al tape is thermally conductive:
http://solutions.3m.com/wps/portal/3M/en_US/3M-SpecialtyTapes/SpcltyTape/ProdInfo/Spec6/AlumFoil425/

Plus, the tape is extremely thin, so any overlap will be insignificant in terms of causing hot spots.

[Double B Reptiles]

I have been mostly referring to thermal conductance, not electrical conductance, since we're talking about heat, and Al tape is thermally conductive:
http://solutions.3m.com/wps/portal/3M/en_US/3M-SpecialtyTapes/SpcltyTape/ProdInfo/Spec6/AlumFoil425/

Plus, the tape is extremely thin, so any overlap will be insignificant in terms of causing hot spots.

Couldn't have given better proof of this point. Good post Krystal!!! Everyone should read the info given in the link. All of the things listed by 3M are things we are looking to achieve by using heat tape in combo with aluminum tape. As stated in my earlier posts, just don't touch the electrical conductors with the aluminum tape, and you will be fine.

[CornNut]

I'm looking at a concrete board meant to go under tile to sandwich 11" heat tape between. It seems dense enough to be a good thermal conductor but I'm worried it might be impregnated with a lot of fiberglass for strength and be a better insulator than I think. Can't imagine it would conduct electricity though.

[stevek123]

Here's what I think is a partial solution. Got myself some plastic hardware cloth 1/2" grid. This can go on top of the heat tape and the tubs can slide over this. This doesn't solve the issue with the old style racks where the tape bows up. The tub height space btw tub top and the shelf above it are too small to allow the addition of this plastic hardware cloth under the tubs, at least on my rack.

[RonzRoyalz]

I'm an idiot. I like it simple. Can we use the aluminum tape under the heat tape and cover the entire heat tape on top except for the end where we connect the wires and the other end where we cover with electrical tape? Simple question, simple answer, yes or no, please. Thanks Ron

[Double B Reptiles]

I'm an idiot. I like it simple. Can we use the aluminum tape under the heat tape and cover the entire heat tape on top except for the end where we connect the wires and the other end where we cover with electrical tape? Simple question, simple answer, yes or no, please. Thanks Ron

Realistically, don't put it under your heat tape. It will cause a heat sink at the bottom. Putting it over the top you can also do, just watch for rub on the heat tape. Then yes make absolutely sure that the aluminum tape isn't touching the conductive leads, as well as insulating the ends with the plastic connector covers and electrical tape.

[RonzRoyalz]

Thanks Brendan, I had aluminum tape under and over, but not touching the ends. Because of all this, I put painter's tape under and on the edges of the top to hold it down. I'm gonna change the top back to a.t. without touching the ends. I didn't think anything was wrong with the way I had it, but reading everybody elses comments, I changed it.

[stevek123]

I hate just having the tubs slide over the flex watt on my old style racks where the flexwatt rubs against the sliding tubs. I can't help but think covering the flexwatt for protection with anything will trap heat. So is the general opinions here that aluminum tape on the top of the flex watt is OK, but below is not?

[Double B Reptiles]

I hate just having the tubs slide over the flex watt on my old style racks where the flexwatt rubs against the sliding tubs. I can't help but think covering the flexwatt for protection with anything will trap heat. So is the general opinions here that aluminum tape on the top of the flex watt is OK, but below is not?

Because of the high thermal conductivity of the aluminum tape, you would be drawing some of the heat out down to the bottom if you had the aluminum tape on the bottom. whereas if you just have it on top of the tape, you are creating a protective barrier from friction from the tubs, as well as creating a heat sink on top of the tape, which is where you want the heat to be right? Touching the tubs. Exactly. This is why it would be ok. Wood/melamine has a low thermal conductivity and would not create a heat sink on the bottom of the heat tape, whereas the aluminum tape is very thermally conductive and would most definitely create a heat sink.. To express the idea of what is more thermally conductive, stick these three objects into a cup of either boiling water or ice water

-a pencil (wood)
-a straw (plastic)
-a nail (metal)

make sure the tops of each are sticking completely out of the water so you can touch them with your fingers. let the objects sit in the water for a few minutes. you will find that object made of metal is going to be very close to the temperature of the temperature of the water itself. The wood and the plastic really wont be anywhere near the temperature of the water. you may feel some temperature change in them, but it wont be much, and this is because they are non thermally conductive materials. Metal is very much so thermally conductive (i.e. aluminum tape.)

[jchavez]

I always use foil tape and have never had a problem. just make sure were you attach the wires you wrap it in electrical tape. I put down the flex watt and completely cover it with foil tape, and it works great and saves your flex watt from wear. Just stop the foil tape short of the connections.

[stevek123]

yeah I always silver soder and tape my ends well.