# Heat cord inconsistency



## Karnyge (Mar 18, 2014)

Hey guys,
I recently changed over to heat cord, I made some groves in a sheet of MDF around 2cm apart wide enough and deep enough for the cord to sit flush with the board, not tight, perfect fit. I originally had a 2m 15w reptile one cord, and made the length of the board and grooves long enough to make 4 runs of the cable, I then placed aluminum tape over the cable, I made one groove a bit deeper and long enough so I could slide the thermostat probe underneath the heat cord. I had two 7l Stiema tubs siting on the tape which had dual thermometers to monitor the hot and cool ends, it was very difficult to maintain identical temps most of time, the tub on the left would be hotter than the tub on the right, sometimes it was hard to maintain a high enough temp in the right tub, I put this down to the the cable length.

While at SOFAR, I purchased a new heat cord, this time 25w 4m, I'm still getting inconsistencies, I've been testing a tub with two probes at the hot end, they have been degrees apart, Ive also tested with a heat gun some spots at the hot end are reading 35 while the thermometers read 32, obviously the heat gun may not be 100% accurate. I've now put a couple of tiles over the aluminum tape, the temps seem a bit more consistent, but when using the heat gun on the tiles they read different temps all over, ranging from 30 -37, I put this down to cool drafts etc. I have the thermostat set to 36 - 38 degrees. Any one have any ideas how to get more consistent temps across the board so I can run two click clacks on the same cord. 

Cheers.


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## GeckoJosh (Mar 18, 2014)

Try putting the thermostat probe inside the tub


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## 86JAP (Mar 18, 2014)

GeckoJosh said:


> Try putting the thermostat probe inside the tub



+1

You want to regulate the temps in the tubs not under them.


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## Karnyge (Mar 18, 2014)

86JAP said:


> +1
> 
> You want to regulate the temps in the tubs not under them.



I was trying to avoid putting the probe in the tub, as its a long metal one with a sharp end, is the heat different at the end of the cable compared to the beginning?


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## 86JAP (Mar 18, 2014)

It should be consistent all the way along, you can stretch it out and plug it in and check it at various points along the length to make sure. You should be able to run a file over the sharp end to smooth it off, if it is the type in thinking of the sensor part should be in the body of the probe just don't go crazy with the file.


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## Rogue5861 (Mar 18, 2014)

What sort of thermostat are you running? It will get pretty solid temps running a dimming or pulse thermostat. Having a heat soak works well but i think you have the cord to close to each other, most people run them every 40-50mm depending on how much heat they need.


Rick


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## Karnyge (Mar 18, 2014)

Rogue5861 said:


> What sort of thermostat are you running? It will get pretty solid temps running a dimming or pulse thermostat. Having a heat soak works well but i think you have the cord to close to each other, most people run them every 40-50mm depending on how much heat they need.
> 
> 
> Rick



Can't remember the make now, no markings,










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## Rogue5861 (Mar 18, 2014)

I would replace with a dimming or pulse thermostat, you should get a more stable temp.


Rick


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## The_Geeza (Mar 18, 2014)

Throw it


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## pharskie (Mar 18, 2014)

You can get decent dimming thermostats with separate light controls and day/night functions for less than 80 bucks.


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## GeckoJosh (Mar 18, 2014)

Even one of the $10 ones from HongKong of Ebay would be better than that


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## Karnyge (Mar 18, 2014)

it's worked well with the heat mat, just not for what I'm trying to achieve now, thanks for the help guys I'll have a look around for what was recommended.

cheers.


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## AllThingsReptile (Mar 19, 2014)

Karnyge said:


> Can't remember the make now, no markings,
> 
> 
> 
> ...



I had one of those, they're sold at almost every pet shop I've been to for $100+….
They don't work too great!


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## Rogue5861 (Mar 19, 2014)

AllThingsReptile said:


> I had one of those, they're sold at almost every pet shop I've been to for $100+….
> They don't work too great!



They are a thermostat suited to a fridge, not for direct heating devices but ambient temperature control.


Rick


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## Karnyge (Mar 19, 2014)

From memory I paid around 70

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## AllThingsReptile (Mar 19, 2014)

Rogue5861 said:


> They are a thermostat suited to a fridge, not for direct heating devices but ambient temperature control.
> 
> 
> Rick



fair enough, then its a bit stupid of petshops to sell and recommend them for use with heatmats, CHE's etc.


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## Rogue5861 (Mar 19, 2014)

Yep it really is stupid, especially the price they sell then for.


Rick


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## Snake-Supplies (Mar 19, 2014)

I'd like to see (if you decide to go for another thermostat) how much things change in your enclosure and whether your "inconsistency'' disappears, and that the heat cord has a constant temperature throughout the cable, providing the only thing you change is the thermostat.

Dimming and pulse proportional thermostats do provide a more constant temperature, though that's not the problem in the question posted, the question I think is why the heat isn't a constant temp through the heat cord.

You say you have measure the temp all around with various thermometers.
Are they quality thermometers? Are they accurate?

I fail to see how the thermostat, changes the heat cord temp.


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## Rogue5861 (Mar 19, 2014)

Snake-Supplies said:


> I'd like to see (if you decide to go for another thermostat) how much things change in your enclosure and whether your "inconsistency'' disappears, and that the heat cord has a constant temperature throughout the cable, providing the only thing you change is the thermostat.
> 
> Dimming and pulse proportional thermostats do provide a more constant temperature, though that's not the problem in the question posted, the question I think is why the heat isn't a constant temp through the heat cord.
> 
> ...



Due to it being an on/off thermostat the cord will heat an cool at different lenghts at different times. I have had variation in temps along cords i have but once running constantly they seem to heat up all over fine.


Rick


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## Snake-Supplies (Mar 19, 2014)

Oh dear, 
I look like a tosser!
I wrote that at work on my phone and was trying not to get caught so I didn't read it properly
Obviously my cut and pastes didn't work.
Should look more like this:

_'d like to see (if you decide to go for another thermostat) how much things change in your enclosure and whether your "inconsistency'' disappears, and that the heat cord has a constant temperature throughout the cable, providing the only thing you change is the thermostat - __*regarding the comment about the cheap ebay thermostats you buy for under $15 as they are both the same on and off principal... and that I cannot see how a $10 Chinese thermostat, could be better than a $75 Australian made thermostat.*_

_Dimming and pulse proportional thermostats do provide a more constant temperature, though that's not the problem in the question posted, the question I think is why the heat isn't a constant temp through the heat cord. __*Just saying what to buy does not give him the right answer, it's best to teach people why.*_

_You say you have measure the temp all around with various thermometers._
_Are they quality thermometers? Are they accurate?- __*regarding the different readings he's getting.*_

_I fail to see how the thermostat, changes the heat cord temp. __*was meant to be cut and pasted to the top paragraph.*_


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## The_Geeza (Mar 19, 2014)

U will always get inconsistent temps if not installed properly


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## Rogue5861 (Mar 19, 2014)

Dangle a heat cord in the air and then test different spots on it for temps, it will heat up all the same. Put it on an on/off thermostat laying down on something and the temps will be all over the place. This is what i have found with them and they seem to work well with a dimming thermostat regardless of installation errors.

Heat mats or flexwatt are also the same, different temps all over it if ran on an on/off thermostat. They are all made to get to a certain temp and stay there, to be set on a timer and ran at 100% power.


Rick


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## =bECS= (Mar 19, 2014)

Remember that the first part of the heat cord (usually to the blue mark) doesn't heat up. If it makes up a row on one side it could be the reason for differing temps.


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## Karnyge (Mar 19, 2014)

Snake-Supplies said:


> Oh dear,
> I look like a tosser!
> I wrote that at work on my phone and was trying not to get caught so I didn't read it properly
> Obviously my cut and pastes didn't work.
> ...



the inconsistency of temps is what I'm trying to fix, I'm using reptile one thermometers, for example I put one probe under the hide (temps would probably be higher) and another next to it outside the hide, the temp outside reads 28 and the temp in the hide 32-33, with the heat gun I get any where from 30 - 37, I checked on the snake he was 34 give or take, I closely monitor the temps so he's not at risk. 

In regards to where the heat cord starts to heat up, there is no blue mark, it feels like it heats up from the beginning of the actual heat cord, I've tried tiles now too, doesn't make much of a difference, the habistat dimmers won't work by the looks of it as they're min 40w (heat cord 25w) 
Appreciate the suggestions and help thanks all. 

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## Karnyge (Mar 19, 2014)

=bECS= said:


> Remember that the first part of the heat cord (usually to the blue mark) doesn't heat up. If it makes up a row on one side it could be the reason for differing temps.



I should mention too, if the first row is not heating properly, it shouldn't be to much of an issue as the click isn't sitting over it just on the edge which makes up the 1/3 if that makes sense. 

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## Snake-Supplies (Mar 20, 2014)

it will probably always be higher in the hide and on top because it will retain the heat inside and the heat will escape through the top.

the temps seem fine to me.

In the hide- 32.5C
Outside the hide- 28C

Heat gun readings, well... I dunno.

Remember your snake will chose where it want's to be, if you find him in your water bowl or trying to get out of the heat too much, it's probably too warm, if he stays in the warm side too much, its probably too cold.


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## Karnyge (Mar 20, 2014)

Snake-Supplies said:


> it will probably always be higher in the hide and on top because it will retain the heat inside and the heat will escape through the top.
> 
> the temps seem fine to me.
> 
> ...



What about both probes in the hide, one reading 30.1 one reading 33


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## Rogue5861 (Mar 20, 2014)

Karnyge said:


> What about both probes in the hide, one reading 30.1 one reading 33



Maybe the probes arent calibrated 100%? Have you swap position of probes around?


Rick


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## Karnyge (Mar 20, 2014)

Rogue5861 said:


> Maybe the probes arent calibrated 100%? Have you swap position of probes around?
> 
> 
> Rick



Yeah mate


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## Snake-Supplies (Mar 21, 2014)

I'd either chose one...
or if you wanna go in between the two temps and average it out??

I prefer the sticky type thermometers, rather than the digital with the probe for accuracy.


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## GeckoJosh (Mar 21, 2014)

Snake-Supplies said:


> Oh dear,
> I look like a tosser!
> I wrote that at work on my phone and was trying not to get caught so I didn't read it properly
> Obviously my cut and pastes didn't work.
> ...



I get acceptable temps from "cheap Ebay thermostats", if the probe positioning is not the fault (which is what I first suggested) then I suggest the OP invest in a new thermostat.

To the Op, just because the thermostat work before does not man it may not be faulty now.


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## bdav70 (Mar 21, 2014)

try putting a tile over the heat cord, it will spread the heat from the cord more evenly resulting in more even temps across the surface. As others have said, put the thermostat inside the tub as that's the critical area you are monitoring


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## Karnyge (Mar 21, 2014)

bdav70 said:


> try putting a tile over the heat cord, it will spread the heat from the cord more evenly resulting in more even temps across the surface. As others have said, put the thermostat inside the tub as that's the critical area you are monitoring



Thanks for the input, but I already mentioned trying tiles, and the thermostat is not suitable to be put in the click clack, just waiting for a different one. Thanks mate


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## The_Geeza (Mar 21, 2014)

Just be aware the distance between cord lay out is critical in the temp u require... Bunch it all in your hand for 2 mins and check with temp gun ... Bet ya get 60++++ deg....


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## AvidRepSupplies (Mar 21, 2014)

The main reason the heatcord is not heating to desired temps across it's length is due to the on/off thermostat.
As others have already said, the current still needs to travel the length of the cord for a short time before it will read a consistent temp along it's length.
This is also affected by the thermostat probe location. e.g. If the probe is near the start of the cord, the temps will reach it's cut off before the end of the cord gets to the same temp.
I would suggest putting the probe closer to the end of the cord length, or alternatively by using a pulsing or preferably dimming thermostat, you will get a better consistency.

Also regarding the temp gun readings, you're getting surface temps. So depending on where the cord is in relation to where you're pointing the gun, the temps will vary and sometimes considerably.
If taking temps with the gun, I'd suggest to put a mark in the tub with pen or similar, and always take your readings from the same spot.


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