HEATING PADS AND THERMOSTATS

August44

Omono
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I want to keep the roots warmer on several larger trees that I collected this fall to help preserve them. I live in zone 5-6. I got some "VIVOSUN" 20" X 20" matts and the digital thermostats to go with them. I set the temp at 40' F, which is as low as it will go, put the probe down in the soil of the trees about 6-8" and plugged them in. The thermostats always light up with what the temps are in the probe area. One reads 34F and the other two read 43-47F. The thermostats are designed to heat to the temps they are set at and then shut off. I have been in communication with the factory (foreign country) via email and not had much luck. I know there is controversy with using heat matts and the like, but if someone has had better luck with another brand/product, I would appreciate hearing about it. Thank you!
 

River's Edge

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I want to keep the roots warmer on several larger trees that I collected this fall to help preserve them. I live in zone 5-6. I got some "VIVOSUN" 20" X 20" matts and the digital thermostats to go with them. I set the temp at 40' F, which is as low as it will go, put the probe down in the soil of the trees about 6-8" and plugged them in. The thermostats always light up with what the temps are in the probe area. One reads 34F and the other two read 43-47F. The thermostats are designed to heat to the temps they are set at and then shut off. I have been in communication with the factory (foreign country) via email and not had much luck. I know there is controversy with using heat matts and the like, but if someone has had better luck with another brand/product, I would appreciate hearing about it. Thank you!
The efficiency of the mats will vary greatly with the manner of use. They are basically designed to add supplemental heat within certain circumstances. I am not sure if your application fits their intended use. If the problem is simply the quality of the product then I can recommend a product I have had good results with. ( note: I have not used it for the purpose you describe, mine has been used for germination and cuttings. )


I have used this Hydrofarm product, Jump Start 20 by 48 mat along with the Jump start thermostat recommended for a number of years with no problems. It is important to understand the conditions they are designed for. Basically they are designed to keep the root area warmer than the ambient temperature of the surroundings. The packaging and instructions clearly indicate what can be expected within certain circumstances and the limitations of the product. For example, use only within situations that the ambient temperature of the surroundings are 10 degrees or less within the target setting you desire for the root zone.

if your primary goal is to protect newly collected trees for the first winter, then I would be more inclined to use a protected enclosure with a greenhouse heater set on frost setting. This setting maintains dormancy but protects from hard freeze on recovering roots or weaker plants.There are plenty of brands available on the market for $150 to $250.I have used a Cafaro brand for the past decade. 8 by 12 poly carbonate twin wall greenhouse. of course it is important to match your structure with your climate when selecting wattage and fan options for effectiveness.
 
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I use cables designed to deice house gutters. I’m not sure if they would work with a thermostat. I have it plugged into a plug that cuts off power if temperatures get above 50°. However, they don’t get very warm(or warm enough to cause a problem). I just have mine snakeing underneath my pots in a bed of gravel To take the edge off the winter cold. Last year I did great with a collected ponderosa pine.
 

Canada Bonsai

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I have tried many heat matts, and after each of them failed in one way or another i finally opted for the more expensive ones that professionals had been recommending to me all along! The only regret i have is not getting them sooner—they are GREAT!

They come in a few different lengths and widths which is very convenient

i have used the heat matts laid over my bonsai benches with the pots placed directly on them, and that worked well!

i have also buried them in 4” of sand to keep the entire sandbed warm, and that also worked well!


I use them with what is by far my favorite thermostat (grateful every day for @JudyB ’s recommendation!):

 

Deep Sea Diver

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Sorry to hear this. It’s-a real pain when a product doesn’t work as expected.

At this point I haven’t had an issue with heat mats. However the area I use these in rarely fluctuates more then 25 degrees. Sometimes it does, like right node when it’s18 degrees outside and the garage door has been open for awhile.

One thing I do to increase the efficiency of a heat mat is to put an insulator directly underneath the heat mat so that the mat doesn’t loose lots of energy heating up the surface below the mat. It can be as simple as plastic atop a double layer of cardboard or better still over a layer of foam insulation or a styrofoam sheet. This can be one reason that a heat mat seem to be acting wonky.

That said, if a product is bad, I’d return it asap and move on to other products or solutions.

Cheers
DSD sends
 

Glaucus

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It is a non-trivial matter to keep the temperature constant with a thermostat. Especially outdoors.

One issue would be the case where the heat mats are on 100% of the time, but do not produce enough heat to raise the temperature to the desired value.
The other is the feedback mechanism overshooting the target temperature, then turning off, and then dropping below the target temperature once more. It will then oscillate around the target temperature but never reach it. Mathematically, this is what always happens. If you can achieve constant temperatures, that is just because it oscillates around the target temperature with a small amplitude.

The first issue has no solution immediate. The efficiency of heat mats is 100% because heat is thermodynamic waste. Being 0% efficient means you are 100% heat efficient. So your watts will be turned into heat ie a temperature raise of whatever it is heating. Getting more watts worth of heating, or insulating or reducing ventilation the plants in some way could help.

For the second issue, a smarter thermostat may be a solution. But likely these cheaper products don't have those.
This is an entire wikipedia page on the simplest device that solves this engineering problem:
 

Glaucus

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Ah and yes, like DSD says, having the heat mat heat something else which can act as a temperature buffer works better in getting a more constant temperature inside your roots.
In this way, you heat the roots indirectly.

You need something with both good conductivity and a relatively high heat capacity. It will cost you more energy, though.
 

chicago1980

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Here is my set up.
 

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Oerc201

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I have tried many heat matts, and after each of them failed in one way or another i finally opted for the more expensive ones that professionals had been recommending to me all along! The only regret i have is not getting them sooner—they are GREAT!

They come in a few different lengths and widths which is very convenient

i have used the heat matts laid over my bonsai benches with the pots placed directly on them, and that worked well!

i have also buried them in 4” of sand to keep the entire sandbed warm, and that also worked well!


I use them with what is by far my favorite thermostat (grateful every day for @JudyB ’s recommendation!):

Thanks for the info 👍🏻 I will try this one.
 

Deep Sea Diver

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Oerc201

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JudyB

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I have tried many heat matts, and after each of them failed in one way or another i finally opted for the more expensive ones that professionals had been recommending to me all along! The only regret i have is not getting them sooner—they are GREAT!

They come in a few different lengths and widths which is very convenient

i have used the heat matts laid over my bonsai benches with the pots placed directly on them, and that worked well!

i have also buried them in 4” of sand to keep the entire sandbed warm, and that also worked well!


I use them with what is by far my favorite thermostat (grateful every day for @JudyB ’s recommendation!):

These are the same heat mats I have been using and recommending for years. They are bombproof!
 

Cable

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Are you a Mirai subscriber? I just re-watched his winter care video from 2017 and he broke down the heat mat setup he uses. Looks a hell of a lot like what @chicago1980 posted! He also goes into detail about how to use, why, and what the dangers are.

In a nutshell his setup is (from ground up) styrofoam insulator, plywood, heat mat, plastic sheet, pumice.
 

Canada Bonsai

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Are you a Mirai subscriber? I just re-watched his winter care video from 2017 and he broke down the heat mat setup he uses. Looks a hell of a lot like what @chicago1980 posted! He also goes into detail about how to use, why, and what the dangers are.

In a nutshell his setup is (from ground up) styrofoam insulator, plywood, heat mat, plastic sheet, pumice.

Personally, if i was going to create heated benches that are ‘permanent’ like Mirai’s, i would opt for water in hoses over electric heat matts

Electric heat matts have a limited lifespan, and are hard to replace when the time comes. They also have a limited temperature range, and consume a lot of electricity.

My next benches will have hoses running through the sand/substrate, leading to a reservoir of water (a bucket will do, but a bigger volume is better), with a simple setup like a $20-40 aquarium heater and $20 aquarium circulation pump to move the water through the hoses.

The combined heater and pump only use a fraction of the electricity that a heat matt uses, and the mass of water in the reserve helps keep the water warm

This is a very common approach, and a very efficient one from the perspective of both resources and getting the job done. Aquarium heaters easily get warmer than most heat matts can too. The bonus is that if something fails it is easy to repair because the heater and pump are accessible, whereas the heat matt is buried in sand (which makes replacing it, in my experience, a nightmare)
 

Kadebe

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Are you a Mirai subscriber? I just re-watched his winter care video from 2017 and he broke down the heat mat setup he uses. Looks a hell of a lot like what @chicago1980 posted! He also goes into detail about how to use, why, and what the dangers are.

In a nutshell his setup is (from ground up) styrofoam insulator, plywood, heat mat, plastic sheet, pumice.
You don't need to be a Mirai user.
Video also on YouTube: Heat mat starts at 35:15
 

chicago1980

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Are you a Mirai subscriber? I just re-watched his winter care video from 2017 and he broke down the heat mat setup he uses. Looks a hell of a lot like what @chicago1980 posted! He also goes into detail about how to use, why, and what the dangers are.

In a nutshell his setup is (from ground up) styrofoam insulator, plywood, heat mat, plastic sheet, pumice.
I basically built exactly how it is described in the heat mat video. It is a short 10 min video in the tier two library. I also asked Troy what specific Matt's and controller that is set up at Mirai.

Basic set up
2 inch insulation
Wood frame
Wood inside the frame as a base
Heat mats
Plastic
Thin amount of small pumice
Pot
Then I surround the pot to the rim in pumice
I water the pots and the surrounding pumice
I occasionally check the soil temp using a plunger Thermometer

download.jpegPXL_20211231_003609438.jpgPXL_20211231_003601294.jpgPXL_20211231_003552476.jpg
 

Deep Sea Diver

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I am…

It’s-a cool set up, yet didn’t Ryan say somewhere not to do this to the same tree Two years in a row?

…. Or am I just showing my age?

Cheers
DSD sends
 
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