# PID Controlled Peltier Heating and Cooling

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
My goal is to rewire a Peltier AC unit by removing the on-board PSU and Analog temperature controller.
I would like to convert the AC unit to Cool and Heat by reversing the Peltier modules polarity.
Then control both heating and cooling functions with a PID. Then running it all with an external PSU.
Inside the unit there are 4 x Peltier modules and 4 x Fans. I have attached some information I've found below.

I've read a lot about H-bridge relays, SSRs, MOSFETs and came across a lot of extra devices from several manufacturers that might work to solve this problem but most of the time it seems overly complicated. I know the simplest solution is usually the best solution.

Currently I'm looking at possibly buying a "ACCUTHERMO TECHNOLOGY FTX700D H BRIDGE AMPLIFIER" as a possible solution.
But I'm not sure how the wiring for that should be setup to control the Peltier's and the fans and the heating and cooling.

Of course, I'm a super noob but learning as much as I can and really fascinated by all of this.
Looking for any help you all can offer! Thank you!
Please use layman's terms and easy to understand wiring diagrams as much as possible in your response.

I currently have a:
**Teca AHP-1800 0-0180-0-000 Solid State Air Conditioner
with (Built-in Analog Temperature Control and PSU)
**Mean Well PS-24-25 600watt Power Supply
**Thinking of purchasing a Solo SL4848-RR or SL4824-RR PID to run the Heating and Cooling Functions.

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#### MrChips

Joined Oct 2, 2009
23,528
Welcome to AAC!

Sounds doable.
Which version TECA did you get?
If it is the 24VDC version then you will need a 24VDC power supply @ 20A min.
What are your target temperatures? You might not need an H-bridge driver. A relay could be used to switch between heating and cooling.

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
Welcome to AAC!

Sounds doable.
Which version TECA did you get?
If it is the 24VDC version then you will need a 24VDC power supply @ 20A min.
What are your target temperatures? You might not need an H-bridge driver. A relay could be used to switch between heating and cooling.

I've attached a screenshot of some of the specs. Thank you!

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#### MrChips

Joined Oct 2, 2009
23,528
If your unit runs on 120VAC is there a control mechanism to switch from heating to cooling?

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
I've attached a screenshot of some of the specs. Thank you!
Yes I believe it is 24VDC

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#### MrChips

Joined Oct 2, 2009
23,528
I see that your unit is 24VDC, Cool only.
Make certain that you know which unit you have.

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
If your unit runs on 120VAC is there a control mechanism to switch from heating to cooling?
From what I understand the only way to switch Peltier modules from Heating/Side A and Cooling/Side B TO Cooling/Side A and Heating/Side B is by switching the polarity. Currently there is no way to do that on the AC unit due to the wiring.

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
I see that your unit is 24VDC, Cool only.
Make certain that you know which unit you have.
I am certain there is a way to rewire it. so that switching the cooling and heating sides can be done. Just not sure what that is.

#### MrChips

Joined Oct 2, 2009
23,528
So far, all I am hearing from you is guesswork.

What is the exact model number of your unit?
What is your application?
What is your target temperature?

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
So far, all I am hearing from you is guesswork.

What is the exact model number of your unit?
What is your application?
What is your target temperature?

Sorry. I posted that info in the attachments.

"**Teca AHP-1800 (MODEL NUMBER 0-0180-0-000) Solid State Air Conditioner
with (Built-in Analog Temperature Control and PSU)
**Mean Well PS-24-25 600watt Power Supply
**Thinking of purchasing a Solo SL4848-RR or SL4824-RR PID to run the Heating and Cooling Functions."

I'll rephrase my goal I want to rewire the AC cooling unit to run as heating and cooling by reversing the TEC modules polarity.
So essentially after all is said and done nothing but the 4 x Peltier modules / 4 x fans and heatsinks will be left in the unit.
All of which will be controlled by the PID and external PSU.

The application will be to temperature control a cabinet.

My goal temperature will be to maintain 68 degree F. With ambient temperature swings of 60-95 degrees F.

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#### MrChips

Joined Oct 2, 2009
23,528
The model you have indicated is for cooling only.
Can you exchange the unit for one that is designed for cooling and heating?

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
The model you have indicated is for cooling only.
Can you exchange the unit for one that is designed for cooling and heating?
Lol, are you messing with me.

I've said 4 times its an AC unit I understand its a cooling unit. No I cannot return it.

The only thing that makes this a cooling unit is the wiring layout which I am positive can be changed to convert it to heat and cool. but I don't have the experience to make that change.

This is ran by Peltier modules which can be easily reversed, unfortunately i don't know how to safely do that.

Thanks for your help though, I do appreciate it.

#### MrChips

Joined Oct 2, 2009
23,528
No, I am not messing with you.
I am trying to provide you with proper guidance but you seem to think that I am not doing so well.

It would appear to me that the TECA company sells units designed for cooling/heating.
Why would you purchase a unit that is designed for cooling only?

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
No, I am not messing with you.
I am trying to provide you with proper guidance but you seem to think that I am not doing so well.

It would appear to me that the TECA company sells units designed for cooling/heating.
Why would you purchase a unit that is designed for cooling only?
A brand new unit with the same quality and power sales for in excess of $1,500 And that doesn't even include a digital controller. The current unit I have cost me$200

The only difference is that the wiring is different. My pocket book dictates I just convert the unit I have.

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
No, I am not messing with you.
I am trying to provide you with proper guidance but you seem to think that I am not doing so well.

It would appear to me that the TECA company sells units designed for cooling/heating.
Why would you purchase a unit that is designed for cooling only?

But in all seriousness. I do need your or this communities help setting this up.
What I have is what I have and if you can help me with the technical side of wiring this up I would greatly appreciate it.

I believe I've supplied all the information that would be needed to give me some technical guidance.
I spent weeks trying to figure out the best way to do it, I'm doing my best to not guess.

Thanks again!

#### MrChips

Joined Oct 2, 2009
23,528
Ok. One solution is to add a space heater.

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
Ok. One solution is to add a space heater.
Yes that's my plan B but id really like to first try to utilize the Peltier features.

#### ElectricSpidey

Joined Dec 2, 2017
1,655
There is a lot more to changing a cooling only unit to also providing heat.

You have to deal with the mechanical issues as well, such as reversing the cooling fans and heat sinks.

#### ElectricSpidey

Joined Dec 2, 2017
1,655
Ok, some questions.

Do you have equal heatsinks on both sides of the TEC units?
Which direction do the fans blow?

Thread Starter

#### JesusLopez

Joined Jun 1, 2021
13
Ok, some questions.

Do you have equal heatsinks on both sides of the TEC units?
Which direction do the fans blow?
I drew up a little diagram of how a polarity reverse test could go for the unit.
Yes there are heat sinks on both sides.

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