1kW Solid State Peltier Heat Pump

Primary/secondary water loops & 12 peltier units with a 0-30°C set-point.

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The purpose of this project is to create a device that can pump 1kW of thermal energy between two separate loops of water.

The primary loop of water is the hot side and acts like any water cooling system. It has a pump, reservoir and heat exchanger to the air of about a 100W. However, there is also a front panel bulkhead port to allow the water loop to travel to larger radiators or (and here's the fun part) just have a continuous source of cold water from the tap flow through.

The secondary loop of water is thermally connected to the primary loop of water via two sandwiched "cold-plates" with 12 40mm Peltier heat pumps in the middle (a 1 kW heat-pump). Combined with the temperature controller, this allows me to set the desired temperature of the secondary water loop. The targeted range so far is 0-30C.

Once everything is up and running I should be able to practically dissipate over 500W with inlet coolant temperatures to the thermal source at 1C.

Both loops have a temperature/flow meter (with alarms) and there is another cut-off temperature controller watching the maximum temperature on the primary water-loop (pump is rated for 65C) that can cut the Peltiers/alarm).

I just wanted to do this for fun.

It also cost a LOT, so parts will be purchased very slowly and assembly will lag behind. Also, the parts list is mostly accurate (it's hard to be sure when you don't have most of them).


Front panel for bulkhead G1/4".

netfabb - 20.79 kB - 01/12/2021 at 06:05



Holds up the tubing.

netfabb - 27.62 kB - 01/12/2021 at 06:03



Little flat feet for adhesive. Can't use the adhesive directly as it's thermally conductive.

netfabb - 684.00 bytes - 01/12/2021 at 06:03



Clamp the plates together in the centre.

netfabb - 17.07 kB - 01/12/2021 at 06:03



Wrap around the ends of the cold plate to really clamp it together.

netfabb - 17.27 kB - 01/12/2021 at 06:03


View all 29 components

  • Peltiers and Initial Load Tests

    David Scholten02/14/2022 at 06:33 0 comments

    So I've received a bunch of Peltiers, but the rating labelled is different from the actual performance. I've been flim-flammed.

    I also received fans - That's always nice:

    (The 12x fake peltiers are just sandwiched in between the heat blocks)

    And a triplet of power supplies! One for loop 1, loop 2 and then the fans:

    Now, to neaten things up I've made some ASA printed peltier spacers that have been superglued on to hold them in position as they slip around on thermal pads/thermal grease:

    I've also made some spacers for the giant fans:

    The whole idea is that the "stack" of components can be lifted vertically upwards, but nothing can move laterally and ruin it. It's like a heat block sandwich.

    In the end I'm aiming for 4x150-200W peltiers in the sandwich.

    Now! Thermal issues! I'm currently cooling with only 60-120W, but I can't get the hot side heat away and am therefore only achieving up to a 4 degree drop from ambient after tuning the input power.

    There are many issues that need to be fixed (of which most will go away simply by completing the planned project):

    1. The current thermal pads are garbage compared with thermal grease - I'm changing it out for grease now that I have the spacers. This is especially important now that I want only 4 peltier units instead of 12 lower power ones.

    2. Heat blocks don't conduct heat from top-to bottom well without water in them! :)

    3. That water likely also needs to move, so statically filling it up may not work.

    4. The cooling thermal losses from the environment heating the pipes is immense and kind of comical. The air around the piping just feels nice. I'm aiming to overcome this with pure power in the future, but I can always start wrapping things in insulation... These PC copper pipe adapters are designed to bleed of heat with hot water from graphics cards, not stop the cold from escaping...

  • Test Load Platform Added

    David Scholten12/19/2021 at 02:19 0 comments

    Using a spare heat-block and some existing 3d printed parts with double sided tape, I threw together a test load platform. If everything goes well, I should be able to have the first loop running with a CPU cooler fan on a heatsink cooling the peltiers and pump the cool-side water to this little thing (drink cooler or more peltiers for cloud chamber?)

    I did notice that the flow rate dropped even lower. Turns out that the pump I'm using is not what I ordered and is, in fact, a quarter of the power of the intended model (plate confirms this). It's clearly struggling to keep up with the flow resistance.
    The good news is the higher power model is the same form factor, but the bad news is I'll be spending more money and that the pressures will be higher than what they are now.

  • First Loop Now Done-Done

    David Scholten12/05/2021 at 04:51 0 comments

    Just finished up making the first loop "permanent".

    Found a smaller diameter pipe to interface with the heat block and I wired in the devices in their final positions. I ended up going with oversized linear 5V regulator modules for the monitoring panel at the front:

    This whole section runs off of its 12V supply and their is a single little relay available to patch through some logic to the final external power supply. Depending on the control configuration of the supplies (for the peltiers), I may need some more relays for interfacing.

    There is also now a 4-switched power-board that I intend to run:
    -->Loop 1 @ 12V
    -->Loop 2 @ 12V
    -->Cooling fans @ 12V (just for low power loads, serious stuff pipes to external heat dissipation or buffering)
    -->Main 1kW power source (with logic interface for on/off I hope).

    On the way in the mail are:
    -->Power supplies
    -->2nd Heatblock
    -->12x peltiers

    Slowly but surely getting there. I'm also concerned about the galvanic corrosion between the copper (which everything is made of) and the heat blocks (only available in aluminium at that size). However, the copper is almost all coated and and permanent installation that has time to start significant corrosion I'd be able to use an anti-corrosive coolant I imagine. Still, I'll try to make sure the aluminium blocks are "removable" just in case and won't trap them in place.

  • First Loop Done'ish

    David Scholten10/29/2021 at 10:57 0 comments

    Stuff has arrived and more assembly has happened:

    I have almost everything required to complete the cold side loop except for a way to mount the higher diameter pipe to the heat block. I've had some ideas, but I'm just not sure yet. I'm not sure how permanent blutac is.

    Still not sure how to practically obtain something safe that can provide 0.5-1kW at 12-48V. 

    I think I'll start some wiring next and get the water going in a way that will stay in the pipes.

  • Back on the project!

    David Scholten09/02/2021 at 07:56 0 comments

    Starting to order something new each fortnight.

    Slowly but surely...

  • Out of Stuff to Assemble

    David Scholten01/20/2021 at 10:19 0 comments

    That's it, I'm all out of stuff to assemble. Now I'm waiting on more money for the pump, flow meter and then heat blocks to allow proper placement of the pipes. 

  • The Parts So Far...

    David Scholten01/17/2021 at 04:27 0 comments

    I originally bought/printed a set of expected parts that I knew would be used regardless of any redesigns. They have since arrived:

View all 7 project logs

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rgordon117 wrote 08/27/2022 at 00:49 point

Hi , I am working on a similar project. I am gathering parts now. The plan is to have 5 peltier sandwiched between two aluminum, CPU  water heat sinks.  Each side will have it own pump, reservoir, radiator and fan.  One radiator and fan will be inside a chicken coop and the other outside.  The goal is for it to act as a heating and air conditioning system. In the winter the cold air outside will boost the heat and in the summer the outside radiator will be in the sun. A temperature controller will switch the polarity of the voltage to switch between cooling and heating.   I didn’t want to do more than 30 amps to keep the electrical costs down. I will use a 12v 30 amp power supply.   I also plan to fuse each of the peltiers for 6 amps did you consider that for your design? 

  Are you sure? yes | no

David Scholten wrote 12/05/2021 at 05:41 point

Now there is!

Just realised the pump I was sent is the 300mA version and not the 1.3A version and it's way to late to do anything about it...

Anyway, the second loop can have the 1.3A version and if that doesn't create leaks, I'll replace the first one too.

  Are you sure? yes | no

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