Water-Tank Temperature Control Device

Authors
François Therriault-Proulx

Affiliation :
Canada

Landon Wootton

Affiliation :
University of Washington, Department of Radiation Oncology

Sam Beddar

Affiliation :
MD Anderson Cancer Center

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Temperature Control Diagram

Version : 1.00

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Bill of materials

Water Pump - Vovyo 22L/min DC12V Brushless Water Pump, Part# DC50C-1220 ($49.99)

Thermocouple - Omega Thermo Couple, Part# NB1-CASS-14G-12RP-TT36 ($50.00)

Temperature Controlling PID - Auber Instruments 1/16 DIN PID Temperature Controller, Part# Syl-2352 ($53.70)

Solid State Relay - Fotek 25A Solid State Relay, Part# ESSR-AC25A ($13.44)

Heating Element - Reliance 4500W Heating Element, Part # 9000092-045 ($9.51)

Vinyl Tubing - Samar 1-in diameter reinforced vinyl tubing, Part # 10066RNL ($1.79/ft)

Power Supply - 12V-60W Switching Power Supply

PVC Fittings*, Wire**, PVC Cement, Plumbers Tape, Silicone Caulk, Hose Clamps, Pegboard, Zipties (Available at Lowes, Home Depot, or other home supply stores).

 

*Itemized list of PVC components not currently available, may require some trial and error at the home supply store.

** Wire gauge specification not currently available, refer to manufacture guidelines or get a conservatively low-gauge wire.

Build instructions

The general form of the device is as follows: the intake hose (vinyl tubing) is connected to the pump. The pump is connected via an adapter to a PVC pipe that runs the water over the thermocouple and heating element. The thermocouple and heating element are in PVC adapters fitted into three-way elbows. The water exits the PVC through a final adapter to the exit hose. The thermocouple is connected to the PID following the manufacturers wiring guide, with an output connected to the solid state relay. The PID switches the relay on and off, allowing current to flow from the power supply to the heating element.

When constructing the device, the first step will be to lay out all the PVC, cut the straight sections to the desired size (assuming one long straight PVC was bought in addition to the various fiitings), and make sure all components connect. This includes making sure the pump, thermocouple, and heating element thread correctly into PVC adapters, and all PVC components interface with one another.

Next, all the components should be connected permanently. For items that thread into PVC, plumbers tape should be used. PVC cement should be used to hold together sections of PVC (e.g. the elbows to the straight sections). Hose clamps should be used at the interface of the vinyl tubing and pump/outtake adapter.

After the PVC cement has been allowed to dry, it may be helpful to fasten the device onto pegboard using zipties. This makes it easier to transport and handle, adds some structural integrity to the device, and will facilitate the incorporation of the electronic components. The pegboard can eventually be cut down to the desired size, but care should be taken not to cut it too small at this stage to ensure there is room for the electronics.

The electronics can be similarly fastened to the pegboard. The PID is wired to the thermocouple and solid state relay. The solid state relay is wired to the heating element and the power supply. Refer to manufacturer instructions for guides on wiring and guage. The pump and PID circuit can be plugged directly into wall current, or into a power strip (helpful if the pump does not have an on/off switch and is always-on when powered).

Finally, pour water into the system with the intake/outtake elevated until it is full. Reposition the system as necessary to remove air-bubbles. Allow to sit and inspect for leaks. If leaks are observed, mark them and apply silicone caulk after draining the system (this can be done with water in the system as well but is less effective).

Applications

This device was originally designed to test the temperature-dependence of detectors in a standard water tank that would be used for beam characterization. However, it could be used for any application in which it is desired that a body of water be elevated to and maintained at a given temperature (e.g. mashing during homebrewing, with slight modifications). 

Additional comments

The pump listed in the bill of materials is not self-priming. To start water flowing, it is necessary to fill the system with water, ensuring there is no air in the pump, or anywhere in the intake. This is cumbersome at first, and requires filling the intake hose with water, plugging it, immersing it into the water tank, and removing the plug. Self priming pumps are available at a higher cost, but may represent a significant quality of life improvement if the device will see heavy use.

Also, though it is obvious, it should be stated that this device can not cool water, only heat it. Any application involving multiple temperatures should order then from least to greatest.

Upgrades

As mentioned above, the pump could be upgraded to be more user friendly (self-priming). A different pump or heating element could be used to adjust pump flow and the heating capacity of the heating element to suit the volume of water to be heated.

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