Solenoid Control ( 12VDC, 18Watt ) with temperature monitor.

Hello and Thanks in advance.

I am in a bind and need some help rather quickly and very inexpensive. I live in the mountains of Montana and am having issues with my fresh water storage tank freezing. I have come up with an idea to circulate the hot water into the tank when the water reaches 33F degrees and stop it using a solenoid when it reaches 35F degrees. The temperature range is not that important here.

I am completely new at electronics, but can program in "C" without any problem, so I wanted to use an Arduino to build my own mini computer to control the solenoid and monitor the temperature of the water tank.

I have already bought a Arduino Zero. I also know I need some sort of motor control, but don't know what to buy to handle the solenoid. If you search for ( JFSV00069 ) in google.com it will be the first link, if you want to see specs. Link also provided below.

I thought about buying a MRKZERO with a MRK Proto Shield to add the TPIC6B595 or TIP102 ( as described in the Solenoid Driver PDF ) to control the solenoid, but have no idea what else I will need as far as resistors, capacitors or other components to make it all work.

I have read through the Playground for controlling a solenoid, but don't fully understand it.

I have some experience in building and soldering components onto boards, as I have built several "OP AMPS", but the layout was provided and I didn't have to do any configuring.

I have reviewed the below links already, but it's still not sinking in completely to build one.

http://playground.arduino.cc/Learning/SolenoidTutorial

I know I am asking a lot from this, but I'm in a hurry and can't spend as much time as I would like to research the details.

Again... Thank you in advance. I hope someone can help me.

Thank you,
Daniel Nadler
Bozeman, MT

A solendoid like that is just an on or off device, so it can be easily controlled by a transistor like that Tip102 or a more modern Logic Level Mosfet.

The circuit in that first link, solenoid driver.pdf looks fine for your needs, just a base resistor, tip102 or tip120 and a diode.

Might be worth while to buy a heatsink for the Transistor or bolt it to a metal case if an insulating kit is used as it has to pass a heavy current 12V at 18w = 1.5Amps.
You will need a 12v power supply of at least 2A , prefereably highter to keep it running cool.

A mosfet might be a better choice as its creates less heat.
http://bildr.org/2012/03/rfp30n06le-arduino/

You are overthinking the process. Is the cold water tank under the same pressure as the hot water tank?

If so, you need a pump to increase the hot water pressure or it won't go into the cold water tank.
You state the actual temperature of the cold water is not important, so, like our well water, can be 45 degrees or more. I can assume the cold water tank is at normal air pressure.

Just plumb a hot water pipe and a ball valve to hot water can go into the top of the cold water tank. You need an air gap so cold water can't feed back to the hot. Adjust the ball valve until your cold water no longer freezes.

Paul

In my case, the fresh water tank and the hot water are not both under pressure. Only the hot water tank is along with all the other plumbing. When a faucet is opened, the water travels the path of least resistance. If that happens to be a hot water tap, then it travels from the pump, through the hot water tank, pushing hot water to the open faucet. The water pump draws fresh water from the storage tank which has a pressure sensor included and pressurizes the system on the output which includes the hot water. I hope this isn't too confusing.

I need to tap into a hot water line and attach it to the fill line of the storage tank... think is, it needs a valve to open a close. I would like this to be automated so if I am not home at the time, it will circulate the hot water into the storage tank, preventing it from freezing up.

The drawing attached shows an ORANGE line, which is what I will be adding, along with the solenoid and controller.

Oh, I see you have an RV/trailer. The drawing is just like our 5-th wheel trailer. We once stayed in Northern California where the city water froze, but the water tank did not. The kitchen is in the back, near the water storage tank. there is a furnace heater vent nearby, which probably kept the water from freezing.

The water pump will need to be running quite often in your design to keep the hot water flowing to the storage tank. This would be a problem in our trailer. Quite noisy!

It's really too cold to be working n plumbing and besides, we are sending you more really cold weather from Central Oregon!.

Paul

Noisy, versus no water? I'll take the noise every now and then.... :slight_smile:

Research "latching solenoid valve 12v". And look for the small ones. You do not need much flow and can leave it on longer with no permanent current draw.

Paul

Wonder if one of those rubber heat pads glued to the side or bottom of the tank would work? It would surely be quiet.