water flow sensor for geothermal heat pump

davew26

I need a method of ensuring water is flowing through a one-inch PVC line. Thinking of using a Piezo vibration sensor
mounted in threaded TEE PVC couple. I want the sensor to vibrate. Is it better to mount the sensor perpendicular or
at a fifteen degree angle to the water flow to get the max vibration of the sensor?

I am building a updated system to my Geothermal Heat Pump system. I use two large Geothermal heat pumps to heat
a 4,000 sqft house in SE Pennsylvania. I have a closed loop water system that circulates water in 2 inch poly butyl pipe,
2.000 feet of it. The pipe lays 7 feet underground. I have the two heat pumps connected in series so that when the
water circulation pumps are running the water circulates through both heat pumps. It is important to have a controller
to keep both heat pumps from running at the same time. Each heat pump is capable of cooling the water down from
50F to 36F before being sent back underground to be reheated by the earth. If the second HP receives 42F or lower
temp water it will freeze the water in the heat exchanger and ruin the heat exchanger and usually the HP compressor.

I have been using a Arduino Mega as my controller and it measures water temp to prevent from freezing damage. But I
want a backup flow sensor. My nightmare is going away for a weeks vacation and have a elec power failure that would shut
down my water well pumps and then restart the heat pumps before the water system can recharge the closed loop system.
Check valves and accumulators only maintain water pressure in the closed loop system for six to eight hours before needing
to be recharged. I also use water pressure sensors on the lines but they could be reading trapped air pressure. A water
flow sensor is the safest.

Thanks
Dave In PA

Chris Savage wrote: »

JayGuy,
·
·· Do you need to detect the amount of airflow or just that there was airflow?· If the latter, consider the Piezo Vibra Tab Sensor we have available.· It is capable of detecting air flow, although you may need an Op-Amp to register this on a BASIC Stamp input.· I hope this helps.· Take care.

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Chris Savage
Parallax Tech Support

Tracy Allen

Dave, I took the liberty of moving your question to its own thread. You had posted to the end of a 2006 thread titled wind sensor, in case anyone wants to look back at that.

Franklin

How can your system be closed loop if it won't hold pressure?

stamptrol

Given the potential consequences of a failure, wouldn't the purchase of a proper flow switch be worth it? They are available in a full range of sizes, are adjustable and are meant for exactly the service you are contemplating.

Omega Engineering would be a good place to start.

Cheers.

dre

Hi Dave,

Would this help?:

http://www.adafruit.com/products/828

cheers, David

Moskog

In my geo-thermal heat pump I use a mix of ethylene glycol and water to prevent freezing of pumps and heat-exchangers. The temperature of this fluid (in the primary loop) is just below zero C when arriving the heatpump and drop a couple of degrees through the heat pump prosess. In the secondary loop (through the floors) the temperature reach up to 40C and here I use water only.