Solar (H2O) Shop Heater

[RWoerz]

I'll start with a little background. Years ago I acquired two 70's vintage 3 ft x 8 ft solar panels that were used to make hot water. I recently moved and the one year old shop came with a 100 year old house. Anyway the guy that built the shop stopped just short of finishing it like no heater. I live in the Boise area and it get very cold here so I'm working on putting the panels to good use.

I'll post some pictures later but yesterday I tested a pressure sensor I bought on Amazon. "G1/4 inch 5V 0-0.8 MPa Pressure Level Controller Sensor for Oil Fuel Diesel Gas Water Air". It wasn't cheap at $16 but you can order it in 4 different pressure ranges. I hooked it to one of the analog inputs on an Arduino Uno. In open air the reading was 111. I then did a linear regression on the readings I took from 5 psi to 80 psi and came up with a slop of 7 and the following formula to compute PSI. PSI=(current_input_voltage - 111)/7. As I only have one sensor and only tested it on one micro-controller you will have to see if you get something close to 111 open air reading but it was very linear so the slope of 7 I think would hold on whatever you use it on. The open air reading might change some with elevation and maybe even weather but that's what I got.

I will also be using flow and temperature sensors on this project. I've mostly been working on the physical part of the project and just recently started on the control part so I don't have any of the software ready even for testing, maybe next week.

I'm not an expert on any of this so I'll take suggestions and will be happy to answer questions.