NiKDo wrote:
..how would one control the flow to regulate the temperature. As well, I wonder if a system could be fashioned that would actually be able to start this and stop it. I am doing AP with the goal of automating things with software that I will write and inexpensive hardware and sensors and servo motors. I think opening a valve and closing it for the oil drip would be easy. I wonder how hard would it be to have something to automatically light it up once the temp drops and you want it to get going again.
I like your line of thought going automated. Though from what I've seen, you shouldn't need to adjust the oil-flow rate, just light the heater and leave it running.
I think it would be easiest and most reliable though to light the waste oil burner once, manually, early during winter nights and leave it running overnight for 12 hours, keeping the air within the whole greenhouse sufficiently heated. Then automate the pump to the heat exchanger with a thermostat, or Arduino chip, to heat the fish tank water only when it dropped below a certain temp.
A well designed waste oil burner "...when adjusted for maximum efficiency, consumes less than one quart ( 0.94 litres) of oil an hour" (
http://journeytoforever.org/biofuel_lib ... h/me4.html)
To prevent the water in the heat exchanger running dry, you could setup a solenoid valve on the heat exchanger pump so it is continously running but if max temp is reached in the fish tank, a solenoid opens which pumps water in a recirculating fashion into a stand alone bypass tank (eg a 200 litre drum) with nothing in it where it didn't matter how hot the water got.
Hard to describe with words, but here's a sketch:
Attachment:
File comment: Heat Exchanger Bypass tank
jonosHeatExhangerBypassTankIdea.jpg [ 51.38 KiB | Viewed 3674 times ]
Scenario:
1) The two purple Solenoids are open, so water in the fish tank flows through to heat pump, then through heat exchanger and recirculates back into fish tank
2) heat pump and solenoids are controlled by a thermostat monitoring fish tank temp. When fish tank temp exceeds say 28 degrees celcius, the thermostat closes the solenoids.
3) Water then flows only through the heat bypass tank
I'm sure there is a less wasteful way to do this? Any suggestions?
RupertofOZ wrote:
Then there's the reality... that most of the heat is lost... during the night... and from the tank surface... or by draw down of cold air through the grow beds....
Indeed.. this is the reason I'm so keen to build a greenhouse to retain as much heat as possible over winter
Backyard Aquaponics
