2 thermostats 1 variac 3 options DIY attempt

[gioufis80]

So after gathering up all the parts I finally finished working on this controller! I modified
further my original idea and added a few more components. Summing up this little box
consists of the following:

3 thermostats (2 for air outfeed SCT-1000,AKO D14123 - 1 for infeed FC-810)
1 analog voltmeter
1 analog ammeter
1 variac (for controlling outfeed fan 2F-1)
3 relay switches DPDT (220vAC 10A)
2 manual 3 position (on-off-on) switches
1 timer (I bought this one http://www.ebay.ie/itm/AC-220V-240V...175?pt=LH_DefaultDomain_3&hash=item2a1ddcbdaf )

The outfeed thermostat has the ability to automatically configure
the speed of the fan depending on its measured temperature. I took
it from a fireplaces supply store and works with a triac. This hums
my big outfeed fan but not my small infeed one so it was used to
control that one.
So this box is set to do the following:
When the temp in the growroom is below 20 degrees C the plug with
the heater is activated. When the temp reaches 23 degrees it shuts
down.
When the temp in the growroom is 24 degrees then the outfeed
plug gets powered from the Variac working at 60% for the outfeed
fan. The infeed fan also starts to work at that temperature but
with minimum speed. At 28 degrees the outfeed fan works at 100%
bypassing the variac and also the infeed fan works at 100%.
If we have set a schedule on the integrated timer then at that time
the outfeed fan will start working at the variacs setpoint speed
bypassing all other thermostat settings. This is good for ventilating
the room at lights out, so as to keep the humidity low.
Also the 2 manual switches have the options to work the outfeed system and heater
in auto (controlled by the thermostats) , completely off , and
on working at 100% bypassing the thermostats.

For those last modifications I made this drawing


Many thanks again to rives for his explanations and to Harry for
his interest in my project.

 

[gioufis80]

I will create labels for each component and stick them on the box at some point.
The final result is this:

 

[Harry Gypsna]

I will create labels for each component and stick them on the box at some point.
The final result is this:View Image

Very snazzy, it should serve you well.
One question, is that housing ventilated, variacs do heat up quite a bit.

 

[rives]

Very nice looking project.

 

[gioufis80]

Hmm I didn't make any openings, mostly because I was thinking on moving my
tent to the balcony so I needed it to be as waterproof as possible...

I ll have to watch the variac's temp for a while and see if it heats up too much.
If it does I ll have to add a small 220->12v power supply and a small (60x60) fan
to remove air from the box.

Thanks for the heads up Harry!