AC gycol chiller build Q...

[wyowolf]

So basically I am hot wiring the Comp and the fan correct? The rest of it isnt needed since I want the BCS via a SSR to control the on off of the AC to set the temp correct?

All you have to do to make the compressor run is disconnect the blue wire from the circuit board and apply 120 VAC to it. This should be through a relay rated for the compressor load current which relay is operated by the BCS. If the BCS has internal relays that can handle the compressor load the extra relay isn't necessary. Doing thus takes the A/C unit's internal thermostat out of the picture.

You will still need the 25 uFd capacitor. That's what spins the magnetic field inside the compressor motor. Without it the compressor will not run. Just hum and get hot.

 

[ajdelange]

If you connect the blue wire to 120 through an SSR controlled by the BCS then you are "hot wiring" just the compressor. The fan will not run when the blue wire is hot unless the unit'd internal controller has told it to. Presumably you would just turn the internal controller off under this arrangement. All control then goes to the BCS.

Now it occurs to me that there is a problem with this. If, for example, there is a brief power interruption obviously the compressor will stop. As soon as the power comes back on the BCS will command it back on right away. This is not a good thing. Starting a compressor right after it stops is very hard on it as it is starting against full or nearly full head pressure. This may have been what failed your cap. The internal controller will not let that happen. It will wait a minute or two after compressor shutdown before it will allow the compressor to be started again. You need to provide this protection to your compressor. I did a little reading on the BCS to the point where I see that it has some ladder diagram control capability. If you can put a timer in there that won't allow compressor startup for two minutes after it has been shut down for whatever reason then put that in there and Bob's your uncle. If you can't do that then I recommend connecting the line side of the SSR not to the line but to the PCB terminal to which the blue wire normally attaches. Set the internal control to as low as it will go so that the internal controller is always asking for compressor except when there has been a recent power interruption but the SSR won't pass the 120 to the compressor unless the BCS is also asking for cooling. This will protect you from power outages and from unplugging the main power source and replugging it but it won't protect against short cycling from the BCS itself. You should really investigate means of doing that from within the BCS.

 

[wyowolf]

yes there is a control capability in the BCS that wont short cycle the compressor. So silly Q, how do i connect? if i just go to blue wire only comp runs, wouldnt i want the fan to run also?

If you connect the blue wire to 120 through an SSR controlled by the BCS then you are "hot wiring" just the compressor. The fan will not run when the blue wire is hot unless the unit'd internal controller has told it to. Presumably you would just turn the internal controller off under this arrangement. All control then goes to the BCS.

Now it occurs to me that there is a problem with this. If, for example, there is a brief power interruption obviously the compressor will stop. As soon as the power comes back on the BCS will command it back on right away. This is not a good thing. Starting a compressor right after it stops is very hard on it as it is starting against full or nearly full head pressure. This may have been what failed your cap. The internal controller will not let that happen. It will wait a minute or two after compressor shutdown before it will allow the compressor to be started again. You need to provide this protection to your compressor. I did a little reading on the BCS to the point where I see that it has some ladder diagram control capability. If you can put a timer in there that won't allow compressor startup for two minutes after it has been shut down for whatever reason then put that in there and Bob's your uncle. If you can't do that then I recommend connecting the line side of the SSR not to the line but to the PCB terminal to which the blue wire normally attaches. Set the internal control to as low as it will go so that the internal controller is always asking for compressor except when there has been a recent power interruption but the SSR won't pass the 120 to the compressor unless the BCS is also asking for cooling. This will protect you from power outages and from unplugging the main power source and replugging it but it won't protect against short cycling from the BCS itself. You should really investigate means of doing that from within the BCS.

 

[ajdelange]

In the connection I am proposing the the fan will always be running because the original internal thermostat is never satisfied. Note that comments about the door have been removed. Those pertain to another post - not this one. There is no door here AFAIK.

 

[wyowolf]

Still waiting on the last temp probe, I used the one from the kettle to test it out though. Worked ok, pump needs to be bigger... barely any flow through the coil... but it cooled down pretty well. It kept wanting to restart a lot until both started to get cold, then they cycling went way down.... got the kettle down to about 44 before i called it a night...

I was surprised how accurate those little strips are on the kettle, it was always very close to what the temp probe inside said, within 1 -2 degrees...

 

[ajdelange]

A professional cylindroconical is coaxial with insulation between the inner and outer walls. Is this fermenter built that way? If not you will get a big improvement in chiller performance by wrapping it in insulation. You want to be cooling the beer - not the room air.

 

[wyowolf]

A professional cylindroconical is coaxial with insulation between the inner and outer walls. Is this fermenter built that way? If not you will get a big improvement in chiller performance by wrapping it in insulation. You want to be cooling the beer - not the room air.

Its a blichman conical, not insulated, and yes I will wrap it in insulation when I am actually fermenting in it... at 44 degrees there was some condensation on the outside of it... i just need a little bigger pump i think... other than that it worked great.

the cycling was way slower when the temp in the F came around 50 degrees... maybe once every 10 min?

thank you for all your help! I couldnt have wired it without your knowledge!

 

[wyowolf]

Finally used for the first time yesterday. Brewed a Czech Pilsner... sitting at 52 degrees waiting for starter to finish... so far works great. I did wrap an old comforter about it to keep it cooler...but it kept 52 no prob...