Wiring an STC 1000

[pjlenn]

I'm building a fermentation chamber using a 110 v. window a/c unit for cooling and a heating pad for the heat.  I'm using a 110 v. STC 1000 dual channel controller and because of the higher current draw of the a/c unit I'm adding a contactor.  I found a wiring diagram online and modified it account for the contactor.  I have had no luck in getting it to work.  I'm a newby on this forum so I'm going to try to attach a diagram of how I've wired it.

There is one connection I'm not sure of and that is the where or if I need to run the neutral leg on the load side of the contactor.

[pjlenn]

Sorry looks like my attachment didn't display the whole page.  I'll see if I can fix that.

[pjlenn]

In checking it looks like you an scroll the image or depending on your operating system you can resize the image.  Hope someone can help.

[ihikeut]

Don't hear to much from Tom_Hampton anymore but he did the same thing your doing in his house. You would have to search his post. He had detail electrical drawings how he wired the Sc100 to the air conditioner.

[KellerBrauer]

Greetings pjlenn,

Your sketch is a bit confusing, but to answer your question, yes you will need to add the neutral to one side of your contractor coil.  Use the controller to energize the coil of the contractor.

Also, it appears you are using a two pole contractor, but I can't see why you would need it unless your ac uniit is 220 volt.  In which case, the diagram and proposed wiring scheme is not correct for that application.

Also, I would recommend using two duplex recepticals as opposed to a single. I have never been a fan of using the break away tab on a receptacle particularly if the receptacle is being used for two loads with different amp draws.

Hope this helps!

Good Luck!!!

[pjlenn]

The relays in the STC are rated at 10 amps.  The a/c unit I'm using runs at @ 8.5 amps, but startup will be considerably higher, likely double.  So I'm using the contactor to handle the startup load.  Here is a picture of the diagram I used, just trying to add in the contactor.

I'll search for Tom H.'s posts.

Thanks for the help.  Paul

   
http://www.gridgit.com/category-diagram/269/

[tom_hampton]

Here is my old post. 

http://www.beersmith.com/forum/index.php/topic,9730.msg41412.html#msg41412

There's probably a few others.

Points of note:

The condenser coils have a tendency to freeze up when you drop below a 60f setpoint.  So, I use a secondary controller that monitors the coil temp and has a setpoint of about 30f. 

In operation what happens is that the room thermostat comes on when the air temp is about 50f.  That power is then controlled by the secondary coil thermostat.  The ac compressor runs until the evaporator coils drop to 30f.  Then the compressor is shut off until the coils warm back up to 36f or 3 minutes expires whichever is last.  Then the compressor comes back on.  That cycle repeats until the room reaches the desired air temp (50f) .

This setup is good for a minimum air temp of about 46f.

You can use a secondary relay to switch the power.  I've done it that way, but don't bother now.   The stc1000 internal relay is usually good for about a year before it fails and I have to replace it. 

[tom_hampton]

There appear to be several issues with your schematic above.  I'm not sure I fully understand what you've done.  I would suggest redrawing it and clearly labeling what is 110v (hot)  and what is neutral (return).  You appear to have both connecting to the bus-bar and your power plug icon.  That makes it hard for me to tell which is intended to be what. 

It is important to get the schematic clear and correct before you start wiring 120vac.  You are dealing with line power and current, which if done wrong can result in fire or injury or worse. 

[KellerBrauer]

Greetings pjlenn,

This is going to sound odd, but the forum has lost a day.  October 27th does not exist along with all the posts that were made.  I, in fact, made a post (along with Tom) on this thread and they are gone.  I notified Brad and he said this is due to a database migration to another server.  So, anyway.....

I took the liberty of creating a wiring schematic for you.  Its a very simple schematic - the wiring for your box does not have to be complicated.  See attached.

My greater concern is your proposed method for cooling your box.  I also remember Tom had some concerns also.  But unfortunately his posts are gone so I cant review and read in greater detail.  In any case, I'm brewing today but will give some thought to your proposal to try and wrap my head around your plan.  I believe it has some fundamental flaws.

Meantime, here is your wiring diagram.  Let me know if you have any questions.

[pjlenn]

OK, these posts have cleared up the problems I was having.  When it comes to wiring I tend to get lost in the weeds a little.  Looks like I need to change how I mount the a/c so that I recirculate conditioned air.  As to the location of the sensor probe, I've read pro's and con's about both and am still a little up in the air.  I'm leaning towards locating it on the fermentor so that I'm actually measuring the temp of the beer.  It seems that this way it will also avoid frequent cycling of the a/c unit.  The other thing I haven't addressed yet is relocating or rewiring the a/c unit's temp probe.  The unit I'm using is an older one with analog controls so it should be fairly straightforward.

Thanks, Paul

[KellerBrauer]

Well okay!  It sounds like you have all your questions answered. That's great!  Stay in touch and let us know how it works out!

Good luck!

[tom_hampton]

Yeah.  I think I'd put the stc 1000 temp probe on the fermenter. However,  be sure to cover it with about 1" of insulation.  I use 4 layers of reflectix and masking tape.  Also, you want to setup the short cycle timeout on the stc 1000 to 3 minutes or so.  I think it is the default, but it's best to check.  That will help keep the ac unit from being cycled too much.

You should not need to modify the ac unit temp sensor.  For your approach you can probably get away with just turning the ac unit all the way to cold.  That should put out about 60f air.  Which should be sufficient for normal ale fermentations around 65-70f (beer temp) .
 

[pjlenn]

Lots of valuable info.  I think I've got the electronics sorted out now.  Thanks to Tom's for taking the time to make up a wiring diagram.  I'll make the modifications to the way I have my a/c mounted and I should be ready to roll. 
One of the reasons I built this is that I was hoping to be able to lager.  Sounds like that might be a stretch.  But while it was hot this summer I was having trouble getting fermentation temps below 73 degrees.  So it will be a help in that respect. 
Again, thanks for all of the great help.  Hopefully I can be of some help to others in the future.  I'll post some pictures when it completed.

thanks, Paul

[pjlenn]

I've finished wiring the controls and tried it out today.  Everything worked as it should.  I modified the chamber to allow the conditioned air to be recirculated thru the a/c unit.  So now I just need to brew some beer and try it out.  I added a couple pictures showing the inside and the controller.  The inside pic is an old one prior to my mods today.  The framework inside is to support my Fast Ferment conical fermentor.  I've also rigged up a pulley system to allow me  to lower the fermentor into the chamber.  It will allow me to lift it when it comes time to keg.  It is also on wheels so it can be pushed out of the way for kegging.

Thanks again for all the help.  Especially Tom H.