Automatic Air Compressor On/Off control idea...

[TheEquineFencer]

Here's my idea. In the shop, all the lighting circuits are motion controlled with a manual override timer paralleled to the motion switch . Both devices can turn on a 120V/20A rated RIB Relay that actually carries the load. I'd like to get a 120V/24V transformer that can be easily mounted to an existing exposed surface mounted 4x4 metal box, feed the 120V from the lighting controls to power the transformer, then feed the 24V to a 24V relay mounted inside the air compressor starter box that's rated to handle the control circuit (pressure switch) for the Air Compressor. That way when I walk in and the lights come on the air compressor does too and cuts off when I'm gone. If I'm outside and need it, I can use the override to keep the compressor running. The 24V wiring will be run separate from the 120V wiring to stay away from the chance of induced voltage. The 24V wiring wouldn't need to be very large as most 24V relays only draw about 1A or less if memory serves me correctly?

 

[bsaint]

Yea it'll work. You probably want a manual override.

 

[TheEquineFencer]

Yea it'll work. You probably want a manual override.

It's already there, the manual timer will power the RIB relay and the 24V transformer that powers the relay for the Air Compressor.

 

[bsaint]

It may work but its pretty mickey mouse. A manual timer is not a manual over ride in the controls engineering field.

 

[TheEquineFencer]

It may work but its pretty mickey mouse. A manual timer is not a manual over ride in the controls engineering field.

I live with an engineer...do you know what and engineer is? Someone that can give you the answer to the 4th decimal place and still might not have the right answer...

I'm sure this might step on some people toes, but that's why they make steel toed shoes.

It's all UL approved and works like a charm. A papered engineer would probably have everything on it's own stand alone system, with a motion sensor to control the operation and another switch that bypasses the sensor for full on 100% operation all the time. Then add another switching method to give the exact same method of switching that I'm doing now.

The end result is I want the system not capable of being left on indefinitely. If you can come up with a way to do what I want, I'll be more than happy to wire it your way. The way I see it, I'll need to buy a transformer, relay and probably some 18 gauge wire.

 

[Notgrownup]

You forgot the magnetron flux capacitor...without that bit you are screwed....

 

[TheEquineFencer]

You forgot the magnetron flux capacitor...without that bit you are screwed....

I'll have to ask my engineer which one to use when she get's back from class tonight. She just left for class. I'm not sure if I should use the one for straight polarity or reversing polarity. I might just use a DC transformer instead.

 

[Notgrownup]

I'll have to ask my engineer which one to use when she get's back from class tonight. She just left for class. I'm not sure if I should use the one for straight polarity or reversing polarity. I might just use a DC transformer instead.

It will work in a bind, trust me....torque it to 125 ft/lbs no less with a 3/4" harbor freight torque wrench.

 

[404]

I'll have to ask my engineer which one to use when she get's back from class tonight. She just left for class. I'm not sure if I should use the one for straight polarity or reversing polarity. I might just use a DC transformer instead.

The DC transformer only works in liquid helium so put that on your shopping list.

 

[TheEquineFencer]

The DC transformer only works in liquid helium so put that on your shopping list.

I thought it was liquid unobtainium it worked in and I thought I was supposed to torque to 125 PSI?

 

[_Dock_]

I agree kind of Mickey Mouse and overly complicated but it would work. Why not just install a wall mount motion switch with your starter circuit. Why do you need the 24 volt relay and power supply?

http://www.louielighting.com/Westga...aign=product&gclid=COHqgoKkksMCFZOCaQodMEcAEA

 

[TheEquineFencer]

I agree kind of Mickey Mouse and overly complicated but it would work. Why not just install a wall mount motion switch with your starter circuit. Why do you need the 24 volt relay and power supply?

http://www.louielighting.com/Westga...aign=product&gclid=COHqgoKkksMCFZOCaQodMEcAEA

You're thinking like an engineer. Why buy another of what I already have? Then I'd have to run more conduit,120V, more wire 12ga. and another switch. All I need is a transformer, relay and some 18 gauge wire. Sensors are $60-$80 transformers are cheap, maybe $10-$15 Relays about the same. Switch, It's all there now why spend what I don't need to?

 

[sberry]

How did I ever get by without it?

 

[_Dock_]

Well I guess I'm not following you then

If you already have the switch and you have access to the lighting wires then just tap off the lighting circuit and tie it directly to your starter. Lights on, compressor starter is armed. I still don't comprehend why you need the 24 vdc power supply and the extra relay.

 

[redmondjp]

Here's one potential problem: if your compressor has the pressure switch-mounted unloader valve, and your added control turns off the compressor while it is running, it will not unload. Then (assuming that the compressor check valves don't leak down which they very well may if left alone for long enough) when you power back up, the compressor is starting against a load. Just something to think about.

Related question that is getting a bit off-topic: do you valve off your air system when you shut down the shop? I turn off the ball valve on mine right at the tank and my compressor will hold pressure for months.

 

[Charles (in GA)]

Here's one potential problem: if your compressor has the pressure switch-mounted unloader valve, and the controls turn off the compressor while it is running, it will not unload. Then (assuming that the compressor check valves don't leak down which they very well may if left alone for long enough) when you power back up, the compressor is starting against a load. Just something to think about.

Related question that is getting a bit off-topic: do you valve off your air system when you shut down the shop? I turn off the ball valve on mine right at the tank and my compressor will hold pressure for months.

redmondjp brings up two valid points here.

 

[TheEquineFencer]

Here's one potential problem: if your compressor has the pressure switch-mounted unloader valve, and your added control turns off the compressor while it is running, it will not unload. Then (assuming that the compressor check valves don't leak down which they very well may if left alone for long enough) when you power back up, the compressor is starting against a load. Just something to think about.

Related question that is getting a bit off-topic: do you valve off your air system when you shut down the shop? I turn off the ball valve on mine right at the tank and my compressor will hold pressure for months.

At last, someone has given me something to think about! I'll have to look into that. I'm not sure how the unloader system functions. It's a Quincy 24 CFM 175 PSI compressor from Northern Tool. I'm going to go out on a limb here and ASSUME something. I thought when the Motor cut of it unloads kinda like a big truck air compressor. I'll give Quincy a call later today and do some asking. Thanks for the useful input.

No, I do not valve it off unless I happen to think about it. Right now I just have the airline coming off the tank. I have a couple of 50ft air reals I need to mount and run lines to. Hopefully I'll get to that later this week.

 

[TheEquineFencer]

Here's one potential problem: if your compressor has the pressure switch-mounted unloader valve, and your added control turns off the compressor while it is running, it will not unload. Then (assuming that the compressor check valves don't leak down which they very well may if left alone for long enough) when you power back up, the compressor is starting against a load. Just something to think about.

Related question that is getting a bit off-topic: do you valve off your air system when you shut down the shop? I turn off the ball valve on mine right at the tank and my compressor will hold pressure for months.

I just went out and took the cover off the pressure switch controls. You're absolutely right! I guess if I were to, even as it's configured from the factory, cut the compressor off manually before it reached cut off, it would be starting against a load. It seems I remember another member posting something about this problem and a "fix" for it. Do you or anyone else know the link to that thread?

 

[sberry]

The ball valve is a super idea. I might consider a simple solenoid to the lights.

 

[sberry]

My starter has an off/on switch. On the rare event its down I would plug in, turn breaker on and use switch. Could go years before you actually had to manually start it. A pressurized tank is the arm of the switch.
My own is hot all the time. 365. I do use 2 comps. I have the breaker off to the secondary and dont normally need it but we use the tank. If I would want to use the thing would turn the breaker on while its at full pressure, again not switching under any load.

 

[jgorm]

It would drive me nuts if my compressor turned on every time I walked in.

 

[sberry]

Right, in reality the usefulness of some of these schemes is not as great as they are in the mind or on paper. If it was a real deal there would be a code requirement.
Millions of these professionally installed with the minimum equipment used worldwide without incident, then a few come along and going to start fixing it, guess who has 95% of the problems?

 

[sberry]

There is nothing wrong with shutting it off. If there was a reason it came on without use then its a thing or if use is very sparse, would shut the valve off and shut the breaker off. If you use air in the middle then it would start under load with breaker but I wouldn't lose any real sleep, have seen them used daily. Not sure how good an idea it is but again, millions do it.

 

[sberry]

It would drive me nuts if my compressor turned on every time I walked in.

Yes, most residential demands for air are not parasitic in nature. They are 1 function, one user and you don't need it for every task. In a home garage I bet I could go a long time without needing to turn air on.
Now we even have battery impacts.

 

[sberry]

We don't use air constant but any time about 16 or more hr a day someone could want to use it. It gets several uses a day even when its slow and is subject to change.

 

[Charles (in GA)]

It would drive me nuts if my compressor turned on every time I walked in.

The circuity the OP proposes is not to turn on the compressor, but to enable the compressor circuit so that if it needs to run, it can. problem is, without a tank shutoff, there will be leaks and every time the OP walks in, the compressor will start up and probably need to pump up a tank from empty. If the OP intends to automate this, then he needs to include an electric operated tank valve to shut off when he leaves and open when he enters. It would be a valve similar to the one mentioned in THIS THREAD.

Charles

 

[LS6 Tommy]

I live with an engineer...do you know what and engineer is?

Someone who drives a train? In my world that term can mean a lot of things, Custodian, Maintenance man, boiler operator, elevator operator... Most of the ones I've met in the HVAC field aren't exactly what I'd call technically proficient. when I was an apprentice a Journeyman tech told me " an Engineer designs a system and puts it on paper. A Technician makes it work right".

Tommy

 

[logixjock]

As for the unloader and shortcycling the compressor, use the 120vac signal from the lighting circuit to arm a compressor enable relay, use an aux contact from the pressure switch to OR the coil of the enable relay. That way if the compressor is running when the lights go out, it will finish it's cycle. Dead simple, no need for the transformer, just use 120vac relays.

If you use air everyday I think it's a fine idea.

 

[_Dock_]

As for the unloader and shortcycling the compressor, use the 120vac signal from the lighting circuit to arm a compressor enable relay, use an aux contact from the pressure switch to OR the coil of the enable relay. That way if the compressor is running when the lights go out, it will finish it's cycle. Dead simple, no need for the transformer, just use 120vac relays.

If you use air everyday I think it's a fine idea.

Your solution makes to much sense. Or, one could just put a shut off valve on the tank and turn the compressor off with a wall switch before you leave but that would be to difficult.

Here in a minute he will come along and advise that your input is useless because you disagree with his solution.

You can buy your transformer here

Www.digikey.com

 

[CarterKraft]

I just went out and took the cover off the pressure switch controls. You're absolutely right! I guess if I were to, even as it's configured from the factory, cut the compressor off manually before it reached cut off, it would be starting against a load. It seems I remember another member posting something about this problem and a "fix" for it. Do you or anyone else know the link to that thread?

Doesn't the manual switch lever dump the air when you switch it off. My
Ingersol does. The tank check valve holds the air in the tank as the manual shut off dumps the air to the head via that 1/4" copper line.

 

[TheEquineFencer]

Someone who drives a train? In my world that term can mean a lot of things, Custodian, Maintenance man, boiler operator, elevator operator... Most of the ones I've met in the HVAC field aren't exactly what I'd call technically proficient. when I was an apprentice a Journeyman tech told me " an Engineer designs a system and puts it on paper. A Technician makes it work right".

Tommy

I'll have to remember that one.

 

[TheEquineFencer]

Well I guess I'm not following you then

If you already have the switch and you have access to the lighting wires then just tap off the lighting circuit and tie it directly to your starter. Lights on, compressor starter is armed. I still don't comprehend why you need the 24 vdc power supply and the extra relay.

I did not want to run more 12 gauge wire and conduit from where the lighting circuit is when I can do it with 24V wire that does have to be up to the code requirements that 12 gauge wire is inside a conduit.
From the above, it would "mixing" the two circuits for the lighting 120V and the 240V for the air compressor. 24V to me is a lot safer for what I want to do. I'd hate for someone to switch the compressor off and think everything inside of OFF and find out there's 120V from another source.

 

[TheEquineFencer]

Doesn't the manual switch lever dump the air when you switch it off. My
Ingersol does. The tank check valve holds the air in the tank as the manual shut off dumps the air to the head via that 1/4" copper line.

My air compressor has a Motor starter and if you look back through there's just the pressure switch to cut it off. There's not a manual On/Off as the breaker for this circuit is with a few feet of the main panel.

 

[Charles (in GA)]

Doesn't the manual switch lever dump the air when you switch it off. My
Ingersol does. The tank check valve holds the air in the tank as the manual shut off dumps the air to the head via that 1/4" copper line.

I've only seen this on cheaper compressors. Wasn't aware that any of the larger compressors had the auto/off lever on the pressure switch (which merely moves the mechanical mechanism of the pressure switch to the off position opening the unloader valve in the process.)

Charles

 

[logixjock]

You're right Dock, His plan makes no sense but it's his shop. I can add no more to this conversation, maybe the diesel kid will come on here and fix us up...

 

[TheEquineFencer]

As for the unloader and shortcycling the compressor, use the 120vac signal from the lighting circuit to arm a compressor enable relay, use an aux contact from the pressure switch to OR the coil of the enable relay. That way if the compressor is running when the lights go out, it will finish it's cycle. Dead simple, no need for the transformer, just use 120vac relays.

If you use air everyday I think it's a fine idea.

I see your main idea of using the enabled pressure switch to latch a relay to allow the compressor to finish it's cycle. That is a good point to keep in mind. I appreciate the input.

I really do not want to introduce another 120V source from outside the 240V circuit that feeds the air compressor. In the event that someone other than myself were to be working on it and think that because the 240V Air Compressor circuit is off everything inside is "dead" it might cause them problems.

 

[TheEquineFencer]

The circuity the OP proposes is not to turn on the compressor, but to enable the compressor circuit so that if it needs to run, it can. problem is, without a tank shutoff, there will be leaks and every time the OP walks in, the compressor will start up and probably need to pump up a tank from empty. If the OP intends to automate this, then he needs to include an electric operated tank valve to shut off when he leaves and open when he enters. It would be a valve similar to the one mentioned in THIS THREAD.

Charles

My main idea is not really to turn ON the compressor as is it to make sure it's OFF when I leave the shop.

Previously with the lighting during the first time the shop was built, the lights would get left on when I was called away to do other task by the "Boss." I added the Motion Controls and cut the light bill almost in 1/2. To be honest, it's annoying to me to be in the office here and have the air compressor come on when I'm not needing it because I left the airwrench plugged in and the tank leaked down.

You bring up a good point with adding a tank shut off.
I could do that by adding a 24V operated valve and use the same low voltage wire that would feed it that turns on the compressor also.

One of my main reasons for using 24V to operate the controls is cost and flexibility. I run 24V wiring cheaper and easier than 120V to do the same thing. If I run 120V wiring in this shop, there will not be any 120V wiring smaller than 12 gauge run and all 120/240V wiring will be in conduit or MC or BX type protection.

As to some of the other comments...I guess there's some in here that think Ford is better than Chevy, Mopar is better than Ford and they can't understand that different people want different things for different reasons.

I asked for input on what I was going to do and problems I might encounter. I've received some good ideas, like the above from Charles (in GA),redmondjp and a few others. They may not be thrilled with what I'm doing but did contribute some useful input. I wish others were more like them. I wish more in here looked at things objectively that objectionly.

 

[sberry]

I agree adding more 120 is a problem, I got a machine I also need to fix before I kick the bucket.

objectively that objectionly.

As for this, they both go together. We see some great ideas here and some brain farts. Some are good enough ideas but are not very practical, some turn costly and a lot of it is cheered on with a pat on the back and is pretty much,,, well not as great as it might appear at first glance. Some we see a grand and cant be finished till next paycheck when a 100 would have worked just as well and is the way a master would have done it.
I am all for automatic safety when its right, a poor system is as good as none and as was eluded to in another equipment thread a lot of stuff would fall under UL that is not considered by every installer etc. It can make up for some bad habits, I automatically unhook air tools, I got other bad habits though... ha I can hear my comp from the office a bit, noticed a while back it didn't sound right, sure as sheet a bearing went south.

 

[TheEquineFencer]

I agree adding more 120 is a problem, I got a machine I also need to fix before I kick the bucket.
As for this, they both go together. We see some great ideas here and some brain farts. Some are good enough ideas but are not very practical, some turn costly and a lot of it is cheered on with a pat on the back and is pretty much,,, well not as great as it might appear at first glance. Some we see a grand and cant be finished till next paycheck when a 100 would have worked just as well and is the way a master would have done it.
I am all for automatic safety when its right, a poor system is as good as none and as was eluded to in another equipment thread a lot of stuff would fall under UL that is not considered by every installer etc. It can make up for some bad habits, I automatically unhook air tools, I got other bad habits though... ha I can hear my comp from the office a bit, noticed a while back it didn't sound right, sure as sheet a bearing went south.

 

[Trey T]

OP: Are you concerning that you lose air overnight or while you're not there? What's brand/model/specs on your compressor?