chh compressor loading and unloading sequence so there's three solenoids we have to take into account we have our mail unloader or male loader and our female unloader back here in the back each of these do their own thing in a separate sequence so let me explain what these control these are your slide valve solenoids there's a valve in here that slides back and forth on the bolt and it's a big just chunk of metal I've had videos in the past where you can visually see this you can go check those out if you're needing a
reference the slide valve loading is very dependent upon the oil level in the system if we do not have proper oil levels we're not going to actuate our slide properly at startup this compressor should go into a full unload state for startup every time most of these smaller ones like this we can see around 40 percent of rla during startup operation I've seen it as high as 50 but 40 percent give or take is the normal during that startup you're going to have energized your unload solenoid and you can take a screwdriver if you don't
know and you'll feel the pull on the solenoid right now neither of these are energized because we're at a constant state we're not trying to load or unload we're trying to hold so at startup this will be energized and your female unloader will be energized which right now it is and I can fill a pull on the screwdriver as I'm holding it you will not have power here but you will have power here when we're ready to load the compressor this solenoid will energize your unloader solenoid will de-energize and you will start pulsing the load
solenoid which means that it will get a couple of seconds of power at a time what that is doing is it's taking the oil from the oil system on the oil input and it's diverting it through internal Chambers to where we're using the oil to physically push the puck inside of here which is what slides the valve operation so the more we push oil in the more load we're going to put on the compressor to move more refrigerant to control the load once startup is finished the female unloader will stay energized for the duration of
operation now let's say we've made made set point on our leaving water and we need to unload this compressor the unload solenoid is then going to be energized and it can be pulsed just like the load we're not going to energize the load solenoid anymore but we will start pulsing the unload solenoid and what that'll do is the chamber that we were stacking oil in to move the puck we will open a port in this valve to allow flow back to the suction of the compressor this will allow that oil to draw out of that
because when it's getting pushed in through the loader it's high pressure from the high side of the system so when we equalize it to the suction side it's going to naturally push its way back out into the suction end of the compressor and that's going to allow that slide to move back and it's going to remove load from the compressor we're going to move less refrigerant and it's gonna do this back and forth to control load throughout all of its operation the eev and everything else Works in simultaneous with the compressor loading and unloading based
off of superheat when it comes time for shutdown we will have the load solenoid de-energized and we will fully energize the unloaded solenoiding it will stay activated and in that process we will de-energize the female unloader to allow the compressor to fully unload and we will do a pump down during this process the evaporator is going to be pumped down by closing the eev and stacking all the refrigerant in the high side of the system then once shutdown is completed we will still have our female unloader de-energized and we will leave our unload solenoid energized
until shutdown is complete then we come back to start up where this the female unloader stays de-energized until we're ready to load and the unload solenoid will be energized until loading commences that is the loading cycle for this machine the female unloader is controlling discharge gas and suction gas on an internal load valve inside the compressor so when it's energized it's allowing discharge gas to close and unload valve to where the compressor won't unload internally when it de-energizes it releases that gas that we built up in the chamber to the suction side it allows that
internal valve to open so the discharge gas will will bypass directly into the suction side of the of the screw compressor and the compressor can fully unload itself while it's in a coast down state and it's also helped prevent any kind of reverse flow or backward spinning on the screws this also allows us to have a minimum startup current so that we don't over pull the evaporator we also put less wear and tear on the compressor this is base operation for a chhh compressor there's a couple of different series there are some larger ones this
one is the smaller one this is only a 70 ton it's the same base operation for the major authority of this series so they're trying to understand what it's doing or what it's supposed to be doing and just using a screwdriver is fantastic you could also use the danfoss magnetic app if you choose I find a screwdriver just the old school way of doing it using your phone works just as well it's going to pick up the magnetic field as you're going give a special thank you to CSG for sponsoring this video sponsoring this channel
they're the guys I went and did that live training for down in Houston if you're looking for them look up Houston hermetics or American hermetics at a Dallas DFW area they do service nationally and they keep a pretty good stock of compressors in-house they specialize in screw compressors receps they got a full complete shop for you from York to train to Carlisle even the Copeland side I highly recommend them they've got a great service of wonderful group of guys they're going to take care of you over there so reach out to Jake I got his
email in the description he'll get you taken care of he'll get you fixed up whatever your compressor needs are even if it's parts or any kind of tech support troubleshooting things of that nature they will go a long way to get you where you need to be
