I recently had the pleasure of installing a Pioneer three-zone split unit on my home and wanted to share some feedback for anyone looking to do this on their own home. I wish there was a comprehensive list I could have followed when I did mine, perhaps this can be your list.
Before ordering the unit, give yourself a reality check. Are you sure you’re ready and able to do this? I ask because many folks aren’t ready for the size and scope of this project, so I want to make sure you’re aware of what you are getting into.
A rough project scope is, with approximate hours (for my job):
- Run electrical to the outdoor location you plan to install the compressor at. This includes installing a breaker (do you have room for a 240v breaker in your panel and capacity for your new system?), running cable from the panel to the outdoor unit, pulling up your siding, installing a block, running conduit through to the outdoors, then installing a disconnect panel on the outside of your wall – about 4 hours.
- Plan your compressor/outdoor unit positioning. For brick walls, a mounting bracket might work just fine; for vinyl-sided houses you might want to buy/build a stand. I did mine out of concrete and paving blocks, then tiled it. Note that you want – need – the compressor at least 12″ from your house wall. Check the manual to ensure enough airflow. Plan to install the unit – and not move it again – for ten years. A masonry stand about 16″ off the ground required about 4 hours.
- Plan your wall unit locations as best as you can, full picture included. You want the indoor unit(s) placed as high as you can, not blowing on people. The easiest, best way to work on them is to have the lines run straight out the back of the unit, through the wall, to the line sets outdoors. The hardest way to install these is to install the lineset flares behind the unit and have them run out the other side (because you have to take it off the wall to test or maintain anything). Anything you can do to get the flare joints outside where you can work on them, the condensate lines outside as quickly as possible, and avoiding studs in the way of the lines will make your life easier. Prepping for this should take about 2 hours.
- Once you’ve planned your location, take measurements to assess how much lineset cover you need, how much lineset you need, and how you plan to run/mount it.
- Once you have the footage per head, look up your potential unit’s specifications. Many include enough charge in the compressor for up to 25′ of line. If you use more than that, you’ll find you need more refrigerant – unless you are EPA 608 certified, you will have a tough time buying this.
- Mount the indoor unit to the wall, pass the lines through, and run your lineset from the flare fittings to the compressor. I recommend you run the line entirely – don’t plan to “clean it up later” as this can cause some very unexpected (bad) surprises. I would allot 4-6 hours per head unit for this.
- Mount the compressor, install a watertight electrical whip to the disconnect box and cut/flare/connect your lines to the compressor. Connect the wiring from indoor to outdoor unit (I would highly recommend using a gland connector for this instead of the factory rubber slip) and ensure the condensation line drips somewhere acceptable outdoors – I would allocate 3-4 hours for this step.
- Here’s the important part, explained below: you must, without a doubt do a vacuum pump down of the linesets, ensuring it holds a vacuum, along with a nitrogen pressure-test/evacuation of the lines. This doesn’t take a long time to do, but requires time to hold vacuum/pressure. Allocate 3-4 hours for this step.
- Once all of this is done, it’s a good time to do another leak test, this time under pressure and with a small amount of refrigerant released (again, see notes). This only matters if you have a refrigerant detector, but can help identify leaks. This shouldn’t take more than an hour or two, if you have the equipment to do it.
- Fire up the unit and enjoy!
Some bullet points that I hope help you out:
- The linesets must be done – enough to not move them again – before you pressure test the system. That’s because moving the lines becomes almost impossible after the refrigerant is released without a pump-down (see below). Moving them after the system is under pressure is asking for trouble – a lot of it – if you’re not a trained HVAC technician. Have them done enough that you’re ready to put the lineset covers on.
- Read up on your local code before installing these. I am not a person who cares much about inspections and permits, but I also pay note to doing the job right should something ever come under fire. I did learn where my suburban town requires me to put the outdoor unit (it was not where I first planned to put it) and specific requirements for the shutoff before doing the job, so I wouldn’t have to rework anything. Upfront, though, had I not checked, I’d be reinstalling the entire system should the town have made me.
- You will absolutely need the tools below to make this work:
- An HVAC pressure manifold, used to measure your vacuum and pressure test. Note that in general, any one will do; you’re not charging or assessing refrigerant based on what’s on the dial, just measuring PSI.
- An HVAC vacuum pump to pull the vacuum.
- A tank of nitrogen (call your local welder supply company, these are rentable for $40 or so) and a pressure regulator for it. Amazon has these (CGA580 inlet, 1/4″ flare output).
- A flaring kit for HVAC work – these are also available on Amazon, you want to ensure you have the correct one (45 degree flare).
- Nylog sealant – this is useful as a general oil for HVAC work, but helps to seal the flare connections.
- A pipe cutter and reamer – for plumbing, it might not matter if you don’t ream a line, but you’ll never flare a pipe properly without a proper reamer.
- A reliable torque wrench that works between 10 and 40 ft-lbs. Preferably one with a digital display, a wrench-style opening and a very audible notice when you’re at the requested torque. I bought a “click-style” one with crowfeet wrench ends and it does not work as expected at lower torque ratings.
- A liquid-based leak detector (required). Even dish soap will bubble when it finds a leak, but there are cheaper alternatives on Amazon that spray on.
- An electronic leak detector is optional but recommended, my vacuum pump and manifold kit came with a refrigerant leak detector that was absolutely helpful in not flying blind.
- I should also mention that linesets can be very difficult to work with. I had two head units with 1/4″ liquid and 3/8″ suction lines, which were bendable by hand (when done gingerly and carefully). One head unit had a 1/2″ suction line and – I am not a proud man – required me to replace it twice because I kept kinking it. You won’t install a 1/2″ line bending it by hand. You will absolutely need a pipe bender. And you should pay attention to any bend you do on smaller sizes, because kinks can destroy your unit.
- Understand how your service valves work and what that means for the system. Mine open/close the inside of the unit to the outside, for example, so they never want to be opened until the entire lineset is tested. You want this to be 100% obvious and understood just in case you have an emergency during the install that requires you to know how to respond properly.
- On flare fittings, you really want to do two things: first, you want to torque them correctly, each and every time. If you are going to overtighten them afterwards, only do it a little bit. The copper flare becomes the seal and, if you crank it right down, you’re just making that part thinner and less strong, meaning it’ll blow out under pressure. Also, don’t move the linesets after the fact, particular around the flares. You can cause the line to break or otherwise fail, and that’ll cause your refrigerant and oil to also go away. Not a good scene.
- Pay lots and lots of attention to your condensate lines. They won’t seem like a big deal until you see a puddle of water and realize you’re taking the entire unit off the wall to fix it. That’ll be painful, because you can’t remove the unit from the wall when it’s got refrigerant in it (if you like to keep said refrigerant, at least).
- Pay no attention to the internet when it tells you to remove the schrader valves. For anything. Nothing you do as a DIYer is going to require them removed, but you’re not likely to return them properly or at the proper time. Imagine not being able to remove your manifold gauges because you forgot to put the schrader valves back in before you opened the service port. I’d laugh at you too.
On “my friend said you don’t need to pull a vacuum”:
You do. Your friend is wrong. You need to pull a vacuum for a number of reasons:
- The lines have moisture in them, and your compressor is filled with oil and refrigerant. Unlike oil you cook with, the oil in your compressor reacts with moisture in air to form acid, which will eat the inside of your unit apart.
- Air makes the refrigerant work much less effectively, and the same acid formed with the oil will get blown through your whole system, eating it inside out.
- Here’s the part that should scare you: in rare cases, large amounts of air being forced at incredible pressures into a hot compressor with flammable oil and potentially flammable refrigerant can be … well, explosive. Don’t put yourself in this situation. Should you not believe me, Google “diesel effect compressor explosions”.
- A vacuum is one of two complimentary ways you can check to see if your system holds pressure.
- Lastly, it’s not something you can undo. Once you mix air with your refrigerant, it’s shot. It has to be reclaimed and processed, and you have to vacuum out all of the refrigerant and oil from your system, refilling it from scratch. This is both expensive and not something you’re likely equipped to do.
And the Pressure Test?
Yeah, also something I would not consider optional after doing my install. Look, I shoot straight: I did mine according to the manual, which did not require a pressure test. I got lucky. I released the refrigerant, and checked for leaks. I had a small one on a flair fitting that I tightened. Having said that, I’ve done a few of these on the side and in two cases, a very gentle move of the liquid line caused it to pop off and blow a ton of nitrogen out the line, telling me I did the flare wrong.
The pressure test is the only way to get the system up to design pressure (which can be 500PSI or more) and test for leaks at spec. Vacuums can draw a seal closed where pressure can force them open. Again, it’s better, cheaper and long-term healthier for the equipment to check the system for leaks before opening a service valve.
How to do a pressure test:
- During this entire test, you will not open either service valve in the compressor, so leave your hex keys in the tool box. You’re only testing the environment outside of the unit.
- Connect the low-pressure manifold to your service port, and the yellow/service equipment line to your vacuum pump.
- Draw a full vacuum on the system, hold it for a while, then close the low-pressure valve to hold the vacuum in. Transfer the service equipment (yellow) line to your nitrogen tank whose regulator is dialed in at 450PSI (or just below the split unit’s design pressure). Open the manifold valve very slowly until the system sits at/around 450PSI – you want to let the nitrogen in, not slam the system with 450PSI immediately. Once there, close the manifold valve. Wait about 20 minutes for the pressures inside the circuit to equalize, then note the exact needle position.
- Check all connections for leaks using your leak bubbler. Any leaks will have to be addressed. Note that you’re dealing with high-pressure lines, so you absolutely don’t want to open anything up (or cause it to open up) in your face, etc.
- Once you’ve successfully leak-checked all connections and you’ve let it sit at least an hour, confirm the pressures have not moved. Note that the first 20 minutes or so can see major swings as the pressure moves through the system and causes temperature fluctuations.
- Once you are satisfied you have a leak-proof system, shut off your nitrogen, unscrew the yellow hose and release nitrogen from your system until it’s at 0PSI by opening the low-pressure manifold (slowly, again), immediately closing off the valve at that point.
- Reconnect to your vacuum pump and draw a full vacuum again, leaving it run for a while to ensure all moisture evaporates out of the system and exits the lines. Never connect the vacuum pump to a pressurized system. It’s a great way to blow the oil inside everywhere and damage it.
- Once you are satisfied you are operating with a completely leak-proof system and have all of the air vacuumed out of the lines, you can open your service valves and fire the system up. I like to disconnect the vacuum pump, ensure the low-pressure valve is closed on my manifold, and slowly but fully open the service valves. That way I can keep an eye on the pressures and remove the low-pressure line with an internal pressure that will keep the outside air from coming in (as it would if you opened it under vacuum).
There is an additional step you can take that adds a bit more leak-checking to the system – a pressure test with a tiny amount of refrigerant in the lines. Here’s how I do this:
- Start with the service valves never having been opened.
- Draw your full vacuum as above, leaving it drawn and valved off to check for leaks.
- With the manifold valve closed and a full vacuum in the system, open the liquid valve about a half turn until you see a small pressure increase on the suction side (about 3 seconds for me), then immediately and fully re-close the valve with a small amount of refrigerant trapped in the lines.
- You never, ever want to open the service valves with any pressure in the lines, as it can force back into the compressor and contaminate the refrigerant.
- At this point, you can re-test the lines with nitrogen pressure, but in addition to bubble leak checks, you can use your electronic refrigerant detector to see if any is being blown out the fittings/flares.
- Evacuate the gas as before, bringing the pressure back to 0PSI before pulling a vacuum.
- After a full, complete vacuum has been drawn at least fifteen minutes, you can close the low-pressure manifold valve, switch off your vacuum pump and release the refrigerant as per normal.
Note that in no case, ever, should the service valves be opened with anything but a full vacuum in the lines. Opening it with nitrogen in the lines first will blow nitrogen into the refrigerant, contaminating it. Opening it with air in the lines opens the Pandora’s Box we talked about earlier.
What if I opened the valves and found a leak?
You can perform what’s called ‘pumping down’ the refrigerant into the unit. This closes the liquid line service valve with the unit on and in high-cool (i.e. compressor is working) and suctions all of the refrigerant back into the outdoor unit. You watch the low-pressure side draw that pressure down from around 150PSI (where my unit sits) to around 0PSI before you immediately close the low-pressure service valve too, trapping all the refrigerant into the outdoor unit. Note that for good sized leaks, I would close the valve before it gets to 0PSI, as it might draw air into the leak and down into the compressor.
You can YouTube search the process using keywords like ‘pumping down hvac split unit’ to see the process, there are good videos out there.
You’ve made it too complicated!
I’ve done a thousand projects myself and found most things – electrical, carpentry, plumbing – very self-explanatory. HVAC is a lot more technical (at least for home versions of these trades). It has to be done very methodically, with tons of knowledge involved in each step. The truth is pretty simply that the worst you can do is burn out your unit, lose your refrigerant, and lose a few thousand dollars on the equipment you just bought, but none of those are easily recoverable. You will absolutely find someone willing to come out and work on your mistakes if you have to – most smaller HVAC contractors or companies will be happy to take your money to do this – but they are not going to provide a warranty on their work, your unit or do it at cutthroat pricing.
HVAC is, as it turns out, a very complicated, specialized, technical and tool-intensive trade. My drawer of mechanical tools meant nothing for most of my project and even misled me into thinking I was torquing something properly. Not following steps (steps that – by the way – you’re not going to know unless you consume a lot of training) is a great way to damage equipment and the environment. After doing a few of these, I find myself feeling confident – both in doing them properly now, but also the amount of work that goes into doing them properly. I also find myself looking at my first install and wondering “well damn, I wonder when that’s going to fail, because I clearly didn’t _____”.
If you find these steps burdensome or don’t want to do them, consider if you want to do the project at all. As I said, I’m a very accomplished DIYer, but I hate these: there are too many details, too much to go wrong, and frankly, I won’t ever do another on one on the side either unless my immediate family needs me to come back and replace theirs.