Monday, April 15, 2024

I Swore I'd Never Install Another Split System A/C!

They're quiet, they're efficient, they're a pain-in-the-ass to install!

I wrote before how I tested a split system A/C unit back in the 1980s when I worked for a large air conditioning company.  They offered us a license to sell them under our own brand name, but we turned them down.  As one executive put it, "Americans want window units!"

And there is a certain logic to that.  A simple window unit A/C system can cost only a few hundred dollars and can be installed in an afternoon, if not in fact, under an hour.  They are ugly and block a window, and the seal around the window leaves a lot to be desired.  But they are cheap and easy to install.

A split system, on the other hand, can cost about $1000 (although I paid a lot less than that for my grey-market Hitachi systems in New York, that ran on R-22 as I recall).  Installation is another thing, though.  Expect to pay as much to install as you would for the system.  I've had HVAC techs quote me $5000 just to install one system, and in some cases, that might be justified, particularly if you are on a second storey.

It ain't easy.  Mounting the inside wall unit seems easy - "you hang it like a picture!" people crow.  True that, but you have to make sure the mounting bracket is screwed into studs, or the whole thing will fall off.  Sort of like mounting a microwave under-cabinet.

But that's the "easy" part.  You have to have a hole going out through the wall for the refrigerant lines, the condensate line, and the electrical connection.  For a wood-framed house, maybe this is not such an issue, other than when you hang the bracket, you have to make sure the "hole" isn't going through a stud. Fortunately, they give you a large cardboard template to work with.

In other cases, it may not be so easy.  The units I put in the basement of our lake house required that I drill through nearly 10" of hard solid concrete. I bought an impact drill and two bits and basically wore all three completely out by the time I was done.

By the way, did I mention that everything is metric?  They kindly stamped "US ONLY" on the wall bracket next to the holes that were on 16" centers, which is pretty standard spacing for US wall studs.  This will come into play later on.

So you get the inside mounted and feed the pipes, cable, and hose through the wall.  Some kits come with a sleeve to put through the hole - and even an escutcheon.  Make sure the hole angles down so the condensate will drain out.  This latest unit had no sleeve, so I put a 2-1/2" piece of PVC pipe through the wall, cut it flush, and caulked it in place.  Maybe this will keep the termites at bay.

Yes, termites - a horrific discovery that delayed the project by a week.  We had the studio and house treated and traps installed.  We'll see where that goes.  Termites are a way of life in the South.  We have them in our historic Goodyear Cottage which is rented by the Arts Association.  Our historic preservationist wasn't too worried about them - "they are a slow-moving hazard" he said.  And I guess they have a lot to deal with.  We regularly go through their dumpster for scrap lumber and other choice things and recently we saw a set of beams from another historical cottage, riddled with termite holes. So it ain't just us!

Now for the outside part.  You need to run electric - 110V or preferably 220V.  I had a 20A 110V line installed for the window unit, so I drilled through the back of the box and through the outside wall and ran the power to a disconnect box.  You need to have a disconnect so you can work on the unit without being electrocuted.  Most electrical codes require this.

The company I bought the unit from (Alpine) offers these things (disconnect box, refrigerant lines, electrical cord, condensate line, outdoor mounting bracket) a la carte.  Turns out, the unit comes with a condensate line, so now I have two.  But figure two or three trips to Lowe's to get other bits and bobs to finish the project.

In New York, I poured  concrete slab for one outside unit and built a small wooden deck for two others (using scrap deck boards).  My garage unit is bolted to the concrete sidewalk.  A neighbor asked me to install a unit for him (and later, a second unit) which I am loathe to do as working on other people's stuff is stressful.  But he had bought wall-mounting brackets which appeared flimsy until you tighten up all the bolts.  It held my weight which is far more than the weight of the unit.

The bracket just "hangs" from the wall with lag screws.  It did support my weight which is 3x the weight of the unit, though.

Ground mounting is problematic as leaves and debris accumulate in the unit. My friend had a "professional" install a unit for him and they left it on the ground, unbolted.  When I found it, it was half-buried in dirt and debris and no doubt not long for this world.

So wall-mounting is really the way to go.

But again, metric.  The screw holes were on approximately 18" centers so I had to drill holes at the 16" mark for the lag screws.  The mounting holes for the condensing unit were "off" as well and I had to drill two holes for the 1/2" head quarter-twenty bolts that hold the condensing unit to the bracket.  No doubt vinyl siding is not popular in Japan, so I had to use rubber blocks between the uprights (which I lad-screwed in as well) to make up for the gap from the vinyl.  Oh yea, I had to space out the top bracket with some plastic blocks to clear the vinyl siding further down.

The bracket, by the way, comes with a bubble-level built-in, so you can easily level the top bracket when installing.  The "arms" have adjustable pads to level in-and-out.

You realize you are working with a technology not designed with American building codes in mind.  Hooking up the electric is like working on a car, not a house.  The electric enclosures are tiny and hard to work with if you have big hands.  It is like wrestling a pig in a phone booth!

The main power goes to the condensing unit outside and then a "control cable" feeds power inside to the evaporator, running the fan and electronic controls.  And yes, they all have remote controls, even the one I tested back in 1982.

Now the hard part - refrigerant lines.  I cut mine to fit, but others don't and I don't suggest that.  Some units come with "precharged lines" that have fittings that pop open when you connect them.  Some claim this causes a loss of efficiency, as there is a restriction in the line. If you don't cut the lines to length, what do you do with the excess? Some neighbors coil this up and even put it on a hose holder (!).  Problem is, there is oil in the refrigerant and it accumulates in these loops and can starve the compressor (at worst) or just decrease efficiency (at best).

So you have to cut the lines and flare them (be sure to put the flare nut on the line before flaring! - I've done that more than I care to admit) and carefully flare the copper.  In traditional American HVAC, compression fittings like this are not favored - we silver-solder lines for a permanent leak-tite seal.  Flare fittings?  For amateurs!  But it is the norm for split systems.

I broke down and bought a new pipe cutter and a new flaring tool (trip to Lowe's #3) as my old tools were worn and making bad cuts and bad flares.  You don't put pipe dope or tape on flare fittings of any kind - the compression is what seals it.  But in my friend's install,the provided a small disc to put on the male fitting to seal, and lately, they offer this goop to put on the fittings.  I used it, but not sure if it helped or not.

For a change, there were no leaks in the system when I pumped it down.  Yes, you need a vacuum pump and manifold gauge set (or at least one gauge, as there is generally no high-side tap on these things).  I pumped it down and it held vacuum, so I opened the low side valve and... promptly pumped out most of the refrigerant!


Leak-checking is a two-stage process. If the system holds vacuum, that is a good sign.  Once evacuated, open up the low-side valve (the condenser is precharged with refrigerant) and let some gas into the system and use a soap solution to check for bubbles.  Make sure the manifold is disconnected or the valves are firmly shut, or that precious refrigerant will back-flow through your vacuum pump!  Duh.

If you do this for a living, you get used to doing it. If you do one every five years, you forget and make mistakes.  Professionals also have a big tank of R-410a in their truck.  I had to order it.  Funny thing, but you can even buy "illegal" refrigerants online if you represent yourself as EPA certified.  So I recharged the thing and it works perfectly.  Supposedly, R410a is being phased out soon.  Oh, well.

I used ordinary plastic gutter downspout (with the back cut out) to cover the refrigerant and condensate lines.  Note the hole where the window unit used to be.

The units in New York I had evacuated and charged by a local HVAC tech, as I didn't own a vacuum pump.  I think he charged less than $300 to do all three, which was cheaper than me buying a vacuum pump and manifold gauge set.

Oddly enough, the present unit ran with a very low charge, it just didn't cool.  Most units will shut down if the charge is too low (or too high) and generate an error code.  I guess it wasn't that far off.  32 ounces later, it runs like a champ.

All that being said, I am not sure I want to do another one, even if I am getting the hang of it after seven installs.

The end result, though, was worth it.  No noise, no vibration (even with a wall-mount!) - just quiet, steady cooling (and heating, it is a heat pump).  Plus, no puddle of water inside some window unit to act as a termite drinking fountain.

All I have left to do is remove a second window unit (also rusted through).  Hopefully the termites haven't made a home there, as well!