Mini split A/C Heat Pump systems

[s219]

I have always been curious about the refrigerant in the mini-split systems -- I assumed after it was installed, it had to be charged up. Especially since you would be adding an arbitrary length of lines between the inside and outside units. Are you guys saying they come pre-charged somehow? How does that work with hookup and running lines of arbitrary length? I assume the systems have a maximum line length spec, but still....

 

[SirReal63]

Mine was precharged for a maximum of 25' of line set, you just pull the vacuume and hold it for 20 minutes then release the charge. Simple as that.

 

[s219]

Mine was precharged for a maximum of 25' of line set, you just pull the vacuume and hold it for 20 minutes then release the charge. Simple as that.

That is pretty cool then -- really makes for an easy install.

 

[tamu94]

That is pretty cool then -- really makes for an easy install.

The Mitsubishi's are precharged and they provide a table to calculate how many feet of line set they can support and the amount to add if necessary. The key is to properly flare and prep the connections. You must use the correct torque and technique or you will have problems. This means having the right tools. I made sure to purchase and use a very expensive flare and cutting tool made especially for minisplits and to use a torque wrench. Last, the amount of vacuum that must be pulled is much higher than the older AC systems. You have to have a high vacuum pump and manifold gauges for Puron. In order to get the factory warranty for most units a certified HVAC tech must do the pump down, leak test, and Puron release. Its worth it to pay for these simple services and will cost about the same as buying the gauges and pump anyway. The trick is finding a tech who will do it.

 

[jbeckham]

I did get a quick response from John at Chiltrix.
Bottom line is that it is very expensive, at least for me. Basically a little over $9k. I can get the "same thing" in a pioneer for $3600.
I'm certain I can buy many extra feet of tubing and get an HVAC guy to sign off my install for $5,500.
Pity too, I liked the technology.

Here are some things I would like to point out about the Chiltrix system that maybe some people aren't wrapping their mind around:

You're not installing an intricate (expensive) refrigerant piping network for the application. You're just using (inexpensive) PVC/PEX piping to distribute the transfer medium (which is just water, instead of a regulated chemical compound that can only be acquired with the appropriate licensing).

Other than any perceived savings on upfront materials costs, why is this approach significant and important..?

Because it leaves A LOT of room for seamlessly integrating any future expansion of the application... Also, (and potentially more important) it easily provides the ability to re-configure the piping network to correct any design/implementation/capacity errors. Or, re-configuring simply based on the personal desire and preference to change (any portion or the entirety of) the implementation of the application itself. You can't very easily (or inexpensively) do that with a hard/soft drawn copper tubing network that has been exclusively allocated for transferring refrigerant.

This is just my 2 cents on the matter/topic... your mileage may vary.

 

[kenmac]

Mine was precharged for a maximum of 25' of line set, you just pull the vacuume and hold it for 20 minutes then release the charge. Simple as that.

How many microns did you happen to pull the vacuum to ?

 

[SirReal63]

I didn't, I had an A/C guy come to run the lines and pull the vacuum. I cannot get on a ladder because of my dizziness and the unit is way up the wall, something like 12' up.

 

[jbeckham]

How many microns did you happen to pull the vacuum to ?

Each manufacturer will have their own guidelines for evacuation procedures and levels. It's best to read their OEM installation manual to understand their requirements... However, you will typically be required to reach and sustain levels between 250-500 microns (for a manufacturer specified amount of time) to meet their warranty requirements.

For what it's worth, 1000 microns is equivalent to 1 millimeter of vacuum as measured by a column of mercury... A traditional (analog) compound HVAC gauge manifold only presents the vacuum level in inches of mercury...which means each mark between 0 and 30 on the compound (negative) side of that gauge is equivalent to 25,400 microns (0 being 762,000 microns and 30 being 25,400 microns). I say all that to say this to the DIY enthusiasts, get a (decent) micron gauge and read it's manual too... Or, you could just call a licensed professional and have them perform the procedure for you.

 

[kenmac]

I would not pull any less that 400 microns on a new system..

 

[jbeckham]

I would not pull any less that 400 microns on a new system..

pulling a vacuum and sustaining a vacuum serve different purposes... however, the process of both yields important information about the conditions within your system. Also, a high pressure test is just as importation as a low pressure test... You can't exert (test) the forces of "normal" operating conditions on the piping network by only performing a low pressure test.

Manufactures will explicitly specify the micron level to which they require to achieve their warranty requirements.