Any residential HVAC guys on here?

[plumbcut]

Seriously considering installing an AC system in my house myself. Would appreciate some advice from anyone whos in the industry or who has done it themselves.

Sourcing parts online -- is it practical? Goodman VS ?? SEER/tonnage/footage

building the air handler/evaporater coils - What do I really need? Plenum design, etc...

Stuff like that. Im very comfortable doing the work (except for charging the system) but I dont have the experience designing and would like to keep the "should haves" to a minimum. Looking to build a very simple system on a budget. Im remodeling a very old house little by little and Im trying to avoid installing more window/wall units. Which work great but look sooo bad on the outside of the house. Not to mention efficiency...

I would appreciate and consider ANY and all advice. Thanks!

 

[Tooljunkie]

When i made the deal on my central air unit, the main outdoor unit came pre-charged and was good for 25' of line plus the evaporator coil.
Hvac guy was my brother's buddy. I drilled concrete to pass lines through,ran a power cable and set a slab of concrete outside. Took him less than an hour for entire job.
Oh, i had to change thermostat and run new control wires. That took the longest.

Bought unit with furnace coil for 1000,gave guy 100 to install.

 

[Grouse Feathers]

Many online HVAC sellers have information on sizing of units and installation instructions. Some also have technical departments that will take calls and discuss your installation options. Unless you specifically want a whole house system you should also look at the ductless systems. I remodeled a three season cabin that has no good options for duct work by adding two ductless heat pumps (there are also cooling only systems). They provide cooling and all the heating down to 0 F.
Before you buy any system or components, check on rebates including state and federal taxes and rebates from your utility provider. I installed my last heat pump for about $2200 total and then got over $1000 in rebates. There are specific performance requirements for the rebates so you need to check first to make sure your equipment meets the requirements. You may also need to find a local HVAC contractor willing to insect and sign off on your installation to activate any warranty on the equipment and to collect the utility rebates. I found a local contractor who signed off for a $100 service call.

 

[nzzshl]

I have installed two systems myself. The sales people sold me all that I needed.........from the compressor to the refrigerant supply and return lines, condensate pan and A-coil. I cut the plenum, installed the condensate pan, installed the drain and condensate pump, put a coil in place, ran the refrigerant lines both directions, poured a concrete pad (with ABS compressor pad on top when cured) set compressor, connected to exterior weather fuse box with 220V line. Hired an HVAC tech to do side job of silver soldering the compressor and A-coil connections. Compressor had near perfect contained pre-charge. Tech connected gauges for pressure test......
all well for 17 years now. After the tech left, I installed new Z-strips and resealed the sheet metal of the plenum and installed dum-dum around the drain and the copper lines. Later installed new programmable stat.

 

[plumbcut]

When i made the deal on my central air unit, the main outdoor unit came pre-charged and was good for 25' of line plus the evaporator coil.
Hvac guy was my brother's buddy. I drilled concrete to pass lines through,ran a power cable and set a slab of concrete outside. Took him less than an hour for entire job.
Oh, i had to change thermostat and run new control wires. That took the longest.

Bought unit with furnace coil for 1000,gave guy 100 to install.

I didnt know they could pre-charge the unit. So after the refrigerant lines are installed, do they have to be evacuated before releasing the gas into the rest of the system? Seems too easy.

you should also look at the ductless systems. I remodeled a three season cabin that has no good options for duct work by adding two ductless heat pumps (there are also cooling only systems).

I seriously considered that but I felt like given the price of the systems (which is pretty significant), I could do something better (Central) for even less money. I have good attic access to run the equipment and ducting.

I have installed two systems myself. The sales people sold me all that I needed.........from the compressor to the refrigerant supply and return lines, condensate pan and A-coil. I cut the plenum, installed the condensate pan, installed the drain and condensate pump, put a coil in place, ran the refrigerant lines both directions, poured a concrete pad (with ABS compressor pad on top when cured) set compressor, connected to exterior weather fuse box with 220V line. Hired an HVAC tech to do side job of silver soldering the compressor and A-coil connections. Compressor had near perfect contained pre-charge. Tech connected gauges for pressure test......
all well for 17 years now. After the tech left, I installed new Z-strips and resealed the sheet metal of the plenum and installed dum-dum around the drain and the copper lines. Later installed new programmable stat.

Sounds great. This is exactly what Im wanting to do. What are Z-strips?

 

[North Idaho Wolfman]

Yes the lines and the evaporator coil needs to be evacuated before charging.

For your duct work look at flex duct, efficient, fast and simple.

Note: Being that your in California, the land of a thousand environmental laws, check with local A/C companies on if they can do any work without permits, most cant/wont.

 

[nzzshl]

I didnt know they could pre-charge the unit. So after the refrigerant lines are installed, do they have to be evacuated before releasing the gas into the rest of the system? Seems too easy.

Sounds great. This is exactly what Im wanting to do. What are Z-strips?

Most Residential compressor units are pre-charged with refrigerant. There are valves on the unit on the high and low pressure sides that control the release. The valves are also used to isolate the unit during vacuum leak check of the lines prior to gas release. Depending on the run length to the A-coil, there may have to be additional refrigerant added to get to normal operating pressure. Z-strips are used in joining two sheet metal edges together without overlap or screws. Also, there are splice locks that couple two separate sheet metal edges together after each edge is folded back into a 180 bend approximately 1/4" - 3/8" deep. The lock strip is then driven from a corner over the 180 degree flanges to couple them together. Talk to your local HVAC shop for details. They're cheap and work well. Foil tape all joints in your system to reduce cumulative air leakage....don't use duct tape!

 

[phabib]

I'm not an AC guy and I just installed two Mitsubishi mini splits myself with no problems. I had to spend about $300 in tools to do it.

You will need a good vacuum pump that can get the system down to <500 microns of vacuum. You will need a vacuum gauge that can read in microns as well. You will need a manifold and hoses to connect it all.

My cheap pump took several hours to fully draw down the vacuum, but it held after that confirming that I did not have a leak.

I'm guessing I saved about $6000 by doing it myself.

 

[MadMax31]

Industrial/Commercial but started in Residential....

Name doesn't really matter. Unless its Trane ( my employer ) its going to have a Copeland scroll compressor in it. Nice things to have are loss of charge switch and hi head pressure switch. They save the compressor. Whatever indoor coil you choose, you want a TXV, not a fixed metering device. The TXV reacts to load and can effectively dial back system tonnage and curb coil freezing.

%99 of residential units right now are R410A, which is less than stellar. Braze your joints, not solder. If somebody pulls the old Union schpeel " StayBright 8 has a higher tensile strength than braze" Only if you can effectively solder and solder doesnt react well to vibrations, braze doesnt care as much. Just braze.

R410A has POE oil which becomes violently acidic when exposed to any amount of moisture. So Pull a vacuum sub 500 microns and purge yer manifold before shoving gas in.

Sight glass is useless with 410A. If somebody says to charge it too a clear glass, they dont know how 410A works and should stick to R22. Google Superheat and Subcooling. Typically 8-12 degrees subcooling with a TXV is fine for most residential units.

Did I mention braze? R410A with a plugged coil can hit 600 psi right quick.

I installed my own system last year with a dry-shipped condenser as I run R407C, honestly the best gas for comfort cooling.

I have some barrels of R11 and R123 in the garage if you wanna clean parts... Just kidding EPA....

I should mention, many of the new Airhandlers have ECM motors in them. So you'll have to run 220/240 single phase for it....