Jump to content

Recommended Posts

Anyone with HVAC experience? I'm doing a few DIY Mini Split AC's. I know about the electrical, disconnects(inside and outside), lines, drainage,evacuation, leak check w/Nitrogen, additional R410a for extra line length, and that it voids the Warrantee. Is there anything else I should know?

Link to post
Share on other sites

I do HVAC as my day job...

You hit on pretty much everything. What brand/size were you planning?

Don't be surprised to find only one service port.

Link to post
Share on other sites

I do HVAC as my day job...

You hit on pretty much everything. What brand/size were you planning?

Don't be surprised to find only one service port.

They're Fedders Inverter units. 12K & 18K. I understand they're tricky to get the charge right due to the variable speed compressor. I also believe there's a 'test' mode that runs at 100% to get past this issue. Am I correct?
Link to post
Share on other sites

There should be a "Charge" mode available from the t'stat. Needs to run about 15 min before checking charge, and at least 10 min between adjustments.

Those should use 1/4" liquid and 1/2" suction lines. The unit is pre-charged for either 15 or 25 ft of line, check the book, but I think it's 15 ft.

Add 0.2 ounces per foot over the specified length before start-up and you should be on the money.

Link to post
Share on other sites

There should be a "Charge" mode available from the t'stat. Needs to run about 15 min before checking charge, and at least 10 min between adjustments.

Those should use 1/4" liquid and 1/2" suction lines. The unit is pre-charged for either 15 or 25 ft of line, check the book, but I think it's 15 ft.

Add 0.2 ounces per foot over the specified length before start-up and you should be on the money.

Thanks! What type of wire is normally used between the Condenser and the Indoor Unit? It seems that some units supply SO cable(extension cord) for this, but it is not In-Wall rated. NM Cable is for dry locations, and solid. I saw one reference to a 'Mini Split' cable which was flexible, and In-Wall rated. I could not find a source online to purchase it.
Link to post
Share on other sites

Update: Unit is pre-charged for 25 ft lineset. Need to use shielded 18/3 wire for connection between units. Only connect the shield at the outdoor unit. Connecting at both will create a ground loop and defeat the purpose.

Link to post
Share on other sites

Update: Unit is pre-charged for 25 ft lineset. Need to use shielded 18/3 wire for connection between units. Only connect the shield at the outdoor unit. Connecting at both will create a ground loop and defeat the purpose.

Are you talking about twisted shielded instrument cable? What limits the current as 1(120V) or 2(220V) of the 3 wires are connected to the incoming feeds. Is a fuse installed to protect the wiring?
Link to post
Share on other sites

More like stranded t'stat cable, you should find it in the same section.

The comm link between units runs on a low (<42VDC) power circuit. The high voltage is only used by the outdoor unit.

Link to post
Share on other sites

More like stranded t'stat cable, you should find it in the same section.

The comm link between units runs on a low (<42VDC) power circuit. The high voltage is only used by the outdoor unit.

They provide a basic schematic, which shows the connection between the units are the 2 incoming lines(power), and 1 comm line. Here's a picture:

FeddersDiagram2.jpg

Edited by 2000_Gold_Taurus
Link to post
Share on other sites

Sorry. There are differences between brands.

Either way, the wire is rated for either 300 or (usually) 600 volts. The current required is less than the 7 amps 18 AWG is rated for, so there's no concern there.

Link to post
Share on other sites

Sorry. There are differences between brands.

Either way, the wire is rated for either 300 or (usually) 600 volts. The current required is less than the 7 amps 18 AWG is rated for, so there's no concern there.

I searched for shielded thermostat wire and found what you were referring to on the Southwire site. They also have the 'Mini Split' wire I couldn't find. Thanks for your help. I'm still in the planning stage, but I may have a question or 2 later on.
Link to post
Share on other sites
  • 3 weeks later...

I got the first unit up and running-no significant issues. I did get some vacuum pump oil in my hose and micron gauge. Still need to secure the line set and wire it permanently. The unit is awesome. It was 97 deg. here yesterday, and the system was using only 450W to maintain my entire first floor(800 sq ft) at 77 deg. Very quiet too-inside and outside.B)

Insidesmall.jpg

Outsidesmall.jpg

Link to post
Share on other sites

Looks good. Centered on that wall would have been better for performance.

Thanks, what you don't see in that picture is a walkway in front of it so the air blows through and circulates around the entire first floor. I actually wanted it more to the left, but as you can see in the outdoor photo, the electric service is right there, then a double stud! I'll post a few more pics when I neaten up the outside.
Link to post
Share on other sites

That inside unit has right and left exits for the connections. Could have got it maybe 6 inches away from that wall.

Link to post
Share on other sites

I thought about that, but the wall is butchered there because there used to be a through the wall unit. All the original second floor wiring also runs there because the breaker panel is right below. Also, then the lines would have to cross the power and phone services on the outside. I decided it would be cleaner to just avoid the whole mess B)

Link to post
Share on other sites
  • 2 years later...

Some things take time. I finally started installing the last of 4 units purchased in 2012. This one is going in the garage. I've always wanted A/C out there. I had to hang the unit from the ceiling as the area where it would normally go has a hydronic heater. This required some creativity as I could find no installs like this anywhere online. Hopefully I haven't overlooked anything.

GarageMiniSplit1_zps23bc6cf7.jpg

GarageMiniSplit2_zpsc35ca0f9.jpg

GarageMiniSplit3_zps598059b0.jpg

GarageMiniSplit4_zps9ae36745.jpg

Link to post
Share on other sites

Nice work. Creative indeed! Is it right over your work bench? If so, might that make you too cold while standing there?

Thanks! The unit is centered so the air blows between the cars while the work bench is off to the left. This unit is a heat pump also, so after more creativity I'm hoping to use it in the winter to keep the garage at 35 Deg. It can only be set as low as 60 Deg by design. As long as this scheme works, my oil burner will stay off-year round!

Link to post
Share on other sites

Very nice. I have a heated garage at home. Just a little electric unit that I can power on and have a perfect garage in an hour or two from ice cold.

Link to post
Share on other sites

Very nice. I have a heated garage at home. Just a little electric unit that I can power on and have a perfect garage in an hour or two from ice cold.

2 Hrs to warm up a garage with a small electric heater in Minnesota? That's pretty good. It takes 4 Hrs to warm up mine to 60 with the hydronic heat when it's really cold out. I have wood doors, so I may replace those with insulated ones in the near future. Based on the other units, I believe this will warm up the garage much faster.
Link to post
Share on other sites

I always go over to my friends house in winter for projects.  They have a fully insulated garage with a commercial grade natural gas heater in the garage, they keep their garage at 50 degrees all winter long.  Perfect for working on just about any project with a sweatshirt.  Although I've seen it as high as 60 degrees when working on a big project and comfort is critical.

Link to post
Share on other sites

2 Hrs to warm up a garage with a small electric heater in Minnesota? That's pretty good. It takes 4 Hrs to warm up mine to 60 with the hydronic heat when it's really cold out. I have wood doors, so I may replace those with insulated ones in the near future. Based on the other units, I believe this will warm up the garage much faster.

 

A few years ago we finished off our garage. Insulated the walls, sheetrocked the walls and ceiling to the storage space above the attic. We have a 3 car garage, and the 3rd stall is a little bit deeper than the other two due to a small addition we put on. It's a great little heater. I've been out there with it on and sweating a bit lol. Our garage doors are insulated aluminum, I believe.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...