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Differance between Auto A/C and house A/C

EagleMark on Sun August 08, 2010 10:29 PM User is offlineView users profile

Year: 1990
Make: Marlette
Model: Manufactured home
Engine Size: none
Refrigerant Type: r22
Ambient Temp: 85
Pressure Low: 0
Pressure High: 0
Country of Origin: United States

I need to move my A/C unit at the house and wondering how much differant they are to service. Questions would be oil? Recover freon in sepr=erate bottle, seal ends and move, hook up new electric and re attach lines. Draw vacuum then?

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1994 Buick Raodmaster Estate Wagon White Woodgrain. My four door Corvette Wagon! 1990 Chevy Suburban Silverado 5.7L 2wd and stuff! R12 Still Works!

Addicted and Obsessed with Fuel Injecting Anything!
[URL="http://http://www.eagle-mark.com/Forums/"]Shared BIN files, Definitians and Wiring diagrams![/URL]

Dave in Texas on Sun August 08, 2010 11:31 PM User is offlineView users profile

same principles and procedures

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

1stbscout on Sun August 08, 2010 11:45 PM User is offlineView users profile

Before removing the lines close the high side valve at the "compressor" run the unit until the low side is just showing a vacuum then close the low side valve at the compressor and shut the system down. This way you have the R22 trapped in the compressor unit.

Cut lines and move the system.

when reconnecting add or change the low side "filter/drier" pull a vacuum on the lines and evaporator. Open the valves you closed before moving the unit and if all has gone the way it should you are finished. You may need to add a few ounces of R22 to bring the system to optimum but if done correctly you should not need to add much.

Rick-l on Mon August 09, 2010 12:14 PM User is offline

Do you have oxygen and acetylene tanks?

TRB on Mon August 09, 2010 1:43 PM User is offlineView users profile

Are you going to be cooling the same amount of Square feet?

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EagleMark on Mon August 09, 2010 3:46 PM User is offlineView users profile

Quote
Originally posted by: TRB
Are you going to be cooling the same amount of Square feet?Yes, same home just built a garage on the side where the A/C sits. So it needs to go to the other side. Plenty of tubing was already attathced, covered in insulation and wraped up in a pile like they were ready to mount it anywhere. Instead of cutting to length they just wrapped it like a garden hose. Good for me now!

Thanks guys. Love the forum and have been reading it on and off for years. Have been sending $ business your way just because of it! :-)

Quote
Do you have oxygen and acetylene tanks? Sure do. Why?

-------------------------
1994 Buick Raodmaster Estate Wagon White Woodgrain. My four door Corvette Wagon! 1990 Chevy Suburban Silverado 5.7L 2wd and stuff! R12 Still Works!

Addicted and Obsessed with Fuel Injecting Anything!
[URL="http://http://www.eagle-mark.com/Forums/"]Shared BIN files, Definitians and Wiring diagrams![/URL]

mk378 on Mon August 09, 2010 4:07 PM User is offline

It takes a rather high heat to properly braze copper lines. On smaller work, it's possible with a MAPP / air torch but a lot easier with acetylene. Do not use soft solder, it will just crack and leak eventually.

See if your unit has isolation valves like 1stbscout was talking about. They're not real common but that would make it simple.

EagleMark on Mon August 09, 2010 9:35 PM User is offlineView users profile

Well thanks for the tip! I would not even have thought that a hand held Mapp gas would not be hot enough... I have one that is MAP//Pro that says next generation MAPP replacement and have soldered many a water line with the older or regular MAP gas.

I will buy a roll of solder just for this job from the local appliance service center. Is there a specific name or brand of solder I should look for?

-------------------------
1994 Buick Raodmaster Estate Wagon White Woodgrain. My four door Corvette Wagon! 1990 Chevy Suburban Silverado 5.7L 2wd and stuff! R12 Still Works!

Addicted and Obsessed with Fuel Injecting Anything!
[URL="http://http://www.eagle-mark.com/Forums/"]Shared BIN files, Definitians and Wiring diagrams![/URL]

mk378 on Mon August 09, 2010 10:23 PM User is offline

The alloy is commonly called "silphos". It is composed of copper, silver, and phosphorus. Sold in bundles of straight lengths, not rolls, because it is a hard metal that would be difficult to roll up and unroll.

Heat the copper joint to a low red heat and apply the braze. No flux is necessary. Practice on scrap metal first of course. The lines must be filled with nitrogen or argon while brazing to prevent black scale (copper oxide) from forming on the inside and contaminating your system. Unlike soft solder, it is difficult to rework by melting and pulling a joint apart. At braze temperature, the copper itself becomes very weak and tends to just tear apart. At least for the beginner, treat it like PVC pipe-- can't be unglued. Plan to cut out or reuse old joints rather than try to redo them.

Edited: Mon August 09, 2010 at 10:36 PM by mk378

Dave in Texas on Tue August 10, 2010 11:14 AM User is offlineView users profile

The lines must be filled with nitrogen or argon while brazing to prevent black scale (copper oxide) from forming on the inside and contaminating your system.
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I'm not disputing that, but how can that be accomplished with two open-ended pieces of pipe?

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

Rick-l on Tue August 10, 2010 12:03 PM User is offline

Would 75% argon 25% CO2 work? What is the reaction in the pipe that forms soot?

EagleMark on Tue August 10, 2010 2:23 PM User is offlineView users profile

I would have the same question, we must both have mig welders...

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1994 Buick Raodmaster Estate Wagon White Woodgrain. My four door Corvette Wagon! 1990 Chevy Suburban Silverado 5.7L 2wd and stuff! R12 Still Works!

Addicted and Obsessed with Fuel Injecting Anything!
[URL="http://http://www.eagle-mark.com/Forums/"]Shared BIN files, Definitians and Wiring diagrams![/URL]

NickD on Tue August 10, 2010 3:15 PM User is offline

I have never seen valves in home units, is this a southern thing? Don't they use valves up north? Oil should be in the sump of the compressor, normally not circulated like in a MVAC system. Also have yet to see a dryer in a home system, but maybe not getting out enough. My 25 year system has a low pressure cut-out switch, my kid's new system doesn't even have that. As long as the thermostat is closed, it will run and run and run, namely because his contractor did a sloppy job of brazing the tubing.

An oxy-mapp torch works fine, if you don't mind spending seven bucks for a small bottle of oxygen. Welding supply shops in my neck of the woods won't fill privately owned brand new tanks, want to rent one of their rusty old tanks for a small fortune each month. Some crap about liability.

Suppose to be a 30% hard dollar tax credit for buying one of these new high SEER units, and maybe even a couple bucks back from your electric company. Never thought I would see the day when they pay you to use less.

mk378 on Tue August 10, 2010 3:28 PM User is offline

To inert the lines you start working at the joint nearest a service fitting, flow gas in there, which will push the air out down the line, and just let it escape from the other end of the tube while you braze. Then move to the next one and so on, finally letting the gas escape from the other service fitting.

I don't know if MIG gas would be suitable. CO2 is not completely inert at high temperatures, and copper is a good catalyst for various reactions. You could test on a scrap piece of tube, flow gas through it and heat it red-hot, keep gas flowing until it cools, then inspect the inside. Nitrogen tanks have the same outlet fitting as MIG tanks so you could buy a tank from your gas supplier and use your existing regulator. Most of the cost will be tank rental, just take it back part full when done.

Typically a filter-drier is not part of the original setup, but added after any major service such as relocation.

I would agree with Nick this is a good chance to replace with a higher efficiency system. The hardware supplied with a manufactured home 20 years ago is likely to be atrocious. Even without any subsidies, the payback can be quick.

NickD on Tue August 10, 2010 5:20 PM User is offline

I'm kicking around installing a heat pump, paying a $1.27 per therm where the equivalent amount of electric energy is costing me $2.70. But with a COP factor of 3.3 at 30*F, we have a lot of above 30*F days here, should be like paying 81 cents a therm, cheaper as the outdoor temperature increases. Break even point between gas and electricity should be at around 3*F, but doubt if I would get enough heat at those low temperatures. Something to play with after its installed.

Thoughts are just connecting the heat terminal on my thermostat to an outdoor thermostat with form C contacts, an added relay. When the temperature is above wherever I set it, fire 24 VAC to the heat pump, if below, fire up the gas furnace.

My kid brother went geothermal up here, he did get a fat tax break, but just doing some rough calculations in my head, would take him about 15 years to start getting a payback. I don't want to wait that long. Was pleased last year by installing a 96% gas furnace, practically got my payback already by doing the installation myself. Wanted twice as much for installation as what I paid for the furnace, and this baby was installed super neat.

Another thought is I would have the option to play games like our gas and electrical utility company are playing, constantly changing the rates by having a choice of using either more electricity or gas.

My electric rates were 4.5 cents a KWH two years ago, in a month they increased to 9.5 cents. Did get an on demand full house electric hot water heater, still in the box, hardly pays to install it.

Also have a closed combustion fireplace, can burn wood, but a lot of work and mess, and really dries out the house. Wife can't take it, she would dry up and blow away, she is too nice for me to do that to her.

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