Thor

The second chart should help you. It is for fixed orfice systems only. You will have to get the indoor dry and wet bulb temps for it to work however. Most of what has been posted here is just not correct, sorry Download Attachment: Charging&TDchart.pdf 101.65 KB

Here is some good info for you. Download Attachment: CompressorRefrigerantflooding.pdf 330.06 KB

Here is Trane's opion on underground linesets. Underground refrigerant line sets Stay away from under ground refrigerant line sets when possible. This design will create two situations: The world’s longest oil trap A vapor line that acts as a liquid receiver Liquid refrigerant will always migrate to the coldest spot in a system; this will likely be the line sets under ground. A vapor line full of liquid refrigerant will slug the compressor on start up—especially during long off cycles. The addition of a liquid line solenoid valve (cooling only units) will reduce the migration of liquid refrigerant and help save the life of the compressor.

ACCA manual J states that rooms calling for less than 30cfm should not be considered for a supply outlet. You will typically find this on small interior rooms such as bathrooms and closets. This would be especially true on an interior room on the lower floor of a 2 story home.

Picture 3 is of a barometric by-pass. You are looking at a zone system, the purpose of the by-pass is to relieve excess static pressure when all zones are not calling. It does this by dumping supply air back into the return air. The gearshift thing that you talk about is a balancing rod for the barometric damper.

Ahhh, I don't think so, at least no one has told the HVAC industry about this.[:-bigeyes

Here ya go,http://www.hvacmodel.com/User_Login.a5w

Go to the ACCA ( Air Conditioning Contractors of America)web site http://www.acca.org/store/category.php?cid=1 and purchase Bob's house, read it and then read it again. This will not give you all the answers but will give you a great apreciation of what a good A/C contractor does and whats important.

I just pulled info on a couple of Trane Cond units and what they say for that model is 5' above unit and should be a min 12" from walls and all surrounding shrubbery on 2 sides and 2 sides unrestricted ( whatever that means). I have always used 4' min above with 1 side min 12" and other sides min 3'. Each system will have minor differences.

The trap is there to offset the negitive pressure of the duct system . Without the trap the water would be held in retention in the drain cond pan with the possibility of overflowing down the RA duct.

Have a ACCA manual J load calc done to make sure you have correct unit sizing for your new system. They is no correct per square foot per ton sizing method.

I've been in the HVAC industry for 37 years and that is just dumb. Each one of the suction elbows is equivalent to almost 8' of straight line lenght ( 7/8"short radius 90 degree ells = 7.8' each). 20 ells = 160 ft equivalent length line set (just in the ells). Also there should be a min 4' above units for air discharge.

[:-angel] I just finished a NCI (National Comfort Institute) certification class on CO (carbon monoxide) and combustion and I would highly recommend against teeing 3 vents together, especially if one is forced draft . If you do not have the tools to check for proper draft don't do it. The chances of back drafting are very great with the production of CO likely. be safe jimj