Automotive Air Conditioning Information Forum

tbirdtbird wrote: ↑Thu Sep 16, 2021 9:11 am The discharge line from comp to cond needs to be the standard equivalent of a #8 hose.
Reduced OD hose is OK but requires special fittings.
Aluminum tube is OK but you need to check the pressure rating of the tubing you want to use. The high side can sometimes (inadvertantly) get to 300-350 psi, I would want a rating of 500 psi for safety

Remember that Cold Hose in Ocala can make special fittings/tubes

Also remember that the more 90s you have that the flow will be reduced, and potentially reduce your cooling. Perhaps not enough to notice, but just be aware

I understand the need for the drop, but why does this have to be tube?

Good helpful info again -- Thank you!! The drop doesn't absolutely have to be tube. It can be a short piece of hose with two 90 deg fittings. I have about 2 inches of clearance at the top, so a regular 90 fitting with hose will still work (not a Tite90). I was talking to local hose shop yesterday and we discussed using hose for the drop and he said he'd be willing to make it a tube if that would be better. If it is a tube I'll make sure it's #8 ID and also pressure rated. Bending it might also reduce working pressure rating of the tube.

Earlier I mentioned by comp is #10 and the old system ran 10 hose to a step-down next to the cond. I might just reverse this operation and place the step down a couple inches from the comp and then run 8 hose to the condenser - easier to route and bend and less stress on the fitting on the condenser fitting.

I notice Cold Hose is in Ocala and Nostalgic AC Parts is also in Ocala - possibly related but a couple miles from each other.

Got it, there is nothing wrong with using aluminum pipe as long as it's well supported and can handle the mechanical forces. Aluminum pipe is preferred by OEMs because it's cheap and durable, hoses are only used where necessary to accomodate movement (like engine rock) or assembly issues like where a tube/hose assembly needs to be bent a bit to get it into place. As long as what your AC guy makes is durable, aluminum tubing is fine.

I'm under the impression that reduced hoses are reduced barrier, i.e. they will probably permeate refrigerant more than standard barrier hoses. I don't think it has anything to do with the pressure rating, but someone else might know more. If it's a tight fit, personally I would use a reduced hose, if not I would use standard hose.

Discharge line pressure drops due to tight right angle fittings don't affect performance much, my opinion is do what needs to be done to make it fit and don't worry about it. The suction line is very, very performance sensitive, build special fittings if you need in order to keep pressure drops low. Lucky for you it seems like your suction line isn't a concern.