PEX for raw water - Airconditioner

[alaskanviking]

I did a search but i couldn't find much on PEX with saltwater.

I am installing an air conditioner, and looking at the raw water system now. was thinking of using reinforced hose from the strainer to the pump but thinking of using PEX from the pump through the air conditioners to the vented loop. from the vented loop to the discharge use reinforced hose again. In theory this makes for a low friction system, however I have a spool of yellow 5/8" PEX (1/2" ID) that would work well. pressure, vibration, and freeze proof of the PEX seem good for this application.

Would PEX work good in this situation, is there something I am not thinking of or considering with this?

Thanks

Robert

[Sailmonkey]

1. Why do you have a vented look in your AC system?

2. What fittings do you propose to use with the pex? I’ve thought of using pex like this as well but couldn’t locate suitable fittings for use with seawater.

3. Most air conditioners require a hose that is 5/8” ID, not 1/2”.

[alaskanviking]

Originally Posted by Sailmonkey

1. Why do you have a vented look in your AC system?

2. What fittings do you propose to use with the pex? I’ve thought of using pex like this as well but couldn’t locate suitable fittings for use with seawater.

3. Most air conditioners require a hose that is 5/8” ID, not 1/2”.

Thanks for the response. I am putting in a vented loop, as that is the standard for running any kind of raw water system where its possible to siphon. the discharge is close enough to the waterline. i don't have fuel in the tanks and a likely genset install will drop that lower.

now that I think of it I am not running the unit underway, and would have the seacock closed. do i need a vented lop? does anyone else put one in? generally I tend towards overbuilding and safety

i had a hell of a time finding fittings for 5/8" pex, its very limited. I did find that regular hose barbs work well without issue. was going to use 2 of the copper compression rings per connection. I did my freshwater system this way and it works well.

I'm running over to pick up the unit shortly, just got delivered, so I haven't had a chance to see what's in the box. I thought the manual said 1/2" but i could be wrong. 5/8" ID is 3/4" PEX I believe.

[Sailmonkey]

A vented loop is used to prevent flooding when there is an item open to the interior of the vessel. The AC system is not that, adding a vented loop to this is adding a failure point. Seacock open or closed, a vented loop isn’t the right thing for use here.

Be carful of using brass hose barbs. They won’t last long. You need either plastic or bronze.

Also remember that you’ll need to periodically take apart the hoses for cleaning (ac systems grow and harbor all sorts of goodies) so you don’t want to use the copper crimp rings.

[Coolerking]

Do not vent the ac raw water!!!
Use 5/8"id hose designed for raw water/exhaust/ heater.
Trident makes a good quality hose that we use extensively.
There are many other options that are available as well.
Double opposed hose clamps on every fitting.
Silicone bronze or sch 80 cpvc only fittings, or cu-ni if you can find them.
Make sure the condensate pan drains efficiency!
Good luck!
Not sure how you think it will siphon, it will drain to the waterline, unless of course you plumbed it with an airlock built in.

[Cpt Mark]

I used pex with nylon barb connectors/reducers. It worked fine for 2 years. I removed the reverse cycle heat pump for other reasons.

[alaskanviking]

Copy-all on the no vented loop.
I got my unit yesterday afternoon. definitely 5/8" ID.
Is there any advantages to using the PEX vice raw water/exhaust/ heater hose?

I was thinking the PEX is slicker so there is less friction for a smidgeon of more efficiency, and in theory harder for algae and critters to grow inside. Cpt Mark have you noticed a lot of growth in your system. curious at this point. I don't have 3/4" PEX (5/8" ID) or raw water/exhaust/ heater hose yet as I am currently on plan D or E of mounting and ductwork.

[Sailmonkey]

This is my Go to hose for ac water

https://citimarinestore.com/en/domet...t-450-psi.html

According to cpt marks profile he’s in Oregon. The further south you are and the warmer the water the more goo grows in the lines. I’ve just replaced a raw water hose on a chiller condenser that was choked closed with barnacles.

[Cpt Mark]

Yes I am in Portland OR on the Columbia river so mostly just fresh water. Certain times of the year we get brackish water but no barnacles