Originally Posted by SkySki
I am going to order my ballast system today. I was looking at fitting sizes. I am going to go with the Johnson pumps.
1. Is there any benefit to going with all 1" fittings and hoses since the pumps are 1/2" NPT and your supposed to get the fitting that converts to 3/4" hose barb?
I was just wondering if the slide over 1" option is really that much faster. It looks like the 3/4" sizing would be significantly cheaper.
2. Will I have to worry about leaks or losing prime with the slip over method on the 1" at the pumps?
3. Do I need to put any type of adhesive on the pump connection with the 1" slip over method or will the hose clamps be reliable?
4. If I go with 1", should I also have the vent/drain be 1"? I assume so, but wanted to verify.
5. If I go with 3/4 for everything, should I go with 1" or 3/4" for the vent/drain?
My suggestion is do it right the first time. The increased cost of using 1 inch vs 3/4 inch is minimal in the grand scheme of boat costs.....and you won't question yourself forever. Here are a few comments...
1. The Johnsons are awesome! Do it! Faster than the Jabsco and much less impeller sticking problems.
2. I can't tell you how much flow rate you will gain or lose by using 3/4 in vs 1 inch but like I said above....take that out of the equation. There are natural bottlenecks in the system already (pump inlet, pump outlet, fat sac threads, etc). But I certainly would not neck it down further by adding in a 1/2 inch NPT thread on the pump in/out and then convert it over to 3/4. Seems silly.
3. Just use the 1 inch and slide it over the outside of the pump in/out and use a hose clamp. On some of the fittings we used a little dish soap and a heat gun to get hose barbs in a little easier. If you do not overheat it and use a good hose clamp you will not have any leaking problems.
4, Those Johnsons will NEVER lose prime! They are sucking machines!
5. You don't need any kind of tape, sealer, or adhesive on the pump to 1 inch connections other than a hose clamp.
6. I run my Johnsons reversible so my fill hose is the same size as my drain hose. Either way i would make them the same size. I don't think the vent hoses are as important. Mine are only used to burp air mainly. So if you need to cut cost then go 3/4 inch vents unless your vent/drain hose are connected.