[JSH]

The car's in the shop next week to install a Pierburg CVA400 pump in place of a Davies-Craig pump, which means doing some piping rework. While it's there, I want to straighten out the tank outlet and inlet fittings and pipe.

In the first photo below, the inlet is on the top and outlet on the bottom. The outlet threaded nipple is 1" OD, but necks down to 3/4" at the 90 elbow. This just ain't right. Every 1/8" makes a huge difference in flow rate.

Why can't I just cap the current outlet and cut a 1.5" outlet hole in the tank and install a straight reducer coupler hose (second pic below) and come off of that with a 90 coupler hose (third pic below) and then use the largest ID pipe possible?

My setup is way too restrictive now. Suggestions?

[JSH]

A big ass site like this one is full of racers, and not one's a plumber?!

[Joshinator99]

If the outlet nipple is 1”, why not just carry that all the way down and back…? Upsizing to 1.5” out of the tank is unnecessary.

[JSH]

Originally Posted by Joshinator99

If the outlet nipple is 1”, why not just carry that all the way down and back…? Upsizing to 1.5” out of the tank is unnecessary.

I agree with carrying the 1" dia. throughout the system, which mine doesn't do now. I would like to take credit for the reducer idea, but that came from Mont MS. The velocity of water increases while flowing from the 1.5" pipe to a 1" pipe through the concentric reducer I'm proposing because the area available for the water to flow through is reduced. As the area decreases, the water is forced to flow at a faster pace to be able to pass through the smaller pipe.

The reducer idea should also work on the pump discharge.

[Joshinator99]

Originally Posted by JSH

I agree with carrying the 1" dia. throughout the system, which mine doesn't do now. I would like to take credit for the reducer idea, but that came from Mont MS. The velocity of water increases while flowing from the 1.5" pipe to a 1" pipe through the concentric reducer I'm proposing because the area available for the water to flow through is reduced. As the area decreases, the water is forced to flow at a faster pace to be able to pass through the smaller pipe.

The reducer idea should also work on the pump discharge.

FYI I’m an HVAC Engineer by trade, so trust me when I tell you your pump selection and pipe sizing will have way more impact on system velocity than a short piece of reducer. Focus on supply and return differential not “velocity”, which technically does nothing for you. As long as the flow is turbulent and not laminar, you’re good. I’d shoot for 10-20 degrees off temperature differential between supply and return.

[JSH]

Originally Posted by Joshinator99

FYI ... pump selection and pipe sizing will have way more impact on system velocity than a short piece of reducer.

Of course, which is why I'm putting a Pierburg on it, and will change out the outlet and inlet fittings. PVC should work better.

[Joshinator99]

Originally Posted by JSH

Of course, which is why I'm putting a Pierburg on it, and will change out the outlet and inlet fittings. PVC should work better.

I should really join you in upgrading my water lines to 1” too but I’m not spinning my new Whipple hard enough to cause any IAT issues. So I’ll probably keep running the 3/4” lines until I HAVE to do something lol….

Good luck in the upgrade and show us how it turns out.