T&T: Shurflo FW pumps

[Larry N. Brown]

I talked a bit about these pumps here a while back and a new issue has
emerged. Need some explication from a hydraulics type. my FW system consists
of 2 x 60 gal Ronco tanks, valved into a 1" Y and 1" PEX that runs forward
30', through a filter and to my Shurflo 5.7. It is plumed into a 3/4" spine
that runs fore and aft in the boat, dropping to 1/2" PEX for the runs to
faucets, etc. Remember this is a variable speed pump; it has no pressure
switch.

When I turn on a faucet, the water trickles out then goes up to a steady
stream only to momentarily trickle again. Shut off the faucet and measure the
pressure- 65#.

Emailed the Shurflo people and went over the system. Told him about the 1"
suction; he said- too big. That's messing with the flow rate sensor. I asked
3/4"; he said 1/2. So, you hydraulic types, why should this be so? Will 30' of
1/2" pipe support 5.7 GPH flow?

I'm going to test it by pocking a 1/2" pipe in a bucket of water in the engine
room to see if the flow normalizes, but until then, any ideas?

Regards,

Larry and Teri
M/V Cigano, 47' Prairie Sundeck Cruiser
Lying: 64 Cypress Road
          Covington, LA