Forget about the pump! What causes backfilling of the tank, thru the pump,
is the fact that most people forget to add a vertical loop in the hose
betwee n
the thru hull & the pump, which goes above the waterline.. Just make this
loo p
& the backfilling will stop
Actually, Ken, this won't help. Even if the loop is above the waterline,
water can still siphon back in. While it might not happen every time, it can
easily start siphoning. If you have a non-positive displacement pump (e.g. a
macerator) then the only safe thing to do is to close the through-hull
immediately after pumping.
Again, this is a good discussion, and it points to good reasons to move to a
positive displacement pump such as the Sealand. For what it's worth, I have
two holding tanks on Island Eagle, one with a Sealand and one with a
macerator. The Sealand has been flawless in 5 years. The macerator has failed
once and clogged once. Plus, I have to manually open and close the through
hull when I use the macerator. Next time it fails I will be replacing it with
a Sealand.
By the way, one other note, I also replaced both of the switches for the
pumps with 15 minute mechanical timer switches. They work like a charm.
Scott Welch
FirstClass Product Manager
www.firstclass.com
Those who make no mistakes rarely make anything.
"Ken Ongemach" <kongemac@tampabay.rr.com> writes:
>Forget about the pump! What causes backfilling of the tank, thru the pump,
>is the fact that most people forget to add a vertical loop in the hose
>betwee n
>the thru hull & the pump, which goes above the waterline.. Just make this
>loo p
>& the backfilling will stop
Actually, Ken, this won't help. Even if the loop is above the waterline,
water can still siphon back in. While it might not happen every time, it can
easily start siphoning. If you have a non-positive displacement pump (e.g. a
macerator) then the only safe thing to do is to close the through-hull
immediately after pumping.
Again, this is a good discussion, and it points to good reasons to move to a
positive displacement pump such as the Sealand. For what it's worth, I have
two holding tanks on Island Eagle, one with a Sealand and one with a
macerator. The Sealand has been flawless in 5 years. The macerator has failed
once and clogged once. Plus, I have to manually open and close the through
hull when I use the macerator. Next time it fails I will be replacing it with
a Sealand.
By the way, one other note, I also replaced both of the switches for the
pumps with 15 minute mechanical timer switches. They work like a charm.
Scott Welch
FirstClass Product Manager
www.firstclass.com
Those who make no mistakes rarely make anything.
