Re: [Amel Yacht Owners] Climma pump non return valve
Andrew & Kate Lamb
Many thanks – that makes a lot of sense
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: 7 September 2016 16:17
To: James Wendell ms42phantom54@... <amelyachtowners@...>
Subject: Re: [Amel Yacht Owners] Climma pump non return valve
There is a good reason to use a non-return valve in this application, although it took a little thinking about it before I realized what it is, and it has nothing to do with the outlet side of the pump.
The suction side of the pump shares a saltwater feed with many other pumps. Engine cooling, toilet, watermaker, etc. If there was a restriction in the suction side of the system anywhere, say a partially clogged intake screen, a vacuum would be drawn and water would flow backwards through the AC pump. This would eventually allow air into the system and break prime for everything.
The AC pump is a centrifugal pump and would offer no resistance to back flow when it is off. Most of the other pumps are, more or less, positive displacement pumps and backflow would be either restricted or impossible.
So, Climmia support is right, the check valve is a potential clog point, reduces flow, and can fail, but it is the small price we have to pay for having a single hole in our hulls!
A take home message is if you are having trouble with raw water feed, remember why that check valve is there and what can happen if it jams open with a tiny piece of trash.
SM #160, Harmonie
Newport, RI, USA
“Ships and men rot in port."