Hot water recirculating pump to conserve water

smckean (Tosca) · Posted: Tue Jun 09, 2020 11:36 pm Post subject:

Oh, I need to add one more comment to respond to some of the observations by others above.

As I looked into pumps etc, what I found was that all (nearly all?) fresh water systems on small boats such as a C-Dory use diaphragm pumps (not centrifugal pumps). Diaphragm pumps use separate chambers and valves to create the pressure differential between the input and output side. As such, and unlike centrifugal pumps, water doesn't pass thru either pump unless it's running. There is no need for any check valves in this installation.

thataway · Posted: Wed Jun 10, 2020 7:12 pm Post subject:

You are correct--no heater under the galley counter--mostly just storage.

The smaller Bosch water heater is well enough insulated, that it will still be hot enough (for us) the next day. We have the heater near the max, and use the mixing valve in the shower to keep water temp proper. We find we had as "much usable" hot water as we did with the lower temp setting on the 6 gallon tank.

Yes, great idea to keep a usable spare pump. One of the spares I learned to always have aboard with a boat which had a pressure water system was a full spare pump, quick release fittings and quick disconnect/connect on the electrical.

A wife in the shower and no water pressure, can be a bad situation....

smckean (Tosca) · Posted: Thu Jun 11, 2020 3:20 pm Post subject:

thataway · Posted: Thu Jun 11, 2020 10:30 pm Post subject:

I had to have little laugh. With my first 25, I pulled out the 6 gallon tank, replumbed the system and put in one of the "instant" water heaters...Turns out it didn't work, because it was not designed for constant pressure. So I had my "Duh" moment along the line too.

smckean (Tosca) · Posted: Sun Jun 14, 2020 4:05 pm Post subject:

Well, I checked under the counter of my galley, and even though I said above "...I probably could have made it work somehow", I don't see a way to install a cube of 14"x14"x11" (the Bosch 2.5 gallon heater) without major surgery. The only way would be to remove the sliding racks that the previous owner installed (David McKibben -- clever man that he is). The racks are extremely useful, so I would hate to give them up.

All this just means, that in spite of my confusion, I am still glad I installed the hot water recir system. It was relatively cheap, takes little room (hangs from under the counter which was dead space anyway), and gives me a backup freshwater pump should the main pump fail.

It does seem to work well in spite of its rube nature Wink