Installing Manual Fresh Water Pump in Parallel with Electric Pump?

[Dancrosswis]

I am redesigning my plumbing.  One of my objectives is to be able to supply water through the galley faucet using either the existing electric pump or a manual foot pump.  I will be using manifolds.  My thought is to run parallel paths from my "intake" manifold (which will receive flow from either freshwater tank or from an antifreeze intake) to my "cold" manifold (which will send flow to the cold faucets and to the water heater).  I am also thinking of plumbing in an accumulator.  I've attached my initial design flow chart, simplified to just show the parallel flow between the two manifolds. 

Am I missing anything?  Will this work?  Do I need check valves in either line?  Any thoughts or comments will be appreciated.

Dan

[Ron Hill]

Guys : I did the same thing by installing a "Y" valve and turning the sea water foot pump in a foot pump for fresh water (after shutting off the sea water thru hull)!   Easy and simple to do.   

A thought

[Ken Juul]

Please explain why you need this dual supply system.  May be clear in your mind, but I see no advantage, and twice the plumbing to take care of.

[Dancrosswis]

Ron:

I plan to re-plumb both of the manual foot pumps.  I am moving the pump tucked behind the cabinet door out and next to the pump on the outside of the galley structure.  One pump will be used as I described in my first post.  The second will have a y-valve running to the refrigerator box and to the raw water (in my area--lake water) inlet.

Ken:

It's not a need.  My last boat was a Morgan 34 with only a foot pump.  We liked it.  We used less water, which was important with the Morgan's limited tankage.  I'm redoing all of the plumbing, so I thought why not.  It will quieter and we'll be able to move water if the pump fails.  With my planned use of manifolds, the extra hose and connections will be limited and accessible.

It's getting too cold here in Wisconsin to do this install now.  So, I'll probably mock up the system over the winter in the workshop and test it out.  I'll report out the results.

BTW, I installed service kits on both of the pumps.  I didn't find any write ups or photos on installing the kits here at C34.org or elsewhere.  I took photos as I worked.  Do you think it would be of value to post instructions and photos?  I'll be happy to do so, if they might be of value.

Thanks for your inputs,

Dan

[KWKloeber]

Am I missing anything?  Will this work?  Do I need check valves in either line?  Any thoughts or comments will be appreciated.

Dan

Dan,

1) The accumulator is simply tee'd into the water line -- water doesn't actually flow "through it" as depicted.  It just acts as a "spring weight" to absorb and release energy, thereby maintaing pressure on the system for a longer period of time.

2) I *think* could simply cross-connect the MP to just to the right of the EP, with a check valve, so that when the EP comes on, it can't back flow to the MP and inlet.  Many EPs integrate a check valve so that the system holds pressure.  i.e., I don't see that you need a cold water manifold. 

ken

[Stu Jackson]

I didn't find any write ups or photos on installing the kits here at C34.org or elsewhere.  I took photos as I worked.  Do you think it would be of value to post instructions and photos?  I'll be happy to do so, if they might be of value.

Dan,

It would be a great writeup, and could be a Tech Note.  Just write it up with your photos and send it to our Tech Editor, John Nixon.  Ir can be published in Mainsheet magazine and then posted in our Tech Notes Online.

[Ron Hill]

Ken : I did it just so I had a back up if the electric pump went out so I could immediately get at the 80 some gallons of water in the tanks!! 

Then I could continue our trip and fix/replace the electric pump at my leisure!!

My thought

[Stu Jackson]

Do I need check valves in either line? 

Yes, in both.  Think of what happens when either is off when the other is on.  Check valves sometimes come with pumps, but rarely for this purpose.

The header could simply be a T in one of the hoses.

Good luck.

[KWKloeber]

check valves

Just a somewhat related word of caution about check valves in the potable water system...

The black Shurflo CV's are for the COLD water lines ONLY.  Never use one as the CV to prevent cold water backflow to the water heater.  Those CVs are not rated for water heater pressure and can let go with a bang  as pressure builds in the water tank.

For the water heater CV, use the Jabsco metal CV meant to prevent backflow to the water heater, or make one up using a 1/2" SharkBite CV (Home Depot online) which is ok for high pressure. 

kk

[Dancrosswis]

From Stu:

"Yes, in both.  Think of what happens when either is off when the other is on.  Check valves sometimes come with pumps, but rarely for this purpose."

I wondered whether the "non-operating" pump would act as a check valve when the other pump is in operation.  Because I was just in the innards of the foot pump, I can imagine that it's internal valves will not let water (moving under pressure from the electric pump) flow backwards through the pump.  I don't have the experience to know whether the impeller of the electric pump will be as effective when the foot pump is operating.  My thinking is the water will follow the path of least resistance, and the impeller will provide some resistance.  I may mock this up in the workshop to test it out.  I'll report out my findings.

Both pumps will feed into a "cold manifold."  I plan to run separate lines to each destination (in lieu of the current "trunk and branch" system).  So, the cold manifold will have outputs for:  hot water heater, galley faucet, head faucet, and a new cockpit shower head.  I will be mocking up the manifolds over the long weekend and will send photos with a flow chart for comments.  I got fixated on the use of manifolds while doing research on home pex water systems.  This may all be a silly use of my limited talents, but I'm having fun.

Thanks for everyone's input.

Dan

[KWKloeber]

From Stu:

"Yes, in both.  Think of what happens when either is off when the other is on.  Check valves sometimes come with pumps, but rarely for this purpose."

I wondered whether the "non-operating" pump would act as a check valve when the other pump is in operation.  Because I was just in the innards of the foot pump, I can imagine that it's internal valves will not let water (moving under pressure from the electric pump) flow backwards through the pump.  I don't have the experience to know whether the impeller of the electric pump will be as effective when the foot pump is operating.  My thinking is the water will follow the path of least resistance, and the impeller will provide some resistance.  I may mock this up in the workshop to test it out.  I'll report out my findings.

Both pumps will feed into a "cold manifold."  I plan to run separate lines to each destination (in lieu of the current "trunk and branch" system).  So, the cold manifold will have outputs for:  hot water heater, galley faucet, head faucet, and a new cockpit shower head.  I will be mocking up the manifolds over the long weekend and will send photos with a flow chart for comments.  I got fixated on the use of manifolds while doing research on home pex water systems.  This may all be a silly use of my limited talents, but I'm having fun.

Thanks for everyone's input.

Dan

Dan,

Potable water pumps don't use impellers, they use diaphragms and internal flapper valves.

There is a check valve on the PWP, because it must hold pressure on the pressurized hoses, but an extra 1/2" check valve would do no harm.   There'es no reason for an elaborate manifold system to distribute the pressurized side, but "YBYC!".

kk

[Ken Juul]

Ron,
I understand, no one wants to be without water.  I just think it is easier to carry a spare water pump.  For that matter, most of the places I have taken the boat usually have a West Marine or Chandelry, so having a spare on board isn't that important.

[Ron Hill]

Ken : I also had a spare electric pump, just wanted to install it at my leisure.

My thought

[Dancrosswis]

I now think the Subject of this thread should be changed to Completely Unnecessary Plumbing Upgrade.

Explanation:  I am retired with too much time on my hands.

Okay, I've been at work in the workshop and on the computer.  I've made four manifolds and brackets.  They are: Intake, Cold, Hot, and Head.  Here's a photo:



What fun, my son loaded Visio on my computer.  Here is a schematic of my planned plumbing changes:



Finally, here is a Sketchup drawing showing where the Intake, Cold and Hot manifolds will likely be installed.  The view is top down looking at the galley counter top.  Part of what I am doing with this upgrade is making room for my AC pump.



Feel free to tell me this is unnecessary.  But, necessity was never a criteria for this project.  Feel free to send any other comments, observations or suggestions.

Having fun in Wisconsin,

Dan
Ennui Went #159

[KWKloeber]

Dan,

A valved bypass so you can drain, bypass, and not need to fill the Hx with pink stuff?
Valved gravity drain off the Hx?
Accumulator?


I'm not following why you have an unvalved cold water supply line tee'd over to the hot manifold?

ken