Water Pump Bypass non-Bypass

[PancakeBill]

My Bypass style water pump just failed, motor does not spin and leaks out the top.  In looking for a replacement, I noticed there are bypass vs. non-bypass styles.  I ordered a bypass to replace the same, but how are these plumbed differently?  This term is a new one to me.

The city water seems to go through the pump, to make system work without the pump I had to plug the pump input.  When I just connected the input to output it was trying to fill my tank, so water off again and plug the 2. 

 

[Gary RV_Wizard]

What pump make/model did you get?  Are you saying the pump has two inputs (city & tank) and one outlet, and that city water bypasses the pump itself when  city pressure is present?  Or simply that water from the output side can flow back through the pump (the usual case for a pump with internal bypass)?  That is NOT the city water passing through the pump - it is a feature intended to stop frequent pump cycling at low flow. It lets water on the output side flow back to the inlet under specific pressure differential conditions.  I never thought about that letting city water pass back through, but I suppose it could.

This Shurflo pump manual describes the bypass mechanism in the Revolution pump. See page 2 - About the Bypass.
https://stage.shurflo.com/images/files/RV_Product_Manuals/Fresh-Water-Pumps/911-1008.pdf

 

[John From Detroit]

Not aware of any "Bypass" type RV pump so will follow this

The Normal pump goes between PUmp and house lines. it has two check valves (inlet and outlet) so city water does not back up into the tank. YOU would have to plug hte OUTLET line if you removed the pump and wished to use city water.  THe INLET line often has a strainer or filter on it.

This is not to say a bypass type pump could not exist. but if it did to use city water without the pump you'd have to connect the inlet and outlet together.

 

[PancakeBill]

55Aquajet. 5.3 gpm

There are 2 ports. city water on one side tank on other side.  If no city water it pushes into the water system, if it were low, I suppose it would add to the pressure as a supplement (pulling water from tank).  Must be a one way valve in there because when I connected the in and out to have water, the tank was filling. 

 

[PancakeBill]

city water===||========>TT>output of pump. pump. inlet to pump <======>tank
                                          //
water supply for coach<===//

Probably will be out of whack when reading but:

City Water can come in and go thru TT to water supply,  TT one way valve to not let city go thru pump.  Output would then feed the water supply,  pump is on it goes past the output too water supply coach. 

When I initially patched I put in and out of pump together, but this allowed water to fill tank from the tank feed.  Realized before overflow.  So then capped both sides. 

New pump on the way.

With bypass there is no use for an accumulator tank, the pulsing is absorbed by the pump between in and out.

Learn more everyday.

New pump has a little more rating than replaced pump, but the same size does not seem to exist.

 

[Gary RV_Wizard]

I'm confused, cause the Aquajet 55 only has an inlet and an outlet.  Yes, city water is present on the outlet side as well - both the pump and the city inlet feed the same water line.

http://www.remcoindustries.com/wp-content/uploads/2017/03/RI_AquaJetMan2016_Man_e1r2_PAGES.pdf

 

[grashley]

Bill, your diagram appears correct, your interpretation is not.

City water goes through a check valve (CV) (not shown) where it enters the RV.  It goes to <TT> and to the coach.  The CV at the pump outlet prevents flow of city water through the pump or to the fresh tank.  Without the pump in place, you must cap the pump side of <TT>.

Using the pump, water comes from the tank, through pump filter, CV, pump, CV to <TT> then to the coach.  The check valve at the city water inlet prevents flow out that port.

The city water does NOT connect to the pump.  Both the pump and city water connect to <TT> to supply water to the coach.

Mine uses the same diagram.