Ok at the place I am employed they have a 1 Hp submersible pump it pumps about 300 ft into the top of a 120 gal storage tank then the water comes out of the bottom of the tank and goes into our grundfos 3-45 booster pump then the water flow out of the booster pump and goes to our rest room and throughout the building our rest room is about 10 feet from the booster pump. Now without using the booster pump and only the submersible pump we can get about 50 psi to our restroom but with 3 hand wash sinks and the urinals and toilets if u run the water very long the submersible pump can't keep a good pressure pumping as far as it does. So I guess that is why our company called a contractor and had them put the booster. The only problem with that is like I said the restroom is only about 10feet away from the pump and we have a pressure gadge on the discharge side of the booster. When the booster comes on it's pushing over 100 psi so the contractor being a plumber and all should have known you can't push that much pressure into a urnal or a toilet with the diagrams and vacume breakers and expect them to work right so they just turned the valves down on everything only prob was they had to so much that u are lucky to get a cup of water to come out of them when u use the Urnals and toilets and u have to flush the toilet to get the wash sink to work at all. U have to drop the water pressure to get the sinks to push any water so long story short is there a way I could adjust the pressure switch on the pump if not would it hurt anything if I put a external pressure switch on the line?