I have a mastercraft 3/4 HP jet pump I use to pump water from the lake into the house. I had a 1/2HP pump before that burnt out, and it had adequate pressure on the second floor. I had assumed (maybe wrongly) that increasing the size of the pump & pressure tank would increase flow & pressure, but now the water on the second floor is merely a trickle. My question is - my pumps cut in & cut out pressures are 20/40. Can I maintain that delta and just make it 40/60? I don't care if it burns the pump out in 2-3 years as we plan on getting rid of the system soon anyway. Just need a solution to get by this winter. The tank has no information on max pressure, so not sure if increasing the pressures will cause the tank bladder to fail immediately or not.
Comments
Kizznez OP t1_iy1yxgy wrote
The pump says it has 25ft of lift, the fittings on the second floor should be about 20ft, so I figured I wouldn't have too many losses getting it there. This pump was given to me with the house, so I didn't really do any research into the pressure of the tank, but my Q is more about the pressure tanks max pressure. Are jet pumps maxed out at that 40psi, or is it the delta that's important? I'd like to have it max out at 60PSI, although 50 would probably work. I just don't want to spend another $500 having a plumber come and hook up a new pump in a month or two if I grenade this one lol
large__father t1_iy24mlm wrote
Generally you should be able to run a jet pump at a higher pressure. If it wasn't capable it should list that which yours doesn't seem to. Hard to give a definite answer as all pumps as a bit unique despite being very similar.
Reading your question again it's clear that you're not worried about maximising life. If that's the case I would turn the pressure switch up and test it at a higher pressure, deliberately cycling it to see how to responds. If the pump on time is reasonable compared to the factory 20/40 then it should work for now even if it's shortening the overall life of your pump.
large__father t1_iy24ymm wrote
I realized I didn't answer your question. Don't exceed 60psi for well tanks. I would stay closer to 50 myself. They aren't designed generally to exceed 60.
festerwl t1_iy34i0y wrote
I've been running a 3/4hp jet pump with a 40/60 switch for the last 15 years.
However changing the pressure limits won't make a difference if the pump can't maintain the flow.
For example my pump will start running about 3 minutes after starting a shower and will continue running holding about 35psi until the water is shut off.
Natural-You4322 t1_iy2iznn wrote
Look at the pump curve. The flow vs head graph.
As for tank valve, all of them can handle up to 40 psi easily.
bobertloy t1_iy2xv8c wrote
My only suggestion is to see if you can bypass the pressure switch (that determines cut in/out pressures). With the pump continuously running - determine the maximum pressure of the pump with a gauge and verify that pressure/ flow is adequate upstairs.
Perhaps you can change or adjust your switches (depends on model), so that the cut off is ~5-10psi below this maximum.
If pressure/ flow is not adequate with pump continuously running - new pump will be required.
kubotalover t1_iy6dog7 wrote
Have you checked your pressure tank to make sure it is functioning properly?
ThreeBlurryDecades t1_iyaahfs wrote
Most jet pumps will run fine at 60 psi when in good shape. Be sure you are incorporating the lift from the surface of the lake to the top of your house into your math. Also the pressure switch should be plumbed right at the pump. A larger tank allows more flow before the pump comes in, and will lower the number of cycles your pump needs to run but has no effect on the pumps ability to do the work. If you need more lift and higher pressure a submersible pump right in the lake is a great upgrade and does not require priming if you ever run the pump dry.
large__father t1_iy1yj4n wrote
Just because it's a higher horse power doesn't mean the pump is designed to achieve the same head pressure. You can have a 50hp pump that's designed for low grade pressures. If your pump cannot generate enough pressure to counter act the cost of lifting the water to the height of the second floor that's why your flow will suffer.
If I remember correctly it's approximately 1psi lost per meter increase in elevation from pump.