Submersible Pump Question

[turnkey4099]

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OP - you probably need to define if this is a submersible sump pump or a submersible well pump.

Either way, leaving them running (in water) with the outlet blocked will build up the pressure to a certian point and stop. The energy from the pump then is converted into heat which can be damaging. They can and will get quite hot. Once or twice I've nearly burned myself grabbing my jet pump that didn't get primed properly.

If it's not in water and running, see my previous response. That's even worse.

Yes, common well and sump pumps will only build so much pressue - no fear of blowing out pipes.

Harry K

 

[Beltzington]

Apparently my question was not worded well:laughing:

Submersible well pump submerged in the water, motor running, spigots all closed. The exact same situation would be caused if your pressure cut-off switch stopped working.
This is a great forum, appreciate the sharing of all your expertise!

 

[Bikewanderer]

You should be OK, I do this all the time with my sprinkler pump and the transfer pump on my fire truck. I just wouldn't do it very long, it wouldn't be the greatest for the pump.

See this. Flow just drops off at a certain point, not increasing pressure any further.

https://www.pexuniverse.com/sites/d...little-giant-shallow-well-jet-pumps-curve.jpg

 

[Carl_NH]

Sorry - Dirtyoldman,

You are right for your pumps BUT wrong for a submersible, a sprinkler pump and a transfer pump on a fire truck are totally different setups than a submersible well pump. The above ground pumps CAN work without output for a while (3-5 minutes) and do not build a lot of pressure due to their design - single volute, single impeller setup.

Now submersible well pumps will build pressure and require some flow to stay cool. Most SUBMERSIBLE WATER WELL PUMP installations include a pressure relief valve alogn with the pressure switch that once that is exceeded it will start to bleed off water if the switch fails to stop the pump.

These pressuire relief valves are normally set at 70-80 PSI, as submersible well water pumps can generate 80-100PSI.

The pressure relief valves on submersible well pump systems allow some flow - usually around 1 GPM to prevent the pump from destroying itself.

Carl

 

[Bikewanderer]

I'll be the first to admit to not being an expert on well pumps.

That said, I believe that a submersible well pump is just a multi stage impeller pump. The principles should be the same. 80-100 doesn't seem that high and seems like what I would expect. I think I'm near 80 PSI at my house in town.

Cutaway view:
http://www.cushingandsons.com/photos/pump_cutaway.jpg

 

[Jimbrown]

The pump will began to over heat very rapidly. Some pumps have a thermal switchand will shut it down.

Total pressure will depend on the pump and the head. You just might build enough pressure to pop the safty valve on the water heater.

 

[SPIKER]

had a amish boy when my concrete was poured last year kill my pump he flipped the Hose wire Handle holder on, being lat in the year and dry for weeks th ewell dried out after about 15 min of running full on while he was cleaning concrete tools he sat hose down and walked away. I heard the pump (0 pressure) running 20 or so minuts later. the pump worked for 2 more weeks and seized up. It had been down 12 yrs from it;s build date. not long for submersiable WELL pump. Cost me 1400 to replace and had the well cleaned at same time.
I've got parts to build my own "Pump Saver" that will shur off the pump after 8 minutes of continous running. I've got to put on a push button reset yet. Parts to build it are about 60 bucks and a commercial one will run about 2X that from ones I've seen.

Mark

 

[Carl_NH]

I'll be the first to admit to not being an expert on well pumps.

That said, I believe that a submersible well pump is just a multi stage impeller pump. The principles should be the same. 80-100 doesn't seem that high and seems like what I would expect. I think I'm near 80 PSI at my house in town.

Cutaway view:
http://www.cushingandsons.com/photos/pump_cutaway.jpg

Yes, submersibles have 12-20 stages of closely staged impeller to volute clearances to produce 5-15 GPM typical, and if you stop the flow pressure and temp builds rapidly. A single impeller/volute type pump it is incapable of mutiplying to the same degree.

Your house in town @ 80PSI is line pressure by the town - thats a totally different scenario - Or do you have a well set at 80 PSI?

I've only worked on 100 or so single pipe or multi stage above ground water well pumps and about the same for submersibles so I could be wrong..

JimBrown - I agree - tho most well installations have a pressure relief below the hot water tank (they should anyway).

Carl

 

[turnkey4099]

Sorry - Dirtyoldman,

You are right for your pumps BUT wrong for a submersible, a sprinkler pump and a transfer pump on a fire truck are totally different setups than a submersible well pump. The above ground pumps CAN work without output for a while (3-5 minutes) and do not build a lot of pressure due to their design - single volute, single impeller setup.

Now submersible well pumps will build pressure and require some flow to stay cool. Most SUBMERSIBLE WATER WELL PUMP installations include a pressure relief valve alogn with the pressure switch that once that is exceeded it will start to bleed off water if the switch fails to stop the pump.

These pressuire relief valves are normally set at 70-80 PSI, as submersible well water pumps can generate 80-100PSI.

The pressure relief valves on submersible well pump systems allow some flow - usually around 1 GPM to prevent the pump from destroying itself.

Carl

The only place I have ever seen PRVs used or even read about them being used is on water heaters - there they are mandatory as a malfunction can cause extreme overpressures leading to explosions in th worst case. Never saw or read anything aobut them for the pump. 90-100 psi is well withign safety limits for residetial water systems, not recommended but safe.

Been maintaining family and freinds systems for 40 years.

Harry K

 

[Carl_NH]

Hi Harry,

Most new systems in the last 15 years have these pressure relief valves as part of the tank tee arrangement. The are preset at aboutu 100 PSI. Mine has kicked off once when I had a malfunctioning pressure switch.

Here's a link to the tank tee and PRV setup. Installation Tee Package For Well X Trol WX-201, 202, 203 and WP20, 32 - WX-T1

Yes, all DHW tanks have the T&P temp and pressure mostly to protect the tank and system in case of a heater failure and overheating and expansion. They technically arent meant to act as a well over pressure system, tho they could as they usually are setup around 100PSI and 200*F to release.