Great forum! This site comes up all the time as I have been researching my new house plumbing design.
First off, we are a family of 5, with 3 pre teen children. I took on GC-ing our new home. It's been a slow process but it is a big project by my standards anyway.
We are on well water. The well was a disappointment, went 300 ft, got 3 gpm, told them to keep going to try for more. after 525' total depth, I ended up with 3.5 gpm. Not great but adequate for house use.
The house has 6 full bathrooms and two laundry rooms on three levels, basement, 1st and 2nd. I chose to go with a hot water recirculation pump and put the hot water heaters on the basement.
For the well, I selected a Grundfos 10gpm 1.5 hp constant pressure pump. I realize the pump can outpump the well's recovery rate but it has an auto-shutoff dry running feature and setting it at 500', the maximum it can output at that depth is 3 gpm so I don't think it's possible to run the well dry. It's a matter of performance.
I created a spreadsheet and charts based on my well, this pump, assumed psi setting. The color chart is my calculation of how long I can run at various flow rates, minimum to maximum. Green is optimal performance, yellow is marginal, red, unacceptable. I plan to set my pump to provide 70psi to assure good pressure to the upstairs baths. I might cut it back to 60 if necessary. With the Grundfos SQE pump, it's supposedly very easy to adjust, just a push of a button.
I am assuming the pressure will drop as the well approaches the yellow but flow will remain relatively constant. As it approaches the red < 30psi, flow will undoubetly suffer until a tap is closed allowing pressure to build.
The graph is the performance curve with various psi settings, 0, 30, 40, 50, 60 and 70. This is what I used to calculate sustained flow durations.
I'm not 100% sure any of this is correct, Does my theory of well pump operation and performance, pardon the pun, "hold water"?
http://www.johnda.com/house/pump-chart.xls
1st sanity check - I assume the peak SUSTAINED use rate will be in the neighborhood of 5-10 gpm. Normal peak use would be 1 shower, 1 bath and 1 washing machine running simultaniously, say 10 gpm for up to 30 minutes. According to my calculations, I can go 60 minutes at 10 gpm before pressure drops from my anticipated setting of 70 psi.
2nd sanity check - I have a 3/4" hot water loop and 3/4" cold supply through the house. I wish I had gone with 1" but sheetrock's up and I'm thinking (hoping) the limiting flow factor here is probably the well supply. The pipe is pex. I pretty much expect to see a degrade in pressure/flow if I have any more than 3 outlets running at the same time. but at 70 psi, I'm hoping 4 at one time will be usable.
3rd sanity check - I purchased 2 80 gallon hot water heaters (electric) and a circulation pump. I plan on hooking them up in series. I think this will be the only way to fly with the hot water loop.
Well guys? What do you think? Am I screwed or am I on the right track? Feel free to punch holes in any or all of my setup. I ask the so called experts and get a different story every time I ask.
Thanks for your feedback in advance.
John
First off, we are a family of 5, with 3 pre teen children. I took on GC-ing our new home. It's been a slow process but it is a big project by my standards anyway.
We are on well water. The well was a disappointment, went 300 ft, got 3 gpm, told them to keep going to try for more. after 525' total depth, I ended up with 3.5 gpm. Not great but adequate for house use.
The house has 6 full bathrooms and two laundry rooms on three levels, basement, 1st and 2nd. I chose to go with a hot water recirculation pump and put the hot water heaters on the basement.
For the well, I selected a Grundfos 10gpm 1.5 hp constant pressure pump. I realize the pump can outpump the well's recovery rate but it has an auto-shutoff dry running feature and setting it at 500', the maximum it can output at that depth is 3 gpm so I don't think it's possible to run the well dry. It's a matter of performance.
I created a spreadsheet and charts based on my well, this pump, assumed psi setting. The color chart is my calculation of how long I can run at various flow rates, minimum to maximum. Green is optimal performance, yellow is marginal, red, unacceptable. I plan to set my pump to provide 70psi to assure good pressure to the upstairs baths. I might cut it back to 60 if necessary. With the Grundfos SQE pump, it's supposedly very easy to adjust, just a push of a button.
I am assuming the pressure will drop as the well approaches the yellow but flow will remain relatively constant. As it approaches the red < 30psi, flow will undoubetly suffer until a tap is closed allowing pressure to build.
The graph is the performance curve with various psi settings, 0, 30, 40, 50, 60 and 70. This is what I used to calculate sustained flow durations.
I'm not 100% sure any of this is correct, Does my theory of well pump operation and performance, pardon the pun, "hold water"?
http://www.johnda.com/house/pump-chart.xls
1st sanity check - I assume the peak SUSTAINED use rate will be in the neighborhood of 5-10 gpm. Normal peak use would be 1 shower, 1 bath and 1 washing machine running simultaniously, say 10 gpm for up to 30 minutes. According to my calculations, I can go 60 minutes at 10 gpm before pressure drops from my anticipated setting of 70 psi.
2nd sanity check - I have a 3/4" hot water loop and 3/4" cold supply through the house. I wish I had gone with 1" but sheetrock's up and I'm thinking (hoping) the limiting flow factor here is probably the well supply. The pipe is pex. I pretty much expect to see a degrade in pressure/flow if I have any more than 3 outlets running at the same time. but at 70 psi, I'm hoping 4 at one time will be usable.
3rd sanity check - I purchased 2 80 gallon hot water heaters (electric) and a circulation pump. I plan on hooking them up in series. I think this will be the only way to fly with the hot water loop.
Well guys? What do you think? Am I screwed or am I on the right track? Feel free to punch holes in any or all of my setup. I ask the so called experts and get a different story every time I ask.
Thanks for your feedback in advance.
John