Well pressure tank size

Scott86MJ

Scott86MJ

Well-Known Member
Joined
May 3, 2006
Location
Dallas
I have a bad pressure tank and I am going to replace it tomorrow. I have a 20 gallon and was wondering if I should go up a size or not. The specs on Lowes says 20 gallon is good for 6-10 faucets/ showers and the 36 gallon is for 10-12 faucet showers. I have 2.5 bathrooms and sink in the garage and three outside faucets, so thats about 10 faucet/showers. I don't know much about my well pump other than its 200ish feet deep and 240VAC

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The pressure tank size determines how frequently the pump cycles. Smaller tank = more frequent cycles, shorter run time. Larger tank = less frequent cycles, longer run time. What's the duty cycle on the pump?
 
maulcruiser said:
The pressure tank size determines how frequently the pump cycles. Smaller tank = more frequent cycles, shorter run time. Larger tank = less frequent cycles, longer run time. What's the duty cycle on the pump?
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Along with this, what is your water usage? Do you have a shower hog in the house, run lots of wash, use the water hose for the garden or the yard a lot? XYZ…. Take all that into account on adding up water usage to size your pressure tank.
 
skyhighZJ said:
Along with this, what is your water usage? Do you have a shower hog in the house, run lots of wash, use the water hose for the garden or the yard a lot? XYZ…. Take all that into account on adding up water usage to size your pressure tank.
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I have 2 daughters and a wife, Lots of shower hogs :laughing:
 
Bigger tank is generally better, so long as the recharge rate of the well isn't terrible. Starting and stopping the pumps is hard on them. The number of faucets or showers is sort of a useless metric. Might be more helpful to think about it a different way - a 2.5 gpm showerhead and a 15 minute shower is 37.5 gallons of water. With a 20-gallon tank, the pump is kicking on every two minutes to keep up with the demand from just that one shower. Assuming a 10gpm pump, it's running for about 30 seconds each time. Double the tank size, halve the cycles and double the pump run duration for each cycle. So 40 gallons would be a minute-long cycle every 4 mins, etc.
 
also you want to consider cycle time you want your pump to run a couple min each time. This will let the water flow and cool the pump. my parents house had a good well 95 gallons a min would fill the pressure tank in less than 40 seconds, so the pump was short cycling. (they have farm)

Remember a 20 gallon pressure tank is only a 6 gallon draw down.
 
I posted this same question not too long ago. I also had a 20 gallon and went to the 36. Similar, I have 10 ish faucets, but they also say to count washers, dishwashers and toilets. I would recommend the 36.
 
I went with the 36 gallon and I replaced most of the fittings and pressure switch. I installed a union so next time will be easy.
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