- Jul 12, 2012
- International, Kubota, Komatsu
Get as big as a pressure tank that will fit, 8 or 10 gallon drawdown and stack the tank in the corner as mentioned above the water softener - and use the CSV - get the best of both worlds - constant pressure when needed, less cycles and not turning on every time you brush your teeth or wash your hands - it's really simple - you want to reduce the starts/stops on the pump.
For the pump, getting a large 1HP pump - 15 GPM is actually a bad idea, it will draw more amps starting and running and be overkill for your house. A Goulds, Grundfos, or AY McDonald 3/4 HP 10 GPM model will produce 12 + GPM at your water depth and with your in flow or recovery rate of (20 GPM) , and a 7 GPM rated pump will deliver 8-10 GPM at your depth and in flow rate to the well.
Personally, I have a Goulds 10GS15 (10 GPM, 1.5HP) for 20 years, set at 365' and it pumps 14 GPM at 50 PSI most of the year, and when the well is low - dry times produces 10-11 GPM, and I wish I put in a 7 GPM 1.5 HP as it would better match our max usage (8-10 GPM) with less cycling.
The key to a long lasting water system is to size the pump and system to your usage and minimize the number of starts/stop cycles over the years, and that is best done with a "right sized pump and storage tank" and a CSV which will minimize the starts/stops and not turn on every time you draw a small amount of water.
You can do what you want, but don't over size the system - 1" pipe, 3/4 HP 7-10 GPM (will produce 8-12 GPM), a 8 gal drawdown tank would be ideal.
Sure you can use a large tank with the CSV. However, having helped a few hundred thousand people through the same process in the last 30 years I can tell you what will happen. Within a few months you are going to call me and say you really love the 50 PSI constant pressure, but don't like the few minutes it takes for the pressure to drop all the way to 40 before the pump comes on. You are going to ask about using a pressure switch with only 10 PSI between on and off instead of 20. I will tell you that works fine, but takes a more expensive pressure switch, and is effectively cutting the tank size in half. Some will go for the 10 PSI pressure switch, others will say the tank is old anyway, and switch to a new smaller tank. Others will say they wish they had gone with the smaller tank to start with and just live with waiting for the big tank to drain off the low pressure. Some even tell me they just turn the shower on 3-5 minutes before they get in, to make sure the tank is empty and they are getting good strong constant pressure from the CSV.
Oversizing a pump use to be a bad thing. It doesn't use more energy as horsepower per gallon is the same with any size pump, the large pump just fills the tank quicker and causes more cycling. Although, with a CSV you can use any size pump. You can put in a pump as large as you think you may need, or even because that is the only pump available at this time. The CSV will make it work like a small pump when using small amounts of water, and will not let the pump cycle itself to death.
When you have a CSV so you can see what I am talking about with the small tank being a mechanical timer, you will understand that the pump does not come on for every small amount of water being used. I know the small tank makes you think it will, but the mechanical timer thing keeps the pump running instead of cycling on and off.