adding guest house to existing well

**jk13** · 11-04-2008, 06:39 AM

Hi, I am upgrading existing plumbing in guest house, and am asking for advice about increased demand from existing well. Submersible, 20/40, 30gal bladder tank, guest house is 60 -70 ft. from existing tank. thanks

**Southern Man** · 11-04-2008, 07:09 AM

If the well never ran out of water in the old house it's doubtful that a little used guest house would cause problems. But of course it depends on your well yield and how much the house is actually used.

I'd set a new pressure tank in the guest house and feed it with a 3/4" line tee'd off the existing line from your well.

**speedbump** · 11-04-2008, 07:13 AM

I agree, but I don't see where the extra tank would do any good.

bob...

**Southern Man** · 11-04-2008, 07:23 AM

It should eliminate the potential for pressure losses in the guest house due to the long run of supply pipe.

**jk13** · 11-04-2008, 07:30 AM

thanks for the vote of confidence, and the suggestion about the second tank, the potential pressure loss is my intuitive concern. We haven t run out of water in the main house but my wife would like increased pressure, any thoughts on that?

**speedbump** · 11-04-2008, 07:34 AM

Increase the pipe size to the guest room if pressure is a concern. The tank will only give you a short burst of better pressure than go right back to what is in the system already.

bob...

**jk13** · 11-04-2008, 07:43 AM

Thanks, - is there a way to increase existing pressure in the main house without changing sub. pump?
john

**speedbump** · 11-04-2008, 08:01 AM

You could try turning up the pressure switch. If you have a sub, it should go higher. I like 50/70.

bob...

**valveman** · 11-04-2008, 02:21 PM

Anything is better than 20/40, turn up the pressure switch. I also agee that a larger line to the guest house will give you better pressure, and another tank will not help.

hj · 11-05-2008, 04:57 AM

As long as the second tank is interconnected with the first one so the pressure switch responds to its usage, it will give better volume.

**jk13** · 11-05-2008, 05:23 AM

thanks for the help, I am curious about the mysteries of these pressure switches. what I am understanding is that they can be treated as a "reastat in ratio" then why are they sold as specific settings, 20/40, 30/50 etc.?

**valveman** · 11-05-2008, 05:52 AM

One pressure tank will give you volume for one minute, two pressure tanks will give you volume for two minutes. After that, all you have is what the pump can supply through the size of flow line you have. And that is only if the pressure tank(s) happen to be full when you start using water. The pressure tank(s) could just as easily be empty when you start using water. You have no control over this. With a 40/60 pressure switch, the pressure could be anywhere from 40 to 60 when you start using water. If it happen to be at 60, you will get volume from the tank. If it happened to be at 41, the tanks will actually be another load for the pump when it starts. So the pump will have to produce the amount of water you are using, as well as refill the pressure tank(s) at the same time. While the pump is refilling the pressure tank(s), you will be starved for volume in the house.

Pressure tanks where never designed to give you volume or stored water, only to prevent the pump from cycling on and off too often. A 119 gallon pressure tank only holds about 30 gallons of water. Even with two of these, you will rip through 60 gallons of water quickly in the house, then again, all you have left is what the pump can produce through the size of line you have. Your stored water is in the ground. There are millions of acre feet of water stored in the aquifers under our feet. This is where your volume of water comes from, not a pressure tank. You just need a large enough pump, and large enough water lines, to supply the amount of water you need. Then if you have a device to limit pump cycling, even a 1 gallon pressure tank is all that you need.