franklin subdrive inline 1100 pump

[jbuggyus]

 Hi, I just have a question about the Frankline subdrive inline 1100 pump. I am going to have our pump house all rebuilt with a new system ( our now is over 30 years old and pipes are rusting out and so is the old galv. pressure tank) The question I have is the company wants to instal The franklin 1100 pump to feed the 6 houses on our well and the farthest house is about 400 feet away and this seems to be a bit of a small pump to me but I am not a well expert, what is your guys opinion? This pump is in conjuction with 2 pressure tanks befor the filter and a water holding tank then the pump to feed the houses. Thanks!!

[Cary Austin]

Those pumps have only been available for a very short time.  Anybody trying one will be a guinea pig.  Except that it is the same type sensor and control as is being used on Franklins Sub and Mono Drive systems.  It is misleading to say that these pumps will vary the speed to match the usage.  They use a pressure switch with 1 PSI between on and off instead of a pressure transducer as other variable speed pumps have.  This “switch” will actually cause the pump to start and stop as much as 45 times per minute instead of locking into a specific speed.  On the submersibles this switch starting and stopping the pump 45 times per minute, or 2 million times per month cause lots of problems and failures.  At least with the booster type pump there is no long shaft to break, or long wire to whip against the casing and drop pipe each time the pump torques.

25 GPM at 50 PSI is probably plenty for 6 houses.  But I know you would be better off with a regular 1.5 or 2 HP jet pump, pressure tank, and pressure switch.  Adding a Cycle Stop Valve will give you constant pressure and reduce the size of tank needed.  This type system will last another 20-30 years like your last system did.  

The Franklin 1100 looks like R2D2, and like all variable speed pumps, is designed to make money for the manufacturer.  This is contrary to lasting a long time and being a good thing for the end user.  If in ten years any of those are still working and if that design still exists, then I might try one.  But that is not going to happen.

[jbuggyus]

Thanks Cary! One more question that I do have is that we have an old Galv. pressure tank(not a bladder tank) that is about 40"wide by about 72" high and the well pump size is 5hp. The shop also wants to replace it with two 81 gallon bladder tanks but doing some research two 81 gal would make the 5hp pump cycle for only 60 sec. instead of the optimum 120 sec.unless I am calculating wrong. I would think that I would need 4 81 gal. tanks for the 120 second cycle is that correct? Also the tank was put in back in 1980,what is the life expectancy of one of those tank? The main reason we are redoing the well system is we have tannins in the water and are going with a seperate tannin media filter along with our regular media filter/softner and need to put a water holding tank in for slow filteration so that the water gets filtered properly and then we have to reestablish pressure again. Is there any other way to establish pressure without using a jet pump? Thanks for all the help!

[Cary Austin]

There is nothing to go wrong with a Galv tank.  So they work until they get a hole in them.  If you are going to a storage tank from the well pump, you don’t need pressure tanks of any kind.  You only need a float switch in the storage tank to turn the well pump on and off according to the level in the storage tank.

I prefer a submersible pump in the storage tank to a jet pump.  A submersible gives you more water and pressure with less horsepower than a jet pump.  With galv pipe to the houses, I would set it up with a 60 PSI Cycle Stop Valve and a 50/70 pressure switch, using about a 40 gallon bladder tank.