Pump leak - undersized?

[loughps]

I have a one year old Hayward Max Flo SP2807X10 1HP pump. It attaches to a multivalve connected to a Hayward S240 300 lb 60 GPM sand filter. Finally there is also a Pentair Mastertemp 250000 BTU heater. There are two 1 1/2 inch drains from the pool to the pump, one in the deep end the other from the skimmer. There are two 1 1/2 eye returns and a 1 inch fountain in the shallow end with a cut off valve.

The sand filter runs at 20 psi clean ever since we had the heater put in last year. After opening I discovered a leaking shaft seal on the Max Flo pump and replaced it. Everything was great for five days and now I notice the shaft seal is leaking again. The service tech at the pool store I've used since moving here three years ago says the Max Flo is an above ground pump and it's undersized for my setup and will just keep blowing seals.

Another pool store where I now buy my liquid chlorine since I started BBB this year says they would recommend a 1.5 HP Hayward Super Pump. I'm thinking a 1.5 HP Super Pump II is better suited to my system based on that high pressure, but I can't get my mind around all the head calculations, plus I'm having trouble finding curves for the Hayward pumps anyway.

My wife is more than a little unhappy about the thought of buying a new pump again this year, so I don't want to get this wrong. I've read that undersized pumps can be OK with an oversized filter. Would the 1 HP Max Flo and a 300 lb S-240 sand filter fit that bill? If so, why am I having the seal issues?

I'm lost and don't want to buy a new pump if I don't need one, but I can't be putting new seals twice a week either.

Any idea? Can anyone help me calculate the head for my pool and suggest a pump based on that?

 

[JasonLion]

For several of their pumps, Hayward shows the head curve as a table of numbers, rather than a graph. I believe that the data for your pump is shown here.

The Max-Flo isn't the best pump in the world, but it ought to be able to handle your situation without any problems. If it was undersized, it would be over heating, not leaking from the shaft seal. I would not get a larger pump. I might get a more energy efficient pump, but not a larger pump.

Unfortunately, I don't have any thoughts on the shaft seal, other than perhaps you got a defective one or maybe there is something else wrong with the pump that is breaking shaft seals. But I don't know where to look next to check either of those theories.

 

[loughps]

Thanks.

Does anyone have an opinion on trying a new shaft seal versus just changing out the motor? The shaft seal is considerably cheaper, so I guess it wouldn't hurt to order a new seal kit from a different supplier than where I got the last one. Maybe it was already old or something. I just don't want to keep throwing seals at it if the motor shaft is what's eating them up.

I'm testing my wife's patience with the pool this year. So far, she's being a good sport. But if I don't get cleared up and stop talking about spending money on things I'm endangering myself.