Question on 2 speed pumps

[Robert53]

Hello to all

I want to change out my old single speed bronze pump with a 2 speed pump for energy savings, I can not afford a variable speed pump at this time. My question is I have read that with a 2 speed pump you need to start the pump in high speed for a minute or two, to prime the pump before switching to low speed operation. If so what would be the best / affordable way to control this without going out every day to flip the toggle switch.
Pool discreption 18000gal inground, 500gal attached spa, spa has seperate pump, 2 speed pump will be used for circulation and cleaning, supply and return are 1.5", has Hayward C-3000-s filter, equipment is about 45' from pool, no rise.
Thanks for any help
Robert

[PoolDoc]

My question is I have read that with a 2 speed pump you need to start the pump in high speed for a minute or two, to prime the pump before switching to low speed operation.

It's possible to set up a timer to do that, and it's not even very hard. But unfortunately, most electricians I've been around don't know how to do that sort of work, unless someone draws it up for them, and sells them a kit with all the pieces.

What many folks with 2 speed pumps do, is leave the pump on LOW 24/7, except when they are vacuuming, backwashing, or having a party.

If you power cycle the pump, it may, or may not, be necessary to toggle from OFF to HIGH to LOW. It depends on your pool's piping. If your piping is laid out so that it does NOT lose prime during off cycles, than the pump should start up just fine on LOW. The reason for starting on HIGH is to pick prime back up, before switching to low. Few pumps self-prime well on LOW.

I'm going to check with another user here, who knows more about pumps than I, and see if he has any recommendations about which 2 speed pump you might want to pick. Pump efficiency is a matter of motor efficiency PLUS pump wet end efficiency, and sometimes very efficient motors have been coupled with not very efficient wet ends.

What I can tell you is, that 1.5" piping, you'll probably want the smallest pump available: there's no pump that can EFFICIENTLY pump more than about 40 - 50 GPM through 1.5"piping. If you want to send me photos of your pool, including inlets, skimmers and equipment, I'll post them. It's easier to select a pump properly if you know what the circulation system is like.

[mas985]

What is your current pump make/model?

If the wet end is in good condition, most pumps can easily be converted to a 2 speed by simply replacing the motor and seal. I converted my pump myself.

Also, I agree with Doc, with the proper plumbing, a pump should not lose prime when the pump is off. If it does, it usually means an there is an air leak on the suction side of the pump.

Finally, you can get a two speed Intermatic timer to control the pump if you want to have a timer for each speed.

[Jimmy C]

I have been running a 2 speed pump for 7 years now. Wow what a difference! I bought the motor from Perry's Pool Pump in Arizona with a shaft seal to put on my old housing. This is a 3/4HP Low /2HP high motor. On high into my 1.5" return piping the restriction is high, and the power meter really spins. On 3/4 HP I get about 1/2 the flow, and the power meter rotation rate slightly increases when turning on the pump.

My setup will prime on low speed, but it might take a minute or two. This happens when I get a piece of dirt, or a leaf on the pump basket O-ring. Otherwise there is no need to prime other than when I clean the basket. I installed a weatherproof dual switch on the house wall right next to the pump. It has low/High and off/on right there for convenience.

The other issue seldom mentioned is low speed with a salt system. First we must have enough flow on low speed to make the salt system flow switch. Second, since a SWG cell produces hydrogen gas, when the pump is on Low, there might be a buildup of gas in the return lines. This happened to me. The buildup was such that after about 4 hours SWG run time, the water return lines were full of gas to the point that the water flow switch tripped off. Turning the pump on high cleared the problem after lots of bubble gurgling from the farthest away water return jets.

One fix for the hydrogen gas issue is to have the return lines rising slightly underground toward the pool, but never sloping down. Of course keeping the pump on High fixes the issue, as would a 2 minute burst of High speed every 4 hours. I picked a third way. My pool has 5 water return jets, and the farthest away from the pump three jets got plugged up from gas. The solution was to put rubber stopper corks over the two closest return jets. Now I had enough water flow in the remaining jets to keep the gas from building up.

For those that don't believe those bubbles are hydrogen, when running pump on low speed we get big bubbles coming from the return jets. Then turn off the SWG cell, and in 60 seconds the bubbles go away. The bubbles will return when turning the SWG back on. Take a BBQ grill charcoal lighter, and you can ignite the bubbles in loud snaps. Be careful though since the return line might be full of gas, and the filter too....Boom!

Jimmy C

[PoolDoc]

All good points! Thanks, Jimmy.