AutoPilot SC-36 Pump replacement question

[mitchman333]

Hello

I have a Autopilot SC-36 unit that is connected to a 1hp pool pump, which I think has been under sized from the beginning. I'd like to upgrade my pool pump to something newer (many rebates abvaialble), and many newer pumps are listed as "Variable Speed" - can I use this type of pump with my AutoPilot SC-36 unit? The manual lists One Speed pump configuration and Two Speed pump configurations.

Any feedback would be great - thank you

-- Mitchman

 

[jblizzle]

First, why do you think your pump is undersized? Generally it seems that most people have a pump that is OVERsized. Can you be more specific on which model pump you have and why you think you need a bigger one?

You can use any pump with your SWG with one stipulation. There is a minimum flow rate required for the SWG to work, so if you got a VS pump, you may not be able to run it at very low speeds. Having said that, just about any 2 speed pump will likely be fine on low speed (1825 RPM) with the SWG. The cheapest option if you wanted to save some money on electricity would be to just replace your motor with a 2-speed on your existing pump and then mostly run on low speed.

If your electrical rates are high and you can get a big rebate, then it might be worth getting a VS pump. Although the incremental power savings of a VS running at slower speeds over a 2-speed pump on low may take a few years to offset the added upfront cost.

 

[linen]

I agree with jbliz, unless you have some high volume water features (waterfalls, spa jets, etc.) most likely your pump is not undersized. Post the model number, or a picture of the labels if you can't find the model.

 

[JamesW]

If you're using the Autopilot as the timer for the pump, you would need the two speed configuration to control a two speed pump. If you use a variable speed pump, you would usually run power directly to the pump and use the timer in the pump controller.

If you went with a variable speed pump, you would want to make sure the Autopilot was timed to come on only during pump run times. Alternatively, you could use a flow controlled relay to provide power to the swg only when the flow was sufficient.

 

[JasonLion]

Many of the newer variable speed pumps are designed for this kind of situation. They start at a higher speed, and then slow down, all on their own. That kind of variable speed would work perfectly with your current setup. The older (and generally larger) variable speeds can be problematic with a SWG as they don't always work well with external control.

 

[JamesW]

Also, some of the new variable speed pumps have a dry contact relay that can control power to the Autopilot.

[edit] I thought that several of the variable speed pumps included an auxiliary load control relay. However, I can only find a reference in the ePump + SVRS manual. I think that the ePump without SVRS also has the built-in Auxiliary Load relay contact, but I'm not sure. If it only comes with the SVRS model, then I think that I probably wouldn't use it as some SVRS systems can be a bit too sensitive and difficult to work with.

The Jandy Pro Series ePump + SVRS is equipped with a terminal bar that provides user access to a
built-in Auxiliary Load relay contact. This normally-open, dry contact is activated under certain operating conditions and is primarily intended to be used to control external devices that require system water flow for proper functioning, such as heaters, booster pumps, salt water chlorinators, etc
http://www.zodiacpoolsystems.com/~/media/Zodiac/Global/Downloads/H/H0414300.ashx

[end edit]

 

[mitchman333]

Amazing feedback as always and fast...! Best forum out there...

OK, I'll have to wait for model numbers/pump pics (it's buried under a ton of snow).

But really high level - I high 19,000 gal, vinyl pool with 1hp Hayward Pump, Autopilot SC-36 as Timer and SWG. I've always been concerned because my pump is 4.5' above water level and the 2 supplies and 3 returns are pretty long runs.

2 supplies (skimmer/bottom drain) = 80' + 115' = 195'
3 returns (low/deep end, water fall) = 60' + 70' + 80' = 250'

That just seems like a lot for a 1 hp pump, and lastly my pool contractor really sucked, in retrospect - I know so much more NOW thanks to this forum. My local electrical supplier is offering $300 rebate on newer pumps, mostly Variable speed pumps and I wouldn't mind getting a nice/new pump for a big discount.

Thank you for the feedback on the Variable speed pumps - really appreciate it.

-- Mitchman

 

[JamesW]

Going to a larger pump really would not help, especially if the pipes are undersized. The resistance increases exponentially as flow rate increases, so your gain in flow rate won't match the increase in HP. It's very inefficient. Also, you could potentially cavitate the pump if the suction pipes are too small, especially with the pump being 4.5 foot above water level.

I think that you would do better running longer times at lower flow rates. The flow rates would have to be high enough to operate the Autopilot (activate the flow sensor).

I think that you could go two-speed or variable speed. I like the variable speed because it's more efficient and it allows you better control of the exact flow rate.

What flow rate does your fountain need?

Note that the relay is a new feature. If you want that, you should make sure that the pump is the updated version. Jandy, Pentair and Hayward all have multiple choices for variable speed pumps.