new variable speed pump and solar heating system

Hello there,

I had a new Hayward 3400VSP pump installed yesterday to replace a 5 year old 1.5hp hayward and it keeps getting stuck priming during Autoprime mode. It happens wether the pump chamber is full of water or if it is not completly full. If the chamber is not full of water it doesn't prime/fill completely and then also gets stuck in autoprime mode. I first checked the lid and gaskets for good seal and did a quick above ground leak check and came up empty. After further investigation this seems to be happening when the solar valve is open to the system. If I close the solar, and power up the pump or change speeds, it stays in prime mode for approx 30seconds, primes completly and then operates at set speed. I can then reopen solar and it functions fine. Since the solar valve comes off the filter on the pressure side, I don't understand how it being open can affect the pump priming? The solar is being automatically controlled by my Goldline system via temperature of the pool and the new pump is on its own timer. The old pump was on "filter" function on the controller so I have that timer set to turn on at the same time as the new pump (when it goes to 2750rpm to run the vac) so that the solar will sense temp/run and the chlorinator will run at that time also. So should I just set the solar/cholrinator timer to come on after the pump comes on/changes speeds and turn off before the pump does to ensure the valve is always closed when the pump starts or changes speed? Or is there a problem with the pump? Also, how many rpm do you think I need to run the pump at for optimal solar function? It seems that the higher the rpm the warmer the water is coming out the returns. Right now at 2750 the water coming into the pool is definitely not as warm as the temp sensor is telling me the water coming off the roof is. Running at 2750 is the pump just not able to push enough water up?

You've got a complex piping system, about which we know little, except that it's complex. I can tell you it's rather common for such systems to create an accidental bypass leak that interferes with priming.

You've also a complex set of controls with the result that neither of us knows exactly what's happening at any given time. This is one of the downsides of control systems: even when they work properly, the pool owner often doesn't fully understand what the system does, so they can't tell us. And, when they work improperly, either because of equipment failures or programming errors . . . well, nobody knows what's happening.

RPM is an arbitrary number: it doesn't mean anything, exactly. The real factor is flow (GPM) but the relationship between flow -- which you don't know -- and RPM -- which you do -- is indirect. Unfortunately, the new VS pumps helpfully 'translate' RPM into GPM, creating the illusion that you know more than you do. In actually fact, the GPM figures are estimates, based on assumptions about how much resistance their is in your systems, and those assumptions are often wrong.

I believe that 2750 RPM is the maximum on your particular pump, and unless you have some extraordinary kind of piping system, the max setting on that pump is more than enough to drive everything. What you may be missing is that EVEN WHEN THE SOLAR UNITS WORK WELL, output temp will drop as flow increases.

Bottom line: I can't tell you anything, because you've got way too many unknowns. Your best bet would be to get a KNOWLEDGEABLE service guy out to your pool. He'll probably disable things, one at a time, so he can isolate the problem. I'm guessing that the guy you need is NOT whoever installed the pump, since if he was, you'd be talking to him already.

If you still want to try to troubleshoot your situation here, let's start with this:

1. Complete the equipment form, http://pool9.net/pf-equip-form, being sure to include ALL equipment that is in the pipe line, including your pump, filter, solar system and solar valves. Include the make & model of all items.

2. Take comprehensive pictures of your piping & valves, and post them on Photobucket, Flickr, Googe Drive, Dropbox, or what have you, and link to them from here.

Good luck!