Solar drain down and motor question

[spc337]

Ive been living a nightmare solar install that has lasted 2 years.

The current setup....

Distance from pump to panel is probably 100 linear feet and 50 Feet of head (3rd story roof).
Pump is making a very loud noise and suspect the bearings are going. Basically can't sit outside with the pump on. The pump is 3/4 hp which I suspect is underpowered but water does make it through the loop.

The main issue is that the solar panels don't drain down. So the water super heats and is impacting the pipe. My controller is goldline.

I saw on the pentair controller user guide that the recommend a drain on the feed side after the diverter specifically for metal arrays but can't see why a PVC array wouldn't benefit but I'm not sure the goldline computer can control that. They also put their vacuum break at the top of the array, mine is about 10 feet up the feed side. Lastly the pentair 3way diverter has a built in check valve which is a great idea, not sure if I can use that valve within my system and with my goldline actuator.

Thoughts, ideas?

 

[mas985]

I think you have identified all the problems. With the VRV located so low and the panels so high, this creates a strong vacuum at the top of the panels when the pump shuts off. When the super heated water travels through the PVC pipe, it can soften the pipe and there is the potential to collapse. Put the VRV at the top of the panels and it should fix the problem.

As for the solar valve, yes you can use that just fine with a Goldline actuator.

BTW, what is the model of your pump. Not all 3/4 HP pumps are the same.

 

[spc337]

Well - went away for a week to come home to a green pool... Pump quit so now I need to replace that too The solar gift keeps giving.

My current pump is a Hayward Super II 3/4 HP. It was getting very loud over the past few weeks to I suspect the bearings finally froze. My Pool Installer suggested this wasn't due to the solar panels and the added load but my naive logic suggests otherwise. The pump was new in 2009 so 3 years in service seems short..

I'm thinking a dual speed pump (Super II 1.5 HP) running low speed at night for cleaning, high speed for Solar Priming in Low Speed there after is a good solution, coupled with moving the VRV to the top of the panel and changing the 3-way diverter value to the Pentair with it's builtin Check Value. I'm hoping there would be enough pressure to keep air out of the system, keeping the VRV shut during operation. My controller is a Goldline Aqua Plus which should support the motor controls along with the Solar system.

Thoughts?

Is changing the pump motor, aside from the electrics, something I can do on my own. I'm reasonably mechanically inclined.. I'm guessing I will need to replace the impeller too.

Sean

 

[mas985]

Your pool guy is correct. Solar does not add more load, it actually reduces it. For most residential pool pumps, higher head loss and higher pressure results in lower flow rates which is a lower load on the motor.

So it would be a mistake to up size the pump. A 3/4 HP is more than big enough. I have a 1/2 HP running solar on a two story roof.

 

[spc337]

I believe yours is a two speed pump. Would you recommend that for my needs? That would still be 3/4 up under normal conditions and 1.5hp for priming.

 

[mas985]

I believe yours is a two speed pump. Would you recommend that for my needs? That would still be 3/4 up under normal conditions and 1.5hp for priming.

That is not how a two speed works. The HP on low speed is 1/8th of high speed, not half. The speed and flow rate is 1/2.

My pump is a 1/2 HP on FULL speed. It is also a custom pump. I downsized the impeller and motor.

As for your needs, a 3/4 HP two speed should be all you need. You could just replace your current motor with a two speed.

 

[jblizzle]

Out of curiosity (and to clarify for anyone that might read this in the future), you are saying he is fine with the 3/4HP pump on a 3rd story roof because it is a Super II, correct?

I imagine that the Super Pump or Superflo 3/4HP would be too small; while the Super II and Whisperflo 3/4HP are more powerful.

 

[spc337]

I believe yours is a two speed pump. Would you recommend that for my needs? That would still be 3/4 up under normal conditions and 1.5hp for priming.

That is not how a two speed works. The HP on low speed is 1/8th of high speed, not half. The speed and flow rate is 1/2.

My pump is a 1/2 HP on FULL speed. It is also a custom pump. I downsized the impeller and motor.

As for your needs, a 3/4 HP two speed should be all you need. You could just replace your current motor with a two speed.

The Hayward super ii says it is 1.5hp on full and 3/4 on low speed. The replacement AO smith motors are like you say with low speed being 1/8 or less of the full hp.

My current motor is 3/4 hp with SF 1.0. So are you recommending I go with the 1.5/.75hp dual or the AO smith 3/4 full ~1/16 low which seems really small..

Is your controller setup to engage high speed when the solar kicks in to prime for 3mins then drop back to low? That's how I read the goldline control should be setup.

Thanks.

 

[mas985]

There is a difference between the motor rating and operating point. The motor rating may be 3/4 HP on low speed but the required power is only 1/8th of the full speed HP.

But where did you see that the low speed rating was 3/4 HP?

As to the current pump, assuming the pump is a SP3005X7AZ, the max head is 75' which should be enough lift to prime the panels but it is a little extreme. I am assuming that the current pump primes the panels, correct?

Is your controller setup to engage high speed when the solar kicks in to prime for 3mins then drop back to low? That's how I read the goldline control should be setup.

The goldline controls switch to high speed when there is solar demand. But for most installations, it isn't possible to run solar on low speed anyway because of the vacuum release valve. Plus there are other issues to be considered running solar on low speed such as loss of efficiency.

 

[spc337]

Final got my new motor. It was supposed to be a AO Smith 1hp dual speed but when the installer came it was an Emerson 1hp dual speed. The low speed on this like you said, 1/8 hp but half the full speed rpms. Hopefully an Emerson is just as good.

I had originally setup two filter timers (when I had a single speed) one at night to filtration and one during the prime solar gain time for heat. No I had the two speed pump and my timers changed to having one for high speed and one for low. I wasn't expecting that so now I need to know the optimal config so I'm filtering on low speed but when solar kicks on having it jump to high speed.

I have the Aqua Plus controller.

Also, since I live in an area that can drop below freezing at night, I have freeze protect enabled but dropped it to run on low speed. I'm assuming that is sufficient movement to prevent freezing.

 

[jblizzle]

Are you relying on the low speed to run water through the solar panels for freeze protection? Because if they are up on the roof, low speed may not be able to prime them.

Although if the weather is that cold, there is no reason to even be running the solar and you should just drain the panels and leave solar off until spring.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[mas985]

Also, since I live in an area that can drop below freezing at night, I have freeze protect enabled but dropped it to run on low speed. I'm assuming that is sufficient movement to prevent freezing.

Where do you live and for how long do the temperatures drop below freezing?

Most of the time, freeze protection is not needed even if temperatures drop below zero. The water in the pipe and equipment will usually take over 12 hours to freeze solid in sub 32 temps.

 

[spc337]

Raleigh North Carolina. I'll be shutting down and draining the pipes before it gets to the full winter temps. So it's just the few hours over nigh that drop below freezing. That's why I think low speed is sufficient.

 

[mas985]

You don't need much flow rate to prevent freezing but if the temps only drop below freezing for a few hours, you probably don't any at all.

 

[spc337]

My main question at this point is the best timer settings. As I mentioned, with a one speed pump, I simply had to timers, one at night for filter/floor cleaner and one during the day for the solar to operate. Now with the two speed pump setup, I have the controller gives be a High-Speed timer and a Low-Speed Timer.

The options as I see them are -

1) Run Low Speed for a longer time period but still over night. Run High Speed during the day during the best Solar time range. basically the same as before.

2) Run Low Speed from 7am to 7pm (basically all day). Leave the Solar (Low Speed to Disable), When Solar Kicks on, I believe the Controller will jump to High Speed (is that true)?

3) Run Low Speed from 7am to 7pm, Set Solar to Enable Low Speed. When Solar kicks on, High Speed should engage for 3mins then drop back to low to prime the pumps.


I suspect I'll have little success running my panels on Low Speed given the Head/Height, I suspect the VAV will allow air to enter the system at the low pressures in low speed. Although #3 would be great, don't think it is viable so Option 1 or 2 seem like my only alternatives.

Thoughts?

BTW - I will be draining and disabling solar for the winter so I don't need the freeze protect for that. Ideally, the array should be fully drained by night fall anyway so night time frost should be an issue..

 

[mas985]

Depending on your controller and if you are using freeze protection, you may not have a choice. It may simply set the pump on high speed until the air temp rises above freezing. Your other choice is to disable freeze protection and run the pump on low speed.

As for #2, you should be able to disable solar so it doesn't turn on. Most controllers allow for that.

#3, if you are using solar, most controllers will force the pump to high during the entire solar demand period, not just priming. But again, you should be able to disable solar on the controller.

But for both #2 & #3, why so long of a run time? If you are concerned about freezing, run the pump on low speed for just the period of time the air temps drop well below freezing.

 

[spc337]

Depending on your controller and if you are using freeze protection, you may not have a choice. It may simply set the pump on high speed until the air temp rises above freezing. Your other choice is to disable freeze protection and run the pump on low speed.

As for #2, you should be able to disable solar so it doesn't turn on. Most controllers allow for that.

#3, if you are using solar, most controllers will force the pump to high during the entire solar demand period, not just priming. But again, you should be able to disable solar on the controller.

But for both #2 & #3, why so long of a run time? If you are concerned about freezing, run the pump on low speed for just the period of time the air temps drop well below freezing.

thanks for your continued feedback..

Freezing was a separate question. Just ignore that for now, I'm ok with how that will work.

What I'm really trying to understand is during normal operations, how to configure the two time ranges. Ideally, when solar isn't on, I would like the system to run in low speed and when Solar is called for it jumps to high speed.

 

[mas985]

The Goldline controllers will automatically switch the pump to high speed during solar demand so that should not be an issue.

 

[spc337]

The Goldline controllers will automatically switch the pump to high speed during solar demand so that should not be an issue.

With that in mind, I would guess running the pump in low speed throughout the day is the best option, and don't use the High-Speed timer at all. Just set the Low Speed time to include the prime solar hours?

It would be nice if I could have multiple timers beyond just High Speed and Low Speed or perhaps the controller could turn on the pump when Solar is available - but that's a conversation for Hayward.

 

[mas985]

The controller can't turn on solar without the pump running because the pump needs to run in order to find out the water temperature.

But here is a suggestion:

Set the pump low speed run time to the minimum run time you would want per day and the start time around the time solar is available. For me this is around 10:30 am.

Next, set the controller for solar extend. This will keep the pump running for as long as solar is available and the water temperature is lower than the controller setting.

This will then allow solar to basically control your run time but there is still a minimum run time set by the low speed run time setting. Best of both worlds.