No Chlorine Generation When Solar Heat On

[djvj]

I have an issue that I can't figure out why is happening.

When I turn my Solar Heater on, my Chlorine Generator reads "inadequate water flow", so it stops generating. I thought at first it was my DE filter, so I cleaned it all out and pressure now reads it's initial charge reading of 10PSI when Solar Heat is off. When I turn the Solar Heat on, it reads just under 14PSI. I'm not sure why pressure is going up, I would think the opposite would happen, but maybe my mind is not understanding the physics correctly of what's taking place.

I've read for efficiency, Solar Heaters work best with 2" piping. The pipes going to the roof are all 2", but get reduced to 1.5" before going into the Salt Cell and then into the Pool with the flex hoses. They are also 1.5" from the basket, through pump, through filter, then go back up to 2" right after the filter. Would this possibly be the reason why?

The output jet into the pool is still very strong when I turn the Solar Heat on, so it's not like I feel reduced pressure there.

 

[Bama Rambler]

The solar panels and installation probably add enough head to the system that it trips the low flow in the SWCG.

You might be able to replace the hose on the return fitting with hard pipe and get a little more flow out of it.

Can you post a picture of the solar setup?

 

[djvj]

Here are some pics, pipes go about 50ft until the 90 up to the 2nd story roof. Hope these are good enough, any better and I'd need to get the ladder out.

I can replace the flex hose for hard on the return no problem. I'd like to not have it reduce down to 1.5" before the salt cell but that would mean having to replace all the fittings and the valve body because its all glued next to each other and no straight pipe in-between

 

[rlab]

Unfortunately I don't think plumbing changes can overcome that amount of increased head up to a second story roof. You are limited by the laws of physics... that's a lot of added head, and your pump is unable to maintain the flow rate needed by the chlorinator.

Your simplest option is probably to install a small inline solar booster pump (they are pretty cheap). Many solar controllers have the ability to also switch on a booster pump when the solar valve is enabled. Its a standard setup designed to overcome exactly this issue of flow loss due to the solar head.

 

[Bama Rambler]

I have to agree with Rlab. That much head is going to be hard to overcome with your current pump. It's not so much the up and down distance that concerns me because they mostly cancel each other out, it's the total distance and the number of restrictions (fittings, valves, check valves, etc.) that is causing the flow to reduce to the point that the swcg isn't happy.

Increasing the size of the plumbing to 2" and changing out the hoses on the system to hard pipe might get you enough flow for the swcg to work, but it might not.

What size is your pump?

 

[rlab]

It's not so much the up and down distance that concerns me because they mostly cancel each other out

Hrm is that true? By that logic I could pump water, say 800 feet into the air with no issues because they cancel out.

Pretty sure the dynamic head is directly proportional to the height of the collectors above water level.

For example I have very simple/direct solar plumbing with the collectors directly above the equipment pad. Still a huge amount of head loss as soon as the solar is on, much more so than the rest of the pool system which has far more complex plumbing.

 

[mas985]

Static head cancels out but not dynamic head. Pressure is lost when water rises and then is gained back again when it falls so there is zero net static head. However, there is still dynamic head due to the water flowing through the pipes.

Are you sure the issue isn't with the priming of the panels? Air is traveling through the plumbing so the flow switch will not engage until all the air is removed but the unit may alarm before all the air is removed.

Which controller do you have for the SWG?

 

[rlab]

@mas985 if roof height makes no difference, then something is massively wrong with my own system. If I calculate TDH using horizonal and vertical pipe run length, 90 elbows, 45 elbows, and panel TDH (from manufacturer specs), with solar on I see a pressure increase on my filter gauge probably double the expected amount (flow rate read from intelliflo VSF). If I add in roof height static head then things work out about right (hence I always assumed roof height increases TDH!).

For both myself and djvj, what other factor could be in the solar loop that increases TDH so much?

 

[djvj]

Thanks so much so far for the help.

My only judge from flow is based on the amount of pressure I see the water shoot to the surface and ripples it causes. I see no visual difference with solar on or off. Flow is very strong. My pump is 83GPM btw.

It does take some time for all the air to work its way out btw. The SWG does go in standby right after turning on the solar. I've given it hours and it never comes back on. I do see the air pushing its way out over 10 minutes or so, which is expected.

I've never heard of a solar booster pump. I'm guessing it would be something that takes a 2" pipe in and out? Do you have a link to one that would work so I can read about them?

 

[rlab]

Booster pump is something like this: Booster Pump | Pumps | In Ground Pool Pumps - Hayward Pool Products

They are put on the same line as your main pump and boost the pressure/flow of your main pump. Commonly used for pressure side cleaners, but also (at least here in Aus) boosting for solar when the main pump can't cope with the added dynamic head.

 

[djvj]

How does that get plumbed in, like right after main pump in series? Because if it was just to assist with Solar, I'd think it would get plumbed in the pipe going up to the roof and only activated when solar is on. Otherwise it's wasted electricity.

 

[mas985]

@mas985 if roof height makes no difference, then something is massively wrong with my own system. If I calculate TDH using horizonal and vertical pipe run length, 90 elbows, 45 elbows, and panel TDH (from manufacturer specs), with solar on I see a pressure increase on my filter gauge probably double the expected amount (flow rate read from intelliflo VSF). If I add in roof height static head then things work out about right (hence I always assumed roof height increases TDH!).

I didn't say that roof height does not make a difference. There are several instances where the panel height comes into play.

During the initial priming stage, the return pipe is empty so there is no static head gain for that side but there is still static head loss for the supply side. So when priming the head loss will spike a bit and then settle down when the return pipe is fully primed. However, if the return pipe does not fully prime, then the static head loss of the supply side remains.

Also, after the panels and return plumbing prime (i.e. fill with water), the net static head is 0 but the effect of the pressure is still there so you will see a pressure decline with elevation increase and pressure increase with an elevation decline. This is simply due to the weight of the water. Same effect in a pool where pressure is higher the deeper the water.

For both myself and djvj, what other factor could be in the solar loop that increases TDH so much?

The panels themselves have quite a bit of head loss. But if you give me a detailed description of your solar setup, I can do a full head loss calculation to illustrate where the dynamic head loss is concurring. But 4-5 PSI rise is not uncommon for solar panels.

 

[mas985]

How does that get plumbed in, like right after main pump in series? Because if it was just to assist with Solar, I'd think it would get plumbed in the pipe going up to the roof and only activated when solar is on. Otherwise it's wasted electricity.

You may not need a booster and it probably won't help with the SWG. So I will ask again, what is the make/mode of your SWG? Also what is the make/model of your current pump?

 

[djvj]

Sorry missed your question.

I have the Hayward Salt & Swim 3C. See attached for pump.

 

[mas985]

Here are some pics, pipes go about 50ft until the 90 up to the 2nd story roof. Hope these are good enough, any better and I'd need to get the ladder out.

Are you sure the roof is 50ft high? Normally each story in a home is about 10 ft. 50 ft would be the height of a 5 story building. That pump would not be able to prime 50' panels.

BTW, the pictures you posted earlier are not available due to a website glitch. Posting them again would help.

To confirm:

When solar is on, all the water goes to the panels and none is bypassed?

Also, you mentioned that when solar is on, the flow out of the returns is strong, correct?

That is an above ground pump. Do you have an above ground pool? A signature with your setup would be useful:

Read This BEFORE You Post

We'd like to give you a few basic pointers of items that will help us, help you. From filling out a signature to posting test results.

www.troublefreepool.com

 

[djvj]

Ok added a signature with my setup and all pictures.

Pump to the house: 45'
Up to roof: 25'
Across roof to solar collectors: 46'
Solar collectors are 15' long x 12' high

When solar is on, all water goes to solar, none is bypassed. Yes the flow on the return is still very strong, I can't tell a difference with my hand.

 

[mas985]

Couple more questions.

How long does it take for the solar panels to fully prime so no air comes out of the returns?

Have you tried to reset the control unit after the panels are fully primed (without turning off the pump)? Does it alarm again?

 

[djvj]

I'd have to time it if you want an exact time, but my guess is between 5 and 10 mins. I'll see it first start out weak return, then it ramps up and air spits out on and off until it finally settles to normal pressure.

According the the manual, you are supposed to stop the pump, shut power off of controller for 2 mins (like when swapping the cell). Then turn power on and wait until it finishes booting and going through its startup sequence and blinks inadequate water flow. Then turn pump on for a few seconds and the inadequate flow led should go solid. Mine never blinks, just stays solid (it's normal behavior) until flow is adequate. I've also tried turning the cell in all different orientations which did not affect it at all.

So I've tried doing that a number of times w/o using solar. But I never tried w/o turning pump off, only because the manual said not to. It made sense as I figured the flapper on the cell had to not be moving so the controller knows it's idle position. But that's my own logic in my head lol.

 

[mas985]

I think the issue is that pump has a very low head curve. It maxes out at 40' of head so it takes too long to prime the panels. I am actually surprised the panels prime at all. But I am not sure what the delay is on the SWG unit before alarming. When solar turns on, does it alarm immediately? Even if you had a larger pump, that may not solve the problem if the delay is short.

 

[djvj]

I'm not sure what the delay before alarming matters because the alarm only tells me the flow isn't strong enough. How much time it took to get there doesn't matter. It alarms within a few seconds of turning on the solar heat because at that moment the valve is moving slowly until it hits its new position, redirecting the water flow.

The alarm then goes away and it starts generating once the valve goes fully back into bypass when I turn the solar off. That happens within 10 seconds of the valve reaching its fully bypassed position.

I also tried rebooting the SWG with the panels primed already but had no effect.

Made a video: