Solar and filter pump relationship

[simonline]

Hi,

Just purchased a house and inherited a pool. Been using the Pool Math app with great success.

The solar pump was not working as there was a PPP error code (Acson controller) and after replacing the pool sensor, it's all good.

Issue is I can't seem to work out how it was all set up and I am getting unwanted behaviours from the system.

Attached is some crude diagrams to help explain what I think is happening. These are my best guess after a lot of trials and it could be wrong. I have reached out to the previous owner but cannot get a hold of him.

Scenario 1: Pool filter pump is on, solar pump is off. Everything seems to be working fine and I cannot hear any water in the pipes leading up to the roof tubing and cannot see water flowing through the solar pump.

Scenario 2: Pool filter pump is off, solar pump is on. Can see water flowing through solar pump, can hear water in pipes leading to roof. The issue is that water is flowing through the pool filter pump (can see in inspection window), flowing the wrong way through chlorinator and flowing out of the skimmer hole. It has likely been through the sand filter the wrong way as it is all cloudy. When I then turn off the solar pump and turn on the filter pump, the filter pump takes a long time to prime and sometimes doesnt at all.

Scenario 3: Both pumps are on. Everything seems to be flowing ok but the jets are putting out an insane amount of water.

Other attachment is an image of the pumps setup.

Is this a typical set up? I want to run my filter pump overnight on off-peak electricity and only run my solar pump during the day when needed.

 

[Rocket J Squirrel]

You should never run scenario 2. The filter pump must run when solar is engaged.

 

[simonline]

If the solar pump runs according to temperature differences and the filter pump runs on a time schedule, how do I ensure scenario 2 never happens?

 

[Rocket J Squirrel]

Need more info about your equipment. Automation or clock timer(s)? I don't recognize the equipment from the photo.

In the simplest case, the solar pump shouldn't get power when the filter pump doesn't. You really don't want unfiltered water flowing through your solar panels' tiny tubes.

 

[simonline]

Solar pump is run by an Acson MS3D controller. It looks at the roof temp, pool temp and desired temp and makes a decision on whether to turn the pump on or not. The solar pump is plugged into the MS3D solar controller for power. The controller turns the solar pump on and off according to temperature differences. The intakes for the solar pump are 2 small grills on either side of the skimmer entrance so there is no way for the solar system to get filtered water from the actual filter. The solar pump has an inspection window with a small basket for leaves etc.

Filter pump is run by 4 time blocks per day, 2 on and 2 off. Can be ON (Manual), OFF or AUTO (timed).

 

[Rocket J Squirrel]

OK, I'm going to have to bow out due to unfamiliarity with your setup. Never seen that before, so better for me not to guess. Maybe someone else on the forum will chime in.

 

[simonline]

No worries, thanks anyway!

 

[yblaser]

I am not an expert, but will reply to give the thread a bump.

This is setup is not typical in the US at least in my experience. To address your main concern of water back flowing through your filter plumbing, you need to install a check valve in you filter plumbing. Since both pumps share the same returns, if one pump is off then the other pump can push the water backwards through the unpowered pump. It looks like you might already have a check valve on the solar side.

Also, where does the solar controller measure the pool temperature? If it is measuring it at the equipment pad, it will not have an accurate measurement of the pool water temperature unless the pump is on and water is flowing past the temperature sensor. This would lead to some unintended behavior with the solar controller.

 

[simonline]

Thanks for the advice yblaser. A check valve would make sense so I will get one installed after the chlorinator to stop the back flow from the returns.

There is a drilled hole in the PVC pipe that leads into the solar pump and the sensor sticks in there. You are correct that it would only get an accurate reading when the solar pump is running. I would imagine it would quickly correct itself if the pipe temp is different to the pool temp.

 

[simonline]

Update to close this out.

I installed a check valve (one-way) just after the pool chlorinator and this has solved the problem. Now I can run my solar pump and filter pump at the same time or individually and it works fine.
I ended up contacting Acson who manufacture the MS3D controller who put me in touch with a local shop who currently installs their product. The guy came out and was very confused with our set up (the company who initially installed it has since gone out of business). He offered the same solution as @yblaser so we went with that.

I also replaced the pool temperature sensor which sits in pipe just before the solar pump. Just search for, Acson MS3D pool sensor genuine, should be about AU$70. Was pretty easy to pull out and replace as it just sits in a rubber lug, no screwing needed. As long as the controller and pump are off, there won't be much pressure on the pipe but take note that when I removed the faulty sensor, about a cup of water spurted out then quickly stopped as the pressure went down. I put some plumber's grease (hydroseal tap lubricant in Australia) all around it to make sure it was watertight. Probably not needed but I had some lying around.

My solar controller is currently in winter mode so I have not regularly run the filter pump and solar pump at the same time. I plan to do this when our solar panels are installed and I get free power during the day. I hope that the fact that both pumps push water to the same 2 outlets doesn't mean they will be under strain if the 2 outlets are not enough to get that volume of water through. Time will tell!