Another Freeze Protection Issue

[mrafal]

Hi All,

I have an Aqualink RS4 that and the cold weather has activated the freeze protection. What I am noticing is that when the temperature is right at the set point, the pump is being turned on and off rapidly (as much as 15 to 20 times a minute). That can't be good for the motor. Is this a "feature" of the RS4 or does this indicate a failure mode. Another related issue is that after the freeze protection is activated, the programmed start times are ignored until I cycle through the service mode at the power panel.

Anyone seen this behavior before?

Thanks
Marc

 

[mas985]

It could be that the air temperature is fluctuating around the freeze temp threshold turning the pump on and off.

One of the biggest problems with freeze protection is that most controllers do not allow you to set the threshold very low. I think Goldline units have a low end of 33 degrees which is still too high in my opinion. This is why I just shut mine off. Some might think that is risky but for climates such as yours and mine, even though the temperature goes below freezing for several hours it will usually take well more than 8 hours of sub freezing temps before the water in pipes will even start to freeze and even longer to freeze solid but you will have to assess your own risk.

What I find useful is to use the SWG diagnostics which shows the temperature of the cell as well as the water temperature sensor. Comparing this to the air temperature lets you know if there is a chance that the pipes are actually freezing or not. Usually, the temperature reaches is lowest point early morning so it is fairly easy to check.

 

[Bama Rambler]

It's definitely not good for the motor or the relays to rapid cycle like that. I can't believe they didn't put a deadband in it to prevent that.

I also can't believe that it doesn't got right back to normal programming once the freeze cycle kicks out. Someone with experience will let us know if that's normal or not.

 

[mrafal]

It's definitely not good for the motor or the relays to rapid cycle like that. I can't believe they didn't put a deadband in it to prevent that.

I also can't believe that it doesn't got right back to normal programming once the freeze cycle kicks out. Someone with experience will let us know if that's normal or not.

I agree, a deadband would be minimal good engineering practice. I am hoping one of the gurus here knows about a firmware upgrade that solves this. The unit is ~15 years old and I am sure the previous owner never upgraded the firmware.

I may just disable the freeze protection and manually turn on the pump if there is a real risk of the pipes freezing.

 

[mas985]

I think I remember something similar happening when I did use freeze protection. Goldline did not put too much intelligence in the way it was implemented. Really, they should of used water temperature sensor instead of the air temperature sensor to trigger the freeze protection. This would have prevented cycling as well.

 

[serge]

Hi Mark...mine is a Pentair easy touch, and this is what I posted a while back...

"...This is a new one...my Easy Touch System" is acting up again. I have been following its behavior lately and discovered that every time the freeze protection feature is activated (usually at night), the following day the filter pump starts (in auto mode) to stop every hour on the hour for one minute. Has anyone had similar issues?..."

 

[mrafal]

One of the biggest problems with freeze protection is that most controllers do not allow you to set the threshold very low. I think Goldline units have a low end of 33 degrees which is still too high in my opinion. This is why I just shut mine off. Some might think that is risky but for climates such as yours and mine, even though the temperature goes below freezing for several hours it will usually take well more than 8 hours of sub freezing temps before the water in pipes will even start to freeze and even longer to freeze solid but you will have to assess your own risk.
.

You do have to be a little careful about supercooling. If the equipment has a view of the sky over a substantial viewing angle, the radiative cooling on a clear night can lower the temperature well below the air temperature. That is the same phenomenon that causes frost when the air temperature is above 32 degrees. I assume that is why the set point is usually set higher than the freezing point.

It would make more sense to use the water temperature sensor. At least on my set up, that sensor is in one of the pipes I am trying to protect. So its temperature, when the pump is off, is precisely what I care about. It would take a bit more logic to manage that because as soon as the pump turned on, the temperature reading would rise as the warmer pool water passed the sensor.

Marc

 

[mas985]

Based upon some calculations I did regarding heat loss, I found that convection seems to dominate under most conditions and only where the temperature is around 32 F, does radiative heat loss become a factor but only because convection is close to zero.

Anyway, based upon the highest air heat transfer rates possible and a sky temperature of 35 F below ambient, I estimated that it would take close to 14 hours with a linear temperature profile going from 32F to 25 F to freeze the water in the pad equipment. Actual freeze times are likely to be more than twice that since worst case conditions rarely happen.

This convinced me that it is fairly unlikely that my pipes would freeze. However, if the temperature were to get down to 20 F for 9 hours, I might start to get worried. Also, on low temperature days, I confirm that the pipes are not freezing by watching the water temperature.

 

[PoolGuyNJ]

Please remember that the freeze isn't instantaneous in the pipe. The water nearest the pvc will start to freeze first, creating a restriction. Restricted flow is bad. Broken ice forming a blockage is worse!

Scott

 

[PaulR]

Seems to me that some regular ol' pipe insulation (the foam kind like you should wrap your househould hot-water pipes with) would go a long way to protecting the exposed plumbing. It's cheap too, you could wrap all your pool plumbing for less than the cost of running the pump one night (around here).
--paulr

 

[jellybeans]

Hello all.
Nice forum!
So, now 2015 (Happy New Year!) and we experienced this same problem last night. Does anyone know the latest regarding this freeze protection glitch, and whether the on/off rapid cycling of the filter & pump during freeze protection can damage the pump/motor, and how this glitch might be rectified?
Thanks in advance.