freeze protector not kicking in

[dnh]

HI,

I recently had to replace the timer (intermatic T104) in the pump control box, which is an Abco FP-100. Everything has been working fine for over a month, but I noticed the pump did not kick on when the temperatures dropped below freezing. I checked all the connections and wiring in case I missed something when I replaced the timer, and everything looked good. I took the thermostat out of the housing and put it in the freezer, and it checked out fine with a meter. You could here the switch click on and off has the set point was changed.

Last night I set it at the max setting, about 48 degrees, but the pump did not kick on at all, even though the temperature was in the mid 30s this morning.

Today, I put a bag of ice on the sensor, the pump did kick on when I had it set at 44 deg, if you turn the dial down, it would kick off around 34, a 10 degree span. Also the relay had a slight buzzing or humming, but that might be normal for AC relays, I am not sure. So everything seems to be wired correctly and working, just the sensor is not turning on at night when it is colder

Since I live in Dallas, there aren't too many nights where the pump will need to run at night during the winter, but I will be travelling some in January and February and want to make sure everything will work.

I have the sensor set at 45 for tonight, it is supposed to get down to around 36.

Is it just not cold enough to trip the sensor? Or is the sensor defective?
Also, is it normal for the relay to make a little bit of humming or buzzing sound when it is on?

Thank you,
Don

 

[duraleigh]

Hard to say from your description (I think it's working OK) but you have no pool issues unless your temps get well into the twenties on successive nights.

 

[JoyfulNoise]

A/C relays can buzz for lots of reasons and it doesn't necessarily indicate a problem. Some A/C relays have an adjustable tension spring on the armature that allows you to control the spring force and, thus, the resonant frequency of the contactor; but not all A/C relays allow for that type of adjustment. It would be fairly obvious as it would look like an adjustment screw on the outside of the relay somewhere.

As for the freeze protection circuit, it sounds to me like the temperature probe might be a bit off but not that far. Next time, if you want to check the probe with an ice bag, the best way to do it is to make up a mixture of salt water and ice cubes. The salt water depresses the freezing point to a temperature lower than 32F so that when you add ice, you can get below freezing. A 1:3 weight ratio of salt:ice can yield a minimum cooling bath temperature of almost -4F. If you just use regular water, the mixture will usually top out a little bit above 32F. This is why you use an ice-rock salt bath to make ice cream

 

[borjis]

If you just use regular water, the mixture will usually top out a little bit above 32F. This is why you use an ice-rock salt bath to make ice cream

Fascinating.

 

[dnh]

Thanks all, pool was running this morning when the temperature was about 32. I had it set for around 38, so seems it is off a bit. Ill keep dialing it down so it only kicks on when the temperature is below 30. I may try the salt/ice idea.