Cellar thermostat question

I have a WhisperKool 8000 split system. The thermostat temperature pickup is on a long cable, with the temp probe designed to be inserted into a wine bottle full of liquid. It has a rubber stopper. Cellar is double deep single bottle racking. With the thermostat set at 56, cellar air temp ranges from 59 to 52, with long run times (8+ hrs) and off times (24+ hrs). System comes on when water bottle hits 57 and goes off at 56 as indicated on the control.
Would it be better to pull the probe and monitor air temp or continue to monitor liquid temp?

The fluctuation in your air temperature is surprising with a bottle probe. I’d expect less fluctuation. That is the benefit of a bottle probe. It may be on longer, but it takes warming the liquid in the bottle (I.e., all your bottles if the probe is similarly located) to engage the system. Is the probe in wine or water? Don’t know if it really matters but put it in wine ( cheapest is fine) as it has greater density.

Do you keep the door open for long periods of time like when lurking, storing, organizing, etc? My cellar with a bottle probe is set at 54. It goes as low as 52 and never higher than 56 unless I leave the door open while organizing or moving in shipments.

The bottle is in the middle of the racking vertically and I’m using water. I keep the door closed except to enter and exit. I’m measuring the air temp with a good thermometer at the same height as the bottle. I’ll try a change to wine instead of water. Oh, and the cellar is at capacity so there is a lot of liquid to cool.
I think I remember an HVAC guy tell me that long run times are better for a unit than off and on, but it gets chilly working in there when it’s at 52.

Keep the probe in liquid. You’ll have less cycling of the cooling unit since the liquid temp changes much more slowly than the air temp. And it’s the temp of the liquid in the bottles that matters. I doubt that water vs wine for probe placement will make any difference as the difference in their insulating properties is probably insignificant.

Thanks Bruce and David. Now I have to get the humidity up. The bucket and towel trick took it from 40% to 45%. I’ll do a portable mist unit until I find something better.

Put the bottle with the probe in the warm part of the unit (I presume the top).

-Al

I would pull the probe and monitor air temperature. Air changes temperature more quickly and is a leading indicator for liquid temperature. Liquid temperature changes more slowly, and it will take longer for it to “react” to cooling (or no cooling).

If the cellar air temperature stays between 56 and 57 (or even 55 and 58) the liquid temperature will almost certainly fluctuate less than it does now - probably only a couple tenths of a degree.

I would pull the probe and monitor air temperature. Air changes temperature more quickly and is a leading indicator for liquid temperature. Liquid temperature changes more slowly, and it will take longer for it to “react” to cooling (or no cooling).

If the cellar air temperature stays between 56 and 57 (or even 55 and 58) the liquid temperature will almost certainly fluctuate less than it does now - probably only a couple tenths of a degree.

/That seems logical. I will try it and see how rapidly the unit cycles.

Phil, it’s likely your cooling unit needs to know if the thermostat is measuring liquid or air temperature as the response times will be very different. If you have access to the owner’s manual you might want to check on how to do this.

I agree that measuring air temp is best. If something goes wrong with the cooling unit, the air temp will tell you of the problem much sooner than the liquid temp.

+1
Also longer run times will dehumidify more, shorter run times (sensor in the air) less.
If your unit cycles on and off too often you may be able to set a larger deadband, mine (not a whisperkool) can be set separately and I keep it at 3 degrees.
If your RH is that low and you have had your unit for a while you could be a little low on freon or your airflow across the indoor coil is low making the supply temp off the coil lower than design.

Thanks guys. I called whisperKool and changed a setting allowing for higher humidity. I don’t know what the setting does, but it was on 0 and goes 0-15, so I moved it to 12. I still have the temp probe in the bottle of water and will wait till this weekend to see what change there is. Airflow should be good as the air handler is 5 ft from the return grate and is a straight shot. I’ll pull the sensor this weekend to see what impact that has. I’ll get my hvac guy to check the freon this spring as well. It was OK last summer when he checked it. I’ll report back.

If your cooling unit runs continuously for eight hours, I find it very surprising that air temp only falls by 7°F. Maybe you could try putting your air thermometer close to the cooling unit and see if the air temp variance increases.

Better to check now when it is cool, it is very common to undercharge in warm weather. The unit needs more refrigerant in winter than summer.
You may be able to confirm the charge level yourself, there should be a sight glass mounted by the condensing unit on the liquid line (smaller copper line) remove the plastic cover (usually white/blue, 1" in diameter) and with the unit running (you must wait a few minutes for it to settle) there should be no bubbles if properly charged.

Get yourself an inexpensive dial thermometer (like the ones Chefs carry in their pocket) and measure both the return and supply temps and report back.

I prefer to measure air temp than liquid because it will react much sooner, the unit will however cycle more often.

Ok. Have to travel for a couple of days but will be back by the weekend. Thanks for the info.

consider using a larger format magnum will take longer to fluctuate and probably turn on less, BUT
It might stay on longer when it comes out of temperature as well.

The Whisperkool units are designed to run off of liquid temperature, having the probe reading air temperature will cause the unit to start and stop too often which is damaging to the compressor. A unit designed to read air temperature has a broader differential much like a air conditioner and refrigerator, so they do not react as quickly.

Thanks Cindi. I’ll leave the probe inn the water bottle. making the change in the “fon” setting did not increase the humidity after 2+ days. 5 gallon bucket and wet towel set-up is still there. Next is to get HVAC guy to come check refrigerant level.