PSA: Calibrate Controller & Probe

[day_trippr]

I recently picked up an MH1210 temperature controller for small $$ (similar appearance to the STC-1K but single stage and reads in Fahrenheit) and had it running in my office for the last couple of days before I realized it was clearly reading low. Surrounded the unit's NTC probe with the tip of my Thermapen and two other digital thermometer probes, all four within a quarter inch of each other, and after giving them all plenty of time to settle down, the three agreed that the fourth was 5.4 degrees low.

I'm going to be installing this in the front of my new keezer lid, and those 5.4 degrees would likely have led to six frozen kegs of beer.

Same old advise writ once more: never assume, always check. In this case it was pretty much dumb luck that I checked. Fortunately the controller provides +/- 10.0°F offset range for the probe channel...

Cheers!

 

[pondochris]

Wouldn't a lower reading result in a higher temp rather than freezing the kegs?

 

[big_len]

Don't just assume its 5° across all temperatures, repeat your experiment with iced water and boiling water if you can!

 

[Cottonmouth]

I have an MH1210 controlling my ferm chamber that was reading 6.3 degrees too low before adjustment.

 

[brewguyver]

Had the same problem with my Johnson analog - hd two that seemed to be off by 10 degrees after a while - I've since moved to digital with a backup thermometer.

 

[day_trippr]

Wouldn't a lower reading result in a higher temp rather than freezing the kegs?

Well, yes, of course. The point is the probe/controller were way the heck out of calibration. In this case it would have caused inexplicably warm beer, but one could imagine the error could go the other way...

Cheers!

 

[Lost_Arkitekt]

I hate to be reopening this thread almost a year later, but I have an MH1210 temp controller, and everything was great except today I look over and the thing is reading 59.1 up to 63.1 (I have it set for a 4 degree increment). However, the beer is the right temp and the controller is set correctly (when I check it), but it cycles through the 4 degrees from the previous mentioned temperatures. Any ideas?

Thanks.

 

[day_trippr]

How long had the controller been behaving itself before things went pear shaped? And where is the probe actually located? Is it submerged directly in liquid?

I'd keep an eye on the actual beer temperature over the next day because it seems unlikely that the controller would hold the beer at the desired temperature with the display ranging beyond the differential setting. I suppose that could be an actual failure mode but it doesn't seem probable...

Cheers!

 

[Lost_Arkitekt]

Temp controller has worked for a good 6 months now. It was working flawlessly in liquid and then stuck to the size of a keg. Too hard to get it stuck to a keg, so I left it in bottled water. Not sure when it went T.U., but now it isn't working right at all. In a submerged glass of ice water it keeps reading from 68.9 to 70.3*F. The freezer is running. The water I had it in started icing up. I have to turn it off or reset the temp controller and order a new one.

 

[Lost_Arkitekt]

Controller functions...just looks like it reads 38*F higher. I reset it for a higher temp. Started working fine.

 

[day_trippr]

So with all that, do you now suspect the probe is on its way out?

fwiw, they're dirt cheap NTC 10K B3435 probes. When I got my mh1210 I picked up a pair of probes off ebay for under $5 delivered just to have on hand...

Cheers!

 

[Lost_Arkitekt]

Would a different K type thermocouple work?

 

[day_trippr]

I suspect the odds of the unit accepting anything other than the probe type it was shipped with are quite small...

Cheers!