Ranco, HERMS, and Mash Temp

[Buttwidget]

Looking for some thoughts and ideas here. I built out my HERMS system and on my second brew with it, I brewed an amazing Mexican Lager using flaked maize for the first time and a multi-step mash and a much shorter brew day than I thought. Its being carbonated right now, but already tastes freaking amazing. Hearing this, one would think that all is well in the land of beer and brewing over here, but I am dealing with an issue that I'd rather not deal with.

I'm using a Ranco controller (single stage) to measure and control the pump that recirculates the mash through the heat exchanger. What I 've found is that the Ranco Controller measures the temperature about 8 degrees too low (in other words, it wants to push my mash temp way too high). I've used three different calibrated thermometers to check against what the Ranco is telling me, and the thermometers agree while the Ranco is the outlier. Additionally, my other Ranco (which controls the burner under the HLT) measures the temperature identically to the first Ranco.

When brewing the Mexican Lager I programmed all of my temps 8 degrees lower than target and based upon my analog thermometers I hit my temps throughout the mash schedule.

I've google searched hoping to find a way to calibrate the Ranco, but its specifically stated that they cannot be calibrated. Do I have to live with this and continue to set my temps low, or is there something I can do to get these controllers properly calibrated?

The other thing that has me thinking is regarding the quality of the Ranco controllers as a whole. I'm using them to control both of my fermentation freezers and while I turn out beer that I generally love, I'm getting concerned that the data I am collecting is garbage because the controllers aren't properly reporting/controlling the temp.

Anyone experience this? Any thoughts on how to fix the issue, or do I have to live with it?

~widget

[Ozwald]

I don't use a controller at all on my HERMS. But I do see that problem in other areas. I have a thermometer (those big brew-dials) where the wort leaves the mashtun & where it comes back in. When I was getting used to it (and I still do occasionally) I'd bury the probe of my digi in the middle of the mash. Over time I noticed a pattern & am able to figure out what the actual mash temp is at by comparing the in/out temps. Same thing happens when I print out a recipe. Every system is a little different & I know if brewing software tells me to strike at a certain temp to achieve correct mash temp, I need to adjust that by 2 degrees for my system. I don't have a problem 'living with it', but I feel that consistency is the most important thing. If you do it the same way every single time & you're exactly 8 degrees off every single time, it's just as predictable as if the numbers didn't need adjustment. Sorry I can't provide input on if you can or can't calibrate it. It is possible that if you make some minor tweaks to your system that number could change.

[Buttwidget]

I don't like being off by 8, its just too much. Especially when I start thinking about my fermentation freezers. If it was 1 or 2 I'd feel a hell of a lot better.

~widget

[Ozwald]

What's the difference between mentally adjusting by 8 or 2, as long as it's consistent. Unless you're Justin & are bound to screw up the math.

[skerrydude]

... I'd bury the probe of my digi in the middle...

Depends on what surrounds the middle...

[EL TIZZO]

where are you putting the probe of the ranco?

[Buttwidget]

I have a thermowell with a depth of 3 inches into the MT (converted Sanke keg) which is about 1/2 or 1/3 from the top of the grain bed depending on the amount of grain I use. Interestingly, I also have a brewmometer whose probe is about 4-6 inches from the thermowell. The brewmometer agrees with two other thermometers I use, the Ranco doesn't agree with any of them.

As to the earlier question regarding just accounting for the 8 degrees, I certainly can (and have, so far) but after spending the money to build out the sculpture, I don't want to have something that "isn't right" nor do I want "just another thing" to think about while brewing. I'm trying to shorten and simplify my brew days.

~widget

[baltobrewer]

Just my .02, but I don't have a probe in the MT at all. I use a PID (Ranco would work just as well) to keep the temp of the HLT at about 6 degrees above my desired MT setpoint. Then I recirc constantly, and the HERMS coil (I use a CFC as my HERMS) keeps my mash temp steady. Sucks for doing step mashes, so it's probably good that I don't do step mashes, but it works like a champ for single infusion. I can raise temps in the mash by about 1 degree every 3 or 4 minutes...