Marcland auto draw off temperature calibration problem

[briansickler]

I bought a marcland auto draw off at Verona last year. It worked great until late in the season. The temp on the display didn't match the actual temp in the pan. It was reading higher than the actual temp in the pan. So it was drawing not yet syrup. I had to set the draw off temp on the Marcland way hi to get it close to syrup. Anybody else had this happen? The probe may have been dropped during a side change...maybe the probe is no good?

Brian

[Brad W Wi]

I clean my probe off every day or two. It builds up with scale or syrup. That would effect the reading.

[802maple]

I clean my probe off every day or two. It builds up with scale or syrup. That would effect the reading.

As will barometric pressure.

[briansickler]

I clean my probe off every day or two. It builds up with scale or syrup. That would effect the reading.

I clean the probe every time I switch sides...1-4 times a night. So I don't think that's the problem. Thanks.

Brian

[briansickler]

As will barometric pressure.

When I compare the reading on the draw off display with an actual reading from a thermometer in the pan the draw off is 2-3 degrees higher. So it's actually drawing off at too low of a temp. I can make it work by setting the draw off temp higher...say 221 on the display. I think when the probe was dropped it hit directly down on the tip of the probe and messed it up. I may have to order another probe?

Brian

[Shaun]

If this is a 100 OHM temp probe You can check it with an OHM meter it should read 100 OHMS of resistance at 32 dgrees F this is typical. If your temps are slightly different your wire connections may be causing more resistance.

[Dennis H.]

If you bought it new from Marcland why not give them a call?

Did you add any wire to the probe to reach the location of the controller?

I am eyeing a PID controller to make my owm drawoff and reading some info on them I have found that for some reason using copper wire or copper contectors can induce as much as 5 degree error. There was also a setting for input offset, I am taking that as a way to adjust the reading on the controller to reflect what the probe is really seeing.

Why not take some hot water out to the evap and stick the probe into the water and check it against a known good thermometer. It doesn't have to be boiling just hot.

[danno]

Brian - I'm assuming when you first began using the probe, it was reading the same temp as your pan thermo, and now it's not?

The marcland I bought at verona last year reads a couple degrees cooler than my pan thermo. On the pan thermo, I never got syrup until about 221. On the Marcland, closer to 219. I'm betting the marcland is more accurate than my pan thermo. Most important - both thermos are consistent, just not with each other. So, I know if I'm getting syrup at 219 on one and 221 on the other, it stays right around there all season. Point being, if the probe is off, but consistent, should work just fine.

[briansickler]

Brian - I'm assuming when you first began using the probe, it was reading the same temp as your pan thermo, and now it's not?

The marcland I bought at verona last year reads a couple degrees cooler than my pan thermo. On the pan thermo, I never got syrup until about 221. On the Marcland, closer to 219. I'm betting the marcland is more accurate than my pan thermo. Most important - both thermos are consistent, just not with each other. So, I know if I'm getting syrup at 219 on one and 221 on the other, it stays right around there all season. Point being, if the probe is off, but consistent, should work just fine.

That's right Danno it started out the same. So something has changed. Mine (after the change) was working just the opposite of yours. 221 on the Marcland...219 on pan thermo.

I emailed Bob @ Marcland about this. He said for me to call him and he he talk me through making the adjustment....very simple he said. "If you know how." very funny.... So I will call him tomorrow from the sugarhouse and see how to calibrate it. While I have him on the phone, I plan to order another valve and a switch to change sides without having to move the valve back and forth...(what a pain). I think that will promote more frequent flow changes to fight the niter monster. At the end of last season, I was changing sides every 2 hrs. I'll post the calibration procedure on here as soon as I get it from Bob.

Brian