Question about what to do with my vinotemp.

[{tpc}]

Ok so a couple years back I got a vinotemp humidor for Christmas. I've had my ups and downs with it, and despite my feelings of just wanting to get rid of it for something better, it was a gift and I have difficulty parting with gifts. I've fixed it once by my own cost, and once by vinotemp sending me all new power supply's, control boards and peltier unit. The same thing I encountered before is happening again however and the unit is getting too cold.

What I mean is that after setting to 66f it starts to creep lower and lower. At first it seems fine, then dips to 65. Then a day later it will be 63. Then maybe back to 65 the day after that, but eventually I will come home and it will be at 58. I actually like anything between 66-70.

Last night I reversed the hot side heat sink fan in hopes that blowing air away from the heat sink instead of directly on it would let the hot side get hotter which should lead to the cold side getting warmer. Still hours later, it is at 63f. I'm thinking that removing the fan all together would be a bad thing. So I just unplugged the unit. This leads to a temp of 72f inside, which isn't terrible, and makes sense due to the home thermostat set to 72-73 at all times.

So I am thinking of disconnecting the power to the peltier, but leave the internal fan running to circulate air. I don't think circulating air alone will bring the temp down to sub 70, but its better than not circulating air. I've also thought of adding some kind of voltage divider with a potentiometer of sorts to manually adjust the voltage into the pelt. I am just unsure of how this will affect the feedback circuit already in place, nor exactly how to wire everything up.

So what to do? It's a small setup, 8 bottle type, so I don't want to spend a million dollars on it, but I would like to correct it. I could contact vino again and get new parts but frankly I figure it will only last another year that way anyways. How do you all handle your thermoelectrics? Should I just stop worrying about the temp being 72 and leave it at that? Anything relatively inexpensive I can try?

Right now i don't have any cc to worry about hatching beetles or anything, but it doesn't mean it will always be that way. I guess I really just want what should be a set and forget type unit to be just that but this one isn't at this point.

 

[modo22]

I am not going to thread jack, but I am having a very similar problem. 
 
My first question would be, do you have a hygrometer inside as well?  or are you just reading the temp on the unit?  if you do have a hygro, what are your humidity levels at as it fluctuates with temp?

 

[{tpc}]

I do have 2 hygrometers inside the unit & both read the same as outside the unit. I haven't been as concerned with tracking the humidity as I realize it will change with the temp. I have also had the same temp issue with no humidifier at all in the box, no sticks, just the two drawers.

I may end up measuring the current and then put an appropriate sized current limiting resister in it so that regardless the peltier will never receive enough current to get that cold. But it will always be running instead of cycling so still not ideal....though even when working correctly I don't think it ever really "turns off" so to speak.

 

[modo22]

well at least your hygro inside is reading the same temp of the unit.  Mine is no doing that, but it will be in its own thread here soon.
 
Does yours have a drip pan on the back for moisture?  Is it sucking all your humidity out? There for making it colder?  Might be a dumb question, but just throwing that out there.

 

[{tpc}]

Well modo, here are some observations, at least with my unit.  I have no drip pan nor have I ever experienced any real condensation inside the unit.  The unit came completely sealed in that respect.  The humidity seems fine, but does change with the temp as one would expect it.
 
So I tried disabling the hot side fine (the outer fan on the heat sink).  It didn't seem to help make the unit inside any warmer, and got hot enough after a short while by itself that I felt it was the wrong thing to do and would probably hurt the unit.  So I reconnected it and then tried removing the input to the peltier cooler, but left all the fans running.  The temp control on the front of the unit just slowed the fans down or sped them up, however the temp appeared to climb up higher than without being plugged it, probably some heat generated by the fan on the inside.
 
So I am back to unplugging it for now.  The next step is the current limiting resistor.  On the low end of the spectrum when the unit is trying to cool the least, it is only drawing about 1.5 amps of current.  On the high end about 4.5 amps.  I may be able to get away with a pot of some sort in there but it will sketchy at best so I will probably opt for a fixed resistor. Going to take some trial and error though.

 

[{tpc}]

Ok so just an update. I tried various resistors in parallel with the feed to the peltier cooler. This had little to no effect so don't bother with it.

What did work (though it has only been one day) was putting resistance in series with the peltier. I don't think it matters which side you try (positive or negative) but I put mine on the negative wire. I settled on three 40 ohm 10 watt resistors wired in parallel with each other but in series with the peltier.

The effect on cooling was a major slow down in reaching set point and so far less overshoot. What used to take 5 minutes now takes about 30. I still think there is something wrong with the control board (located inside the front door of the unit) but if this keeps me at 66F, then I'm happy.

My thought or hope is that the issue with the control board is that it is taking too long to react to the unit reaching set point and thereby overshooting a few degrees before finally turning off the output to the peltier. If this is the case then by slowing down the unit by use of the resistor it should allow enough time for the unit to react and turn off without major overshoot. But we shall see.

 

[wkoti]

Have you ever thought about a temperature controller with a probe thermometer? Plug your unit into the controller and the controller into the wall. Place the probe in the fridge, set it at your desired temperature and once your fridge raises above your programmed temperature it turn on the unit. The unit will run until it's at the proper temperature and then it will turn it off again.

 

[{tpc}]

Yes I thought about it but it seems to costly for something so small. It's a shame that a brand like vinotemp doesn't have the quality. Maybe they never did, but these electronics they are using out of china are pure junk. I'm thinking that their regular units (not thermoelectric) are better.

Eventually this will be replaced with something much nicer, so for now its my little project that shouldn't be a project lol. I'm sure if I emailed the guys at vino they would probably send me out a third set of electronics but I doubt they would fair any better than the first two.