ranco temp controller reading off by 10deg

[xinumaster]

I just pick up a ranco temp controller yesterday, but when I placed the probe in my tank it reads 88F while my ACpro reads 79F. I don't think my tank is at 88F cause it feels cold when I touched the water. The ranco looks very new it does not look like it has been used before. Does anyone have this same experienced?

 

[GreshamH]

Never on a new unit. IIRC you can calibrate them but it's been many many years since I had to cross that path. Get yourself a true mercury thermometer (hard to find but they are still out there) and check it. Find what it's running at and just adjust to that. I doubt it's having any other errors besides that. Look for a break in the probe as well,

 

[xinumaster]

do I have to open the box to cal the unit?

 

[zepplock]

I was frying my tank for 2 month cause POS coralife digital thermometer was giving me 10 degree difference. I had 90 instead of 80.
Please keep a regular glass thermometer handy and use it for reference.

 

[xinumaster]

Where do you get a glass thermometer?

 

[GreshamH]

glass alone isn't what I would use. Get a glass with mercury. A glass one from a LFS is basically useless and highly undependable as the paper insert can move around.

 

[GreshamH]

www.mcmaster.com is a decent source. I forget where I get mine but they specialize in lab gear.

 

[sfsuphysics]

You can get alcohol based thermometers that have decent resolution as well, and I mean nice long ones too not the little finger length ones they sell in LFS

 

[Elite]

Perry, don't you have a fluke meter one? Anyway, if you find a glass one, LMK. I want to buy one too but haven't been able to find one.

 

[tonggao]

Perry, I am looking for one too but could not find one. Very interested in what you find.

 

[xinumaster]

[quote author=Elite link=topic=6888.msg89240#msg89240 date=1237256696]
Perry, don't you have a fluke meter one? Anyway, if you find a glass one, LMK. I want to buy one too but haven't been able to find one.
[/quote]

That wasn't mine, Phong. But I can borrow it again from work. ;D

I opened the box last night to see if it has a pot for calibrating the unit, but didn't find any. The temp reading do change if I put the probe on cold water or warm water.

 

[sfsuphysics]

Try sending the company (Ranco?) that makes the controller and email maybe? Could be something as simple as a tiny screw that you need to turn as well that maybe you didn't see.

 

[chicken]

Interesting topic. I just ordered a thermometer a few days ago and now this. I bought a high quality mercury thermometer at vmrlabshop.com, part # 61027-147. Problem is since it is mercury based there is a hazardous shipping fee tacked on to the order.

 

[sfsuphysics]

Its California too surprised there isn't an environmental clean up fee added to it as well!!

 

[chicken]

Just an FYI for those interested in buying a high quality mercury thermometer. I just got an email from vmrlabshop.com and they are having 15% off sale until April 3rd. Use promo code APRIL. There is a hazardous shipping fee though so you are best to try to find a few other folks to go in with you on an order as the fee is a flat rate (~$20 iirc)