Ranco Controller Problem?

[klasiksb]

Has anyone had issues with there Ranco controller not reading the correct temp.?

I will have to verify my temp. with a glass floating thermometer, but i'm thinking my Ranco has been giving me a reading quite a bit higher than actual temperature.

My 'little time & temp'' thermometer is reading 72.5 while my Ranco reads 78. I had the LT&T running in a smaller tank and it was giving me a reading of 78.5 and the water felt much warmer than the tank(s) with the Ranco controlling them. The Ranco has a set point of 78 degrees, 77 and the heaters come on, 79 and the fans come on.

I then took a small cup of water and put 3 ice cubes in there and put the LT&T probe in and let it sit till the temp. settled down and it did so at 33 degrees. I put the Ranco probe in the same glass of water and it settled out at 39 degrees. :confused:

I've never had weird reading on the Ranco which would lead me to belive the probe is bad, but I suppose that's a possibility. The unit is probably about 1.5 years old.

[DarG]

Hmmmm ... do you know that the Ranco temp probe is NOT supposed to be submerged in water? I know alot of people do it and not many problems are reported but the manufacturer states that water will seep in (through the cord seal) and ruin the sensor. I wonder if your's suffered that fate.

I have one controller in which I have placed the probe in a test tube and siliconed the cord into the open end of the tube to form a seal. You may need a new probe and to waterproof it next time.

[klasiksb]

At the time I bought it, there was no mention of them not being waterproof and haven't heard anything about it until a recent thread.

Do you know what is involved in putting a new temp. probe on?

[DarG]

I understand. I didnt know either until recently. Mine was always run in the dry temp. well in the chiller until recently. For about a week i ran a second probe in the tank until I found out about them not being guaranteed waterproof. Thats when i sealed it in a test tube.

Anyway ... Ranco recommends NOT desoldering and resoldering the cable to the board inside the controller. You can just cut the old wire and wire the new wired to the old wire. preferably it would be soldered and heat shrunk. personally, I would solder it directly to the board inside the controller but Im good at that kinda stuff. So, to be safe, just cut the old probe off and wire the new cored to the old. it's only 2 wires I believe.

[fatboyjoe]

This is what I used to waterproof my probe. http://www.rancoetc.com/thermal-well-aquariums-clear-heat-shrink-tubing-p-150.html

[reefergeorge]

It could be waterproof. Mine came with a chiller, and has a water tight titanium tube on the sensor.

[klasiksb]

I checked the temps today against a digital thermometer that is used for liquids. It matched up to what the ranco is reading and my LT&T was about 6 degrees low.

[pjf]

You may want to purchase a non-toxic liquid-in-glass thermometer. Electronic measurement tools tend to drift, so I use a glass thermometer to calibrate my Medusa controller and Eheim Jager heater once or twice a year. I have a $40 Miller & Weber “PerformaTherm” (http://www.hmalabsupply.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=271&category_id=c4010d0af4879b637fb5a209933a4e58&option=com_phpshop&Itemid=1) but others have reported good results with a $16 Tropic Marin (http://www.aquariumguys.com/thermometer1.html). Both thermometers have practical temperature ranges from the 60s to the 80s.