View Full Version : Snow melt control
02-24-2010, 08:49 AM
Does anyone have recommendations for snow melt control? We curently have 3 separate systems. Two of them have a temp/moisture sensor in the concrete. They have a heater in them and when the temp is below 35 deg. the snow will melt on the sensor and bring the system on. When the sensor dries it shuts off the system. They have been a constant problem and I was just quoted $1000.00 just for the sensor. The third system has a cup mounted outside. When it fills with snow it turns the unit on. It seems to work better but occasionaly I have to fill the cup by hand to start the system if the wind blows the snow over rather than in the cup. Any sugestions?
02-24-2010, 10:19 AM
Does your system have a web enabled front end?
You might want to use the NOAA's weather data in your control logic and turn the sensors on anytime it's supposed to be snowing.
02-24-2010, 11:37 AM
Never had to worry about that around here....
What about using OAT & OAH sensors to determine if it is snowing?
Is this what you currently have? http://www.networketi.com/19036.htm
02-24-2010, 01:00 PM
Sounds like the Tekmar 090 snowmelt sensor.
We always had good luck with them pending they are installed properly.
02-24-2010, 06:00 PM
Like CerealKiller says,
this is what we have. No problems here.
02-24-2010, 08:10 PM
Two of the three look like the tekmar and the other one I'm sure works on the same principle as the cit-1 snow sensor. I'm not sure of the brand. Johnson Controls suplied and installed them during construction. I'll have to take a closer look at the cit unit and see if any other suggestions come in.
The ETI sensor is what we use to prove snow. With the slab temp. & OAT, we initiate Idle mode at 32-35 deg. OAT; with a slab StPt of 38 deg. When we get a closed Di from the ETI snow sensor, we initiate Melt mode and raise the slab StPt to 45 deg. We run the SnowMelt HX valve to control H2O temp at 120-130 deg. It sounds like you might have to relocate your ETI sensor to a less windy area.
02-25-2010, 03:54 PM
does the ETI sensor provide a contact closure or do I need an interface board?
It has a switch. It closes if OAT is low enough and if there is snow in the cup. It's a 4 wire device, 24 vac in with dry contacts for status. No interface board needed. We hook it directly to our NDIO's UI.
02-25-2010, 05:02 PM
CIT-1 datasheet shows it as 3 wire device going to some sort of interface board.
I am looking for what you have.
I sent the cut sheet for the one we use to the email addy you have on file here. It's the ETI LCD-3H.
02-26-2010, 12:17 AM
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