Help setting up controller for 3 way valve

[sdrobertson]

I have my system up and running but I'm having difficulty setting up my 3 way valve control.

Equipment on hand:
Valve - Honeywell Motorized Valve Linkage (0 to 10 volts)
Controller - Siemens RWD62U
Sensor - Siemens Immersion Temp Sensor Nickel 1000Ohm

I purchased the software to supposedly program the controller but I thought I could set it up from my desktop and take it to the boiler room but the controller does not remember what I programmed so I have to take the desktop to the boiler room.

What I want is the following:

No Power - Valve Closed(heated water straight to tanks for boiler protection in case of power outage).
Under 125 degrees Valve Open(10 volts) so water circulates back to boiler inlet.
Over 165 degrees Valve Closed(0 volts) so water goes to storage tanks.
In between 125 and 165 voltage varies to modulate valve so I don't get a rush of cold water to boiler from bottom of tanks.

I guess my question is has anyone had any experience using this style of controller in this application and how did you set up the parameters. Or is there a better way to change the voltage to the valve depending on water temp to modulate like I want it to?

 

[steam man]

I am not familiar with the siemens controller you have but it sounds strange that it loses its program when the power is off. Either there is a battery needed for it or it should burn the program into an EPROM. What would you do if the power goes out? What is the output of the controller? If it is a 4-20ma out I think you'll need a 500 ohm precision resistor across the load to get 0-10 volts for the valve actuator. I'll have to check that. I use signal conditioners to change signals. If the controller has a setpoint function block you can use that to regulate the valve for a specific set point.

Mike

There's nothing time and money can't solve.................

 

[sdrobertson]

OK - had a little time today to work on this controller. I'm figuring out the programming, but at 10 volts - the motorized valve only opens 1/2 way. So this leads me to believe that it will take 24 volts to open it all the way(which happens when I jump it at the motor). What is the easiest way to "double" the voltage leaving the controller and going to the valve? I can figure out the mechanics but the electronics are not my strong suit. Thank you for any help.

 

[steam man]

We're going to have to know what your actuator requires for a signal. What model is it? I'll have to look up specifics for the controller. If the valve is 24 vac that may be a problem. Did you put 10 vac or dc to the valve?

Mike

 

[steam man]

I just looked at the controller specs: 0-10 vdc out. Now-the model valve actuator?

Mike

 

[sdrobertson]

I just looked at the controller specs: 0-10 vdc out. Now-the model valve actuator?

Mike

Model is M7284A1012. Now I also see that this is not spring loaded so this means that if I loose power, this unit will not return to closed by itself will it? I was planning on using this for overboil protection by dumping heat into tanks during power outage.

Thanks again for helping
Shannon Robertson

 

[steam man]

The actuator motor is 24 vac but may have use line voltage with a transformer. The signal is 2-10 vdc or 4-20ma. Since it isn't spring return it is just going to stay right where it is on power loss. The signal you can deal with. The application is another issue. I am not sure how you are going to mount that actuator to a valve but you could use a UPS backup to provide power to the setup. It probably only needs to be a small one. I am no fan of complicated safety control schemes but it could work fine. I may have a signal converter laying around. Let me check it out.

Mike