I have push pull pumps on two buildings that are piped with primary/secondary, what I am looking for is a controller that only looks at temperature difference,[between push & pull] the temperature would need to adjustable maybe 2 -20 degree range or something like that. What I want to do is cycle one pump off when the system is not loaded, then when it senses the temperature difference of the cycle on load, that the other pump turns on. every thing I have looked at has a set point also, [solar stuff]can't use that because of large swings in operating temps.
Temperature Differential Controller -needed
- Thread starter bigburner
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
I think Tekmar makes a couple of controllers that might solve your problem. I seem to remember 156 or 157 as a model number, but I might be thinking of something else. I don't have any, so I hope someone who actually knows something will chime in with specifics.
There are more expensive solutions, of course.....
There are more expensive solutions, of course.....
The Azel DST 932 differential control lets you vary a lot of the parameters- perhaps the range for the differential might be wide enough for your use?
If you want to run the pumps on a differential then a solar controller is what you want. All have adjustable on and off. Typically they are set with a 12 on and 8 off, they are adjustable down to 1 degree. So when sensor 1 is 12 degrees warmer than sensor 2, the relay is activated.
When sensor 2 is within 8 degrees of sensor 1 the relay is opened. Many of the controllers offer variable speed function on the relay so as the delta t gets wider the pump speed increases. As the tank, or load warm the speed decreases. This saves energy and helps limit pump short cycling.
You can buy controllers with just one output or up to 6 or more. Most have multiple differential functions and the ability to use an output as a setpoint (thermostat) function.
For a basic one output I like the Caleffi i-solar 2. Two outputs use the i-solar plus. For four outputs the i-solar BX.
I use the i-solar plus to fire the boiler pump with the thermostat function, on at 150F off at 140F. The sensor is located on the pipe at the top of the boiler.
The second output runs the circ from the primary loop to the buffer tank on a differential function and variable speed.
Most of the new digital solar controllers have a 120V output with a 1 amp relay. Larger loads would require an isolation relay.
www.caleffi.com will show you a dealer in your area, or online at www.houseneeds.com
hr (Caleffi employee)
hr
When sensor 2 is within 8 degrees of sensor 1 the relay is opened. Many of the controllers offer variable speed function on the relay so as the delta t gets wider the pump speed increases. As the tank, or load warm the speed decreases. This saves energy and helps limit pump short cycling.
You can buy controllers with just one output or up to 6 or more. Most have multiple differential functions and the ability to use an output as a setpoint (thermostat) function.
For a basic one output I like the Caleffi i-solar 2. Two outputs use the i-solar plus. For four outputs the i-solar BX.
I use the i-solar plus to fire the boiler pump with the thermostat function, on at 150F off at 140F. The sensor is located on the pipe at the top of the boiler.
The second output runs the circ from the primary loop to the buffer tank on a differential function and variable speed.
Most of the new digital solar controllers have a 120V output with a 1 amp relay. Larger loads would require an isolation relay.
www.caleffi.com will show you a dealer in your area, or online at www.houseneeds.com
hr (Caleffi employee)
hr
Gold line GL 30 differential controller might work. It is adjustable to 25 degree differential. I got mine though a pool supply company, but it is a solar controller.
- Status
