I am looking for a differential temperature controller, (preferably with an adjustable differential). I'm trying to help some one solve a problem with the controls for their wood fired boiler system.
This person has a wood fired boiler and when the boiler is firing a pump runs to transfer heat from the boiler to the storage tank. This pump is currently activated by an A419 temperature controller with a sensor located at the boiler. So the owner fires up the boiler and then sets the setpoint to about 15 F above the storage tank temperature. Once the fire has heated the boiler to this temperature the pump starts to pump water from the tank through the boiler. 15 degrees seems to be a good temperature because it means the fire is hot enough to keep the pump from cycling off when the colder tank water gets pumped into the boiler and cool enough that it won't shock the boiler when the pump kicks on.
Does anyone see the problem yet? The pump should stop when the boiler stops firing (burns out) but it continues to run because the water in the tank has been heated and is being pumped through the boiler where the temperature is set. So the owner either has to manually raise the temperature setpoint once the fire is out to shut off the pump. Or it just keeps pumping until its cooled back down to its initial temperature.
So the differential temperature controller would have a sensor at the boiler and a sensor at the tank and would only enable the pump when the leaving boiler temperature was 15 F warmer than the storage tank. My problem is that I cannot find a sensor that will do this. Does anyone know of an affordable, off the shelf solution?
This person has a wood fired boiler and when the boiler is firing a pump runs to transfer heat from the boiler to the storage tank. This pump is currently activated by an A419 temperature controller with a sensor located at the boiler. So the owner fires up the boiler and then sets the setpoint to about 15 F above the storage tank temperature. Once the fire has heated the boiler to this temperature the pump starts to pump water from the tank through the boiler. 15 degrees seems to be a good temperature because it means the fire is hot enough to keep the pump from cycling off when the colder tank water gets pumped into the boiler and cool enough that it won't shock the boiler when the pump kicks on.
Does anyone see the problem yet? The pump should stop when the boiler stops firing (burns out) but it continues to run because the water in the tank has been heated and is being pumped through the boiler where the temperature is set. So the owner either has to manually raise the temperature setpoint once the fire is out to shut off the pump. Or it just keeps pumping until its cooled back down to its initial temperature.
So the differential temperature controller would have a sensor at the boiler and a sensor at the tank and would only enable the pump when the leaving boiler temperature was 15 F warmer than the storage tank. My problem is that I cannot find a sensor that will do this. Does anyone know of an affordable, off the shelf solution?
