What are you using to measure the 2 hours? Separate time delay relay? Or does the Ranco have a timing function.
Also where did you put the Ranco sensor to measure the temp of the pellet boiler?
Staging A Pellet Boiler With An Oil Boiler With An Ecobee SmartSi Thermostat
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Also where did you put the Ranco sensor to measure the temp of the pellet boiler?
The Ecobee thermostat
It is a 2 stage Ranco and I wasn't using the second stage. The first stage is to prevent the pellet boiler's circ pump from starting before 130F. The sensor is in the same thermowell as the Biowin's sensors.
Every day that goes by I have another strategy. I'm not sure I'll stick with the above, but it should be flexible enough to make the changes easily.
My latest strategy is not to use time, a deltaT of 3, and to start with an outside oil boiler cut in of 10F, and a setback of 2 degrees for each transition in cold weather. Setbacks could be varied with abandon in not so cold weather, since the staging won't be on because of outside temperature. The trick is getting the outside temp setting right, and seeing how setback return works. Probably will get a feel for that over the course of the winter.
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Just to followup, I've decided to abandon this effort, and set the boiler back to 15 kW.
Reasons include:
-Ecobee thermostat stage 2 didn't behave as expected; stopped calling stage 2 when above setpoint (eg, 68) + differential (.5) - staging differential (3) = 65.5. I was under the impression it behaved such that it would reach 68 in the example
-Using thermostat required locking out oil when above a certain outside temperature - difficult to dial in
-Uncertain of results of both boilers running in all scenarios
-Lower power meant longer recovery, if at all, from setback in cold temps; I think I like using setbacks
-At 15 kW, it takes about 2 hours to charge up the tank, which isn't that short
I'm going to fool around with buffer tank settings some to get longer runs
Reasons include:
-Ecobee thermostat stage 2 didn't behave as expected; stopped calling stage 2 when above setpoint (eg, 68) + differential (.5) - staging differential (3) = 65.5. I was under the impression it behaved such that it would reach 68 in the example
-Using thermostat required locking out oil when above a certain outside temperature - difficult to dial in
-Uncertain of results of both boilers running in all scenarios
-Lower power meant longer recovery, if at all, from setback in cold temps; I think I like using setbacks
-At 15 kW, it takes about 2 hours to charge up the tank, which isn't that short
I'm going to fool around with buffer tank settings some to get longer runs
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