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Posted by HeatPro on December 05, 2005 at 19:28:38:
In Reply to: results of temperature experiment and Phase III posted by Dave on December 05, 2005 at 18:29:57:
: With boiler temp set to 180, it took about 5 minutes for water temp in boiler outlet to come up to 140 degrees from a cold start.
: It took a total of 17 1/2 minutes for Phase III to reach 130 degrees.
: With the boiler temp set at 150, it again took about 5 minutes for outlet temp to come up to 140 degrees from cold start and a total of 22 1/2 minutes for the Phase III to reach 130.
: Do these numbers seem reasonable? I would assume that 150 degree water being used to heat DHW from the buffer tank into the Phase III would be a worst case scenario, as the buffer's aquastat would be set to fire the boiler at 150.
+++ Not too shabby. This would be what a separate high-input gas water heater could do. 5 minutes isn't a significant time difference.
: In the first situation with the boiler temp set to 180, the boiler ran the entire 17 1/2 minutes, but in the situation where the boiler temp was set to 150, the boiler cycled on and off 3 times as it was able to reach 150 and shut off.
: Of course, if I had the second stage of the burner turned on, so all 300K btu's were being put out, both times probably would have been faster.
+++ But you might have heard considerable sizzling and banging. There is no need to get the heat higher while the 140,000 btuh input already exceeds the Phase III exchanger rating. All that input for 50,000 btuh worth of hot water is senseless.