Thought I would try a thermostatic return valve on my system for this season. I installed the new Caleffi 281 valve with the built in Wilo Star 16 pump. I was concerned about adequate flow. I installed flowsetter valves to monitor the gpm flow rates.
On speed 2 I get 11 gpm, speed 3 14 gpm. Piping between the boiler and buffer is short, a handfull of fittings and the Quicksetter is in the circuit, I calculate maybe 4 ft. hd. pressure drop. The valve is listed at a conservative 10 gpm flow.
Actual performance matches the Wilo curve closely.
I think the key is a big port, low pressure drop thermostatic valve. Smaller port valves chew up more of the pump output and flow drops off. The 281 Thermoblock should handle 100- 120,000 btu/ hr flow rates.
hr
On speed 2 I get 11 gpm, speed 3 14 gpm. Piping between the boiler and buffer is short, a handfull of fittings and the Quicksetter is in the circuit, I calculate maybe 4 ft. hd. pressure drop. The valve is listed at a conservative 10 gpm flow.
Actual performance matches the Wilo curve closely.
I think the key is a big port, low pressure drop thermostatic valve. Smaller port valves chew up more of the pump output and flow drops off. The 281 Thermoblock should handle 100- 120,000 btu/ hr flow rates.
hr
