I am planning a power loss dump zone using a 1 inch normally open zone valve. Power keeps the valve closed. I recieved the valve via ups the other day. I have notice the opening thru the valve is a very small 3/8 ths of and inch. I know other folks do this. My one inch loop can dissapate 12,000 btu's. How Can this happen thru that small opening?? Any thoughts ? I know you can only deliver about 10,000 btu thru a 3/4 inch pipe, so will I only get 5,000 btu thru this valve?