SylvanLMP
quote:
Originally posted by Harold Kestenholz:
While maintaining pressure in the system high enough to keep air out of the system (4 pounds positive pressure at the highest point in the system) bleed the air from the air vents. There is a valve near the boiler to let water in and there are manual or automatic air vents in strategic high points in the system.For more information about hot water systems, go to the free lessons at:
http://www.hydronic.net
Hey Harold give this person a CRASH course in hydronics like the following.
Tell them to take the height of the HIGHEST radiator from the top of the boiler and use the constant . 434 to find the no flow static pressure.
Then knowing the combination PRV and automatic feeder is factory set at 12 PSI which will elevate the water to a height of approximately 28 feet they can then decide to increase this pressure with the set screw to 15 PSI which will now elevate this water to a height of 34.65 ft
Now figuring this is a two story building and figuring the height/static pressure is 25 ft 11 PSI (approx) static by looking at the altitude reading on the tri gauge we can now determine we need 4-5 PSI more t make it a pressure positive system. TO KEEP AIR OUT
So we simply take the static reading as per gauge cold reading (NOT HOT as this would throw off the reading due to expansion) of 25 ft times this by . 434 ADD another 11′ 6″ ft for the 5 PSI increase and thus set our automatic feeder to compensate for this increase BUT not too high to pop the relief valve and size the expansion tank accordingly.
WHY complicate this? Stop thinking like an Engineer and think like us plumbers KEEP it Simple whew
