I am piping out a hot water condensing boiler that has its own boiler loop and circulator pump aside from the heating system loop and circulator pump. The manufacturer supplied a recommended circulator pump for the boiler loop which is sized for 50 ft. of equivalent length of pipe. The instuctions go on to say that it may require a higher flow circulator pump if you pipe it out more that 50 ft. of equivalent length of pipe. It then gives a chart of how much each fitting and valve is equal to as a length of pipe. My question is, do i size the circulator pump just based on the fittings and valves equivalent length, or do i also add up the amount of actual pipe in between each fitting and valve to come up with the amount?Please help, im not understanding this.
The pump they supplied for the boiler loop will be sufficient for most applications, but the building loop pump will have to be calculated. They are two separate systems even though they are connected together with a Decoupler loop. You convert all the fittings to equivalent length of pipe, and then add that number to the actual length of pipe in the system. This is used to find the resistance to flow in the system. In some cases, where the pump is almost large enough, the diameter of the pipe and fittings can be increased a size to reduce the friction losses. Call the manufacture for Tech support if possible.
