Proper Sizing Of Hydronic Circulators

Steve Curran_3

I Have A Question On The Size Of A B&G Circulator. I Have A Refuler Building With Two Trane Hot Water Forced Air Units Hung From The Ceiling And Also A Hot Water Coil In A Make Up Air Unit With A Burnham Natural Gas Boiler. What Information Is Needed To Size The Circulator For This System. The System Is Small A 60 Series B&G Circulator Is On There Now And I Do Wonder If The Circulator Is Sized Right. Any Help For This. E Mail Steve

JimGPE_3

You need the flow rate information for each heating appliance except the boiler which is then summed up for your gallons per minute.

Then you need to imagine you are a drop of water. You leave the pump and flow to each appliance then through the boiler and back to the pump. You need to add up the pressure drops for everything you flow through - the check valve, hand valve, supply pipe, balancing valve, shutoff valve, strainer, coil, control valve, hand valve, piping, fittings, air separator, strainer, shutoff valve, etc.

Once you add that up for the whole path from the pump to the forced air unit, then do the same for the other forced air unit, then the makeup air unit.

Pick the largest pressure drop for one of those three paths and that is your pump pressure requirement. (Do NOT add all three paths together!!!)

The coil and boiler pressure drops should be available from the manufacturer's data.

Once you have the capacity in gpm (gallons per minute) and the pressure drop in feet, you can select a pump or verify the selection of the pump you already own.

Good luck!