ROBERTS MECHANICAL EQUIPMENT COMPANY RECOMMENDS ARMSTRONG PUMPS:

To keep the terminology consistent let's speak of the BOILER pump as the 'Primary' pump while the SYSTEM pump is the 'Secondary' pump.  Our company has had terrific success with the Armstrong pumps.  Parts are easily attainable locally and our local support has been great!  For the most part the RBI line uses the S Series Armstrong pumps.  Based on about 30' of pipe, standard fittings and the flow requirements of each boiler, we recommend sizing your pump in accordance to the chart below .  As a rule of thumb, use ALL BRONZE pumps for water heaters.  Pay close attention to the grains of hardness (8-18 is acceptable).  If you know you will have above normal make up or the water quality is poor, you should up size the pump and consider a cupronickel heat exchanger.  The faster flow (faster than 7 gallons per second) will help to carry solids out of the exchanger, while the cupronickel will help to hold up to the additional flow.  Engineers be specific in your specification as the cupronickel heat exchanger combined with a larger pump can increase the unit cost by 8-15%.  The competition may try to avoid this important design aspect to be competitive!   Below is a guide AND addresses only normal conditions, water hardness, and piping pressure drops. All of our pumps are available factory mounted and wired to the boiler with pump delay (option for minimal add).

You are always advised to contact us by phone or email ( info@robertsmech.com ) to assist you with your pump sizing!  Each boiler manual will also address pump sizing offer a very informative pump sizing curve for your review.

Armstrong S series:   PUMP CURVE  |  BROCHURE  |  SUBMITTAL