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Condensate return pump

I have a customer heating a building using oil fired steam. The building is split into 2 zones using zone valves. Zone 1 is the 1st floor which has a steam main traveling out to a coil in an air handler. Zone 2 goes to the second floor radiators. Zone 1 has one return coming back from the air handler. Zone 2 has 2 returns coming back from the 2nd floor rads. All three of the returns are sarco trapped (see pic) then enter a condensate return holding tank with pump. The pump then sends the condensate back to the boiler. I would like to convert Zone 1 to gas fired hot water. Can I simply feed the existing coil with hot water? Zone 2 would remain steam but a new gas boiler would be installed to replace the oil. Does zone 2 boiler then still need the traps and the condensate pump? If the coil cannot be converted to hot water and remains steam I am still going to split the 2 zones using two new gas fired steam boilers then. What about the condensate pump in that scenario? I suspect the existing oil fired steam boiler is not the original and that the original boiler was a coal fired monster that held significantly more water. Is it possible the new smaller system was boiling off to much water on a call for heat then either over filling because of an auto feed or shutting down on low water? Will I still need the pump if I downsize the boiler even more with the new gas one ? Some thoughts please.


  • Pumpguy
    Pumpguy Member Posts: 612
    Not an expert here.........

    but past comments here about converting from steam to hot water is the difference in pressure.  The question is, is the piping up to the increase in pressure needed when converting from steam to hot water?

    If zone 2 is a 2 pipe arrangement, then yes, you need traps to keep the steam from entering the return lines.  Can't answer weather you would still need the condensate pump.  You need someone familiar with your boiler and piping arrangement to answer that. 

    As far as water storage capacity goes, you need to know if the boiler has enough water holding capacity to fill the fill the zone with steam before running out of water?  If yes, you should be OK.  If no, you will need a separate boiler feed pump set to send feedwater to the boiler when it runs low.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.