Condensate pump wouldn't stop running

Tareq Hasan

Hi,

I have a steam system run by gas.  I have 2 McDonnell & Miller MD-67 (24 Volt) connected to the boiler.  One works as low water cutoff and the other one turns the condensate pump on and off as needed.  Problem started when pump did not stop and flooded the system.  After changing the McDonnell & Miller MD-67 which controls the pump it fixed the problem.  But the problem returned after one month.  Now,  the pump wants to run all the time.  I had to turn of the power for the pump to stop the flooding.  One person told me to change the relay for the pump.  Should I change the relay?  Any other ideas?

regards,

TH

Jamie Hall

Pumps

on a steam system are a pain in the neck...



That said, the first thing to check is that the float in the M&M controlling the condensate pump is free to move.  You do blow it down from time to time, I presume -- but they do get stuck.  Not, I must admit, usually in the down position... but anything can happen.



Second thing to check is that the switch in that control is working -- it should be open when there is enough water in the boiler, and closed when there isn't.



Having checked those items and making sure they are OK, then continue on with the checking through the circuits controlling the pump, to find out where along the line a switch or relay isn't opening when it should.  Relays have been known to stick closed -- although it is not all that common.  You should check, too, to make sure that there isn't some other source of power to that pump or relay coil.  Shouldn't be, but...



Be aware in all of this that you are dealing with 120 volts.  It can fry you.  If you aren't happy with playing with power electricity, don't.  Get a pro. who is!