Tuesday, October 20, 2009

Non-Pumping Pump


I’m having my RV winterized for storage. The dealer called to tell me that the pump doesn't work. It is located underneath the fresh water holding tank. They unhooked it from the tank to pump antifreeze into the pipes and it wouldn’t work. Is it a suction pump? Does it have to be connected to the holding tank to work?
Walter, (Wichita Falls, TX)

Walter, it’s not uncommon to disconnect the water pump from the fresh water tank in order to pump the RV antifreeze through the system. A better setup, however, would be a tee in the suction line between the pump and the fresh tank with a dedicated shut-off valve just for the winterizing purpose. This is easily added. 

RV water pumps are self-priming pumps, but on rare occasions they can develop an air blockage. When they told you the pump didn’t work, do they mean it runs, but does not pump? Or does the motor not run at all? If it does not run at all, it is probably a 12-volt DC electrical issue and not a priming problem. But if the power and ground connection is correct, it then may be necessary to “prime” the pump by pouring water directly into the inlet hose connected to the pump. RV water pumps do “suck” the water out of the fresh water tank and they also “push” the water through the rest of the fresh water system whenever there is a demand for water. If an air bubble exists on either side of the pump, suction or downstream, it could cause a water flow issue. Further investigation may be in order here.

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