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Mark My Words: Water heater bypass, dead battery

Editor’s note: This information is provided by the Escapees Club.

Q. My 1997 motorhome has a bypass valve in the water heater plumbing that, when turned to the bypass position, keeps water from entering the water heater’s inlet. Water can still flow out the hot water faucets but, of course, won’t be heated water. So what’s the bypass valve for? If I don’t want hot water, I just turn it off using the electrical switch.

— Richard

A. That is called a water-heater bypass, and it is used when winterizing the rig. It allows you to completely bypass the water heater so that, when you fill your fresh-water system with RV-safe antifreeze, you don’t have to fill the whole water heater as well. If you don’t winterize, just leave it in the normal non-bypassed position.


Q. My one-year-old house batteries are dead. I just spent about a month hooked up to 30-amp power.  Was I supposed to disconnect the house batteries?

— Larry

A. You would not normally need to disconnect your house batteries, but have you been checking the water levels in those batteries regularly? Some RV converters continuously trickle-charge the batteries at about 13.5 volts. This causes them to use water at a fairly high rate. You should check them at least every two weeks until you have a feel for how fast the water is being lost. If water is needed, use only distilled water to fill battery cells. If your current batteries are dry, they are toast. Running dry is the most common cause of early battery death.

About Mark Nemeth

In 1997, Mark quit his aerospace engineering job and became a full-time RVer. For almost five years he traveled the country while maintaining his website, Mark’s Fulltime RV Adventure ( posting monthly travel logs. Mark now travels part-time and works as the RV Safety Education Director for Escapees RV Club providing technical training at Escapees Boot Camp seminars, as well as assisting in many other areas of the club. He is also technical advisor for Escapees magazine. Learn more about Escapees RV Club at

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