The question says it all - I have a 4,200 sqft house with two water heaters - one on the far side of the house in the garage and the other in a small closet by the master suite. The latter is at least a decade older.

I have no idea how they're set up. They could be in a sequence, series, or maybe even one does part of the house and the other does the rest. Is there a way to determine this as a layperson with virtually no home repair knowledge?

  • Or post a picture of the plumbing.
    – Tyson
    Oct 7 '18 at 23:44
  • You can feel the output hot water line on a water heater and tell if it is delivering hot water or has recently done so. If both heaters haven't been drawn on for a while so both output lines are cold, turn on the hot water in the master bath and then feel both hot water output lines at the respective heaters. Now do the same for the kitchen sink. Oct 7 '18 at 23:52

If either heater has a shutoff valve in the incoming cold water pipe, turn it off and see which hot water taps/washer/dishwasher work and which ones don't. If they all continue to work when one heater is off then the heaters are essentially parallel. But since they are in different areas I suspect you'll find a split - possibly one for all bathrooms near the bedrooms (eg to always have hot showers) and the other for kitchen and laundry.

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