plumbingwater-heater
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?
It sounds like you are describing two different problems.
First, there are two ways to hook up two water heaters: series and parallel.
Just turning off one heater should not cause the pilot light on the other to go out.
Is the toilet next to the bedroom or by the exterior wall under the window? If it is by the bedroom you may be able to remove the base board in the bedroom with minimal damage and cost to get access in the wall directly behind the toilet. I am going to guess that the vent pipe is cracked in-side the wall and allowing vapors to creep in.
After making a small hole in the wall smell for stronger odor if so you are in the right area. You do not smell the sewer vapor in the whirlpool cavity because it is probably sealed off from the toilet vent. Repairing the leak will be another issue. One step at a time. Good luck--hope this helps. If toilet is by outside wall then I would smoke the pipes.
Best Answer
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.