Dual water heaters to one

[Halfplumb]

We currently have 2 @ 50 gallon water heaters in parallel...gas upstairs, electric downstairs. All the kids moved out so only need the output from one water heater.

1. Can I take one of the heaters off line for an extended period? ...and how?

2. They each have a ball valve on the cold water inlet, but no valve on the hot water exit. Do I need to put a valve on the hot side so I can drain it?

thanks.

 

[Master Plumber Mark]

shut it off

just shut off the ball valve going into the cold side

and turn offf the gas to that unit and it will work just fine...


I am not sure why you wan tot drain it, but yes you would have to
install a ball valve on the hot exit line to do that

 

[Sponsor]

 

[Halfplumb]

Thanks.

If I don't really need to drain the tank, then that makes it easier. I was just concerned about bacteria or slime growing in the still water in the tank.

 

[Jadnashua]

Before you turn it off, you could run the temp up as high as it goes and let it sit for an hour or so...it will kill most bacteria that can be left in the water. Normally, there isn't much in there in the first place, but it couldn't hurt.

 

[hj]

heaters

I can't imagine how a gas and an electric heater, with one in the basement and one in the attic could possibly be piped parallel. Either they would be in series with the hot water from the gas one going to the electric one, or they are two different systems entirely. If either of these is the case, you cannot just shut one down and still get hot water everywhere.

 

[Halfplumb]

I just assumed they are parallel.

When I turn off the cold side to either of the two heaters (tested with enough time in between to let all the hot water in the pipes cool), I get hot water to any faucet/shower in the house.

I'm currently running with only the upstairs gas unit. The downstairs electric is turned off and the cold water valve closed.

If they were serial, would turning off the water to one shut down all the hot water flow?

 

[hj]

heaters

yes. And given your situation there is no way a parallel installation could ever be balanced to equalize the flow through the heaters.

 

[Halfplumb]

Interesting.

It sounds like what you are saying is that for any single faucet/shower, one or the other of the water heaters will be closer and provide the first of the hot water, rather than an equal share from both at the same time.

Does that impact my energy costs?