Parallel vs. Serial water heaters

[ssanto]

Hi,

Our house has two 40 gallon water heaters. They house is about 6 years old. At first, it worked just fine and we never noticed running out of hot water. But lately, it seems that randomly we'll get less hot water than we'd expect when showering. Both heaters are running and the light is blinking that it is OK.

They are plumb in parallel and I've read that that kind of design is very sensitive to equal and balanced flow through both heaters. Perhaps over time something has gotten out of balance?

I was thinking that a quick fix could be to replumb them to be in series.

Thoughts?

Thanks,
Sal

 

[Twowaxhack]

No problem, pipe it in series

 

[ssanto]

I just checked the pipes further and they aren't even plumb symmetrically!

 

[Twowaxhack]

Put the expansion tanks on the cold water. You could upsize the tank and use one or keep the two small ones and use two on the cold water side of the system.

 

[ssanto]

Right now there are two expansion tanks - one on each cold inlet to the two water heaters.

If I plumb them in series, do I just have one expansion on the cold inlet? Or have another expansion tank in the "cold" inlet to the second heater (which is the hot output of the first)?

Thanks!

 

[Twowaxhack]

Put both on the first water heater cold piping. Or get one big tank.......

The second water heater will be fed with hot water.......

If they’re 6 yrs old, I’d replace with one big expansion tank.