# Water heater hooked up backwards



## gfuterfas (Jan 6, 2009)

Hi,
I just moved into a duplex the other day, and have a question about the way my water heater is hooked up. It looks like the hot and cold ports are reversed, but I'm not a plumbing expert. 

It's a duplex and the landlord lives upstairs. There's a common water supply and meter to the property, and there are two water heaters side-by-side -- one for the downstairs unit (ours) and one for the upstairs (hers). 

There is a common pipe connection between the "hot" side of our water heater and the "cold" side of hers, and there are two shut-off valves on this pipe.

Shouldn't the two water heaters be connected to the cold sides, if that's the main water supply? 

I think our water heater may be new (not sure if it was here for the last tenant), and I don't want to run to the landlord with something like this unless I'm more positive that something is wrong. 

Thanks for any input,
-Graham 
Los Angeles, CA


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## jerryh3 (Dec 10, 2007)

Pictures would help a lot.


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## gfuterfas (Jan 6, 2009)

Thanks -- here are some pics. Let me know if this helps.


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## Nestor_Kelebay (Jun 17, 2008)

Yes, the piping diagram I've drawn out here according to your photos does look strange.

I would have a friend feel the various inlet and outlet pipes on both heaters while you draw a bath in your unit. Feeling the water pipes heat up will tell you the flow directions in this piping. And, that'll tell you whether the hot water from one heater IS actually going through the other water heater.

If you find something wrong, draw a flow diagram for your landlady and tell her you suspect something MAY be wrong with the way the heaters are plumbed. She might not be technically minded, but if your diagram is clear, she will understand it and realize that a problem exists herself.


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## nap (Dec 4, 2007)

can you draw out the system. I can't quite get my head around your explanation.

I have a couple thoughts but without understanding how things are actually plumbed, all simply guesses at this point.


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## angus242 (May 1, 2008)

I admit, I don't truly understand it. BUT, from what I see, your hot output is going to her cold intake. GENIUS!!!!!!
That means your tank is filling her tank with HOT water! I bet her gas bills are half of yours! Her tank never has to heat the water. It's already hot!


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## nap (Dec 4, 2007)

angus242 said:


> I admit, I don't truly understand it. BUT, from what I see, your hot output is going to her cold intake. GENIUS!!!!!!
> That means your tank is filling her tank with HOT water! I bet her gas bills are half of yours! Her tank never has to heat the water. It's already hot!


that is my suspicion as well. This is used to series water heaters to effectively double the capacity but I have never seen it on a duplex before.

is the gas a shared cost or is your included in your rent?


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## angus242 (May 1, 2008)

Ah, I couldn't let it go. I was just kidding. Actually, I see a pump of some kind off to the right in the one picture. Perhaps you have instant-on hot water? When you open a hot spigot, is the water instantly hot? If so, that might be a recirc pump. What that does it constantly (or based off a timer) pump hot water through your pipes so you don't have to wait for the hot water to get to each fixture. This would entail a return pipe from each hot fixture back to the supply to get heated again.
I'm no plumber so I hope I described that OK. :icon_redface:

(or maybe my initial goofy guess was right)


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## gfuterfas (Jan 6, 2009)

Yeah, I thought it was that my heater heated her water, but now I don't think that's the case. It looks like cold water comes in to both the heaters off the split, but the installer switched my cold and hot lines. So instead of feeding cold water to both heaters, I think it feeds cold water to the hot side of my heater.

I just moved in and don't even have the gas turned on yet (not until tomorrow), so I can't tell which of my pipes are hot by feeling them -- there's no hot water coming off my heater.

I pay my own gas, water is paid by the landlord (I'm assuming this, since it wasn't discussed but I only found out about there being only one water meter just yesterday when I was looking around). 

What happens when your water heater is hooked up backwards? Anyone know?

Thanks,
-Graham


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## nap (Dec 4, 2007)

if your pipes are backwards, you will want to correct that or you will run out of hot water really fast compared to when hooked up the right way. Recovery will be a lot slower as well.


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## biggles (Jan 1, 2008)

if you get a gas bill then your on your own meter there.if the gas valves are teed off each other then you might be paying the gas bill for both the heaters.does your hot water come from your owners heater on his hot out to his space......sounds like they are in series with you preheating his cold and basically keeping his hot water cycles and billing down.if your just giving him money for utilities then its tricky.if you are getting your hot water after his heater just shut your gas valve to PILOT position and his will run to pick up cold water passing thru yours that will proof it out and result on a knock on your door ASAP:thumbup:


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## gfuterfas (Jan 6, 2009)

Yes, separate gas bills. If they're plumbed in series, is there more cost to me for preheating her water? Would it be typical to put water heaters in series in a duplex?

Thanks,
-Graham


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## biggles (Jan 1, 2008)

yours would be the lead heater as your pix show, so unless the showers are going bigtime in the AM.the lag/hers would never run till the lead/yours had to make up hot water and hers would see unheated water coming in....basically your heater is keeping hers off as the hot water goes out of hers your hot water is repalcing hers being used......she might cycle to heat a little coming in,but your supplying the main hot water to both spaces.do you see 2 seperate gas lines one to each heater piped in?


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## handyman78 (Dec 29, 2007)

gfuterfas said:


> Yes, separate gas bills. If they're plumbed in series, is there more cost to me for preheating her water? Would it be typical to put water heaters in series in a duplex?
> 
> Thanks,
> -Graham


Graham- seperate gas bills should indicate seperate heaters. Only the cold water should be coming in equally to both unless that is seperately metered too. In that case one cold pipe from each water meter to each heater.


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