Author Topic: Dual Water Heater (50 gal)  (Read 749 times)

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Dual Water Heater (50 gal)
« on: June 13, 2018, 07:13:30 AM »
Hi,

I bought my house a few years ago and it is a 2-story and there's a total of four of us: me, wife and 2 kids.  We finished the basement after moving in.  The previous owners had installed 2 - 50 gal water heaters.  One was from 2005 and one from 2003.  I'm now seeing water leaking from under the one from 2005 so I would think that one is shot.  In researching it, I'm wondering if we can get by on just the other water heater until that one goes too (surprised the one from 2003 didn't go first). 

I saw a calculation that you should multiply each person in the house by 12 gals to determine how large of a water heater you should have so that would put us at 48 so a 50 gal tank.  The previous owners were a family of 5. 

I think the water heaters are natural gas powered.  I'm wondering, on the tank that is leaking is it as straightforward as turning off the water valve filling the tank and then draining the rest out of it to just put it out of commission and continue to run the other one or would I need to do something else to it to completely "deactivate" it?   I don't fully understand how water heaters work, so I'm not sure if the natural gas would still be running to the drained tank.  Any guidance or input would be appreciated.

Thank you.

zolotiyeruki

  • Magnum Stache
  • ******
  • Posts: 2747
  • Location: State: Denial
Re: Dual Water Heater (50 gal)
« Reply #1 on: June 13, 2018, 07:47:40 AM »
Step 1 is to figure out where the water is coming from.  A couple months ago, the relief valve on our 12-year-old water heater failed.  It cost me all of $15 for the part (available at your local hardware store), and less than an hour to replace, including draining the tank and refilling it and bleeding out the system.

If the tank on the water heater is rusted, then yeah, it needs to be replaced.  At its age, it's to be expected.  I'm assuming the water heaters are hooked up in parallel, since that seems to be the most common approach.  If you want to isolate it, you'll need to close off two valves, one on the inlet and one on the outlet.  Also, unplug it and turn off the gas to it.  On valves, perpendicular means shut off.

On your remaining, non-leaking tank, you'll want to replace the anode ASAP.  Water heaters basically last until the sacrificial anode is completely consumed, after which the tank will start to rust.  Most people don't realize that the anode can be cheaply replaced, thus extending the life of the water heater greatly.  I just did that as well, and it cost me $35 including shipping.  It sure beat having to pay $900 for a replacement forced-draft water heater, plus hours more installing it (or hundreds of dollars to pay a plumber).  I've attached a picture of our old anode next to its replacement.

Also, your water heater should get flushed annually, to get rid of scale buildup inside the tank.

Fishindude

  • Handlebar Stache
  • *****
  • Posts: 1829
Re: Dual Water Heater (50 gal)
« Reply #2 on: June 13, 2018, 09:34:04 AM »
I'd replace those two old ones with a single 50 gallon, high efficiency unit.   Should be plenty of hot water for four people.

SwordGuy

  • Magnum Stache
  • ******
  • Posts: 4306
  • Location: Fayetteville, NC
    • Flipping Fayetteville
Re: Dual Water Heater (50 gal)
« Reply #3 on: June 13, 2018, 09:44:51 AM »
If you've already got natural gas, I would suggest a tankless on demand water heater.   After the initial expense, you'll only pay for hot water you actually use, instead of heating it all day in the expectation you might use it.     Has the added benefit that if your family size grows, or you have company, or a teenager who takes forever in the shower, you won't run out of hot water.

It's a luxury I adore. :)

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #4 on: June 16, 2018, 05:46:57 PM »
Thanks zolotiyeruki.  I am checking to be sure that it is not the relief valve by putting a little bucket under it.  I detected this leaking issue just as I was doing a final sweep of the house before going out of town for a few days so no I'm back working on it.  Thanks Fishindude and SwordGuy for the recommendation on a high efficiency / tankless replacement too.  I'll very likely go with a 50 gal tankless when I confirm I need to replace these. 

My intent was to deactivate the leaking one, drain it and just let the other one run until it gives out.  zolotiyeruki with the one still running being 15 years old, do you think it'd still be worth the time and effort to replace the anode rod?  I'm all for it if it may extend the life of the water heater further still.  I am seeing some corrosive type discharge on the exterior of the tank in places (photo included). 

I've run in to an issue in trying to drain the water heater that is leaking.  At this point, I'd just as soon use one of these water heaters anyway to save on energy costs.  I think my family of 4 can get by with just one instead of heating two year round. 

I've shut off the valve for the natural gas to the water heater and the cold water supply (circled in red for both in attached photo).  I also turned the pilot light setting to off.  I've attached a hose, opened the relief valve and have had a good flow of water consistently coming out (photo included) but it has run like that for probably and hour and a half and doesn't appear to be slowing down.  I think somehow the tank is refilling or something? Anyone familiar with this?  I have shut it off for now. 



« Last Edit: June 16, 2018, 06:25:45 PM by Mr. Freedom »

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #5 on: June 16, 2018, 06:15:30 PM »
As I think about this now, maybe because there's two water heaters the other functioning one might be refilling the one I want to deactivate and permanently drain through back flow in the outlet pipe?  I see the two outlet pipes from each tank joining into one near the joists and there's no shut off valve up there for either tank so I'm wondering if that's what's happening.  In that case, I may end up having to just replace them both now with a tankless, because I'd otherwise be stuck with one that would remain filled but continue to leak (if it turns out to not be the relief valve which I would then try to repair).  If anyone has any other thoughts on this or can see something I'm missing I'd appreciate it.  Thanks again for your help on this. 
« Last Edit: June 16, 2018, 06:28:04 PM by Mr. Freedom »

FireEngineer

  • 5 O'Clock Shadow
  • *
  • Posts: 21
Re: Dual Water Heater (50 gal)
« Reply #6 on: June 16, 2018, 06:32:39 PM »
Yes. I was about to reply, the discharges are connected and the other is back feeding. If you want to remove the old one from service you will need to cut and cap/valve the discharge line. To do this I suggest turning off your second water heater [gas and water] draining the tank you are removing, cutting the line and adding a cap where the removed tank used to be.

I don't suggest a valve, because you could reinstall a heater there later and you don't want your water heater to be able to be a closed system. In theory that's what the temp and pressure valve is for, but why set yourself up for failure.

Edited to add:
And with a valve you have the ability for hot water to come gushing out of that valve if someone or something knocks the valve open.
« Last Edit: June 16, 2018, 06:34:20 PM by FireEngineer »

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #7 on: June 16, 2018, 06:50:23 PM »
Thanks for confirming that FireEngineer.  I just want to make sure I'm understanding.  What you outlined is what I'd have to do to successfully drain the leaking tank (first turning off the water and gas to the functioning tank) and keep it out of service by cutting the discharge line on the leaking tank and then capping it.  But are you also cautioning against doing that due to risks of messing things up if I want to eventually get a new water heater installed where the leaking one is now and/or if the valve/cap on the cut discharge line ever got knocked off it could result in gushing hot water? 

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #8 on: June 16, 2018, 07:03:28 PM »
It is looking more like the leak is coming from the the relief valve and not from under the tank.

If that's the case, I'm wondering If I can get the relief valve fixed can I just leave the gas and cold water inlet turned off on that water heater and just have the other one running as a way to save on the cost of otherwise directly heating two 50 gallon tanks year round?  I don't know if the existing working water heater would then be using more energy trying to heat the water in the other tank which would just have cold water in it from the backflow because they would remain connected through the discharge lines. 

FireEngineer

  • 5 O'Clock Shadow
  • *
  • Posts: 21
Re: Dual Water Heater (50 gal)
« Reply #9 on: June 16, 2018, 07:41:14 PM »
Sorry for the confusion.

I'm cautioning against a valve. I am encouraging a cap. For the hot water pipe [discharge] where you disconnect the dying water heater.

If you remove the dead tank and have a valve there someone or something could bump the valve and spray hot water everywhere and hurt someone.

If you install a valve and then later install a water heater and leave the valve someone could turn that valve off to the water heater and create a closed system which would rely on the tpr ptr? valve to vent pressure to prevent a dangerous situation.


If it the relief valve I would look at replacing the anodes on both with the goal of extending the life of them, as mentioned above.

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #10 on: June 16, 2018, 08:06:03 PM »
Thank you, I"ve got it now.  That simplifies it for me.  That would be a great outcome to get them both back to working with hopefully some life left in of them with the additional maintenance.  I appreciate it!

zolotiyeruki

  • Magnum Stache
  • ******
  • Posts: 2747
  • Location: State: Denial
Re: Dual Water Heater (50 gal)
« Reply #11 on: June 17, 2018, 08:56:34 AM »
Thanks zolotiyeruki.  I am checking to be sure that it is not the relief valve by putting a little bucket under it.  I detected this leaking issue just as I was doing a final sweep of the house before going out of town for a few days so no I'm back working on it.  Thanks Fishindude and SwordGuy for the recommendation on a high efficiency / tankless replacement too.  I'll very likely go with a 50 gal tankless when I confirm I need to replace these. 

My intent was to deactivate the leaking one, drain it and just let the other one run until it gives out.  zolotiyeruki with the one still running being 15 years old, do you think it'd still be worth the time and effort to replace the anode rod?  I'm all for it if it may extend the life of the water heater further still.  I am seeing some corrosive type discharge on the exterior of the tank in places (photo included). 
Replacing the anode at this age is a low-risk, high-reward proposition.  The tank may be too far gone already, but it might not.  If the former, you're only out the cost of the anode.  If the latter, you've just saved yourself several hundred dollars.

When I did my anode, there was a little rust on the water heater, but that was on the outside casing, not the internal tank, and the corrosion I saw was because the inlet connection was actually leaking slowly.

Mr. Freedom

  • 5 O'Clock Shadow
  • *
  • Posts: 22
Re: Dual Water Heater (50 gal)
« Reply #12 on: June 17, 2018, 09:12:24 PM »
Thanks zolotiyeruki.  I'm going to take care of replacing the anode on both this week.