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Hot Water Heater question

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Jan 14, 2014, 10:13 AM
Hot Water Heater question
Hello to all and HNY.

We have two 80 Gal HW Heaters that are interconnected side-by-side. The house was built in 2005-2006. We do not have a water softener system. The house is two stories and both units are in the attic.

I was sleeping in the guest room upstairs, and heard what sounded like someone playing hockey in the attic. I assume there are sediments in there and when the unit is being used, the particulates bang against the h-element and sides of the unit. To my knowledge, they have not been previously flushed.


Since they are interconnected, what is the best way to flush them?

Do I flush while the water is hot or do I turn to pilot and take a lot of showers until cooler?

Do I flush with the shut-off valve opened or closed?

When flushing and draining, is it ok to leave just pilot light on while temp knob is turned all the way to off? Will not leave bottom of unit without a little water. Other?

Finally, I am going to run a garden hose from the drain valve to outside drive there a chance of getting a piece of debris larger than the ID of the hose that would get stuck?

Thank you very much for your time with these questions. All tips and feedback are welcomed.

Jan 14, 2014, 07:38 PM
Dang it tstex! You've jumped all over one of my pet peeves so now I've got to yell at you!

It's a water heater. It takes cold water, heats it and makes it hot. If it were a "hot" water heater then it wouldn't have any purpose now, would it?

OK, I'm done now. Moving on.

You can flush each tank one at a time. Keep the water on. Keep the burners on. Hook up a hose to the drain spigot, run it outside and open the spigot. With hot water in the tank and full pressure you have the best chance of things getting flushed out. You can flush one tank and then move immediately over to the other. So the whole process is fairly easy.

That's the good news.

The bad news is that if there is a lot of calcium in the bottom of the tank then it is very common for the drain valve to be plugged up. If that happens you may have to snake up through the valve to clear it or even completely remove the valve from the tank. To do this you do need to turn the flame off and it will be easier to work with if you run most of the hot water out and replace with cold. Plus, you'll need some form of waterproof catch pan. If you are lucky you can clear the valve by only spilling out a little bit of water but you need to have a plan of what to do with all the water if things go wrong.

At least, you can attempt the easy drain method first and only worry about removing the valve if things don't work.

Jan 15, 2014, 09:30 AM
When I stated "hot" water heater, that's bc she's a real beauty and looks really "hot". If it were a male unit, then it would be just a "water-heater". Big Grin

Thanks for the info. I guess leaving the water on is to ensure greater pressure to push out any larger precipitates, correct? I sure hope the valve does not get clogged.

To prevent clogging, would trying it first without the water pressure on work to see what type of sediments I am getting? I was also thinking when nearly drained, turning the water on and keeping the valve open would really agitate any solids in there for removal. If so, I guess I would have to open a HW valve to prevent air locking. I was always told to open the tub since the aperture is larger and no screen like sinks.

Since I am up in the attic and going down 2 flts of stairs, the leave the water on technique sounds a lot more attractive. I would, however, turn the unit to just pilot to not waste the hot water, unless leaving the heat on makes the sediments rise to the valve for exit.

Thank you,
Jan 15, 2014, 10:56 AM
House water pressure is supposed to be set about 50 lbs of pressure. If you leave the water on, then you'll have that pressure to help push stuff out the drain valve. Or you could turn the water off, open the pressure relief valve to let air in, and then you'll only have gravity to push the sediment out. Best to leave the water pressure on.

No need to touch the heater control to pilot, if the water heaters are fairly clean, then you don't run the water for long at all. You don't drain the tank. If, however, it is badly plugged, then you're in for a lot more work.

And as sediment is getting pushed out, you generally can hear bangs, and clicks, and the stuff is going out the garden hose. That helps to know when it's clear.

But exactly what to do depends on how much sediment or how badly plugged up the system is. And since you'll be in the attic, having someone to watch the other end of the garden hose for sediment might be helpful -- or the other way around.

This message has been edited. Last edited by: Re-mdlr,
Jan 15, 2014, 11:22 AM
You could run the house through a kitchen screen strainer to catch the sediment to see if you're getting any out.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Jan 15, 2014, 12:32 PM
"You could run the house through a kitchen screen strainer to catch the sediment to see if you're getting any out."

I do not have a kitchen screen strainer that is that BIG ! Uh oh, Jaybee is going to send you a pet-peeve nasty gram - Eek lol

Went ahead and drained with water pressure on...I was immensely surprised to see that the sediment pieces were not any larger than 1/4" x 1/4", give or take an 1/8". I ran each for about 5 minutes after all the water was cold and I could not detect too much of anything. Then I turned each the water off, opened the upstairs bath H-water handle, and then opened the valve on the water heater...did this until it got real low on water. Then I closed the HW handle in the tub upstairs, then turned on the water-line to agitate the water in the W-heater, then opened the water valve to the both instances, I did not see that much more come out...

After completing the flushes of both tanks, then getting back to normal op temp, if I hear the noise again, am I SOL on the heating element perhaps? I guess million dollar question is, can a w-heater make all that noise with not that much sediment or large particulates inside?

Thank you folks,
Jan 15, 2014, 07:08 PM
From the way you were talking it sounded like these are gas water heaters? If so, then there is no real heating 'element'. The flame on the bottom heats up the bottom and a central chimney to heat the water. While sediment can be a real problem for an electric water heater, it doesn't bother a gas unit as much.

Yes, there can be all kinds of noises but not only because of sediment. Usually there can be some air in the lines that make the most noise.

One other tip: Since you have stirred things up a little inside the tank, you may need to remove each individual strainer on the end of your faucets. Check for any collections of sediment there.

Jan 15, 2014, 07:36 PM
Thanks Jaybee.

Yes, these are gas heaters. I have 2 eletric and one gas in the country and have replaced the heating elements before, so for some reason, my mind did not make the switch...

When I stirred-up and drained multiple times the tanks, I opened the tub hot water on the tub [larger aperture] and no screens to purge the air and first round of dirty water. Did the same thing in the other tub on the other side of the house, and the jacuzzi too, but removed the screen first.

then went to each of the 9 faucets and took the screen assembly off, then purged all of the hotwater a lot of things out of the lines, and I cleaned out each screen and all.

Tonight I will determine if the water heaters bang or not - I will post back.

Thanks for everyone's feedback.

Jan 15, 2014, 07:44 PM
what you have is a water heater and a storage tank.
unless the tanks are piped, EXACTLY the same..the water will travel the path of least resistance. flow into the first tank,be heated and move out to your faucets. the 2nd tank will just sit there and heat and reheat the same water in the tank over and over
instead of 2 80 gallon tanks you have 1 80 gallon.
Jan 15, 2014, 08:20 PM
Never thought of that, but picturing it in my brainbox I can see your point. Never to old to learn.

Popeye only reached for the Spinach can as a last resort...
Jan 15, 2014, 08:30 PM
back in the 80's i had a owner tell me to pipe his water heaters togather
i told him it would not work, and was informed he was an engineer..and it will
10 years later, i was plumbing a house on the same road as that house
the owner aproached me and asked if i would undo what i did 10 years before.
cause it does not work....
Jan 15, 2014, 09:23 PM
Engineers, draftsmen and code officers, lump them together as book smart for sure. But not having the need to operate in real world situations, sorely lacking in some areas. But we still need them, that's for sure. Wink

Popeye only reached for the Spinach can as a last resort...
Jan 15, 2014, 09:43 PM
We've hooked two water heaters up together in series many times - always works well. One heater is heating cold water until it's hot and the second in line takes in already hot water and basically keeps it warm.

Of course, the two WH's can be split so that they service two different groups of faucets. Almost like being in two different houses.

This message has been edited. Last edited by: Jaybee,

Jan 16, 2014, 07:54 PM
We've used the water heaters in series to solve two common problems; Trying to fill a large whirlpool tub or to make up for low height water heater locations. (very common for water heaters to be installed in crawl spaces around here.

For the large tubs, there is no option other than to increase tank capacity (or go to a tankless). Overall it's worked well. The parallel system as shown in the link claims to provide a higher volume of hot water. But the limiter would still be the size of the hot water line after it leaves the heater(s). As it points out, the line may need to be upsized to do this. Most of our installs are in existing houses where it is not an easy nor cheap thing to install a larger size line to all locations.

Jan 19, 2014, 12:06 PM
This has been a great post from the original topic and I have learned some and had other suspicions clarified.

As mentioned, this house has 2 heaters side-by-side interconnect. Our other house by the same builder was small, but both had a Jacuzzi. At the other house w 1 WH, you could not fill-up the Jacuzzi to the level you wanted w hot water bc the WH could not heat it enough. This house has a larger Jacuzzi and you always have enough hot water. However, it takes literally 3-4 minutes in the kitchen to get hot water. This is bc both the linked WH's are upstairs in the attic on the polar opposite sides. They should have made the water lines to the remote side of the house a lot larger, or put in a 3rd WH on the other side. The builder did however, install a heat-cir-pump 5 yrs later on their own nickel, but now I have electricity in an otherwise all gas-based utility.

So the conclusion, plenty of good design up front will pay both efficiency and performance on the backend.

Now, I did drain both WH tanks, w water pressure and w out. However, I still hear the banging, but not hear as profound.

I called a plumber friend of mine and he told me that I probably had some dime-penny size deposits in the WH. He said on the normal size faucets/bibs they have to drain the tanks are worthless, the aperture when fully opened is max 1/4 - 5/16 inch. This will trap the larger pieces. He said to pre-configure [using my words now] a 3/4" ball-valve with 3/4" pipe on both sides with Teflon tape, then a male adapter for the larger garden hose you can find. Now this is where it gets interesting. He said to slightly tighten the bib before you loosen it, and then loosen and take off. He said since the tank is air-locked, he can pull the bib and insert and tighten the 3/4" pipe and not lose any more than 2-4oz. I said since mine are in the attic and both above tons of sheet rock and ceilings, I'd rather place my bets in my poker game. I'm draining my tanks.

Finally, once the new drain system is installed, he said to get a 5 gallon bucket and drain the first part into there and see what you get?

To conclude, I googled WH's, bib's, draining tanks, and many articles stated basically that the WH manufacturers all install crappy bibs with sm ID's..the less debris you can get out, the more it tears up and limits the life of your WH...

Thanks for everyone's input and I hope my last comments can help someone to extend their WH's life and efficiency.


This message has been edited. Last edited by: tstex,
Jan 19, 2014, 01:45 PM
And with all those Googled articles, how many called it a HOT water heater? Smile

Jan 19, 2014, 02:38 PM
Actually, you get the same results either way. Big Grin lol