The Tank › Hot Water Volume Too Low
- January 26, 2019 at 12:57 pm #24545
New to the forum, so thanks in advance for hearing of my hot water woes… First a bit about my house:
Single family home which was repiped with copper in 2007.
Purchased AO Smith GNR 40 200 in August 2013.
I had the best showers of my life for 4 years! Was a happy camper. Sometime last year, I noticed that the hot water volume was decreasing, I thought.. could the city be reducing the pressure at certain times or all my neighbors were taking showers at the same time? All irrational, but with copper, i thought my water pressure woes were behind me.
I am a heavy water user with several ponds and landscaping that puts me in the upper quartile of water users in my area.
We also have very hard water here which is great for my pond fish, but not so good for humans. So, a few weeks ago, I decided to install a water softener. We added a loop off the main feed and installed the softener 2 weeks ago.
I then decided that I needed to tackle the lower water volume issue, so I decided to flush my water heater. After the initial effort, the volume got even worse! I called my handyman friend and we spent about 3 hours coat hangering out as much sediment as we could (see picture attached) I had done nothing with the water heater since installing (big mistake I know now).
Incredible amounts of sediment and scale came out.
Then, working with Randy, I ordered and installed a new anode, my old one was completely consumed, no evidence I ever had one, actually. When this work didn’t help my water volume issue, I did more:
Replaced the copper flex feed tubes.
Flushed pipes in house by blocking a faucet and forcing cold water back through the hot water line, no sediment removed.
Inspected water heater dip tube – in good condition.
Confirmed that water heater pressure matches house pressure at 65 pounds.
Visually checked flow from main to heater by attaching a hose to pipe fitting – it appears to be normal, no drop off apparent.
Tested flow rate by filling a one gallon container from a tap with aerator removed, as follows:
Cold fill: 7 seconds
Hot fill: 23 seconds
When opening this sink tap, hot water pressure drops from 65 pounds to 0 pounds, measured on a gauge connected to the water drain. Normal faucet with aerator drops it to 40 pounds.
My pipes are under warranty by Repipe Specialists. They want a $125 refundable deposit to come out and inspect and fix any workmanship or material defects. Anything else needed will be estimated and I lose the $125.
I have uploaded a 40 second video showing the difference between the cold and hot water. https://youtu.be/o7hGCr5RBdc
Any insight as to what I can check before they come out would be appreciated!
BobJanuary 26, 2019 at 11:17 pm #24546
Hello, Here’s a simple test to start. Hook up a hose to the drain of the heater and let it run, wide open. What pressure do you measure in the tank when this is happening? Or, does the hose just trickle? If it does, you know the flow restriction is in the cold supply to the tank. If not, It’s downstream. Now, try bypassing the softener and doing the same test. Any difference? Also, does the shutoff valve to the heater open fully? It sounds like a flow restriction someplace and it needs to be found. 😎
Yours, LarryJanuary 28, 2019 at 2:33 am #24547
Thanks for the response. With full pressure on, the flow out the drain valve acts exactly the same as at the faucet, strong at first, then slows down. Gauge measures 65 pounds, same as house pressure at the main connection.
Tomorrow I will bypass the softner, but this problem has been present for weeks, maybe months prior to the softener installation.
I checked the ball valve and it is functioning properly.
I wonder if the issue is at the point where the main cold branches to the line feeding the water heater. Could an accumulation of excess solder from the repipe collect over time and cause a blockage? Any kind of pipe issue is going to be tough to locate.
I will report back on the softener bypass ASAP.
Bob H.January 28, 2019 at 12:00 pm #24548
Hello, There usually aren’t many places upstream of the water heater that can clog up. That’s good news! Is there a hose bibb in the main line, where it enters the house? If so, test that and see if it has good flow that doesn’t drop off. That would eliminate the meter as a concern. Can you trace the line visually from where it enters the house to where it branches off to the heater? … Is there a crawl space? If so, look at everything and see if there are any devices in the line. If it’s just new copper the whole way, than your thought of solder bits could have merit, though I’ve never seen a main line clogged by solder bits. With the right listening tool, (maybe good ears) you could also run water from a hot tap and go down the line where the clog is suspected to listen for the hiss of restricted flow. As a side note, look for piles of solder left where new connections were made. If you see lots of drips, the technician used too much solder and there is more chance of solder in the pipes causing trouble. Only a novice plumber would have done that… and left the mess. 😕
Yours, LarryJanuary 28, 2019 at 1:25 pm #24549
Yes, I have checked the incoming pressure and it shows 65 pounds. There is no drop off on the cold line.
As far as the potential pipe/solder issues, I will let Repipe Specialists troubleshoot since this is covered under warranty. Copper was installed from the meter to the house and is primarily in the crawl space.
My goal is to eliminate every possible non-pipe related issue before Wednesday.
Thanks again for your input Larry!
Bob H.January 28, 2019 at 9:57 pm #24550
Hi, One more thought. If a pipe end dug into the soil, it could have picked up some dirt or gravel. If so, cutting and backflushing the line might be the best fix, even if not much fun 😕
Yours, LarryJanuary 29, 2019 at 2:38 am #24551
Not sure this test proves anything, check out this video. https://youtu.be/Z_fQAhROLPM
I did contact AO Smith and they told me that if the inlet and outlets are not blocked, it is a plumbing issue, I am not convinced yet.
Any input would be appreciated.
BobJanuary 29, 2019 at 5:55 pm #24552
I have proven that the water heater is the cause of my low flow. A colleague of mine suggested a very obvious solution: bypass the water heater. I had an old piece of flex tubing which I used to connect the input and outputs together:
Now I get to fight with AO Smith on warranty replacement.
BobJanuary 29, 2019 at 11:43 pm #24554
Hello, Based on the first video, it’s pretty clear the obstruction is between the copper flex connector and bottom end of the dip tube. I’d remove the dip tube and have a close look. I might even remove the dip tube and temporarily try hooking up the inlet to a nipple on top of the tank and see what flow you get. Some dip tubes “swirl” the water and have only small outlet holes, which could get clogged. 😕
Yours, LarryJanuary 30, 2019 at 2:43 am #24556
As always, thanks for the input. I went through the dip tube on Sunday. It is intact though I suspected that it may have shrunk in overall diameter, which would shrink the holes which disperse the incoming cold water. There were 7 small holes and all were clear.
I have seen some dip tubes that are straight and open on the bottom, mine is curved with the holes facing down. The end is closed,
Needless to say, opening up the existing holes and adding 8 more did not improve the flow.
I took a video and will post to Youtube tomorrow.
Bob H.:shock::shock:January 30, 2019 at 12:20 pm #24557
Hi, Did you try running water with the dip tube removed? Thee aren’t many places for an obstruction to occur between the cold supply and end of that funny dip tube. :cool:Yours, LarryJanuary 30, 2019 at 12:50 pm #24558
No, I didn’t try with no dip tube.
I drilled an additional 8 holes, to 15 total. This effort did not improve flow.
I need to see what a factory fresh dip tube looks like. Mine measures a hair over a half inch in diameter. Has it shrunk? How big should the holes be? Maybe cut off the curved section of tube and let the water flow straight to the bottom?
Seems to me that 7 small holes are not adequate to pass 65 pounds of pressure…but the heater worked great for the first 5 years.
BobJanuary 30, 2019 at 10:44 pm #24560
Hello, Here is the dip tube Randy sells on this site: http://www.waterheaterrescue.com/OrderPages/Curved-dip-tube.html There have never been flow problems with it. Depending on how the present dip tube is installed, a steel lip may need to be drilled out to make this tube fit. I use a 7/8″ core bit to do this. I still would like to see just what is causing the restriction though. Mysteries and water heaters shouldn’t go together. 😀 Perhaps the present dip tube is full of solder bits?
Yours, LarryJanuary 31, 2019 at 2:37 am #24561
Hi Larry, your link didn’t work for me. My dip tube had no blockages whatsoever. I could easily blow air through it.
Today, I spent a lot of time with AO Smith trying to get warranty coverage for my water heater resolved. They finally gave me a parts voucher, i have to pay labor. I then spoke to an AO Smith authorized local plumber, who told me that he has seen similar failures before, due to our extremely hard water. He would not service my heater. He said that the tank is failing internally and that no parts, other than a complete replacement will solve my problem. Unfortunately, because I don’t have a leak yet, I may be out of luck.January 31, 2019 at 1:48 pm #24562Randy SchuylerKeymaster
Larry inadvertently added a character or something when he made the link. Click on it again, and in the command line, delete the gunk that shows up at the end, past “html” and it will work.
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