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#4659128 - 02/07/18 01:57 PM gas water heater troubleshooting / replacement
greenjp Offline


Registered: 05/19/04
Posts: 1306
Loc: Germantown, MD
Howdy folks,
Our hot water heater lately hasn't been making the volume of water it did in the past. It's a 75 gallon Rheem. ~75k BTUs and if I recall correctly a recovery volume of ~68 gallons. Anyhow we have 3 adults, 3 kids, and a jacuzzi tub, and in the past there wasn't anything we could do that would exhaust the hot water supply. Showers, dishwasher, baths, washing machine, etc, it never ran out.
Now it does run out, especially when filling the jacuzzi. When it's hot it's as hot as usual. It seems to kick back on as you'd expect. There is a little bit of leaking from time to time from the drain spout.
The trick is this thing is 20 years old or so. I suspect that whatever the problem is, the real answer is probably "get a new one".
I've never done any maintenance or repairs on this thing and have never purchased a water heater before, so any thoughts would be appreciated. It's an "atmospheric" vent type and I do plan to stick with that, so don't need info on forced exhaust, tankless, etc.

jeff

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#4659138 - 02/07/18 02:03 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
Wolf359 Online   content


Registered: 04/27/12
Posts: 4759
Loc: MA
They're pretty simple. The usual suspects would be to drain the tank, could be sediment on the bottom. Then it's possible it's the inlet water tube. Depending on where that breaks off, you'll start getting cold water instead of hot water. Cold water fills from top and hot water is at the bottom. If it breaks off near the top, you won't get that much hot water before you end up with cold water. You can replace the tube, but most people usually give up at that stage and just get a new one.

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#4659142 - 02/07/18 02:05 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
tmorris1 Offline


Registered: 07/15/03
Posts: 2364
Loc: MN
Probably a buildup of minerals and calcium inside which is making it less efficient. You are on borrowed time. Replace it before it bursts and floods your basement.

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#4659156 - 02/07/18 02:17 PM Re: gas water heater troubleshooting / replacement [Re: tmorris1]
28oz Offline


Registered: 04/20/17
Posts: 344
Loc: Utah, USA
Originally Posted By: tmorris1
Probably a buildup of minerals and calcium inside which is making it less efficient. You are on borrowed time. Replace it before it bursts and floods your basement.


+1 Replace it. My Rheem (less than 10 years old) started splitting and leaked. Didn't flood, fortunately, but the new one my plumber neighbor put in has slightly less BTU, but performs 100% better. New ones are much more efficient anyways and at 20 years old? Don't chance it. Replace it!
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1990 Nissan 300zx - Castrol Edge Euro 0W-40
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#4659180 - 02/07/18 02:47 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
CT8 Offline


Registered: 10/09/14
Posts: 11003
Loc: Idaho
Time to replace.
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#4659196 - 02/07/18 03:13 PM Re: gas water heater troubleshooting / replacement [Re: Wolf359]
BrocLuno Offline


Registered: 09/06/15
Posts: 5521
Loc: Kalifornia Kollective
Originally Posted By: Wolf359
They're pretty simple. The usual suspects would be to drain the tank, could be sediment on the bottom. Then it's possible it's the inlet water tube. Depending on where that breaks off, you'll start getting cold water instead of hot water. Cold water fills from top and hot water is at the bottom. If it breaks off near the top, you won't get that much hot water before you end up with cold water. You can replace the tube, but most people usually give up at that stage and just get a new one.


Wrong way round. They both fill and exit from the top, but the cold goes to the bottom though a high temp plastic inner tube called a "dip tube". It carries the cold to the near-flame area. If that tube has cracked or broken it will let cold water in at a different height and you will have less hot water ...

You have replaced your anode rod every 3~5 years right? So you know what the top fittings look like. Take off the cold feed side and see if you can fish out the dip tube? Check it for length against the side of the tank. It should reach from near the top to the thermostat'ish. If it's short, that's your answer. Go to big commercial plumbing supply and get new dip tube. While you are at it, get new anode and change both smile
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#4659198 - 02/07/18 03:13 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
Oldmoparguy1 Offline


Registered: 01/21/05
Posts: 5613
Loc: Charlotte, NC
If you are on well water or any supply with high mineral content, then your cold water in pipe, (downtube), has corroded and fell off. Time for a new one.
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#4659201 - 02/07/18 03:17 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
silveravant Offline


Registered: 01/03/15
Posts: 247
Loc: Cleveland, OH
Actually the dip tube takes cold water to the bottom where it's heated and rises to the top.

Do you ever hear a rumbling noise? That's water boiling under a layer of sediment. The sediment insulates the heat from the water in the tank making the unit less efficient. Sometimes it's possible to take the drain valve out and break up the sediment with a piece of wire, etc. and flush it out the drain.

If it's really 20 years old it's probably time to replace.

Unfortunately water heaters have become much more expensive.

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#4659202 - 02/07/18 03:17 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
PeterPolyol Offline


Registered: 03/06/16
Posts: 1345
Loc: toronto
Blow it down at least and get the loose deposits out, as mentioned buildup can easily drop your efficiency. I'd personally pull the plastic drain valve out and replace it with a ball valve for one, in the process conducting the blow down. How is your water hardness? How is your anode rod? Our tank, natural drafted like yours installed in 2003 with the Unitrol set to HIGH.

Hopefully your dip tube is not broken (seems unlikely, they usually break during transportation laying on it's side) that would indeed cause a sudden drop off in heating.

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#4659255 - 02/07/18 04:14 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
JLawrence08648 Offline


Registered: 01/20/17
Posts: 237
Loc: NJ
The sediment on the bottom acts as insulation preventing the flame below it from heating the water as much as it should. Turn the burner off, drain the tank, and turn the water on with bursts trying to knock the sediment loose, flushing out again by draining, repeat several times, then refill. You may need to invest in a new heater.

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#4659328 - 02/07/18 05:41 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
Donald Offline


Registered: 03/21/04
Posts: 20463
Loc: Upstate NY
Drain sediment and see if it helps.

Snap the drain valve and see if it shuts all the way, or replace. They crud up and leak. Never open it to test unless your about to replace it. Once open, if there is crud it may never go back fully shut.
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#4659336 - 02/07/18 05:51 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
cjcride Offline


Registered: 11/06/09
Posts: 1815
Loc: Ontario Canada
20 years old. It owes you nothing.
You deserve a new one.

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#4660091 - 02/08/18 03:25 PM Re: gas water heater troubleshooting / replacement [Re: greenjp]
Audios Offline


Registered: 11/19/11
Posts: 888
Loc: Lyndhurst NJ
Just replace it, like someone said you dont want it to burst, take it from me. Came home to my sump pump blasting waster out on my street. Found shin deep water in my basement, tank burst and kept trying to fill for who knows how long. Insurance covered it, but they opened every wall in the basement up, ran huge dehumidifiers and had to spray the [censored] out of everything with mold killer. Was a huge nightmare, especially for the 800-1000 or so the new one cost, ours was a 40 gal so much smaller than yours.
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2002 VW Golf TDI-Mobil 1 5/40 TDT
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2007 Mercedes GL320 CDI Fuchs 5/40 GT Pro XTL

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