Gas water heater not so hot any more

[Christopher Nelson]

I have a gas-fired water heater. I'd say it's 30 gallons but I'm not sure without checking again. I'm not sure how old it is, it was in my house when I bought it a couple years ago. When we moved in, 4-5 people could shower within an hour or so in the morning and everyone got hot water. Lately, the third shower is often cold. I nudged the thermostat up a few degrees and that helped a little but not enough.

I've heard that with electric water heaters and hard water (which we have), the elements sometimes scale up or deposits accumulate in the bottom of the tank, gradually decreasing the effectiveness of the heater. I understand *that* can be address by draining the tank (and the accumulated junk) and then refilling and letting it go.

Is there a similar kind of maintenance that can be done on gas-fired heaters? If not, is there something else I can do besides replace the water heater?

TIA for any tips.

Chris

[hrhofmann]

Yes, you should drain the heater to get rid of the "junk" that accumulates on the bottom of the tank, that junk keeps the heat from transferring as well as when it was new. Have someone stand near the heater and see if it turns on partway thru the first shower. If it does not, the thermostat may be faulty.

[jamesgangnc]

All of them can have that problem. It's easy enough to hook a hose up to it and drain it. Make sure the gas is turned off to it or the control is set to not heat at all. If you get a whole lot of small white crumbly bits see the next paragraph.

One of the other common problems is the disintegration of the plastic tube inside the tank that causes the cold water to be feed all the way to the bottom. This failure causes the cold water to start mixing with the hot as soon as you start using it. The result is that the water becomes luke warm pretty quickly and soon gets cold even though the bottom of the tank has hot water in it. You can usually remove the cold water inlet and attempt to slide this tube up. If all you get is a stub then that's your problem. It is possible to get new tubes but they can be a pain to install because a lot of people do not have the head room over the tank to get the new one in.

Lastly it is also possible that the thermostat control is failing. Those are replaceable but may or may not be within your skill set. You have to replace that whole square unit where the gas connects and wher the control knob is. They are not designed to be serviced and usually have anti-tamper screws in them. Can be a little pricey and depending on the age of the unit you might be better off with a whole new water heater. If you are not certain then you probably ought to get someone to do it. Mistakes with gas can become a big problem.

[N8N]

I'm having the opposite problem - this was evident when I moved into my house. The water heater is 22 years old, so I suspect it is close to time to replace it. The *first* shower of the day is cold; if you wait 10-15 minutes between the first shower and the second then the second shower is nice and hot. When I moved in, the thermostat was set too low, and I had a bad T/P valve (which would cause it to pop off after raising the thermostat setting) once I rectified that and then set the thermostat for 130F water at the kitchen faucet after the burner had shut off, everything was fine. Now I'm having the same problem again, it seems like the water is allowed to cool down too much before starting the burner - the first shower now is not warm enough even if you set the control to all hot, whereas if you let it sit and then try the hot water, it'll scald you. Is replacing this control a DIY project, or should I just suck it up and start saving to have a new water heater installed? I realize that it is a crapshoot to keep repairing a water heater that's so old but I have no indications that it's in anything but excellent shape, and I replaced the anode a little over 2 years ago.

nate

[jamesgangnc]

they tend to be close to a hundred so at that age I'd think hard about a new wh. Replacing the control is not bad if you are handy. Check carefully for gas leaks with soapy water. Usual proceed at your own risk disclamer.

[Stormin Mormon]

I'm told they aren't bad to replace. Gas line, and some thing else. The aquastat threads out of the tank, the new one threads in. Teflon tape and rectorseal on the threads, please.

[Stormin Mormon]

I'd want to check and replace the diptube, before you did much else.

[Christopher Nelson]

Update: it's a 40gal A.O. Smith manufactured in 2005. That means it is outside the age range where defective dip tubes were common. I guess draining it is an easy first step. I can't get to that for a week or so.

[hallerb]

Well draining cant hurt but start in early AM and allow all day.

If the valves plastic once opened it may never close again, and may nt open enoughto get any trapped crud out. It will be stopped by the valve.

So buy a cap that screws on the valve exit in case it drips since it probably will.

if little crud comes out the main valve thermostat is likely bad. they can be a PIA to get out. Think rust in place.

I suggest you shop for a new heater in advance of disturbing the old one in case it fails somehow.

I highly recommend upgrading to a larger capacity tank with a higher BTU output.

A 75 gallon 75,000 BTU tank costs more but can provide nearly endless hot water.....

In november 2000 I went from a 40 gallon 34,000 BTU tank to a 50 gallon 75,000 BTU unit, the biggest that would fit the available space.

Best move I could of made It was a 6 year guarantee tank but is still going strong today, nearly 10 years..........

[Stormin Mormon]

I can't comment on the date range. But, a short dip tube will give those symptoms.

[Stormin Mormon]

My only experience with the instant tanks. They have one at church, where they run several hundred galon of water to fill the baptismal font. They have been very pleased with the instant tank.

[Tony]

I still don't understand why crud, minerals and/or rust, will make any difference unless it's filled with crud all the way up to the lower heating element.

[hrhofmann]

The crud dioesn't allow the water to be heated as easily. Imagine a sponge all across the bottom of the tank.

[Stormin Mormon]

The OP said several showers. If the tank is clean, the burner will be adding heat while they are showering. If the tank is dirty, the tank will run out of hot water, and the burner will, slowly, reheat the water much later in the morning.

[Christopher Nelson]

Unless I'm really confused, there isn't a heating element in the water (as in an electric heater), it's a gas burner below the tank. As I understand it, the crud accumulates in the bottom of the tank and essentially insulates the water from the burner.

[Tony]

My bad, didn't read the subject. I'm thinking electric water heater. But still with electric heaters they tell you to flush the crud out of it on a regular basis and the heat isn't coming from the bottom?

[Tony]

Sorry, I didn't pay much attention to the subject line. I was thinking electric heat. So why do they recommend flushing out electric water heaters?

[hallerb]

it acts like insulation preventing good heat transfer

[Phisherman]

Flush the tank once, or if your water is extra hard, twice a year. That will extend the life of the tank. Expect a tank to last maybe

10-15 years, certainly not too much longer with 5 people.

[Puddin' Man]

I gotta 40 gal A.O. Smith (gas) that I installed in '93, still works fine.

If yours is only 6 years old, I wouldn't start by draining. Just take the plate off and watch operation of the unit whilst folks are showering. Do the burners fire when expected? Does the flame look like a clean burn? Etc, etc.

If needed, check the users manual (if any) or search the net for basics of operation.

If all of that looks OK, -then- consider other suggestions in this thread. If not and you can't sort it out, report back here.

P

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