Gas water heater problem

[WobblyElvis]

The 40 gallon gas water heater is about 8 years old and is the older non power vent style. Problem is, if I don't use any hot water for maybe 12 hours or more, and then I go to use a lot of water, it only produces about 1/2 the volume of hot water it should. If I use it a few times a day [dishes, laundry, shower] I never have a problem.

Is this normal? The thermostat is mounted low in the tank so I would think it should fire up before I have any kind of problem.

Any ideas?

 

[Nick1994]

I wonder if it could have a lazy thermostat, that since it isn't used for a while it quits sniffing out the temperature.

Adjust the temp a little lower or higher and see if that helps. I don't know if they're replaceable?

 

[CT8]

8 years old buy a new one. It is getting up in age.

 

[tmus2122]

Originally Posted By: CT8
8 years old buy a new one. It is getting up in age.


My 50gal propane is 21 years old and going strong, knock on wood.

 

[JTK]

Sounds normal to me, if you've got the T-stat dailed back too far for your usage.

 

[oldhp]

Do you open the bottom hose valve to flush out the crud from time to time? I do it every time I start the AC for the summer, using the AC drain hose, about a 1/2 cup's worth of crud comes out. Pop told/showed me that to keep the crud from building up in the bottom which doesn't let it heat up like it's supposed to.

 

[zzyzzx]

Originally Posted By: CT8
8 years old buy a new one. It is getting up in age.


My gas water heater was made in 1996.

 

[mehullica]

Be prepared to replace the heater if you do any draining or cleaning. I'd drain the tank & remove the thermostat. See if the probe is damaged. You can maybe see inside through the probe hole for mineral buildup. Exercise the thermostat on the bench & clean the probe. If you have a DVOM, check the circuits as you adjust the temp settings & you might find you have a bad spot in the potentiometer.

 

[bullwinkle]

You've got crud in the bottom, it acts as an insulator between the burner flame & water. Put the gas valve on pilot, put a hose to a drain, open it & let 'er rip, you'll see a big difference. My usual issue is the tank rusts out & starts leaking. Electric water heaters have the element in the tank, immersed in the water-gas heaters have the burner underneath, sediment slows the recovery way down.

 

[CT8]

Originally Posted By: tmus2122
Originally Posted By: CT8
8 years old buy a new one. It is getting up in age.


My 50gal propane is 21 years old and going strong, knock on wood.
Mine last about 10 years on average. You must have nice water.

 

[Wolf359]

The other possibility is the dip tube in the water heater broke off. What happens is that once the water heater fires up, all the water is hot, but as you use it, the cold water ends up going out the hot water side if the dip tube inside the tank has broken off. You can replace them, but you usually have to take apart the fittings to get at the dip tube. The simpler explanation is that the thermostat is getting lazy, sometimes just turning it up or down resets it.

 

[JTK]

I wouldn't recommend touching the junk plastic drain valve. Check my thread on that from a few months back. The stock plastic valves don't have an opening large enough to flush anything appreciable out anyway. It's basically a little needle valve in terms of flow ability.

 

[HTSS_TR]

Originally Posted By: tmus2122
Originally Posted By: CT8
8 years old buy a new one. It is getting up in age.

My 50gal propane is 21 years old and going strong, knock on wood.

My 40 gallons natural gas was 17 years old in my previous house was running very well, produced hot water at 17th year as it did the first year.

 

[WobblyElvis]

I have opened the drain valve a few times of the years and next to no crud comes out. My previous water heater lasted 15 years and this one looks very good from the outside. I'll try turning the thermostat all the way down and back up a couple of times. It's a lazy stat or a new water heater is called for.

 

[JTK]

That's what I would do. Try different T-stat settings if you haven't touched the dial in a while.

In regards to the drain valve, like I say, if you get the chance to see through one of them, they couldn't pass a bee-bee the orifice is so small in them.