I suddendly got air in my hot water lines. Not all the time but has happened three or four times. At the same time it seems as though I have less hot water than I used to. Is it an element or do you think that it is a fill line issue? 40 gal Rheem electric in a mobile home 1996

It sounds as though you need a plumber...

It sounds as though the cold water feed pipe is a low pressure supply from a storage tank (rather than the mains) and something has become blocked or displaced.

The pipework needs tracing to locate the fault and rectify it as the heater will need a good continuous supply of water if it is to function properly. If it is an instantaneous type heater check with the instruction manual as that type of heater often need a high pressure supply.

Unless you are using a tankless hot water heater, there is a limited amount of hot water available in the tank. Electric and gas water tanks need time to recover after use, and if you are using heavily, it can exhaust the available supply. That said, there are a couple reasons why you may have less hot water than seems normal. In both electric and gas water heaters, silt can form in the bottom of the tank. This will build up over time and displace water. It also reduces the heating efficiency of gas units. There is a drain valve on the bottom of water heater tanks to allow for purging of this silt periodically, but few ever do it. You could also have, in the case of an electric hot water heater, a bad element or thermostat. Most electric heaters have an upper and lower element and thermostat. If one fails the other will still work, but the water takes longer to get hot and will deplete faster.

Following link has general troubleshooting:
http://waterheatertimer.org/pdf/Troubleshoot-recirculation.pdf

If I had to guess... debris is blocking the rotor.
Disassemble connections and see if you can flush pump.
Gene


Water Heater Timers Save Money

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I have a couple of thoughts. You may have air in the boiler water circuit at the loop that feeds the tank. You'll have to find the vent in the loop to get it out. Second, the automatic valve that opens for hot water may not be opening fully. Have you felt both the boiler water lines that go in and out of the tank? If the water going in is hot and the line out is very cold you have very little boiler water going through the loop. Make sure the isolation valves on the loop are open. Is your boiler full of water? If the boiler loop lines are hot going in and coming out, the tank is full of rust or debris and no water can get to the fins on the internal tubing to pick up heat. If that's the case there is no repair and its time to get a new tank. Hope this helps good luck.

Copy following link to troubleshoot by type of gas control valve, including directions for cleaning air intake screen, and or replacing gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html
http://www.thetankatwaterheaterrescue.com/forums/forum3/

7 flashes: Gas control valve might be bad.
4 flashes: FV overheat, clean air intake.
Soot indicates clogged air intake slowed combustion venting possibly causing overheating and lockout. Clean air intake screen located on bottom of unit.

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This is common problem with tank-less electric water heaters. There a a couple of things you can do. Turn the temperature down on the thermostat, this will lower the power requirement. The other thing you can do is replace the safety thermal cut-off switch. If you have two or three replace then all at the same time. Thermal safety switches are manufactured by the hundreds of thousands and go bad quit often. Contact the manufacture for free replacement parts.

Knocking water pipes are caused by air trapped in the pipe. If the pipe only went uphill and horizontal, the air releases out of the faucet and doesn't cause a problem. But if the pipe takes a turn back down, there is an opportunity for the air to remain trapped. Try this ---. Turn on all of your hot water faucets full blast at the same time. Start with the highest faucet farthest from the hot water tank and work your way back to the one closest to the hot water tank. Count to ten, then close them in reverse order. If that doesn't clear the air, then look for a place where the pipe travels horizontally then back down. If such a place is accessible, and if the pipe is copper, buy a self-piercing tap of the type that are used to supply water to an ice maker. Install it and let some water out and hopefully some air out. If you also attach a section of clear hose you and you open the valve very slowly, you will be able to see the air bubbles in the hose. I use just such a setup on my hot-water heating system and it works like a champ. Good luck!

You may need a circulating pump but I can't explain why it was fine before and not now. What I would do is turn the supply off to the water heater along with the power, remove the outlet supply. Open all hot side faucets in the home, using compressed air blow through the pipes if the air comes back at you, then there is a blockage before the hot manifold. If air moves, shut one faucet off at a time to try and determine where the culprit is. I don't know what else to tell you other than that. If air moves through the faucet every time, then you may want to put a circulating pump on. The only other expination is that when they repaired the pipe, some debris or eccess solder is blocking the hot supply. I have seen rocks in units as well. Because of the fix, you may want to take apart each faucet in the house and using a flashlight, look in the hot supply side to see if you can find any debris in those as well. Its not unusual after a repair, to have debris caught in them. Hopefull this helps.

Check voltage at the gas valve and at the thermocoupling. If you are reading more then 24 volts at the gas valve then replace it, or less then replace it also

It seams alot of people have this same problem All must get ahold of manufacturer and report this it must be there pump's thank you for useing fixya