Tip & How-To about Plumbing

Home Water Heaters Hot Water Heater Problems

Whether you have an electric hot water heater or a gas hot water heater, getting into the shower only to find that the water is cold is not a fun experience. Likewise getting all lathered up and then getting cold water to rinse off with can be rather annoying also.

What are some of the things that can cause these problems?

First we will look at the electric version of the hot water heater.

  1. Remember that a 4500 watt element (which is the majority of US electric heaters) is only going to give you 22 gal./hour of hot water. So use more than that and your going to get cool water…
  2. If the top element goes bad you are out of luck. The top element always needs to heat before the thermostat on the top will switch to the bottom element.
  3. If the bottom element is bad then you will get about 1/3 of a tank of hot water. The top one will heat and switch to the bottom which does nothing…
  4. If either on of the thermostats becomes corrodes beneath it and does not contact the tank well, the over heating will trip the reset on the top element.
  5. **** in the bottom of the tank that covers the bottom element will burn it out and every one you try to replace it with. Clean out the junk in the bottom if it is up to the hole when replacing the bottom element.
  6. Remember where the wires go by marking them well when replacing anything.

Now the gas version of the hot water heater

  1. When filling the tank for the first time you will see water dripping on the flame. No!!! The tank is probably NOT leaking, but you are making condensation that makes it LOOK like the tank is leaking.
  2. The venting on the top of the tank MUST go UP hill and not down… hot air rises and does not like to travel down hill. This will cause all sorts of problems and could result in the death of the occupants of the residence.
  3. If the pilot light refuses to stay lit after holding the red button down for five minutes then the thermocouple needs to be replaced. This is easy to do and be careful not to cross thread the end that goes into the gas valve.
  4. Gas valves do go bad and are a pain to replace. The tank must be drained to replace the gas valve. Getting any kind of wrench in the valve without damaging it is nearly impossible.
  5. The relief valve will blow off if you live in a Town or Boro that insist that you need 90 Lbs. of water pressure and will not install a reducing valve or an expansion tank. Insist on the reducing valve, that much pressure will blow out any inexpensive faucet also…
  6. If your hot water heater if LP Gas then all the threads are reversed to prevent using Natural Gas parts on them.

This will give you a quick guide to some common things that you may encounter when working with hot water heaters. There are other things that can happen…





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1 Answer

Why does the water suddenly runs COLD after many minutes of running hot?

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.

Nov 04, 2015 | Water Water Heaters

2 Answers

i have to turn the hot water tap on full open to get hot water

Type of water heater is unknown
If you have single-handled faucet the faucet cartridge might be bad.
If you have recirculation system, then check valve might be bad.
Copy following links for troubleshoot.

Jul 16, 2012 | Water Heaters

1 Answer

Shower goes cold intermittently like there is a restriction in hot water delivery. Plenty of hot water when it comes back, but the cold blast is not fun. No shortage of hot water for long showers or other indication of problem with the electric water heater. For some reason the flow of hot water gets is reduced every few minutes. Cause???

Has nothing to do with the expansion tank, the expansion tank whole enough air so that when the heater heats the water it does not build up pressure. You know from school that you can compress ait. you CAN NOT compress water. When you haet water it expands until it turns to steam. So lets rule that out.

First look at all the plumbing in the house where there is a cross conection. This would be like a shower valve that has a personal shower head on it. and you turn of the water using the personal shower handle and not the valve at the wall. This then would let cold water to go into the hot water side piping.

Most people do that with out knowing it at the laundry sink. they put a hose on to was the dog and forget to turn off the faucet and then BANG cold water in the hot side.

Go around the house and turn off all the faucets and valves by using the handles. no add on things.

Now last could be the shower valve itself. . Do this happen in just one shower or all of them???

If its just the one and you spend the day doing the walk around, even check the bidet if you have one

its the valve. you need repair to that.

Best of luck in your hunt Tom

Sep 08, 2011 | Amtrol ST-5-C THERM-X-TROL ASME Expansion...

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