How do you know if your water heater is full?

Turn on the hot water side of a faucet, when you get a steady stream of water with no burping or belching of air, you know it's full. I run ALL the faucets (hot side) for a bit just to be sure.

Also, make sure you're not in bypass mode.

If you turn on the hot water faucet, and water comes out instead of air. If in doubt, carefully open the safety valve and see if water comes out.

Txsurfer wrote:
Ok - so I have read never turn on the 110 heater coil in your water heater unless it has water in it - how do you know if its full or not?

Before you turn on the hot water heater, ALWAYS, turn the water on at the kitchen sink and watch the water steam, you are looking for any air spurts mixed in the stream, continue running the water until you see NO air bubbles/or spurts. When the water stream is a steady stream, your hot water tank is full and you can now turn on your water heater. Too be extra safe you can run the faucet in the bathroom as well.

Johno02 wrote:
If you turn on the hot water faucet, and water comes out instead of air. If in doubt, carefully open the safety valve and see if water comes out.

Doing that with water supply on can get rid of the air pocket.

Water heater fills when water supply is on and you purge air out of hot water lines via a faucet....provided it is valved for normal service

Air pocket will form at top of WH Tank by design....helps control pressure increases due to 'swelling' of water as it is heated.

djgarcia wrote:

Txsurfer wrote:
Ok - so I have read never turn on the 110 heater coil in your water heater unless it has water in it - how do you know if its full or not?

Before you turn on the hot water heater, ALWAYS, turn the water on at the kitchen sink and watch the water steam, you are looking for any air spurts mixed in the stream, continue running the water until you see NO air bubbles/or spurts. When the water stream is a steady stream, your hot water tank is full and you can now turn on your water heater. Too be extra safe you can run the faucet in the bathroom as well.

If you're going to be dry camping, be sure to do this at home, or where ever you fill your on board tank, BEFORE filling the tank, that way, you're not using 6 gallons of your limited on board supply, to initially fill the heater.

Just to re-enforce what malexander said: make sure your heater bypass valve(s) are closed.

If the valve(s) are open, water will come out the hot water faucets and the electric heater element will burn up in seconds.

Close all faucets/water outlets. If there is air in any lines, the water pump will run for a short time, intermittently. Either slowly open the relief valve on the water heater till water flows or do as others have said and let the faucets flow until no bubbles.

IF Heater is not in bypass AND water flows out of all hot water faucets THEN Heater = full.

Not a good idea to use the pressure relief valve as it is not designed to survive multiple manual activation's, it will eventually fail.

when dewinterizing I first flush all the lines then turn the bypass off and open the pressure relief valve until water starts coming out the valve. Then finish by running the hot water at each location before turning on the gas or electric heating element

malexander wrote:
Turn on the hot water side of a faucet, when you get a steady stream of water with no burping or belching of air, you know it's full. I run ALL the faucets (hot side) for a bit just to be sure.

Also, make sure you're not in bypass mode.

Great point on making sure your're not in bypass mode. I just recently burned up element in our 5V because of valves being in bypass mode.

I messed up by not switching the valves back to their normal operating position JUST AS SOON AS I completed draining & blowing out water lines.

When I come back in spring, I falsely assumed that WH had water in when I turned water on. Bad mistake, you know the rest of the story!

Short story is, yes, turn on water at each faucet and/or open WH safety valve to ensure that a solid stream of water is flowing.