Filling and draining the water heater

TMfor4ofus · 10-17-2017, 08:07 AM

If I drain the fresh water tank does it also drain the water heater? I'm just wondering if the water heater holds water all the time unless its pumped out? Usually we're not hooked up to city water. I'm wondering because when we get to camp we fill the water tank and I turn on the water heater once I get the gas on and have lit the stove for a minute. Just wondering if I should run the water pump first? Does it try to fill the water heater right away? The pump usually only runs for a second unless a faucet is open. ??

ThePair · 10-17-2017, 08:56 AM

Quote:

Originally Posted by TMfor4ofus

This brings up a question or questions. If I drain the fresh water tank does it also drain the water heater? I'm just wondering if the water heater holds water all the time unless its pumped out? Usually we're not hooked up to city water. I'm wondering because when we get to camp we fill the water tank and I turn on the water heater once I get the gas on and have lit the stove for a minute. Just wondering if I should run the water pump first? Does it try to fill the water heater right away? The pump usually only runs for a second unless a faucet is open. ??

I would always run the pump and open the hot tap on both kitchen and bathroom sink faucets before starting the electric water heater. This ensures no air trapped in the tank, and keeps the heating elements happy. It's become reflexive habit for me.

Despite this, I, too, know the annoyance of burning out the element -- it's an easy fix if it happened. More important is to know if this is the issue and fix it, as mentioned above.

BrucePerens · 10-17-2017, 10:49 AM

Quote:

Originally Posted by TMfor4ofus

If I drain the fresh water tank does it also drain the water heater?

When the water lines drain, the heater does too. Don't count on them being full when there is no water pressure. And you need to let the air out of the hot water faucets when the pressure is first turned on.

TMfor4ofus · 10-17-2017, 03:48 PM

Quote:

Originally Posted by BrucePerens

When the water lines drain, the heater does too. Don't count on them being full when there is no water pressure. And you need to let the air out of the hot water faucets when the pressure is first turned on.

Okay thanks. I didn't even realize the WH had an electric heating element. So in theory if everything is drained out and I fill the fresh water tank does the water heater get filled too? Or does it need the pump to fill it? If I turn on the pump it would need to run for a while to fill the water heater right? It never does though - I turn on the pump and it only runs for a second or two then stops. I just always turned on the inside switch and wait for the flame up after turning on the gas and lighting the stove. The third thing I get going is the fridge (dry camping that is) Does that sound right? Next time out I'll look in the outside panel to see if the switch is on. If it is I probably blew the electric element a while ago? When its sitting in the driveway or out in the street I sometimes plug it in to charge it up and / or get the fridge chilling? Yikes I hope the switch is off for that?

**commodor47** · 10-17-2017, 04:44 PM

TMfor4ofus,

Filling the fresh water tank will not also fill the water heater. To fill the water heater you would need to connect to city water or fill it using the fresh water tank and the DC pump. The reason you don't hear the DC pump run long when operating from the fresh tank is due to air in the water heater preventing water from entering. Either that, or you already have water in the water heater. To fill the water heater, either by the city water connection or fresh water tank you need to open the nearest hot water faucet. That will allow the air to leave as water enters the tank. Once the water flow from the hot water faucet is constant, the water heater is full. In the past you may not have drained the water heater. It sounds like you may have turned on the propane source to the water heater before checking to make sure it was filled? If so, that could damage the water heater. If the water heater had water in it when you connected to shore power, and the electric heating element was turned on you probably caused no damage to the element. It is easy to test: fill the water heater using the city water connection, connect to shore power, turn on the electric heating element and test for hot water by opening the nearest hot water faucet. You should have hot water in about 20 minutes.

When dry camping I first light one burner on the stove; then the water heater on propane; then the refrigerator on propane.

Dick

TMfor4ofus · 10-17-2017, 06:46 PM

a bit confusing but okay. It must not be draining the WH when I drain the FW tank because either way I dont get a lot of air out when I do turn on the pump and hot water faucet. A few spurts then hot water? Right now its closed up, so in a few weeks we're going to the beach for a couple of nights and I'll check a few things on the subject then. Thanks

**Bill** · 10-18-2017, 06:12 AM

Quote:

Originally Posted by TMfor4ofus

If I drain the fresh water tank does it also drain the water heater? I'm just wondering if the water heater holds water all the time unless its pumped out? ... It must not be draining the WH when I drain the FW tank because ...

and then

Quote:

So in theory if everything is drained out and I fill the fresh water tank does the water heater get filled too? Or does it need the pump to fill it?

Curt and Jennifer -

With regard to draining: Draining the fresh water tank by itself does not drain the water heater. Take a look at this diagram in my Tech Stuff album to understand why.

http://www.trailmanorowners.com/foru...&pictureid=435

The fresh water tank, and nothing else, empties through the left-most drain valve, while the water heater drains through the second valve. And before the water heater will drain, you must turn on at least one hot water faucet to admit air into the water heater as the water drains out.

This means that the water heater does not have to be pumped out (your original question). As others have said, it will gravity-drain if you open the separate drain valve, and turn on a faucet.

As for filling, Dick is right that simply filling the fresh water tank does NOT automatically fill the water heater. Look at the diagram again. If you fill the fresh water tank, water would have to flow through the pump to get to the water heater. As it turns out, very little water will free-flow through a pump if it is not running. Beside that, in my 2720SL at least, the water heater is higher than the water tank, so water would have to flow uphill to get from one to the other. So in order to fill the water heater, you must either use the pump, or hook up to city water.

Summary. The fresh water tank and the water heater should be treated as two separate devices. They do not automatically fill together, and they do not automatically drain together. As long as you are aware of how to handle them both, you are good to go.

Bill

TMfor4ofus · 10-18-2017, 08:33 AM

Quote:

Originally Posted by Bill

Draining the fresh water tank by itself does not drain the water heater. Take a look at this diagram in my Tech Stuff album to understand why.

http://www.trailmanorowners.com/foru...&pictureid=435

The fresh water tank, and nothing else, empties through the left-most drain valve, while the water heater drains through the second valve. And before the water heater will drain, you must turn on at least one hot water faucet to admit air into the water heater as the water drains out.

This means that the water heater does not have to be pumped out (your original question). As others have said, it will gravity-drain if you open a separate drain valve, and turn on a faucet.

As for filling, Dick is right that simply filling the fresh water tank does NOT automatically fill the water heater. There are two reasons. Look at the diagram again. If you fill the fresh water tank, water would have to flow through the pump to get to the water heater, and very little water will flow through the pump if it is not running. Second, in my 2720SL at least, the water heater is located higher than the water tank, so water would have to flow uphill from one to the other.

Bill

Thanks Bill, that clears it up. Then my WH pretty much is always full because I only drain the FW tank before traveling unless I know I wont be able to get water at the destination. So now I'm just waiting till we open it up again to see if the switch for the WH is on or not. It hasn't sat for more than 2 months since we got it so the water doesn't get too bad hopefully. My original thought was about blowing the electrical heating element for the WH. Sorry for hijacking the electrical thread and thanks again for your help. Curt

ThePair · 10-18-2017, 02:50 PM

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Originally Posted by TMfor4ofus

Thanks Bill, that clears it up. Then my WH pretty much is always full because I only drain the FW tank before traveling unless I know I wont be able to get water at the destination. So now I'm just waiting till we open it up again to see if the switch for the WH is on or not. It hasn't sat for more than 2 months since we got it so the water doesn't get too bad hopefully. My original thought was about blowing the electrical heating element for the WH. Sorry for hijacking the electrical thread and thanks again for your help. Curt

Please note that the comments on the drains only apply to the front two drains by the tire. The back two drains (by the gray/black dump valves) are for the pressurized hot and cold lines. The hot line could cause some drain of the hot water tank (not the whole tank, but possibly some) depending on where the water is taken from the tank. If you ever release those drains, it could result in a less-than-full hot water tank.

This is why I always check before turning on the heater -- just good practice!

BrucePerens · 10-18-2017, 10:05 PM

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If you ever release those drains, it could result in a less-than-full hot water tank.

Trailmanor uses cheap plastic bleed valves (or used them when they made my 2004) that will eventually start to drip, and then the hot water runs down on its own. About the easiest replacement is to use a Shark Bite valve, otherwise you will need a PEX ring tool.