Water Heater Noise

gator67 · 06-11-2011, 08:19 PM

A new noise. When we turn on the sink or shower to the middle or hot position, there is a hum or hiss (hard to describe) coming from the water heater. It's louder in the middle postion, not so loud in the full hot position, and the noise stops when the water is in the full cold position. I drained the water heater and flushed it, but that didn't seem to make a difference, but everything seems to work okay. Does this portend something expensive?

F&D ABQ · 06-12-2011, 10:39 PM

I've not had that problem, but if you have a separate water heater (ours is a Suburban 10 gal electric ignition) and are plugged in to shore power, try turning off the electric heater and using gas. If you're on gas and have no shore power, get the water hot and turn off the gas. See what happens to the noise. Then re-post.

Wizard · 06-13-2011, 07:36 AM

Probably check valves on the WH water connections. Can sometimes sound like the pump is coming on. Lots of people remove them but I replaced mine, they would sometimes hum, sometimes rattle first time mine did I thought it was an electrical relay chattering.

Mine was plastic but I replaced with brass valves.

gator67 · 06-13-2011, 11:19 AM

Where is the check valve? Is that the first thing coming out of the hot side of the water heater? Does this mean it's going to die soon and I won't have any hot water? We should be at an RV service center within a couple of weeks.

bcbowers · 06-13-2011, 02:36 PM

There's a brass check valve attached to the top of the water heater where the hot water comes out towards the top and typically inside under the kitchen counter. Yours could be about to break which is what mine did. If it breaks (like mine), the plastic plunger can push against its seat and not allow hot water to come out. I removed the valve, removed the plunger, spring, and retainer, and put the "empty" check valve back in. I found that I had hot water once again and haven't noticed a difference in hot water operation ever since.

The valve could be important when using bypass valves around the water heater for winterizing but I blow out my entire system after completely draining the hot water tank.

I did stop at CW on my way home and they had a totally brass check valve that looked slightly longer than the original. I was concerned that additional modifications might be required so I didn't purchase it. The nice thing about their valve was the fact that NO plastic pieces are incorproated which seemed to me to be more reliable. Again, my hot water is working well without the valve so ....

wa8yxm · 06-13-2011, 04:11 PM

I will second the check valve as well.. It opens and closes rapidly as the pressure differential in the lines and heater is enough to overcome it's spring. Then as water rushes into the line (There is an air chamber near the faucet) the pressure in the line goes up (inertia after all) and the valve closes.. Then as the pressure in the line drops it opens (Which is where we started this loop, so you can go to start of loop now)

Removing the check valve (Not needed at all if you have a 3-valve bypass system by the way) fixes this. Your city water inlet can do it too. Oh, the check vavle is also not needed if you winterize by the "DRY" method. (Or the "S" method like I do)

Wizard · 06-14-2011, 06:34 AM

Sorry not to get back to you quicker, You may have a check valve on the inlet and outlet of your tank, some have only one.

Removing the guts is an option if you don't winterize, otherwise I would replace it.

I think I have one going bad again as sometimes when I turn on the hot water, it sounds like the pump starts running but I can see that its not the pump. Well this new to us MH probably has the plastic check valves, will find out soon.