Ticking hot water heater...?

Philip53

2021 2500 Sprinter 170, 4 cyl gas
On the last night of our recent trip, we had a strange occurrence. My wife was lying on the corner bed of our "J" model and asked if I heard the clicking noise coming from under the bed (where the hot water tank is located). Sure enough there was a fairly audible clicking that began to increase in frequency. We were plugged in to shore power at the time, and suspecting temp expansion in an overheating tank, I turned off the electric element and immediately the clicking reduced in speed and quit altogether within a minute or so. Had never heard this noise--on any RV.

Before starting to work on it, I was wondering if anyone else had experienced this?

Thanks
 
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Old Crows

Calypso 2014 View Profile
What kind of WH? Tank types may “talk” under some conditions. It is the expansion/contraction of the aluminum tank. First check that the over pressure relief valve is working (cold! Never hot!!!!!!!!)

No leaks or drips? Igniters click. Usually only two or three times if there’s no LP. Then they stop for safety.

If everything looks good, I’d say it was OK & normal operation.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
Aluminum tank, only made noise on electric operation. Did notice a little water at bottom outside of access vent from T&P valve. Definitely not igniter noise (LP turned off)--was surely expansion noises.

The leaking T&P valve would not cause expansion noises, but may be a symptom of a bad thermostat, relay, or the electronic control module causing the overheating & resulting expansion. I have a few urgent things my wife thinks I need to do first, like mow the yard and our new pasture, before I tackle this project, but I will definitely post here what I find. Surprising no one has had a similar problem, and I do believe it is a problem, as noise was definitely not normal. And the fact that the 'clicking' noises began slowing almost immediately after I cut the electric power to the HW heater should point in the right direction.
 

Alphacarina

2006 Itasca Navion 23H
I would check the temperature of the hot water at the tap, both with LP and electric operation just after the heat cycles off and see if they are similar . . . . before I took anything apart or attempted any repair

Don
 

Old Crows

Calypso 2014 View Profile
Clicking slows when you it the electric power. Sorry, missed that on the first post. The thermostat may be triggering a high voltage relay to the 110v element. And it is the relay. Click - ON. Click - OFF. Etc.. Or, it is the thermostat.
 

bayleysview

2011 Sprinter/2012 WBGO View J
I have a 2012 J and the WH makes and "grumbly/growley" noise to remind us that it is time to turn it off. I started this about a year/8,000 miles ago. I wish you success in detrming the cause and look forward to reading what you find. My research has not found anything conclusive.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
Thanks for all the suggestions, hope to work on it tomorrow. Will post here the results whenever I figure it out.
 

smiller

2008 View J (2007 NCV3 3500)
On the last night of our recent trip, we had a strange occurrence. My wife was lying on the corner bed of our "J" model and asked if I heard the clicking noise coming from under the bed (where the hot water tank is located). Sure enough there was a fairly audible clicking that began to increase in frequency. We were plugged in to shore power at the time, and suspecting temp expansion in an overheating tank, I turned off the electric element and immediately the clicking reduced in speed and quit altogether within a minute or so. Had never heard this noise--on any RV.

Before starting to work on it, I was wondering if anyone else had experienced this?
I have experienced the same symptom, quite frequently in fact. It isn't loud, but it is audible. I had always assumed that it was indeed a normal tank 'talking' sound as described by Old Crows. The noise goes away after power is removed because the mechianical effect of heat are causing the noise, and when power is removed heat is lost and the noise decreases. That is my theory anyway, has been going on for several years of heavy use with no problems so for whatever that is worth.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
I have experienced the same symptom, quite frequently in fact. It isn't loud, but it is audible. I had always assumed that it was indeed a normal tank 'talking' sound as described by Old Crows. The noise goes away after power is removed because the mechianical effect of heat are causing the noise, and when power is removed heat is lost and the noise decreases. That is my theory anyway, has been going on for several years of heavy use with no problems so for whatever that is worth.
Good to hear I am not the only one, but this is the first time, over a long time for me, and it is different. Enough so that it concerns me. Could be coincidence, but the fact that the T&P valve just happens to begin dripping for the first time, the same night that the expansion clicking noises were evident leads me to believe there is a correlation. The manual says that the tank should be drained at least yearly, and the T&P valve exercised occasionally. Oops, missed that one.

Plan to drain & flush the tank, remove & inspect the valve, and as per the manual as well, inspect the t'stat and wiring connections. Then I'll fire her up on LP & check temps, then on electric only & compare the temps. And listen for the tick....tick...tick..tick.tick. Will let you know.
 

smiller

2008 View J (2007 NCV3 3500)
Seeping from the T&P valve can be caused by air trapped in the top of the heater tank, maybe that has something to do with the noise. Check out the purge procedure for your water heater and see if that doesn't cure it.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
Seeping from the T&P valve can be caused by air trapped in the top of the heater tank, maybe that has something to do with the noise. Check out the purge procedure for your water heater and see if that doesn't cure it.
The Atwood service manual says that the tank is designed to have an air pocket (cushion) in the top of the tank, and that it may cause the T&P valve to leak if it is NOT there. In fact, the manual stated that weeping of the valve is not necessarily a defect and should be considered normal--go figure. You may be right that the air cushion (or lack thereof) could have something to do with the expansion noises. I had to add a separate expansion tank on my home solar hot water heater system, as the higher temps caused the hot water system pressure to build past 100psi. The tank has a rubber diaphram that separates the water from the adjustable air charge above. This fixed the high pressure problem on the solar hot water piping. On the Atwood tank, the air cushion is eventually absorbed by the water and must be periodically 're-instated'. Who knew...? I guess this could cause pressure to build high enough to expand the aluminum tank. Aluminum has a very high coefficient of expansion, and maybe that's it. Very likely, though, it is a combination of a couple different 'issues' causing the abnormal noises.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
OK, got it all back together, and so far no ticking, not even once. I drained the tank & blew it out, but saw no debris of any kind. Exercised the T&P valve, and as per the service manual, removed and cleaned all the spade connectors and multi-pin connectors. The spade connector to the t'stat had some sort of black coating--did not look like regular corrosion. Sanded & cleaned it, and applied deoxit to all connectors. Also, rotated & checked t'stat & secondary ECO snap switches for good contact to tank. By draining and refilling, the air cushion was restored. After filling with water, I powered up on 110v, and checked the temp when it cut off--144 degrees. Let it cool & did same on propane--the same. As it should be, as both are controlled by same t'stat. Also no weeping from the T&P valve during testing.

Conclusions: Not completely sure. Most likely a combination of reduced or missing air cushion, corrosion of t'stat wire, and maybe not a good 'connection' at the t'stat snap switch to tank. We'll see....hopefully won't see (hear) this again.
 

Old Crows

Calypso 2014 View Profile
Glad you got it fixed. Probably Crow overthinking things.... again! If the T&P valve was leaking, that means the tank was not up to it's designed operating pressure (the T&P valve limit). If the pressure in the tank was lower than it should have been (slightly) it could have been generating some focal boiling near the heater element due to lower pressure on the tank. That could have been the source of the noise. (Sort of like a car radiator..... you need a pressure relief cap to hold keep the fluid from boiling at ambient pressures.) When you cleaned and cycled the T&P valve it now seats properly and holds the correct pressure. Just a crazy idea.

I make it a point to cycle the T&P valve every time I take the RV out or drain and refill the Atwood tank.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
Great idea to cycle that valve often, but most people never think of that. Here is a copy of the Atwood service manual regarding the T&P valve. Very strange to me that the weeping of the valve is considered normal. I guess the small closed system simply creates a bit more pressure than the valve can handle, and maybe they don't want to go up to a higher pressure point valve for safety/liability reasons.

PRESSURE-TEMPERATURE RELIEF VALVE
Weeping or dripping of a pressure-temperature relief valve while the water heater is running DOES NOT mean it is
defective. This is normal expansion of water as it is heated in the closed water system of a recreation vehicle. The
Atwood water heater tank is designed with an internal air gap at the top of the tank to reduce the possibility of weeping
and dripping. In time, the expanding water will absorb this air. To replace the air follow these steps:
Step 1: Turn off water heater
Step 2: Turn off incoming water supply
Step 3: Open the closest hot water faucet in the coach
Step 4: Pull handle of pressure-temperature relief valve straight out and allow water to flow until it stops.
Step 5: Allow pressure-temperature relief valve to snap shut, turn on water supply and close faucet.
 

Old Crows

Calypso 2014 View Profile
I could see an occasional dripping from the valve if the internal pressure was just high enough to “lift” the valve a wee bit. Or an out of spec spring could do it. It is supposed relieve excess pressure.

For quite a few years I’d been opening the relief valve when re filling the tank. Then I realized that I was reducing the air expansion bubble I the tank and that was probably not a bright idea.
 

Philip53

2021 2500 Sprinter 170, 4 cyl gas
Crows, I'm not sure you were reducing the air cushion, in fact you may have been 'restoring' the cushion every time you did that. If you look at the procedure Atwood describes above, the last step is to open the T&P valve & let the water flow out. This is assuming you had the water supply turned off when you cycled the valve. Can't see that it would matter much if an inside faucet was open during the cycling of the valve. It appears you are simply letting the volume in the tank above the valve act as the cushion, and that is what you were doing (at least if you waited till the water stopped flowing out).
 
I've noticed the same ticking noise at night when all else is quiet early on with my 2016 24J. Since then I simply turn off the electric water heater at night when on shore power. I also turn it off when on 12v/propane power so it doesn't cycle on at night. The noise from a propane powered water heater would be a real nuisance when trying to sleep.
 

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