Hot water tank

Bottom Line

Bottom Line

Well-Known Member
Oct 6, 2006
1,809
Table Rock Lake(Branson MO)
Boat Info
2003 360 DA
2002 Sea Doo GTI (sold)
2002 300 DA (sold)
Engines
Twin Mercruiser 8.1L
Westerbeke Generator
Over the weekend, I had water coming out of a thru hull vent...like when you fill your water tank and it is full. Except this on the starboard side, by the water heater. I felt the water...and it was hot water. It was not too hot to touch, but was fairly warm. I climbed down in the bilge, and saw nothing leaking on the inside. I turned off the breaker for the water heater in the MDP, and the flow slowed to a slow drip. This was the first time this year we used the water heater. Is there a setting the water heater? Is it too hot? Some sort of valve going bad? Something not done right when winterizing/dewinterizing? Thanks for the input....

(Also this caused my water tank to empty in less than 24 hours)
 
Jeff,

I had the EXACT same experience this weekend. Turned on the heater for the 1st time this summer. Came back to the boat 2 hours later and the water pump is cycling every 3 minutes or so. I start investigating and hear a small water stream on the port side of my boat coming from a small drain type through hull. Knowing I had just turned on the heater, I figure it had to be from it so I turned it off along with the water pump for the night (like you, I also checked the temperature and it was quite hot). Next morning, I raise the engine hatch to find out that the drain line that was running water is connected to the pressure relief valve on the water heater (actually cool that Sea Ray drained it out outside the hull instead of into the bilge). I messed with the valve a bit (rotated the knob to try to get it to seat better etc.) and turned the heater and water system back on. Sure enough as the heater warmed up, the pump started cycling again. This time much quicker and the drain line outside the hull was running a steady stream. Again, shut the heater off and as it cooled, the water stopped running out the drain line.

To cut to the chase, I called Atwood Mobile Marine today and described these symptoms. Their customer service guy told me to go back to the boat, turn the heater on for about 15 minutes. Then run the hot water for about 3 minutes and take the temperature. It should be at 140 degrees plus or minus 6 degrees. He said if it is hotter than 146 degrees than the pressure relieve valve is doing its job and the thermostat needs to be replaced. If the water is within the 140 degree range, then he said to replace the pressure relief valve.

I don't know if you have the same water heater, but thought this might help as it is my course of action.

If anyone else has had similar experiences, I would sure like to know it as these kind of things get me hot under the collar.
 
Randy...just wondering what you found out about your hot water heater? I haven't tested my temperature yet....but when I moved the pressure relief valve around, it would stop leaking for awhile....so I think it may be my valve...but I will check the water temp just to be sure.
 
replace water relief valve, they leak quite often
you can pick up a replacement even in home depot
just be sure that specs are the same
 
Jeff,

I did check the water temp. and it was just over 130 degrees. As such, I assumed the relief valve was bad. Went to a local RV dealer and got a direct replacement. Installed it in about 30 minutes and fired the heater back up.

NO LEAKS, so no pump cycling and plenty of now even hotter water.

Based on what you are describing, it looks like a new valve is in order for you as well. I think mine cost around $25.00 and it was easy to replace.

The heater has been working fine now for the last few weekends.
 
boatmailster said:
replace water relief valve, they leak quite often
you can pick up a replacement even in home depot
just be sure that specs are the same
Click to expand...
Make sure it's the right size threads. I had to go to an RV store to get the right size!
 
Ok...I finally got around to making this repair. I pulled the old pressure relief valve off and brought it home...to make sure the replacement would work. I went to a RV shop and got the replacement...but I have a couple of questions. The old valve has a longer temperature probe, than the new one...will this make a difference? Also...the old valve was 210 degree, 75 PSI...the new one is 210 degree, 150 PSI. Will the difference in PSI cause a problem??? Safety issue??

Is the white teflon tape suitable for coating the threads....it appears that is what was on the threads of the old valve I removed.
 
Bottom Line said:
Also...the old valve was 210 degree, 75 PSI...the new one is 210 degree, 150 PSI. Will the difference in PSI cause a problem??? Safety issue??
Click to expand...
I'm no plumbing expert, but wouldn't you want to stay at 75PSI to protect the pipes in the
water system. If you had an elevation in water pressure for some reason you could be at risk for splitting a water hose somewhere in the system.
 
1. Before you go changing the TP valve, use the manual pop lever and hold it open for 5-10 seconds. This will flush the valve seat and allow it to re-seat. Sediment and debris in the valve is the #1 reason for this valve to cause nuisance blow by.

2. The longer probe length is for different tank dimensions, and the 150psi rating is for copper tubing/plumbing, like in your home water heater. Go with the same specs as the OEM valve.

3. Teflon tape on the pipe threads is common practice.
 
Last edited:
jg300da said:
1. Before you go changing the TP valve, use the manual pop lever and hold it open for 5-10 seconds. This will flush the valve seat and allow it to re-seat. Sediment and debris in the valve is the #1 reason for this valve to cause nuisance blow by.
Click to expand...

I have tried this on 2 different occasions...and it still leaked.



I have called 2 other RV shops...and all they carry is 150 PSI relief valves. So then I called Attwood Mobile...talked to customer service...and they referred me to Attwood service dealers in my area. I called a service dealer for Attwood (about 1 hour away and is an RV dealer)....and he told me, all the Attwood replacements for the hotwater heaters are 150 PSI. He also indicated he had never seen a 75 PSI. So asked him about the water systems on RV's...and they seem like they are alot like a boats...using hoses for the hot and cold water lines. So for you guys who have replaced their valves...do you recall what PSI you used. If you used a 75 PSI valve...where did you find one at?

My plan was to go to the boat tomorrow night and put the new valve on......thanks again for the input.
 
Jeff,

When I got to the RV store and told them of the Atwood part number I needed, they came out with the generic equivalent. Guess what, it was 150 PSI and 210 degrees. I gave them my old one and said what gives. After a perplexed look, they went and pulled one from an identical new heater in an RV and it matched these new numbers.

Being the skeptic, I said NO, please order me the DIRECT replacement from Atwood. Just then, a guy comes from the parts room with the actual Atwood replacement in the original packaging with matching part number.

I give you one guess!!! Of course this valve cost 1.5 times the generic one they brought me with the same higher PSI.

I assumed, if atwood packaged it as a part number matching replacement, it was good enough for my heater.

BTW, yes the probe is longer than the original.
 
Randy...thanks for the info...so you ended up using the 150 PSI?? Did you buy the generic or the Attwood brand? Do you recall what brand it was you purchased? The one I took out was a Wells 1XL 75 PSI. We have a large plumbing wholesaler I am going to call tomorrow and see it they carry this exact Wells brand replacement. I looked at Home Depot tonight and they carry the Well brands...but only carry the 3/4", not the 1/2" I need.
 
Bottom Line said:
Randy...thanks for the info...so you ended up using the 150 PSI??
Did you buy the generic or the Attwood brand?
Click to expand...

Yes, I purchased the direct replacement packaged by Atwood.

I figured if it caused a problem, I would at least be able to tell Atwood that I used their direct replacement part and not an equivalent.

Bottom Line said:
Do you recall what brand it was you purchased?
Click to expand...

I do not, but can look it up this weekend.
 
I have finally found a 75 PSI relief valve. The one that went bad was a Watts....and the new one is the extact same Watts model. I was about to give up, and just install the 150 PSI I had already purchased, but called one more place...they didn't have it in stock, the they ordered it and had it sent to my house. I will install it tomorrow.
 
I have a similar problem. The issue I have the release valve open and water comes out in doing so it empties entire water tank . The differece with my issue is the water heater is off. The water coming out is at room temperature so it has nothing to do with temperature. I thought the release valve may have been bad because of presure 75 psi and I went ahead and order a replacement Atwood original and the issue persist. I still have the same issue as before I replace the valve. I could be that the new valve is bad but that would be a lot of coincide so what else could it be?
 
About the only things that could cause your issue are:
a) another bad valve
b) the valve is in the open position (handle sticking straight out)
c) water pressure over 75 PSI which would be hard to do using the water pump.
 
The valve is not on the open positions , this would leave two issues , Another defective bad valve or high pressure . I have two water pumps do you think if the pressure regulator is bad on one of the pumps and it could be causing this issue . If it runs and does not stop it could raise the line pressure above 75 psi and therefore the valve could be doing its job. This sounds like it would be easy to detect just by listening to the pump but if the valve is defective the pump would not stop any way . Any suggestions
 
Assuming your 480DB also has a breaker for each pump, you could try running one at a time to see if the problem goes away. I'd think if you were building 75 psi you would be seeing freshwater leaks at some fittings.
 
Just get a water pressure gauge that will screw on to your hose bibb and see what kind of pressure you are running at
they are at the big box store for cheap--great to have on board.
 
Let' my try that , this way I will know for certain if the issue is pressure or another defective valve ,

Great idea thank you
 
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