Water Heater Discharge

[SV Bella]

05H41DS - Force 10 11-gallon water heater. I have staining on my port hull from the Water Heater Discharge thru-hull. I've owned the boat 2.5 years. Never happened before (I just did a 12-hour motor for the first time - engine did not get hot). The Temperature Control Valve on the water heater is routed just like this pic I found on the internet. The engine coolant goes directly into the water heater. I've googled that the TCV is no longer available and were very prone to failure.
What is causing the discharge? Thanks.

 

[twalker H260]

Not sure if there is a temperature/pressure relief valve on the tank that leads to the thruhull, but I expect it is releasing after a long stretch of motoring. I believe the tcv valve was to prevent the tank overheating by turning off the engine coolant flow when the tank water reached a fixed temp. That is now bypassed in this configuration which would allow the tank water to continue heating until it matches engine coolant water temp which will be too hot for the temperature/pressure relief valve.


Edit. I see your pressure relief/temp relief valve behind the looped hose (blue disk/yellow label). It should have an indication of temperature and pressure settings at which it activates. I suspect it will be below engine coolant temp which is likely in the 180-190+ range.

 

[Slipin Away]

I cannot see a hose leading off the P/T valve which would be attached to the thru hull fitting. If there is no hose then the thru hull must be used for another purpose. Also it would be unlikely that the thru hull fitting would be above the level of the P/T valve

 

[SV Bella]

the pic of the water heater isn't mine. I took it off the internet. It's similar in that the TCV is routed on itself.

Here's where I got the pics and their remedy.

http://mvsanderling.net/Blog/?cat=21

 

[JamesG161]

What is called the TCV is really a Pressure Relief Valve to prevent the Water Tank from fracturing.

Jim...

PS: All Water Heaters have them, even Landlubber ones

 

[JamesG161]

Picture from internet of a new one.

The Bronze valve is the Pressure Relief Valve.

Jim....

 

[JamesG161]

I am confused on who labeled your first picture.
The thru hull is for the discharge of the PRV which pops open when the tank gets too hot.
You should have a PRV for safety reasons.

Jim...

 

[Captain Mateo]

Had a similar issue with my original (2002) Force 10. (I ended up replacing because i also found a leak in the bottom where it had corroded, but that was another issue). The photo you posted does have a temperature control valve but it is not doing anything from the way it is routed. Don't worry about that at all. The issue is most likely the pressure relief valve which, as others have said, is that blue disc with yellow tag. Verify on your set up that you have a hose connected to it - this likely leads to the thru hull.

Over time during normal operation the water in the tank will expand causing increased pressure and causing the pressure relief valve to weep. This is normal. The water heater tank is designed with an internal air pocket at the top of the tank to reduce the possibility of dripping. ln time, the expanding water will absorb this air and it must be restored. This is most likely what is causing your pressure relief valve to leak and discharge at a higher rate than normal. Here's how you restore the air pocket.
1. Disconnect the power supply to the water heater. 2. Let water cool or let faucet run until cool. 3. Turn off the main water supply. , 4. Open the hot water faucet closest to the water heater. , 5. Pull the discharge handle of the pressure relief valve and allow water to flow until it stops. 6. Allow the valve to close. 7. Close the faucet. 8. Turn water supply back on. 9. Restore the power to the water heater. 10. Turn on water heater and test.

There is also a more permeant solution to prevent this and if interested, feel free to PM me. Hope that helps.

 

[Captain Mateo]

What is called the TCV is really a Pressure Relief Valve to prevent the Water Tank from fracturing.

Jim...

PS: All Water Heaters have them, even Landlubber ones

No, Jim. The TCV is actually the Temperature Control Valve in the photo. It is labeled correctly. It may look confusing because it is plumbed to be bypassed. The new ones just dont have them anymore. Look closely behind the TCV and you can see the pressure and temp relief valve. it has a blue disc with a yellow and white tag. It just isn't labeled in the photo.

 

[JamesG161]

The TCV is actually the Temperature Control Valve

yes I see that now, but you might also replaceTCV it with "Thermostatic Mixing Valve".

His thru hull his for the PRV and the picture does not have PRV.

The PRV simple fix is to push the relief valve manual release a few times or replace it.

 

[Captain Mateo]

yes I see that now, but you might also replaceTCV it with "Thermostatic Mixing Valve".

His thru hull his for the PRV and the picture does not have PRV.

The PRV simple fix is to push the relief valve manual release a few times or replace it.

100% agree with you on adding a thermostatic mixing valve. The older units cant get very very hot and with the TCV bypassed or not working, water can definitely scald. The thermostatic mixing valve will prevent the exiting water from scaling the user.

Just to reiterate and not confuse @SV Bella, the TCV and/or thermostatic mixing valve is likely NOT the issue. Definitely focus on the pressure relief valve.

 

[sailme88]

Multiple issues going on here.. First, the that hose to nowhere is kinked.. Rigid gray pipes should have a rubber hose attachment to the tank to remove shock loading of the plumbing in seas. The relief valve should have a hose on it to divert hot water into the bilge and prevent scalding should it release while hands are close by. Guess if this was my boat I'd remove the TCV totally and directly attach the hot water out line to the tank.

 

[JamesG161]

First of all that is not his picture above.

This is taken from WestMarine Advisor.

@SV Bella wants to know why his thru hull discharge is showing a stain. They need to trace that thru hull back to the Pressure Relief Valve and probably have to replace that PRV which are available and not shown the picture from WM.
Jim...

 

[SV Bella]

Here is a pic of my actual water heater.

I believe my pressure relief valve worked. Because the engine coolant enters the water heater non-regulated and constantly, the water in the water heater became too hot during the long running of the motor.

 

[JamesG161]

the water in the water heater became too hot during the long running of the motor.

I think you got the right answer.
Jim...

 

[DeniseO30]

I'm not going to repeat all the great advice from everybody else but I will say this. Once a TP valve opens (and it should because it's a safety device and that is why it should be piped to discharge somewhere safe) but once they've opened, they often do not re-seat and drip. Sometimes we get lucky but many many times the the TP valve doesn't re-seat and it starts to drip almost constantly unless, the pressure is low. most likely you will have to replace it.

 

[SV Bella]

The pressure release valve lever was hard to move and once it did it did leak. I took the pressure release valve off to replace it.
I'm thinking of capping the coolant lines at the engine short term until I can purchase a newer model.

 

[JamesG161]

I took the pressure release valve off.

Just push and lift the lever on it few times to re-seat the PRV, but never remove it !! [Safety for you and boat]
Once the PRV is set, it should not pop again. Note it is a 125 PSIG - PRV

Or buy a new PRV by the model number on it.

Your Heater looks good to me.
Jim...

 

[JamesG161]

The lever was hard to move and once it did it did leak

If it leaked around the stem of the PRV , that is normal.

It takes a lots of heat to pop it.
Jim...

 

[SV Bella]

I bought the new Kuuma. It has the temperature control system which is my real problem. Should be a drop in replacement.

https://www.amazon.com/gp/product/B007G2IR6O/