I had some time last weekend to work on the mystery leak some more. I confirmed that the leak occurs even when not hooked up to shore water (i.e. just the fresh tank and the pump.) Basically I’m getting leaks anytime the hot water heater runs, electric or gas, shore water or pump. In thinking about this, it makes sense given the anti-backflow valve on the shore water intake. Basically it’s a closed system inside the TM.
Additionally, I did a better job of capping off the hot and cold supplies to the external shower. These were the original leak spots. After doing this, I started to get leaks in three places: The hot water output from the hot water tank, the hot water supply to the internal shower, and where the fresh water leaves the pump. These leaks are worse than what I was seeing before at the ext shower. The leaking is also more pervasive when a full tank of cold water is being heated vs just an incremental heating cycle to reheat after using maybe a gallon or so of hot water.
The hot water heater manual claims the t/p valve should release at 210 degree or 150 psi. Both of these seem crazy high. I have never seen the t/p valve release on its own – and I had some time to kill and watched it. I measured the water temp and it was ~135 degrees. I haven’t measured the pressure at the hot water heater output yet – need some adapters - but I might for grins. 100 psi breaks ¾” pvc lawn irrigation. I would imagine 150 psi would blow apart the TM PEX plumbing. I did pull the lever on the t/p valve and allowed water to flow through it so I’m sure it’s not outright clogged. This did not change the leak behavior. I also tried the suggestion in the manual to make sure there is an air pocket in the tank. That made no difference – or maybe made it leak a little bit more.
Immediately after a full hot water heating cycle (leaks had started up), I turned on the hot faucet in the kitchen sink and could hear the pressure release from the tank. It’s not like it was spitting air out of the lines, but the pressure release was noticeable as I have the TM pretty much empty and the cabinet doors open. Cleary the hot water heater is generating more pressure than the TM PEX plumbing can handle.
It seems to me that one of maybe 4 things is happening here:
1) The t/p valve is somehow faulty and should, as normal operation, always weep or otherwise let off pressure every time the tank heats up. My impression from reading the manual is this shouldn’t really be the case. Has anyone noticed otherwise?
2) The t/p valve is not really relevant given its high limits and somehow the hot water heater took a turn for the worse and creates pressure above what the PEX system can deal with but below the t/p trip point. Need to have the hot water heater replaced.
3) I’ve had this leak (at the ext shower) from day 1, never noticed it, and the assembly of my TM was poor. This is possible given our TM is only 2.5 yrs old and our use model. All leaks are happening on ½” pipe threaded connections. At least on the outside shower, there was no teflon tape nor pipe dope. Does anyone know if these are typically applied to the PEX connections w/in a TM? I used Teflon tape to improve the temporary cap at the ext shower and that started the Pillsbury Dough Boy affect.
4) The system is designed to leak at the ext shower, the low point in the system – but not really designed as a drain. This is rot waiting to happen.
Thoughts?
(I hate plumbing! Electrical systems are much more deterministic
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