What the heck is this gunk?

Javelin

Dear Heating Pros,

Went down and looked at my indirect water heater this morning and in the well where the probe/sensor goes, there is white calcium like buildup on both the metal at the top of the well and the HOT (but not cold) nipple fitting.

Anyone know what this is? Is it bad? Should I scrape it off?

Thanks,

Jay

unclejohn

You will have to disassemble and then re dope and reassemble the fittings. That can wait until your out of the heating season since the probe is on the boiler side of the system. The manufacture may void the lifetime warranty if leaks like that aren't corrected.

Javelin

So you're saying it's a water leak? I could see that from the hot water fitting, but there was no connection made at the well.. it's just a tube you slide the sensor down - no threads or connection as far as I know...

Is it a build of hard water or something? Would salt water softener or one of those electrical ones help?

THANKS!

Grallert

The well is threaded into the female tapping. That's where the leak is judging from the picture. You know about the hot water side. I bet if you pulled the probe out of the well it's clean?
That stuff in minerals, I think mostly calcium.

Javelin

Heating Gurus,

So I took another look at this gunk today, and found something that might be related.. My mixing valve seems to be no good anymore.. doesn't seem to engage when I turn the handle.. I'm thinking it probably isn't actually "mixing" anything anymore. Also, when I tap on my expansion tank it seems waterlogged.

Couple of questions if you don't mind.

1) This is the 2nd time my expansion tank seems waterlogged - I replaced it already about a year ago.. could my non-functioning mixing valve be to blame in some way?

2) If the expansion tank is in fact waterlogged and not functioning, could this be one of the factors contributing to the buildups in any way would you think?

Thanks in advance!

Jay

PS - Photo of my setup attached.

unclejohn

The well is a threaded connection. It is replaceable. The mixing valve screw needs to be loosen and the dial pulled out to set. The expansion tanks needs to be set to your water pressure, either add air or let air out of tank to match incoming water pressure.

kcopp

Is that a galvy coupling on the T&P valve??

HomerJSmith

You seem to be in a hard water area. The thermostatic mixing valve can get calcified on the spring movement and wax element inside the valve and that can limit its regulation. CLR can clean it.
As has been said, the cap may be in the locked position (unclejohn). If your expansion tank is water logged, check the schrader valve by depressing the valve pintle, quickly, and if water comes out replace the tank. If your EX tank is water logged, I would expect a discharge out the T & P valve. You can shake it and sometimes you can feel it. If no water comes out the schrader valve then take a pressure reading on the tank with a tire pressure gauge. It should be equal to the street pressure coming into the house. You have to measure both. If the tank pressure is less than the house pressure, you need to inflate the EX tank. To do that, close the cold water feed valve and release the W/H tank pressure (drain some of the water out). Inflate the EX tank to the required pressure. Normally, I would replace the schrader valve with a new one, but your tank is new. It is just a tire valve. It is probably a good idea to tighten the schrader valve with a schrader valve tool which you can buy at any auto parts store.

Yes, with a check valve on the cold water feed and a water logged EX tank, as the water heats up in the W/H, the water expands and it has no where to go as the water pressure increases except out the T & P relief valve. It does put added pressure on the threaded fittings, but I would suspect if the threads were properly prepared that they would not leak. You need to address the leaks. I use a combination of Teflon tape and joint sealing compound to stop problem leaks. Be sure and clean the threads well before applying any tape or compound.

Experienced plumber know you tighten any threaded fitting until it breaks and then give it one more turn.

HVACNUT

Its typical of a TT/WM indirect. I bet it's the welds
Lifetime warranty because you're gonna need it.
WM no longer rebadges the TT. They went to a coil HX.
AND IT HAS A DRAIN VALVE!! YEA!
Pull the temp sensor out. Is it wet?