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View Full Version : Update on my Thermal Exapansion issue


adamw
01-15-2008, 09:46 PM
Hey guys.
I just thought I'd give you an update on my thermal expansion issue. The original thread was a bit long and crowded, so I figured I'd start a new one.

I have a pro scheduled to come out Thursday morning to install the TE Tank. The pressure still gets very high (of course) when the WH is heating. I have to relieve pressure at a cold water tap, or the new T&P valve on the WH will start to drip. I sure hope this all goes away after the Tank is installed.

In the meantime, I found that I had to replace a wax ring on my master bath toilet. It seems to have been slowly leaking for possibly over a year. Some stains have formed on the ceiling of the room below. So I pulled the toilet up, and removed the old ring. It did not have a plastic gasket, which can't be a good thing. I could tell by looking at the area immediately around the mounting plate that some water damage has occurred. The floor in that bathroom is tile, so I have very little access to the subfloor. I took a screwdriver and was able to poke through a portion of it. I hope there isn't too much damage there. I think the only way I'd be able to tell is to rip up the tile around it, which I really don't want to get into.

I'll post again after the pro does the tank install on Thursday.

Thanks.

biscuit
01-16-2008, 10:13 AM
YOu should be good to go after a new T&P and addition of the expansion tank. Let us know how it works out.

DuckButter
01-16-2008, 03:30 PM
Water is a solid.

A solid doesn't cushion expansion like air, vapor or gas, how ever slight it might be.

The temperature increase from your hot water heater amounts to a very slight volume, despite the fact that it boosts the pressure substantially.
Once water reaches it's boiling point, the expansion increases dramatically to 1,680 times its original mass..thats why T&P valves are rated at 210 degree's, water boils at 212.
Thats the reason expansion tanks work so well and also why it's SO important to have a working T&P.

ToUtahNow
01-16-2008, 04:05 PM
Duck,

Good explanation, I generally tell the home owner you can compress air but you cannot compress water.

Mark

Bob D.
01-16-2008, 08:24 PM
Isn't it 1728 times it's original volume when water at 212 vaporizes to steam at 212 and 0 PSIG?

i.e. 1 cubic inch of water becomes 1 cubic foot of steam at 0 PSIG.


12*12*12 = 1728

gear junkie
01-16-2008, 08:35 PM
Doesn't the boiling point of water get increased in a distribution system because the water is under pressure so 212 deg is not the boiling point?

Bob D.
01-16-2008, 08:52 PM
Doesn't the boiling point of water get increased in a distribution system because the water is under pressure so 212 deg is not the boiling point?

True, the boiling point is raised when the process fluid (in this case water) is under pressure. But the 1:1728 ratio is at 0 PSIG (14.7 PSIA). If the water is under pressure then the expansion does nto occur...until a leak develops or a pipe breaks :eek:, then you've got a problem :shocked2:

gear junkie
01-16-2008, 09:03 PM
True, the boiling point is raised when the process fluid (in this case water) is under pressure. But the 1:1728 ratio is at 0 PSIG (14.7 PSIA). If the water is under pressure then the expansion does nto occur...until a leak develops or a pipe breaks :eek:, then you've got a problem :shocked2:
Why doesn't the water expand? I was referring to it can't turn to steam at 212 but it should be able to expand. Uh oh- get 2 seabees talking; this can't be good.:)

DuckButter
01-16-2008, 10:16 PM
Bob, lol...1728 is the number of cu inches in a cu foot.
Steams expands to 1,680 times it's original solid water mass, most guys just round up to 1700 even.


Ben, formula for pressure given the boiling point is :

Pressure = (boiling point minus 198, divided by 14) squared

OR in reverse:

Boiling point = 14 X sq root of (the pressure minus 198)

PLUMBER RICK
01-16-2008, 11:39 PM
a good example of water boiling when pressure drops. ever hear a heater rumble when you open a faucet?

the super hot sediment on the bottom of the tank will boil the water surrounding it as soon as there is a pressure drop in the system. a person opening a faucet creates that pressure drop and the boiling point goes down. this is typical of a very dirty heater as the sediment has built up and is the first to get heated at the bottom of the tank.

rick.

adamw
01-17-2008, 09:27 AM
Pro came exactly on time this morning. He was out of my house in about 50 minutes. 10 of those were probably taken up by me asking him questions. He probably could have been out in 30 if I just showed him the WH and left him alone. This probably would have taken me 5 hours to do myself.

Only cost $130 including the tank. Not too bad for a pro install and a lot less hassle for me!

So I used the shower after the install, and watched the pressure when I was done. Never rose above the normal 50ish.

Shame I replaced the PRV and wasted that $100! Next time, I'll listen to you guys, not the shmoe at HD!

Thanks!

PLUMBER RICK
01-17-2008, 09:54 AM
Pro came exactly on time this morning. He was out of my house in about 50 minutes. 10 of those were probably taken up by me asking him questions. He probably could have been out in 30 if I just showed him the WH and left him alone. This probably would have taken me 5 hours to do myself.

Only cost $130 including the tank. Not too bad for a pro install and a lot less hassle for me!

So I used the shower after the install, and watched the pressure when I was done. Never rose above the normal 50ish.

Shame I replaced the PRV and wasted that $100! Next time, I'll listen to you guys, not the shmoe at HD!

Thanks!

with all the pro's here telling you the same thing, why would you listen to a h.d. employee?:withstupid:

rick.

NHMaster3015
01-17-2008, 11:40 AM
Gee, I thought the people at Home Depot were all experts, They're not?

:itsover:

DuckButter
01-17-2008, 05:00 PM
There's an HD I frequent where one guy could teach me plumbing..in fact he does.
He's a retired commercial mechanic.
I pick his brain every time I'm there...he knows me by full name as soon as I call in...we spend time ragging eachother, laughing and most of all, talking plumbing....and, of course...bad mouthing HD.
Call after his shift and you get another guy.
The "other" guy doesn't know a thing about plumbing, but will tell you he does.
First time I ever spoke with this guy he argued with me over what a ball valve is after I asked if they carried WATTS ball valves, insisting that "ball" was a general term for all water shut-offs.
I showed up in person, explained what I do for a living..he then acknowledged "ball" wasn't a general term when I presented physical examples for him right there.
If I were to make the assumption the he knew what he were talking about and got a tutorial on how to install my own water heater, boiler or gas fixture..it could be dangerous.