Thermal Expansion - Plumbing Zone

robthaplumber · 01-26-2010, 09:53 PM

A thermal expansion tank is required by code only on a closed system. This means a check valve, pump sys. w/solonoid, and prv without integral bypass has been installed. Do the integral bypass prv's really work? I've had to install expansion tanks even with an integral bypass prv to prevent T&P discharging.

slickrick · 01-26-2010, 10:01 PM

Rob, I didn't mean a discussion with yourself. Find a current topic your interested in. It's going to be alright.

Protech · 01-26-2010, 10:10 PM

Those integral bypasses won't work if the high pressure side of the PRV is over 80PSI. It will only dump the pressure back into the municipal system at the pressure the municipal system is at. I really don't see the point of those integral bypasses other than a last layer of defense.

Miguel · 01-26-2010, 10:38 PM

If the expansion tank alone isn't doing the job then it's either undersized or something else is screwy.

This reminds me of something . . . Crap! WHat was it?

Btw, Hi robthaplumber. Welcome to the Zone.

**Bill** · 01-26-2010, 10:48 PM

Quote:

Originally Posted by Miguel

This reminds me of something . . .

Crap! WHat was it?

What? Are you getting old? They say the first thing to go when you get old is, uhh, I ummm, let me see, no thats not it, umm, maybe.......Oh heck, someone give me a clue

Plumber Jim · 01-26-2010, 11:09 PM

The bypass works upto the outside city pressure. so if you had a city pressure of 100 psi then the pressure wouldn't go over 100 psi. So you always need to know the pressure on the city side of the prv if you are depending on that bypass to work. I just installed an expansion tank the other day because the guy had some company replace his main and they put in a prv and it didn't have a bypass but they didn't bother to tell him that it would make his T&P pop. Oh, and this was an inspected job too. lol

01-26-2010, 09:53 PM	#1
robthaplumber 2nd Generation Plumber Join Date: Jan 2010 Location: Nashville TN. Posts: 149 My Photos	Thermal Expansion A thermal expansion tank is required by code only on a closed system. This means a check valve, pump sys. w/solonoid, and prv without integral bypass has been installed. Do the integral bypass prv's really work? I've had to install expansion tanks even with an integral bypass prv to prevent T&P discharging.

01-26-2010, 10:01 PM	#2
slickrick Senior Member Join Date: Sep 2009 Location: Gilmer, Texas Posts: 2,684 My Photos	Rob, I didn't mean a discussion with yourself. Find a current topic your interested in. It's going to be alright. __________________ "I believe human-beings and fist can co-exist peacefully....." GW

01-26-2010, 10:10 PM	#3
Protech Super pex man Join Date: Sep 2008 Location: Polk County, Florida Posts: 4,931 My Photos	Those integral bypasses won't work if the high pressure side of the PRV is over 80PSI. It will only dump the pressure back into the municipal system at the pressure the municipal system is at. I really don't see the point of those integral bypasses other than a last layer of defense. __________________ Plumber, Repiping, Replumbing, Leak Detection, Solar Water Heater, Drain Cleaner, Pipe Leak, Polk County Plumber, Lakeland Plumber, Winter Haven Plumber, Haines City Plumber, Bartow Plumber

01-26-2010, 11:09 PM	#6
Plumber Jim Senior Member Join Date: Jun 2008 Location: Colorado Posts: 1,379 My Photos	The bypass works upto the outside city pressure. so if you had a city pressure of 100 psi then the pressure wouldn't go over 100 psi. So you always need to know the pressure on the city side of the prv if you are depending on that bypass to work. I just installed an expansion tank the other day because the guy had some company replace his main and they put in a prv and it didn't have a bypass but they didn't bother to tell him that it would make his T&P pop. Oh, and this was an inspected job too. lol __________________ Broomfield Plumber , Denver Plumber , Boulder Plumber , Lafayette Plumber

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01-26-2010, 10:38 PM	#4
Miguel Gone fishing Join Date: Aug 2009 Location: Sunset Country, Ontario Posts: 628 My Photos	If the expansion tank alone isn't doing the job then it's either undersized or something else is screwy. This reminds me of something . . . Crap! WHat was it? Btw, Hi robthaplumber. Welcome to the Zone.

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