Ballcock with pressure relief built in - Page 4 - Plumbing Zone

pauliplumber · 02-07-2010, 12:26 PM

Quote:

Originally Posted by Ron The Plumber

I have never seen them here, heck every single resident I go to I never ever see an expansion tank, in commercial yes. I guess it's an Oregon thing, no one puts them in and there is no problems around here.

Same in Massachusetts.

TheMaster · 02-07-2010, 12:28 PM

Then its not a closed system,plain and simple.

pauliplumber · 02-07-2010, 12:39 PM

I'm sure your right. It's not code to use an expansion tank here, and nobody does it.

Most of Mass is on city/town water (highly populated state) and most of us have a meter, a shutoff, and nothing else where water main comes into residence.

Ron · 02-07-2010, 12:43 PM

Hey Redwood,

If you was to pre-charge the TET say +20 or even higher above the system pressure would this extend the life of the tank, or is the time it would take for the 0% raise and the 20% or higher in the pressure insufficient to make a difference?

TheMaster · 02-07-2010, 12:53 PM

Quote:

Originally Posted by Ron The Plumber

Hey Redwood,

If you was to pre-charge the TET say +20 or even higher above the system pressure would this extend the life of the tank, or is the time it would take for the 0% raise and the 20% or higher in the pressure insufficient to make a difference?

A higher setting may or may not extend the life of the TET but a lower setting will for sure decrease the life of the bladder. It al depends on how much and how often the pressure builds up. A higher seting would just delay the time until the tank kicked in and relieved the pressure.....during this delay the systems presure may be relieved by a fushing toilet,ice maker or any other use of water......so the higher setting may allow more time for somthign else to relieve the presure.

Ron · 02-07-2010, 01:06 PM

My math is not that great, so sorry for asking this.

As water heats to expands, in a closed system how much is the pressure increased by each 1° of rise?

TheMaster · 02-07-2010, 01:09 PM

To be clear the TET will never relieve the pressure...just control it at the set point of the air charge. In my post above I stated that the TET would kick in and relieve pressure...thats not really true....I meant to communicate that it would CONTROL the pressure.

Redwood · 02-07-2010, 01:16 PM

Good answer TM ya took the words right out of my mouth.

The biggest thing you are doing is keeping the pressure stable prolonging the service life of plumbing system components.

One of the biggest savings will come on prolonging the service life of the water heater. It's a pressure vessel and there is a certain degree of flex built into it. Each time the pressure climbs and drops would be a pressure cycle. There are only so many cycles that can be absorbed before failure both from the glass lining cracking and corrosion which results from the cracks in the glass and also metal fatigue of the tank itself from the flexing.

I usually use the Aloha Airlines flight 243 as an example of metal fatigue in a pressure vessel. The aircraft was not among the oldest in the fleet yet because of its use in short hops between the islands it had a number of pressure cycles much higher than most other aircraft in the fleet which shocked the aviation community into a new realization of the effects of pressure cycling on a pressure vessel.

TheMaster · 02-07-2010, 01:19 PM

It would be easy to build a test rig to play around with. Get some 3/4 copper pipe and a relief valve,stop valve,gauge,thermometer. Build all that up and connect it to your garden hose to fill and pressurize it. Now with your stop valve turn off,disconnect from your hose. Now use your torch to heat the pipe filled with water. watch the gauge and the thermometer. It will rise.

Redwood · 02-07-2010, 01:20 PM

Here is a good read for those interested...

http://www.watts.com/pro/divisions/w...n.asp?catId=64

Here is a calculator program you can use as well...

http://www.watts.com/pro/divisions/w..._DETsizing.asp

Without using TM's pipe bomb experiment...
He's trying to kill you Ron...

02-07-2010, 12:39 PM	#33
pauliplumber Senior Moment Join Date: Feb 2009 Location: dinner with your wife Posts: 1,885 My Photos	I'm sure your right. It's not code to use an expansion tank here, and nobody does it. Most of Mass is on city/town water (highly populated state) and most of us have a meter, a shutoff, and nothing else where water main comes into residence. Last edited by pauliplumber; 02-07-2010 at 12:49 PM..

02-07-2010, 12:43 PM	#34
Ron Senior Member Join Date: Jun 2008 Posts: 8,635 My Photos	Hey Redwood, If you was to pre-charge the TET say +20 or even higher above the system pressure would this extend the life of the tank, or is the time it would take for the 0% raise and the 20% or higher in the pressure insufficient to make a difference? __________________ Stephen Hawking: If the government is covering up knowledge of Aliens, they are doing a better job of it then they do at anything else.

02-07-2010, 01:06 PM	#36
Ron Senior Member Join Date: Jun 2008 Posts: 8,635 My Photos	My math is not that great, so sorry for asking this. As water heats to expands, in a closed system how much is the pressure increased by each 1° of rise? __________________ Stephen Hawking: If the government is covering up knowledge of Aliens, they are doing a better job of it then they do at anything else.

02-07-2010, 01:16 PM	#38
Redwood jA-Rod dat u? Join Date: Sep 2008 Location: Connecticut Posts: 9,252 My Photos	Good answer TM ya took the words right out of my mouth. The biggest thing you are doing is keeping the pressure stable prolonging the service life of plumbing system components. One of the biggest savings will come on prolonging the service life of the water heater. It's a pressure vessel and there is a certain degree of flex built into it. Each time the pressure climbs and drops would be a pressure cycle. There are only so many cycles that can be absorbed before failure both from the glass lining cracking and corrosion which results from the cracks in the glass and also metal fatigue of the tank itself from the flexing. I usually use the Aloha Airlines flight 243 as an example of metal fatigue in a pressure vessel. The aircraft was not among the oldest in the fleet yet because of its use in short hops between the islands it had a number of pressure cycles much higher than most other aircraft in the fleet which shocked the aviation community into a new realization of the effects of pressure cycling on a pressure vessel. __________________ *"Fascism should rightly be called Corporatism, as it is the merger of corporate and government power."* ~Benito Mussolini~ Lloyd Blankfein for President 2012 - Save Money Cut Out The Middleman! 411 Plumb Appliance Stimulus Package

02-07-2010, 01:20 PM	#40
Redwood jA-Rod dat u? Join Date: Sep 2008 Location: Connecticut Posts: 9,252 My Photos	Here is a good read for those interested... http://www.watts.com/pro/divisions/w...n.asp?catId=64 Here is a calculator program you can use as well... http://www.watts.com/pro/divisions/w..._DETsizing.asp Without using TM's pipe bomb experiment... He's trying to kill you Ron... __________________ *"Fascism should rightly be called Corporatism, as it is the merger of corporate and government power."* ~Benito Mussolini~ Lloyd Blankfein for President 2012 - Save Money Cut Out The Middleman! 411 Plumb Appliance Stimulus Package

02-07-2010, 12:28 PM	#32
TheMaster Registered Member Join Date: Jun 2009 Posts: 6,437 My Photos	Then its not a closed system,plain and simple.

02-07-2010, 01:09 PM	#37
TheMaster Registered Member Join Date: Jun 2009 Posts: 6,437 My Photos	To be clear the TET will never relieve the pressure...just control it at the set point of the air charge. In my post above I stated that the TET would kick in and relieve pressure...thats not really true....I meant to communicate that it would CONTROL the pressure.

02-07-2010, 01:19 PM	#39
TheMaster Registered Member Join Date: Jun 2009 Posts: 6,437 My Photos	It would be easy to build a test rig to play around with. Get some 3/4 copper pipe and a relief valve,stop valve,gauge,thermometer. Build all that up and connect it to your garden hose to fill and pressurize it. Now with your stop valve turn off,disconnect from your hose. Now use your torch to heat the pipe filled with water. watch the gauge and the thermometer. It will rise.

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