Gas valve question

[programmergeek]

I found a gas valve for a master cut off but it is 1/2" all the lines into the house are 3/4. I have 2 furneses in the houwe a hot water heater and stove that all use gas. Will this cause a bottle neck? Normally I would get the bigger valve but it is about a $300 price difference. I know in water it doesn't really matter not sure with gas since the psi is much less.

 

[JonW]

I would not step it down to 1/2" for a master cutoff. The pressure of NG is so low, the flow will not be made up by an increase in back pressure.

 

[justinm001]

Depending on the price of the 1/2" one couldn't you split the 3/4" into 2- 1/2"'s. Actually you'll want to have 3 or 4 of the 1/2"'s to split to equal the volume of one 3/4". I'm assuming the 1/2" is so cheap because it's used in most appliances and the 3/4" is only for the main line.

 

[hult]

I found a gas valve for a master cut off but it is 1/2" all the lines into the house are 3/4. I have 2 furneses in the houwe a hot water heater and stove that all use gas. Will this cause a bottle neck? Normally I would get the bigger valve but it is about a $300 price difference. I know in water it doesn't really matter not sure with gas since the psi is much less.

Search eBay for (eg) : ASCO 3/4" gas

... Marc

 

[programmergeek]

I found a gas valve for a master cut off but it is 1/2" all the lines into the house are 3/4. I have 2 furneses in the houwe a hot water heater and stove that all use gas. Will this cause a bottle neck? Normally I would get the bigger valve but it is about a $300 price difference. I know in water it doesn't really matter not sure with gas since the psi is much less.

Search eBay for (eg) : ASCO 3/4" gas

... Marc

Called ASCO they don't make anything that will work. All there require about 5psi of pressure.

My purpose is also just not the house but for gas grills out side to turn off the gast etc.... Shuting of the gas to the house is just one request I had.

 

[SteveQ]

Why not add a shutoff to each appliance? I think you would have more flexibility and would be better for things like gas grills, fireplaces, and the like. Shutting off the gas to the whole house because the grill was left on seems to be overkill.

Steve Q

 

[hult]

Called ASCO they don't make anything that will work. All there require about 5psi of pressure.

My purpose is also just not the house but for gas grills out side to turn off the gast etc.... Shuting of the gas to the house is just one request I had.

Hi programmergeek,

You've created confusion both by starting two threads on the same identical topic within 48 hours and (at least for me) not explicitly stating that what you wanted was to install normally open valves instead of conventional, readily available, normally closed valves.

In my opinion your unconventional approach is dangerous and ill-advised for the applications you've mentioned -- which is part of the reason that you haven't found what you seek ...

In the other thread you started I posted chapter and verse on how to obtain suitable, conventional, normally closed ASCO valves, including inexpensively on eBay witth Buy-It-Now, and won't repeat those suggestions here.

... Marc

 

[sda]

In my opinion your unconventional approach is dangerous and ill-advised for the applications you've mentioned --

All my gas using appliances have manual shutoffs attached to the gas piping that are normally open (hvac, water heater, stove, dryer). The only valve that's normally closed is the gas fireplace.

How would placing a normally open automated valve downstream of the existing manual shutoff be dangerous? If there is a gas leak, the worst that could happen is the valve stays open, which is status quo.

Anyway, I was under the impression he was looking for a whole house gas service cutoff, not to control individual appliances. Maybe that was the other thread?

In that other thread, I posted a link to the earthquake valve that's service rated, exterior rated, and can be triggered to close. That's pretty nifty and if I was paranoid about gas leaks I would use that or something similar.

Now for the gas grill, I can see a use for it. I've got a propane grill now, and every now and then I leave it on and use up the tank. I used to have a nat gas grill and once I left it on for several days. Oops. Having a timer hooked to a normally closed valve supplying the grill makes sense. Set it for 30 minutes, cook, and even if you leave the grill on the gas is turned off.

 

[hult]

In my opinion your unconventional approach is dangerous and ill-advised for the applications you've mentioned --

All my gas using appliances have manual shutoffs attached to the gas piping that are normally open (hvac, water heater, stove, dryer). The only valve that's normally closed is the gas fireplace.

Key here is "manual". The powered ones (eg HVAC) are internal and are normally closed .

How would placing a normally open automated valve downstream of the existing manual shutoff be dangerous? If there is a gas leak, the worst that could happen is the valve stays open, which is status quo.

The problem isn't if there is a gas leak. The problem is if the gas is turned off automatically but not manually as in the case of a stove or grill exactly as the OP proposed.

If the grill is turned off automatically (leaving the manual valve open) and then normally-open automatic valve inadvertently and unknowingly opened because the dc power failed, or a button was inadverently pushed, or programming error, or a touchscreen touched, or software restarted, or computer rebooted or etc Etc ETC , what happpens when the unsuspecting spouse goes to light the grill or there is a spark, or cigarette? Kaboom.

In my region we are observing the 30th anniversary of a gas explosion in a school that killed or sent 37 people to the hospital. Woulda been much worse but for the fact that most were in the cafeteria at the other end of the building when it blew.

Dunno the cause, but don't underestimate the power of a natural gas line connected to an effectively infinite source.

A natural gas line is qualitatively and quantitatively different from a small, finite propane tank IMO.

And IMO, the appropriate fail-safe state of a gas valve is to be closed, not open.

Anyway, I was under the impression he was looking for a whole house gas service cutoff, not to control individual appliances. Maybe that was the other thread?

The Op wrote in this thread: "My purpose is also just not the house but for gas grills out side to turn off the gast etc.... Shuting of the gas to the house is just one request I had."

I know from personal experience that the utility company in my area will absolutely -- no discussion, no waiver -- refuse to turn gas supply back on once they have shut it off until and unless they send someone inside the house to assure that stoves, water heater HVAC are in the proper state.

My opinions FWIW... Marc