# Gas dryer supply line sizing



## llamafilm (Jun 13, 2014)

I bought a gas dryer, Samsung DV5200. It's 22,000 BTU/hr, and the gas connection is 3/8 MIP. The installation manual recommends using a 1/2" supply line and a reducer. My question is why not use 3/8? I have a 3/8" flare valve on the wall, so I could buy a 3/8" supply line with a 3/8 flare to 3/8 FIP adapter. Is there some benefit to a 1/2" line? I don't mind spending a few extra dollars if there's a good reason to.

Also, it says to add a 1/8" test port immediately upstream of the dryer. Is this really necessary? If I ever wanted to test pressure, I could just disconnect the dryer supply hose and test it that way, right?


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## ColeMaude (Jan 10, 2017)

ebalsley said:


> I bought a gas dryer, Samsung DV5200. It's 22,000 BTU/hr, and the gas connection is 3/8 MIP. The installation manual recommends using a 1/2" supply line and a reducer. My question is why not use 3/8? I have a 3/8" flare valve on the wall, so I could buy a 3/8" supply line with a 3/8 flare to 3/8 FIP adapter. Is there some benefit to a 1/2" line? I don't mind spending a few extra dollars if there's a good reason to.
> 
> Also, it says to add a 1/8" test port immediately upstream of the dryer. Is this really necessary? If I ever wanted to test pressure, I could just disconnect the dryer supply hose and test it that way, right?


Thank you!


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## GASCo (Jan 23, 2017)

ebalsley said:


> I bought a gas dryer, Samsung DV5200. It's 22,000 BTU/hr, and the gas connection is 3/8 MIP. The installation manual recommends using a 1/2" supply line and a reducer. My question is why not use 3/8? I have a 3/8" flare valve on the wall, so I could buy a 3/8" supply line with a 3/8 flare to 3/8 FIP adapter. Is there some benefit to a 1/2" line? I don't mind spending a few extra dollars if there's a good reason to.
> 
> Also, it says to add a 1/8" test port immediately upstream of the dryer. Is this really necessary? If I ever wanted to test pressure, I could just disconnect the dryer supply hose and test it that way, right?


I don't see the reason to increase to 1/2 just for the connector hose and reduce back to 3/8 a couple foot later. If you were to use 20 ft of 3/8 piping I would see a problem. 

The test port might be necessary to adjust the burner manifold pressure. If that is something that is actually adjustable. I have a gas drier but never bothered looking to see if the manifold pressure is adjustable. Anyhow, if it is adjustable - and if it doesn't have a port on the valve itself - you'll need a port installed in the piping so you can monitor the pressure with them burners on.


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## Bret86844 (Mar 16, 2016)

Supply line sizing is based on flow and line length. Your supply line may already be 1/2", with a reducer to a 3/8" valve. Did you have a gas dryer before?

In any case, unless you replace the piping back to the main, 3/8" isn't going to make a different in the few feet from the wall to your dryer. 22,000 BTU isn't a lot of gas.


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## supers05 (May 23, 2015)

3/8 piping isn't legal here. It can only be used to connect an appliance via an adapter. (ontario) 

Without knowing the working pressure, you can't be sure that 3/8 is enough. (at 7"wc and less then 0.5"wc drop, 3/8 is good for less then 31ft.) 

Cheers!


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## supers05 (May 23, 2015)

GASCo said:


> ...
> The test port might be necessary to adjust the burner manifold pressure. If that is something that is actually adjustable. ...


You don't measure upstream of a regulator to measure it's output. In this case; upsteam of the gas valve trying to measure the manifold pressure doesn't work. 

The test port is for a working pressure measurement not for static pressure. (WP= pressure while every appliance is running. SP= the same as disconnecting the gas line to measure without the port.) 

Cheers!


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## GASCo (Jan 23, 2017)

supers05 said:


> You don't measure upstream of a regulator to measure it's output. In this case; upsteam of the gas valve trying to measure the manifold pressure doesn't work.
> 
> The test port is for a working pressure measurement not for static pressure. (WP= pressure while every appliance is running. SP= the same as disconnecting the gas line to measure without the port.)
> 
> Cheers!


Makes sense!! Shame on me!!

I was comparing to the valves that have two ports, one before and one after. But you are right, the before one is not necessary...


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