My Natural Gas Pipe Calcs.

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Old 12-01-12, 05:07 PM
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My Natural Gas Pipe Calcs.

I didn't want to hijack the other thread with my personal gas project. So here is what I have/figured:

I have about 14' of pipe to my boiler. 105,000 BTU input
Another 29' (43' total) to my range. 52,000 BTU input
From there 45' (total 88') to my dryer. 22,000 BTU input
Those are a total of 179,500 BTU with 88' to the furthest appliance.
Current pipe diameter is 3/4" throughout.

I am planning a hookup for a portable generator as well. If I have figured usage correctly, it will need 14,000 BTU. The gen's hookup will T off someplace between the range and dryer. It will not be the furthest appliance.

If I use the 90' column in the .5" WC chart, I need to upgrade to 1" diameter (207 CFH) from the meter to my boiler. After the boiler I can retain the 3/4" pipe (110 CFH).

With my current appliances and the generator, I will be below 200,000 BTU. I do have dreams of expanding the kitchen and adding another over. I figure that would need an additional 20,000 BTU max. Even with the genny, I would stay below 110,000 BTU. Ideally, I would like to have an electric cook top with two gas ovens in this kitchen expansion. If that happens, I won't see an increase in gas usage in the kitchen.

If I figured right, I would need to replace as much as I had thought. I thought the entire main would have to get bumped up. Hopefully this will save me a few bucks. Maybe I should come in with 1 1/4" up to the boiler just to give myself some extra padding for future expansion/needs. It might not be that much different in cost for that distance.

Thoughts? Opinions?
 
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Old 12-01-12, 05:18 PM
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Gas pipe sizing is a little like VooDoo magic..... a little of this and a little of that. No two plumbers say the same thing.


You have 3/4" from meter to boiler now ? That sounds small. Usually it's out of the meter at 3/4" and then bumped up to at least 1" right away..
 
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Old 12-01-12, 05:21 PM
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Well your undersized with the 3/4...

But what is the btu of the gen and why are you tapping that area for your gen?
 
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Old 12-01-12, 05:32 PM
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Well, if I recall correctly. there is a small 1" nipple after the meter and then it goes back down to 3/4" before it enters the house. This house is old. I don't know when the converted to gas, but I imagine it was quite awhile ago. Since the upstairs was converted into an apartment around 1950 and had a gas range, I would think prior to that date.

What really messes things up is the distance to the dryer. The dryer is on the second floor in the back of the house and the gas meter is at the front. Before we moved in, the 2nd floor was setup as an apartment. There was a 3/4" gas line that ran up to that area for a small gas range. When we moved in, I moved the drier up there, but on the other side of the room. To get the gas line over there, it went behind the wall into a side attic and around 2 sides of the room. That really added some length to the pipe.

I think the gen is 14,000 BTU. I'm getting this calculation from converting the HP of the engine (5.5 hp) and converting to to BTU (1hp = 2,544 BTU). I plan on tapping it in that area because it is geographically close to where I want my hookup to be. The exact location is yet to be determined.
 
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Old 12-01-12, 05:40 PM
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Typically you would put the gen near the meter and add a tap there. Then repipe the home at a later date .
 
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Old 12-01-12, 05:46 PM
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This is a portable generator and doesn't require a lot of BTUs. The last thing I need is to have a generator on my front lawn as easy pickens. The place where I would like to have the generator will keep it somewhat concealed and hopefully help reduce sound transmission. As you said before, I need to repipe without the generator.
 
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Old 12-01-12, 05:50 PM
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If I locate the hookup for the gen in the back, I could also use it to setup a nice steam box so I could do some wood bending.
 
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Old 12-01-12, 06:13 PM
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I would probably run some 1 1/4 in then pipe accordingly from theer. Better to do it once and have enough gas then be border line.

Draw a diagram. I could help you figure.
 
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Old 12-01-12, 07:33 PM
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Old 12-01-12, 07:39 PM
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Quick question... What is distance from boiler to that stove?

Oh never mind....

Be back in 10. Will draw it up....
 
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Old 12-01-12, 09:21 PM
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Well you are the guy whose calc comes over sized. What that other gent was saying in another post. Yes it would seem why run 30 ft of 1 " when you can run 15 ft 1" and 15 ft 3/4???

Which is how your home calculates.... So in the end your home will have larger piping then needed unless you calculate wisely.

Most contractors dont deal with that for labor purposes. They say why reduce. Run the same pipe an extra 20 ft... Its only one length of pipe... easier IMO.

Have you ever cut and thread pipe building row homes???? I have...

It is what it is. This is what I came up with...

Name:  Droo.jpg
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Old 12-01-12, 09:34 PM
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yes cant see pic.... i will work on getting it bigger....
 
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Old 12-02-12, 04:35 AM
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yes cant see pic.... i will work on getting it bigger....

Read more: http://www.doityourself.com/forum/pl...#ixzz2DthVlU2y
This is why I hate the embedded pics. They are too small to get the detail we need here.
 
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Old 12-02-12, 06:43 AM
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Try this... .
 
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Old 12-02-12, 07:21 AM
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Ok. So what is the reasoning behind running the 1"? Since I have 3/4" installed now, my intention was to upgrade to 1 1/4" to the boiler and then connect to the old 3/4" after? Is there an advantage to the 1" for that length of pipe? There definitely won't be any appliances installed in that area.
 
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Old 12-02-12, 07:31 AM
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Ok. I think I see why. To give me room for the future oven and to also run the genny. I'll see how much extra that costs. If I'm running off the genny, dryer use is going to be a low priority. If we need it, then we can not use the kitchen appliances at the same time.

Maybe I should see how much I need to run my grill off natural gas. If I'm going to install an exterior hookup, it may be worth it.
 
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Old 12-02-12, 07:50 AM
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Hah! My grill would be another 63,000. I would have to run the 1" all the way to the back of the house. Then I'd need 3/4" off the tee for the grill. That's gonna an expensive hose. Hmm. At this point, I don't know about that. I think it will be most economical to just run the new 1 1/4 at the front so I am no longer undersized.
 
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Old 12-02-12, 07:56 AM
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Yes your gas set up and btu is border line. When you figure it, yes you can go from the 1 1/4 right to 3/4 but you will be limited and maxed at btu.

You can run 15 ft 1" then change to 3/4 the other 15 ft. Thats what that other poster was suggesting.

Where you reduce you calculate that you are putting a tee there, But when I did the math it cam out that its easier to run 1" the whole distance.

In your set up you will have plenty of gas at any point in your line for future upgrade.

Some houses are like that, and some are on the other spectrum where the BTU is spot on.

Your issue is you have a low btu load with a long 90ft run
 
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Old 12-02-12, 09:19 AM
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Yes your gas set up and btu is border line. When you figure it, yes you can go from the 1 1/4 right to 3/4 but you will be limited and maxed at btu.
Right now I don't want to spend too much on this. So I think just upgrading to the boiler will be my plan and then do more if I need to at a later date. Thanks for the help. I'm going to have my friend do the work since he is experienced in this area. Once I get the gen and know for sure what I need to do for that, I'll give him a call.
 
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Old 12-03-12, 07:06 PM
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Ok. So I I didn't get the BTU calcs for gen right. I don't know why I didn't see this earlier, but under load, the gen will consume 10,000 BTU per HP. So that would be 55,000 BTU for my generator. I will need to upgrade to 1" all the to the back of the house to run everything. This does make more sense than 14,000 BTU.
 
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Old 12-07-12, 05:44 PM
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Off topic but droo I did your calc with 14K from what you told me no?

Revisit your thread regarding this.
Bump. Mike, you must have missed my latest posts. See above.
 
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Old 12-07-12, 06:40 PM
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Yeah I did this quick for you. So check it.


Depending on the length why not just run though the basement from the gas meter to the gen???

Use trac pipe. !/2 is good if less then 50 ft.

May save $$$

80ft @ 1/2 = 57k
 
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Old 12-07-12, 06:53 PM
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Yeah. That's the stuff my buddy used to extend the gas line for my dryer. I'm sure he will want to use that again. Don't forget I need to upgrade my gas line already. I don't think going all the way from the meter to the gen is going to do much for me.
 
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Old 12-07-12, 07:00 PM
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Yeah droo I forgot what you have in the home. I think you had 1" then 3/4" ? I know you had a post....

But if you run from the meter and the home side is good it will not matter. Run from the meter will not effect anything.
 
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Old 12-07-12, 07:04 PM
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I have all 3/4". I need to at least upgrade from the meter to the boiler. Then I could run 1/2" all the way from the meter to the gen. I don't know how the trac pipe is priced, but it does come in fixed length, does it not? I might as well replace everything I have anyway. Once I get my friend over, we'll figure out exactly what to do.
 
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Old 12-07-12, 07:56 PM
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Trac pipe you buy a roll and cut to length. Its like $5 bucks a ft. More with the bigger pipe. But save on labor big time. Well worth it IMO.

You need certification to install. ( I'm certified...LOL)

I would do all trac pipe if it were my home...
 
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