Gas piping calculation

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Old 03-04-09, 03:44 AM
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Gas piping calculation

I am installing
24 90,000 BTU gas dryers
4 200,000 BTU tankless water heaters and
1 100,000 BTU gas-fired unit heater
what size gas pipe do I need to supply these?
 
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Old 03-04-09, 09:52 AM
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that is not a diy question, that is a contractor question and one that should be answered by the plumber installing all that piping

this is a commercial job which makes it illegal in most every part of the country for an unlicensed novice to install

not to mention we need a lot more information to calculate it
 
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Old 03-04-09, 10:32 AM
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Thank you for your well thought out posting, dantheplumberman. I am aware that this job is for a trade professional and not for the common handyman.

I have my reasons for asking so if anyone has an educated answer, please post.
 
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Old 03-04-09, 04:12 PM
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There are a few ways that this might be done. It could be with an intermediate pressure from the meter to manifolds at the various appliances and then terminal regulators at each appliance or it might be several appliances on one manifold run back to the meter and this method duplicated several times for ease of piping. One thing I'm pretty sure of is that it won't be a six inch header from the gas meter to all the appliances.

Even if I wanted to go through the calculation (which I really don't) I would need scale drawings of where the various appliances were located, where the gas main is located, the pressure on the inlet side of the meter and the size of the meter and probably other things that I can't remember anymore.

It isn't as complicated as sending an astronaut to the moon but it IS quite a bit more than figuring gas piping for a single family residence. Generally you would have an engineer on this size project and he (or she) would do the calculations and provide working drawings. I suspect that the gas utility (and the local building department) will require stamped drawings from a registered professional engineer along with the calculations before issuing any permits for this job.
 
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Old 03-04-09, 08:37 PM
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There is a 2" supply pipe to the meter in the building now and I have been doing some research and have found 2 other similar applications 1 that is is using 2" pipe to the meter and another using a 3" inch pipe, am I missing something?


Originally Posted by furd View Post
There are a few ways that this might be done. It could be with an intermediate pressure from the meter to manifolds at the various appliances and then terminal regulators at each appliance or it might be several appliances on one manifold run back to the meter and this method duplicated several times for ease of piping. One thing I'm pretty sure of is that it won't be a six inch header from the gas meter to all the appliances.

Even if I wanted to go through the calculation (which I really don't) I would need scale drawings of where the various appliances were located, where the gas main is located, the pressure on the inlet side of the meter and the size of the meter and probably other things that I can't remember anymore.

It isn't as complicated as sending an astronaut to the moon but it IS quite a bit more than figuring gas piping for a single family residence. Generally you would have an engineer on this size project and he (or she) would do the calculations and provide working drawings. I suspect that the gas utility (and the local building department) will require stamped drawings from a registered professional engineer along with the calculations before issuing any permits for this job.
 
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Old 03-05-09, 10:41 PM
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yes you are missing a lot. we need to know what pressure is on the outlet side of the meter, total distance to the furthest fixture, what the pressure loss is and where each fixture is in line just for starters. you may need a 2" line or you may need a 3" line but without all the other information we can not even guess at what your specific situation needs. as mentioned this stuff is usually calulated by engineers even though we can do it most of us have only done it on a small scale like a house not a laundrymat.

good luck finding the FREE information you are requesting from a website where people VOLUNTEER their time and expertise to help people with specific and mostly minor problems and questions
 
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