Will all of this run on one 3/4" natural gas line?

wynswrld98April 5, 2013

I'm getting different opinions from plumbing contractors I'm getting quotes on to replace my old electric water heater with a gas tankless re: if a new line needs to be run from the gas meter to the new tankless (85' run) or if the whole house can run off the 3/4" line which is already running right next to the electric water heater.

Here's what I have:
Gas Furnace: 154,000 BTU
Gas Fireplace Insert: 40,000 BTU
Existing Gas Tankless Water Heater: 199,900 BTU
Additional Gas Tankless Water Heater to replace electic water heater: 199,900 BTU
Gas Clothes Dryer - ? BTU
Gas Cooking Stove/Oven - ? BTU

I already have e-mailed my gas company the same specs above for them to verify the meter is sized appropriately to handle the load but my question remains re: how do I figure out which contractor is correct re: if the one 3/4" line can handle all of this?


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P.S. the 3/4" gas line is all iron, not the yellow flex line.

    Bookmark   April 5, 2013 at 10:32PM
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592,900 BTUs identified, with more to be added?

I do not have a gas table handy but that sounds like way to much for a single 3/4 inch line.

    Bookmark   April 6, 2013 at 10:47AM
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No more being added, that was the complete list. Ofcourse not all of that would be running simultaneous. I don't know the BTUs for the gas dryer and stove/oven as they are older but was able to find out the exact BTUs for the rest.

    Bookmark   April 6, 2013 at 6:30PM
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The nameplate for the appliances should have their BTU marked.

    Bookmark   April 7, 2013 at 1:15PM
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Gas Dryer: 22,000 BTU
Stove/Oven: 67,000 BTU

I just looked at the gas piping and the existing tankless water heater is piped such that the line that goes to it splits right at the meter into it (which is on other side of wall from meter) so essentially of the list above everything would be on the one 3/4" gas line running in the house except for the existing tankless water heater.

    Bookmark   April 7, 2013 at 3:51PM
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A short length right after the meter should not be as much of an issue as a long run of only 3/4 inch.

    Bookmark   April 8, 2013 at 4:51PM
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Right, that is why I brought it up since it should be considered

    Bookmark   April 8, 2013 at 5:42PM
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bump. Any experts out there? If so, thanks in advance!

    Bookmark   April 9, 2013 at 11:28PM
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I've been talking to the natural gas company to find out if my existing gas meter is large enough to deal with everything I have planned for it and the response was that it needs to be upgraded. However, they want to charge me $1325 to upgrade the meter. Major OUCH!

I asked what the BTUs are for the existing meter so I could gauge how much of what I have it supports and the response I got was 300,000 CFH. I did some Googling of converting CFH to BTUs and didn't understand the responses.

Anyone know how to convert the 300,000 CFH figure the gas company gave me to see how many BTUs it will cover (from my list of BTUs above)?

If I have to shell out $1325 to the gas company I'd guess switching the electric water heater to tankless is a "no go" based on way too expensive with tacking on the meter upgrade, just would make more sense to keep an electric water heater, I don't like it but it's hard to justify massive amounts of $$ to go tankless. But if my meter is close enough (the reality is only two people live in the house, all of the above things would not be running simultaneous) then perhaps it is a go and I skip the gas meter upgrade.0


    Bookmark   April 10, 2013 at 6:13PM
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1 cubic ft of natural gas is approximately 1000 BTU

    Bookmark   April 10, 2013 at 6:20PM
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So when I total up all of my BTUs it's 682,800. So how do I relate that to 300,000 CFH my current meter is able of providing? I'm guessing the 'H" in CFH is 'hour' meaning 300,000 cubic feet per hour but BTUs are stated per an instant in time so do I need to do some conversion of time here too to figure this out since CFH is apparently per hour but BTUs are per second or some such?

I'm completely new to all of this so I appreciate your patience but we're talking $1325 just to upgrade the meter and I'm trying to figure out how much of the BTUs the current meter is capable of handling.

Thanks again!

    Bookmark   April 10, 2013 at 7:34PM
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This is a quote from the gas company when I asked how CFH and BTU relate to each other, is what she saying correct?:

CFH is cubic feet p/hour & BTU's are british thermal units, same difference. The capacity of the 630 meter that would replace your meter is good to 1.2 million cubic ft p/hr.

    Bookmark   April 11, 2013 at 11:58PM
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