Gas Piping Question

[Tim]

I am getting different answers on this one in the field and I'd like a little help.

I need to supply gas to a new hybrid water heater. According to the manufacturer, it requires a 3/4" input line.

The gas line comes directly from the gas meter via a 1" line to the water heater closet. There, it goes into a Tee. The Tee is a 1" (from the meter),

3/4" that feeds the rest of the house (furnace and stove), and 1/2" that feeds the existing water heater. Some say I have to remove the Tee and go with one that gives me a 3/4" line to the rest of the house and a 3/4" line to the water heater. Others say I can just put a bushing on the 1/2" line, taking it up to 3/4" and I'll be fine.

I've tried talking to the manufacturer and they do not want to get involved in "construction matters" (liability worries).

This is in California (1/4 pound pressure gas).

Any thoughts? Go with a new tee or bush up the old one? Or any other idea?

Thanks Tim

[RicodJour]

Under the bush-up logic, you could have a 3/4" line come into the house and bush up to a 1" and have it be the equivalent of a 1" line. I don't believe that is quite the way it works. With the smaller pipe you have a restriction, which is the limiting factor.

I am surprised that the manufacturer didn't give more guidance on this. The normal manufacturer response in such a situation is along the lines of "you need 3/4" so use 3/4" for the supply line, not just part of it."

R

[Wayne Whitney]

What is demand of the new water heater in BTU/hr?

To properly answer this question, you need to tell us:

The length of the 1" pipe from the meter to this Tee. The length of the pipe run from this Tee to the new water heater. The demand of the other appliances (the furnace and stove).

Basically, in designing gas piping systems, you are allowed 0.5" w.c. pressure drop from the regulator to the outlet. Using a 1/2" port on the tee with a 3/4" bushing will cause more pressure drop than using a 3/4" tee would. Depending on the pressure drop in the rest of the system, this may or may not be acceptable.

Cheers, Wayne

[dpb]

Tim wrote: ...

What could possibly be so hard about simply putting in a 3/4" tee and going on?

--

[jamesgangnc]

Agreed, T in at 3/4" point. If it makes it more convenient you could replace some of the 1/2" with 3/4" and T in further down. T'ing into the 1/2" could create flow problems for the other appliances. I would not do that. As another poster pointed out there are formula for calculating the pipe size based on the demand of each appliance and the length of pipe.

[Tim]

Really nothing I guess.

We are not plumbers. We are doing this as part of a huge remodel. We can't use "unions" as such and we know we have to use a left/right connection. Personally, I have had bad luck with right/lefts over the years. It always seems like one side is too loose when the other is tight. I get tired of fighting it. I always make sure both sides start at the same time and all that, but it seems like it just never goes on cleanly. It was just me trying to get something done easily and without a problem.

[Steve Barker]

just put the 1/2" line on the water heater. Especially for that short distance. Sounds like your "T" is within a couple of feet of the heater. You'd need a dam big heater to require any bigger line. Most water heaters can be run on a 3/8" line.

[Steve Barker]

Well depending on where the next union is, (or IF there even is one) he may have to deconstruct the entire run to the furnace and stove.

[PeterD]

Bottom line: if you are not qualified to do the work, get someone who is.

[Tim]

I believe most general contractors are pretty much the same. We all came into this doing something like electrical or tile or carpentry or something else and we get licensed to be able to do it all so we don't have to bring in someone who may or may not be more qualified. The fact that we do not know EVERYTHING about a given topic doesn't necessarily mean we are not qualified. We could debate the "is the general contractor REALLY qualified to do everything?" question for 100 years.

[George]

A general contractor is not licensed to "do it all" in any jurisdiction I know. And just because someone can build a perfect foundation or set the most fabulous tile job doesn't mean they understand gas piping or whatever else. That doesn't diminish them and there really is no debate.

Just consider your present situation. You say "someone said this" and "someone said that" and then pose the question in a newsgroup where your only hope is to get more "someone said this" and "someone said that" responses. Will you decide by tallying up the responses?

My buddy had a log home built about five years ago and hired a gc who is very skilled but thinks he can do everything. The foundation elevation is perfect, the foundation is dead on square and level and the logs and beams are installed perfectly. But my buddy is having constant issues with the heating system, aerator pump and electrical system because the job looks good but the guy didn't understand the fine points of what he was doing.

[PeterD]

That may be (or 'is') true, but for gas projects you may find that there are additional (legal) requirements that you must be able to meet to pass the buiding inspection. My comment is based on this being a gas line (were it a water line, I'd have not bothered). Just that most places are *really* sensitive about gas installations! (yep, it's

*almost* impossible to blow up a house by plumbing the crapper wrong!)

[Tim]

Here in the left coast, as a GC, I can do everything except fire sprinklers and well digging. The interesting thing for me is that I cannot sell myself as a plumber, let's say, UNLESS I am also doing framing, electrical and tile, for example. THEN I can be a plumber.

My original question about unions in gas lines was in some part to evoke a debate. I also asked the inspectors in the city I am doing work in right now. Even THEY had different answers. One guy only really has an interest in life-safety issues and if something works, it works. He'll accept things not in the code based on if there was really no other way to do it and it isn't a life-safety issue. A union for him was, in some cases, potentially acceptable. Another guy said no way, under no circumstances, impossible, don't even think about it. You read the responses, some yes, some no. I guess it is enough of a grey area that no one can give a good answer. Some guys said "Look at a gas meter, there is a union there". Here in California, the gas utilities also run plastic pipe from a gas main to a meter (wouldn't I love that). But there is no way I can run plastic gas pipe inside a house. Some cities won't even let me run corregated stainless steel gas lines (even though it is in the code) becasuse it takes jobs away from union pipe fitters.

Different strokes for different folks...

[ransley]

How many Btu is this "hybrid" and whats a Hybrid, is it Tankless? 3/4 gas is a monster commercial tank, My 16 unit apartment tank has 3/4" gas going to it, so I will assume its a tankless and give you my experiance on my tankless. If you dont get full required gas flow you wont get 100% output and will be pissed all winter. Regardless of what you see in your line size a Manometer must be used to verify gas supply, some meters may need adjustment or replacing, in winter and with other apliances on gas flow is reduced and you must figure that in. In winter my total supply can go down 10-15%, you must plan on that. 3/4" is recomended, and after so many feet 1" is needed, its standard and tabled. If its Tankless gas flow must be tested or you will enter the ranks of "tankless sucks" by guessing and under supplying it. Sure it may work today, but on the coldest day around Christmas when every neighbor has every gas apliance running full bore you may have a cold shower. Manoneters are cheap, and the gas co can help you on winter pressure reduction estimates. I would not hook to

1/2" anything.

[ransley]

"Just Put 1/2" when mnfg says 3/4", no wonder you cant get a tankless to work, your answer is a hacks answer. Did it ever occure to you his Hybrid needing 3/4 , needs 3/4" and is probably tankless. The only Tankless ive seen leave you cold was put in by hacks undersizing the gas. In reality after checking it with a manometer with competing apliances on full and calculating winter reductons, he may just need major meter and line work. Right , just use 1/2", what a joke.

[fftt]

Your "hybrid" sounds like a mini-tank with tankless heating capacity / gas usage. Getting the pipe sized correctly is important to heater performance.

What is the maximum gas consumption of the heater? I'm guessing something in the 200K btu/hr. Depending on run length and other gas demand; 3/4" should be fine

Do a proper analysis of your gas piping, considering all your current & added gas usage...its not that difficult

google natural gas pipe sizing

and choose the third hit

or take a look at 5th hit...its a bit more detailed

Making up a connection via a "left/right" can be a PITA but if you use GOOD quality teflon tape & a couple extra wraps that will be more forgiving on the connection. Also, building in some piping compliance with make the connections easier. Consider CSST which gives you the benefits of "unions" without the arguments from inspectors....well, if CSST is allowed in your area.

cheers Bob

[ransley]

"should be fine" my table shows 1" after 10 ft if I remember it right, if flow is minimal 1" might be needed for all of it. You can live with a heating system starved a bit and stay warm, but I dont like cold showers.

[Tim]

This is a true hybrid. Look up the "Eternal Water Heater". That is it's REAL name. The Eternal system is a very good heater and puts out something like

26 gallons a minute. My homeowner is getting the larger of the two systems. Most people have never seen anything like this system.

How many Btu is this "hybrid" and whats a Hybrid, is it Tankless? 3/4 gas is a monster commercial tank, My 16 unit apartment tank has 3/4" gas going to it, so I will assume its a tankless and give you my experiance on my tankless. If you dont get full required gas flow you wont get 100% output and will be pissed all winter. Regardless of what you see in your line size a Manometer must be used to verify gas supply, some meters may need adjustment or replacing, in winter and with other apliances on gas flow is reduced and you must figure that in. In winter my total supply can go down 10-15%, you must plan on that. 3/4" is recomended, and after so many feet 1" is needed, its standard and tabled. If its Tankless gas flow must be tested or you will enter the ranks of "tankless sucks" by guessing and under supplying it. Sure it may work today, but on the coldest day around Christmas when every neighbor has every gas apliance running full bore you may have a cold shower. Manoneters are cheap, and the gas co can help you on winter pressure reduction estimates. I would not hook to

1/2" anything.