question on lp gas piping

[dec]

I have a question on running propane lines in new construction. Now some time back we put in some heating systems in a subdivision that didnt have natural gas. Everything was pipe by the plumber for propane and not much more then a year later natural gas came to the subdivision.

Now we ended up going out and converting the furnaces and water heaters for natural gas after the same plumber came in and redid all the gas pipe being he only sized it for propane.

So my big question is ........... is there any problem in sizing gas lines on a new house for natural gas instead of for propane in case it ends up natural gas down the road ????????

I would have thought that would just have more capacity available if it was needed and if it were changed to natural gas ........ you wouldnt have to redo it again. I cant see where the larger gas pipe would be all that much more if it was a builder that was not a nickle and dimer ........ and this builder isnt.


so tell me , other then material costs, would their be any reason not to size the lp piping for natural gas if its being done in black pipe????


Just like houses that put in on demand water heaters and then figure out they should have used a larger unit, but now the piping is too small for the larger unit. Wouldnt it make sense to possibly use a little larger gas pipe ??????

[oil lp man]

No problem, the bigger the better.

[progressive]

I always pipe for NAT gas load. Then you do not end up with what you have now, a unhappy customer having to spend more money to repipe a year old home. Just good business.

[cem-bsee]

make it easy -- run 1.25inch BI to furnace area, dropping off 0.75 tees for dryer, stove, HWH, fireplace, OD grill = "main" -- then make branches smaller -- kit @ 0.75" if "long" --
good storage -- nobrainer --

pipe is cheap --
distribution pressure may drop or fluxuate!
think long term -- furnace may be there 45y.
HO may add 30% more house in 10- 15y.

I used 1.25 in early 1960s because that was ok to thread by hand.
"make it big, bury it deep"

[Black Adder]

If 2lb gas pressure is available there will be no need to repipe the systems at all. Check if this is an option...

[dec]

I dont have a clue what your saying Black adder.

what are you talking about .... 2 lbs. If the piping was in sized for propane ....... dont think it will fly on natural unless your saying you dont need as much on on demand water heaters.

Im guessing thats maybe what your saying, that you can get by with less then your 3.5 lbsnatural or 11 lbs propane pressure on the on demand water heaters ????? Seems like I have seen that on a few brands installation manuals.

[hvaclover]

If I was even fairly certain of nat gas coming thru I would definitely size for it.

[hearthman]

For example, in each of these cases, use 0.5 wci pressure drop, 0.60 sp gr for NG and 1.50 sp gr for LP. Use 11 wci for Lp and 14 wci for NG: 50 foot runs


3/4 Sch 40 black iron pipe
255 mbtu lp
151 mbtu NG


1/2" type 'K' copper tubing
79 mbtu LP
47 mbtu NG

Usually, you can increase the gas pressure at the point of service and get by with undersized lines. For NG, this may entail the gas utility installing a 12.2 wci spring in the meter's regulator or a 2 psi regulator for either NG or LP. This also works when you add high BTU loads such as pool heaters.

If they used copper, you must determine from the utility if their gas contains more than 0.3 grains of hydrogen sulphide per 100 cubic ft. If so, must replace with iron or CSST.

When dealing with copper, you need to determine what type of copper tubing: types K, L or AC/R tubing. Type K has a smaller diameter than L. AC/R is referred to by OD while K&L use the ID. Therefore, 1/2" K& L + 5/8ths" AC/R in the sizing charts.

Because LP has about 2.4 times more BTUs per unit volume of NG, the same pipe under the same pressure will flow a lot more BTUs of LP. However, it isn't exactly 2.4x as you can see above. Multiply 2.4x 151 BTUs pf NG in the first case you get 362.4 yet the charts say you'll actually get only ~255 of LP. This is partially due to the higher friction loss of the more viscous LP than NG.

HTH

[t527ed]

we don't do a whole lot of propane but when we do we size it for ng.

[contactor]

No problem here.