Hi all,
I’m replacing a couple stoves in a rental house I own. Old stoves were LP, but the new one’s I’d like to install with nat gas. These are small 20″ wide apartment stoves with tiny ovens. Burners are rated at 9,100 btu/each and oven 17,000 btu (53,400 btu total possible I guess).
The old stoves were fed with a 3/8″ (OD) flex copper. Local Utility allows flex copper lines for nat gas (as long as flare fittings aren’t in walll cavities obviously).
I’d be attaching the flex to some 1/2″ black iron gas pipe in the basement, and the flex run would be about 30′ to each stove.
Anyone have an idea if the size on my existing flex can handle the btu’s for these little stoves? As I undersstand it, LP operates at higher pressure. Should I be worried about getting enough btu’s thru with natural gas?
Thanks for any ideas.
Edited 6/12/2002 11:49:27 AM ET by Stray
Replies
Is the whole basement/crawlspace gas pipe 1/2"? If so you may have to calculate the total load and determine the proper main line to supply the house.
It is common in our area to pipe in 1" blacke pipe as a main trunk line, drop from tees to specific appliances with 3/4" or 1/2" to match BTU consumption.
Stationary equipment is hard plumbed with drip leg into the control valve. Stoves and etc are plunbed in black pipe to the back of the appliance and valved with an attached flexible stainless supply line to the appliance.
Local codes do not permit copper on natural gas because the "odor" chemical causes the copper to corrode and flake into the line. The corrossion offall will fowl valves. There also may be a chance (?) of line failure and a leak................which I've never seen or experienced.
FYI.....................................................Iron Helix
IH,
Does the local code dictate the 1" supply or is that just the common practice? What code do you work to? IMC 96, IFGC 2000?
Stray, most codes that I have dealt with, in regards to fuel gas pipng, have pretty good sizing charts. Get a copy of the code that applies to you, or get a copy of the International Fuel Gas Code 2000, and see what you get when you follow it.
BTW, LP is commonly (though not always) rated at 11" wc pressure and NG at 0.5 or 2 psig. Also, LP has more energy per volume than NG. Size the pipe based on the pressure service and fuel you have, or if any of this makes no sense, call the plumber.
The local meters are 1" for residential set ups. 1" will supply most homes, but we do collect the data from all houshold appliances/heaters etc and use corresponding charts to size the loads and distances for exact piping size plus the correct size of flex connectors. Ditto for LP.
Sorry my answer was so general, but the data was incomplete. At least we got the thread moving.
....................................Iron Helix
Thanks for getting the thread moving...
Piffin, Yep a DIY (Gag, spit, roll the eyes ;)
I'm a landlord and I rehab places to hold and rent. It's my 2nd job, but I'm definietly no plumber (More of a carp).
The main NG line coming into house is 2" Takes off from there to 1/2" black iron lines
one 1/2" line runs 15' to 50 gal DHW tank
two 1/2" lines run 20' to stoves (already)
What I want to do is leave the 3/8" OD soft copper lines in the walls, and just put NG through them instead of LP. Anyone have a link to National Fuel Gas Code, or related site, that would have sizing charts? I'd rather not drop $80 to buy the code book for this (got to spend the $ on diapers instead of code books). Thanks all.
Use what you've got, obviously leak test, etc. .
17 kBTU/hr is such a small load 3/8 is plenty big.
The mercaptans (usually methyl) for odor are H2S based so do react with Cu to form sulfides, with a very remote chance of orifice fouling in the future. For safety, Codes that allow Cu usually specify L or K tube where the thickness is such that centuries would be required to react all the way thru the tube wall.
For some specifics on LP to NG conversion, look at:
http://www.ccbda.org/publications/pub14E/14e-publicationp1.html
Junkhound,
Wow, what a great link. Just what I was looking for re. sizing charts, etc... THANKS!
Regarding your recommendation to use what I've got because "17 KBTU/hr is so small".... The 17k BTU figure was only for the oven. Burners (9,100 btu/each) and oven totaled up = 53,400 btu possible draw. At this level, would you still suggest sticking to what I have?
I'll double check w/ the utility co. tomorrow to see what nat gas pressures they typically deliver to the meter. Then I'll know for sure which chart to use.
Thanks.
Do yourself a favor. This is dangerous stuff. Hire a competant pro. You obviously do not have the knowledge to deal with this dangerous stuff.
Sorry to be so blunt but your questions are scary!
Gee Wet Head, thanks for being so encouraging. I'm not sure what was so "scary" in case you care to elaborate. Anyway....
Finally got my hands on a copy of the 2000 International fuel gas code.
Copper is allowed, so long as the sulfer content of your local supply is below a certain level (Most areas, including mine, are well below according to local utility co). At this level, scaling and related orifice clogging is not an issue.
According to the sizing charts for 0.5psig my 30' run of 3/8 OD will NOT handle the btu/hr rating necessary however (Damn). I'll have to stick with my LP tank; or re-pipe it anyway. Looks like I'll be using 1/2" black iron if I do it at all. Definitly not the quick fix I was hoping for (my usual luck).
Thanks all.
Here is what is scary. Someone who is not knowledgeable about gas lines messing around with them. If you think there is nothing scary about that.... well.... that is twice as scary.
PS. Did you know improper gas line sizing can kill you? It has killed people in the past. I know you say that is why you asked here. There are very few here who are remotely qualified to size gas lines. And even then without seeing the situation it is risky giving that kind of advice.
Edited 6/21/2002 9:22:09 PM ET by Wet Head Warrior
Wet,
I appreciate your candor, and do understand where you're coming from.
I have healthy respect for things that can kill me, and yes...that's why I was trying to do my homework first. Agreed that you can't ask for advice over cyberspace and expect people to comprehend the situation fully enough to have your life depend on it. That's why I was looking for sizing charts, etc...
This forum is a great resource, and one I turn to regularly. It is not, and should not be, anyone's sole resource for such important matters.
-Stray (still alive, despite of my mischievous ways)
Based on yout last response I feel better about it. It really is none of my business but I do care about this stuff. Good luck.
Our installations are also 1 inch trunk lines , reducing in the wall to 3/4 inch to any outlet. I don't know why, but I do as the romans do. The only flex line we use here is only about 3 ft for connecting appliance, with connectors already installed.
Tim Mooney
I use LP not natural but here's how I go about sizing.
Start with a call to the appliance manufacturer. They can tell you how much flow they requirer to feed the beast. I give that info to the licensed technician who will do the install. He can figure the line size based on lenghth of line, etc. If he can't figure it, he isn't licensed and maybe shouldn't be doing it...
But I do things like that thru delegation. Sounds like you are DIY?