Is flexible copper okay for connecting gas line from black pipe to water heater?
First things first. That flexline you are talking about is not copper but a brass aloy. The safest way to connect the appliance to the houseline. Be sure to use the correct adaptors though as they will not connect to a plack pipe with them. In the old days sometimes the 5/8 type would be connected to the black pipe but that wasn't correct as the threads wern't the same and ther was no flare. Do not use any coppen with gas as the copper reacts to the mercaptian sulfate in the gas (thats the odorizer) and turns it into copper sulfate that eats away at the copper line. Also use any new type one piece flexline some of the older flexlines had a but weld at the ends the soldier at the weld will breakdown after time. They have not sold that type in over twenty years though
The majority of the answers on this question get it wrong, no surprise. The truth is that it is now fine to use copper pipe with natural gas, and it is now done all the time. Once upon a time the additives that make natural gas smell bad, which are Thiophane or t-butyl mercaptan were used in much heavier amounts, which were then corrosive to the copper pipe. this is no longer the case, and in fact it has been safe to use copper now for over a decade. Please read a past Yahoo Answer on this topic from a year ago Is it safe to use copper pipe with natural gas? which answers this very well. Also the web site www ppercanada.ca topic copper natural gas systems proves they build with it in canada all the time, and in many areas of the US it is being done as well. Some local codes may be out of date though. One thing I will mention is a direct connection of copper from black iron pipe will cause electrolysis and corrosion. A 6 inch piece of brass pipe should be used in between. Also flexible stainless connectors are readily available, so why not use one? It just bugs mw when so called plumbers and former gas company employees on here misinform the public. You should do a little research before answering if you have doubts people!
I feel D2 had the best answer. not having the draft hood the appliance will pull harder to evacuate combustion products.It will pull the heat through to quickly and the efficiency will be lower. the draft collar is not to prevent back drafts or flame roll out in fact there is a greater risk of carbon monoxide with it on from an operational viewpoint because the combustion gasses can escape from the flue at the draft collar if the flue is blocked. Having said that You need to determine what water heater you have installed. The heater has to be Mobile home rated(I am assuming that it is in a MH because it is in an outside alcove.)if the home is manufactured after 1973 it falls under HUD and installing something other than original will void the HUD sticker and make it illegal to sell until it is brought back into compliance. Your insurance company can deny a claim for the same reason. IF you installed a DV type water heater it will not function properly WITH the draft collar. This type of heater is direct vent or sealed combustion and requires combustion air to be brought in through a vent sealed to the heater through the floor.These heaters are much more expensive and are rated for an inside alcove in mobile or manufactured houses only.
