Working on a natural gas stove install. When I had gas run into the house twenty years ago, the plumber put all of the fittings together using black Permatex and it is now rock hard. I had the plumber put a "T" in the main line for this stove install, so I have an easy connection to the main line [B][U]IF[/U][/B] I can break loose either the cap on the end of the 4" nipple or the nipple from the "T". The main gas line, "T" and nipple are 1 1/4" black iron pipe. I needed the pipe oversized as my house is 600+ feet from the gas line on the street and needed more "volume" of gas according to the gas company. Anyway, I'm expecting it to be an absolute pain when I try to take off the cap or the entire cap/nipple from the "T". Does anybody have any suggestions to soften up hardened black Permatex? I have a heat gun, but definitely don't want to use any open flame on a gas line to soften up the Permatex. I plan to scrape any built up Permatex from around the exposed threads and fitting, but looking for some "miracle" solvent that might work into the hidden threads. I have a 24" pipe wrench that I plan to use with a "cheater" pipe, but trying to get this apart as easy as possible. Thanks in advance for any suggestions.

I have a tankless water heater for a bathroom that produces hot water to the sink but when I turn on the shower, the cold water has to be turned on for the hot water to flow. In other words, the hot water will not flow unless the cold is turned on. I don't understand why it works fine at the sink but when it comes to the shower, it does not flow. I ran the shower to see if the lines were crossed some how, but when I touch the pipes near the shower valve, the hot is hot and the cold is cold. I tried turning off the cold water ball valve behind the shower in the access panel and leave the hot water valve turned on to see if the hot would run but it doesn't. I'm confused.