I've got an aging (but still cookin') Max-E-Therm heater with a hairline crack in the outlet pipe. I've ordered a replacement, and the PVC union came right off with just a little effort, but I can't get the pipe out of the manifold. I tried dousing it with WD40 Rust Penetrant spray (it says it works on and is safe for plastic) and giving it a few minutes to work; I did this a total of three times over about an hour and a half, and no dice.
I'm using a fairly good sized rubber strap wrench to try to remove it, and I'm getting a fair amount of torque on it, but it's just not budging. I've tried some whacks with a rubber mallet as well.
Any hints on how to approach this? I really want to make this work, because replacing the entire external manifold is a $250 proposition. Should I try a pipe wrench? A bigger/better strap wrench? Some other tool?
One of many pictures can be seen on this Amazon listing for the whole manifold; unfortunately (possibly a big "unfortunately"), my version does not have the ribbed tubes like this replacement. Mine has smooth tubes.
Amazon.com : Sta-Rite Natural Gas/LP Gas Pool Garden