I shut my boiler down a few days ago due to the warm weather, and the contracting of the metal must have caused it to spring a leak (oh no!). I believe it's around the seal for one of the sensors, but I cannot be sure, as the Maxim is spray-foam insulated and I will not have time to tear it down until next summer ... so I'm thinking about using a boiler stop-leak solution. Has anybody else tried these? Will the plug my valves/pumps/sidearm/water-air hx? I could try isolating the boiler, but it'd mean cutting into my pex and doing some plumbing, and even then the circulator would be exposed (I'm of the opinion that I'd have to leave it running to make sure the stop-leak was mixed in well). So bummed. I bought it used and it's been fine for a month, so I have to imagine that the stress of moving it is to blame. It was still under warranty when I bought it, so the guy who had it before me would've just had it fixed had he already had this problem. EDIT - right now I'm using my water heater to heat up the boiler through the sidearm (still coming up to temp), with hopes that the tolerances will change and the leak will stop/dry up. At the least I can get it hot enough for the stop leak (I can't fire it up because the water is shorting one of the sensors).