i wouldn't worry about incirculated hot water..it has hot water running through it all the time when running, eh? i don't believe that's the issue. it's the issue of whether your heater has a cool down fan system or not. i have a jandy 2. it says nothing that i've found to indicate there is such a system in it..what it has is 2 schedule 80 pvc pipes with the intent to bleed off hot gases over their length so it's not so hot when it hits the schedule 40 pipe about 8 inches past the schedule 80 tubes. sounds great in principal but given i've been there with melted pipes when in my old system, i forgot to turn the heater off 15 minutes before the pump and came out the next morning to find water shooting all over and my pipes bent like spaghetti. i can laugh about it now, but if it had got to the pipe that goes into the ground..that could have been some major trouble. so, i have a 12 minute pre-shut off switch built into my system to shut the heater off that amount of time before the pump. works great and the only time i would have a potential problem is in an electrical storm and a lightning strike (same problem frankly that a heater with a fan would have..power goes out, your screwed)..so..whatever you do, shut the heater off in an electrical storm