Temperatures going into the low teens here in ATL, not traveling at the moment, but was wondering if having the engine heater on will help in any way to prevent any freezing issues? I've secured the bays that need it with some light bulbs(still have a few incandescent bulbs) to keep the freeze factor low. We had single digits 2 years ago at Christmas and got through that, but thought about the engine heater. Seems like I read that some engine heaters don't even work anymore, how does one check to know if their heater is working? Thanks in advance, I hope everyone stays warm.
Engine heaters use a lot of juice and the heat is very localized. You need to check the wattage on the heaters and see if it's working with one of these meters: 110V watt meter (use search engine). HD or Lowe's will have them.
Best not to use a block heater unless you are going to start the coach within a couple of hours. If you have a 50/50 antifreeze in the engine, the cold won't hurt anything no matter how low the temp gets. Charged batteries won't freeze and be damaged. Just drain the water with the OEM drains from the hot water heater, etc. Flat reptile/grow tray heater is good for water tanks.
Pierce
The cord will be warm if the heater is working .
You can check it with one of those non contact (infrared thermometer) temp guns. Lift up the bed platform and aim the temp gun at the engine block on the driver side between the starter motor and the exhaust manifold. Get a cold reading, then turn on the block heater. Wait about 15-20 minutes and take another reading. Should see a BIG jump in engine block temp if the heater is working.
Good tutorial on changing out a block heater on the 8.3L Cummins:
Block heater replacement Cummins C8.3 325 hp (https://www.foreforums.com/index.php?topic=41717.0)
Like Pierce said, if your antifreeze is ok, the engine will be fine just sitting there. Running the block heater would do nothing to protect the rest of the coach.
Mike and Chuck both give you easy ways to check the block heater.
If you are really worried about your winterizing job, just run your furnaces during the cold snap.