Hi to the 600+ members of this forum which will continue to be a great resource as our coaches age.
Experienced an END to hot water (and heat) from our Hydro-hot furnace. Check of control board didn't show any warning lights and had plenty of electric, diesel & coolant.
Reading the Shop Manual troubleshooting manual I started with the very first area of 'control thermostat' which was open (via simple Ohm meter) and only reading 2.7V back at the control board. I replaced the thermostat wires with a 5amp blade fuse and the system started right up the way it should have.
Ordered the 'gold standard' thermostat and installations instructions from Roger Berke
www.RVHYD.com and took the time to do maintenance on nozzle and fuel filter while boiler was cold. First time I've been into the guts of the furnace. Quite a piece of engineering. Anyway...
Pumped out the overflow and 1.5 gal of coolant first. Changed fuel filter (think it was original - printed with Hydrohot). Unbolted and pulled burner - very careful of hoses, wires. Replaced nozzle and checked electrode gap. Opened air intake fully per several postings. Removed and replaced Control Thermostat using a deep 7/8 socket before re-installing burner making thermostat removal much easier. Pumped coolant back into boiler, started electric coil - IT WORKED, then started diesel, it shut down after 3 minute cycle because fuel had not fully primed. Just shut off diesel switch turned back on and it went thru normal cycle. Lots of smoke the first 10-15 minutes because old nozzle was pouring fuel instead of atomizing. I had reported this last winter and finally got-around-to-it today. After old fuel had burned off the exhaust is barely noticeable and smells more like a clean running diesel engine than a mosquito fogger! Made sure the diesel would cycle off and no leaks before buttoning up. ALL RUNNING LIKE A CHAMP!
Whole process took a little over 2 hours to accomplish by myself and only hit head once. Sat in lawn chair most of the time to work on it (except when I hit my head) and no heavy lifting required. Surprised at light weight of the burner assembly and ease of removing filter, nozzle and thermostat. Hardest was loosening Fat Cap - ended up using a strap wrench.
Sure was nice to take a hot shower afterwards!
Best to All,
