Hydronic heat: aqua-hot 450-de/dm
What it is
Aqua-Hot heats a boiler tank of propylene glycol antifreeze/water with a 12V diesel burner (primary) and a 120V electric element (secondary, needs shore or generator). That hot fluid heats the zones through fan heat exchangers and makes continuous domestic hot water on demand (no stored hot water). The 450-DE can also preheat the engine coolant.
FLUID TEMP|Held about 160-190°F by the control thermostat
WARM-UP|Diesel burner 10-20 minutes; electric element 1-2 hours
FUEL CUTOFF|Won't run at or below 1/4 tank of diesel
BAY TANK STAT|Set fresh water bay heat to 40°F minimum
Never run the burner or element without fluid in the boiler. Never run the diesel burner in a closed building. Switch it off when refueling. Fluid at temperature can scald.
Won't run: check first
Access cover fully installed. It will NOT run with the cover off.
Diesel above 1/4 tank.
Fluid level at the expansion tank. Check only at max temperature (right after the burner cycles off); it should be at the HOT mark.
Electronic controller faceplate: any RED lights?
Burner switch light out and no burner: loose terminal strips/plugs on the controller (4 faceplate screws), loose plugs on the burner controller under the access cover.
Controller lights
LOW TANK-LEVEL CUTOFF (red)|Boiler fluid low|Burner/element shut down. Auto resets when the level is corrected.
LOW BATTERY VOLTAGE (red)|12V too low|Burner shut down. MUST be manually reset after voltage is restored: burner switch off ~30 seconds then on, or press the Low Voltage Reset button through the faceplate hole with a non-metal pick.
OVERLOAD (red)|12V short or controller overheated|Short in the main 12V supply, or high 12V load plus a hot controller. Auto restarts when corrected.
ZONE light RED|Short in that zone|Zone thermostat or heat exchanger (fan) circuit shorted. Green = zone calling and fans powered.
PUMP #1/#2/#3 RED|Short in that pump circuit|#1/#2 are zone pumps (run on a zone call). #3 is the boiler stir pump (runs during continuous hot water use or when not up to temp).
ENGINE PREHEAT RED|Short in the preheat pump circuit|Light is only active with preheat switch ON plus burner and/or element ON.
ELECTRIC ELEMENT RED|Short in the element's 12V control circuit|Green = element heating.
Heating Status green = the control thermostat is calling for boiler heat. Off = neither source is heating.
Domestic Water Priority: during continuous hot water use (showers) the zone fans and zone pumps are disabled on purpose. 'No heat while someone showers' is normal.
Maintenance
Annually: diesel burner tune-up with a new fuel nozzle and fuel filter (use the specified parts).
Fill: expansion tank to HOT, open the air release valve on the expansion tank connection until air is out, hand-tighten closed.
Fluid must be FDA 'GRAS' propylene glycol boiler-type antifreeze.
Winterize the domestic side with RV antifreeze through the demand pump suction (zone heating can still be used after).
AQUA-HOT|Aqua-Hot 450-DE/DM Hydronic Heating System Owner's Manual, 2008 (via myrvworks.com)
Keep going on furnaces
Learn it
Prove it
- Furnace blows cold
- Furnace sparks but never lights
- Furnace keeps shutting off, fan keeps blowing
- Thermostat clicks, furnace does nothing
- Comeback: furnace quits again