Furnace runs but blows cold
Part way through our two week trip our furnace stopped working. It's an Atwood Hydro Flame 8500-IV, in a 2000 Airstream Land Yacht. Does anyone have experience with these furnaces and if so can you su...
Forum Discussion
The sequence
T-state says "I'm chilly, Warm me please"
Control board starts blower blowing
Sail switch closes when blower is "up to speed"
Solenoid valve opens (Propane flows in theory) and igniter sparks.
Next step is an A/B Most Atwood and Suburbans are B
A: Thermocouple (Flame sensor) sends about 0.480 volts to the control board this causes current to flow and board says "OH. Flame is on" and heat continues till T-stat says "Ah. Nice and toasty, you can stop now" or Over temp cutout cutouts.
B: many Furnaces have a single wire ignition/sense system. in this system the wire carries roughly 1000 VAC during sparking and then switches to Sense lookin for the 0.480 volt DC thermocouple out. IF the TC (Thermocouple) is carboned up it may not get hot enough to generate the needed voltage and current.
Or if the change from Spark to Sense flubs Pop goes the sensor chip
(My theory of what killed mine.. And when I inspected the replacement which came from Dinosaur boards it appears it was their theory as well)
There is a LED on the furnace control board that will flash in most cases if it fails.. Whta is the pattern.
Page two... Even if it is working normally so much air flows it won't feel all that warm
T-state says "I'm chilly, Warm me please"
Control board starts blower blowing
Sail switch closes when blower is "up to speed"
Solenoid valve opens (Propane flows in theory) and igniter sparks.
Next step is an A/B Most Atwood and Suburbans are B
A: Thermocouple (Flame sensor) sends about 0.480 volts to the control board this causes current to flow and board says "OH. Flame is on" and heat continues till T-stat says "Ah. Nice and toasty, you can stop now" or Over temp cutout cutouts.
B: many Furnaces have a single wire ignition/sense system. in this system the wire carries roughly 1000 VAC during sparking and then switches to Sense lookin for the 0.480 volt DC thermocouple out. IF the TC (Thermocouple) is carboned up it may not get hot enough to generate the needed voltage and current.
Or if the change from Spark to Sense flubs Pop goes the sensor chip
(My theory of what killed mine.. And when I inspected the replacement which came from Dinosaur boards it appears it was their theory as well)
There is a LED on the furnace control board that will flash in most cases if it fails.. Whta is the pattern.
Page two... Even if it is working normally so much air flows it won't feel all that warm
