Hot air furnace - Page 3

calclimber · 10-15-2008, 08:27 AM

This last weekend our first night was at about 1000 feet or so the heater worked perfect. On our second night we were at 4000 feet and the heater wouldn't fire. I bleed the propane tank for about 10 seconds and tried again, nothing. I bleed the tank a second time for about another 10 seconds. This time after about three attempts it fired and worked flawlessly all night.

oclv · 10-15-2008, 10:06 AM

Calclimber, or anyone else experiencing this furnace issue,
Next time this happens, with the thermostat in the "off" position start up the van and let it run for a few minutes. Then turn the thermostat up and see if it starts. Thanks. oclv

calclimber · 10-15-2008, 04:50 PM

will do.

Jeffrey · 10-15-2008, 06:51 PM

Do you mean your house battery? Can't you monitor the voltage with a meter or controller? If the culprit is volts, then know how many you actually have.

calclimber · 10-15-2008, 09:17 PM

Just following through on what you ask , I know i had plenty of volts and think its more on the gas than antything else.

oclv · 10-15-2008, 10:46 PM

Apparently the volt droppage needs only to be slight, especially at elevation to get the computer in the furnace to not allow the gas to flow and ignite. I don't have a volt meter and I don't know if I would trust the plug in type to be accurate enough, but maybe they are accurate. oclv

oclv · 10-27-2008, 09:39 AM

Just to add confirmation for those that have had this problem it seems to work that you just start the van and let it run for a few minutes, then tun on the furnace with the thermostat and it seems to work every time. We were at Saddlebag lake at near 10,000 feet this weekend and it was below freezing each night. The furnace never started with the thermostat alone. It would just run the fan for 30 seconds and then shut off. I would then start the van for a few minutes then turn the thermostat all the way up and the furnace started every time. After a few more minutes I would turn the van off. oclv

veritea · 11-04-2008, 11:30 AM

Hi,

I don't know if this will help, I do not own a Sportsmobile (mine is a Pleasureway Traverse), but my family and I got caught in a snowstorm last year. We pulled into a gas station, asked the attendant if we could park for the night, then turned up the furnace and went to bed. We woke up a couple of hours later freezing cold. The furnace had never given us problems before.

I tried power-cycling the unit, it would restart briefly, then kick off again (sometimes it would light, but usually not). Checked the propane, tried running the van and starting the furnace, no luck. We made it through the night by starting the van to warm it up and then sleeping until it was too cold again.

When we returned I took it to a dealer. It turns out I had two issues: the first was that the propane pressure regulator was malfunctioning and the pressure reaching the furnace was too high. The second was that the burner had 'burned out'. I'm not sure what they meant by that (maybe I was taken for a ride, but the price for the burner assembly was reasonable). They replaced the burner and pressure regulator and the unit has worked well ever since.

It seemed odd that the furnace would malfunction all of a sudden, I had been using it for camping all week without problems. The only thing I can think of that may have contributed to the problem was that I parked with the exhaust port facing into a very strong wind (gusts over 40+ mph). Maybe the wind blowing into the exhaust port combined with the over-pressure propane did it in.

Anyway, I thought it would be useful to point out that sometimes there is an actual mechanical problem with the furnace so it may be worth having it looked at by a technician.

Scalf77 · 11-04-2008, 02:22 PM

It would make sense if your usage(battery) was the same and you tried to use the heater at sea level that it may work but would not actually start at a higher altitude. As explaned the Suburban heater has saftey circuit that checks and makes sure that the fan is blowing. Their documentation states that it must be at 75% RPM. Well, they don't actually messure RPM , they use a a sail switch to measure air pressure put out by the fan. I haven't found the specs on the switch but I imagine it is set to close if the air pressure put out by the fan at 75%. Since the reported low operating voltage is 10.5 volts I am guessing that that would be the voltage that puts the motor at 75% RPM. The motor actually spins both the combustion blower (squirrel cage) and a fan for the forced air heat. The sail switch is on the forced air side. So as you go up in altitude the thinner air would require more RPM's from the motor to get the appropiate amount of airflow to close the sail switch. That would mean higher voltage input at the motor. I would suspect that the airpressure required to engage the sail switch may actually be higher then what it takes to keep the switch closed. This would explain how you could start the engine get it started and then shut it off and the furnace woulkd run.
So as you go up in altitude you would need a higher starting voltage to operate the furnace.

Also any blockage either on the ehaust side of forced air side could effect the output of the fan.

Greg

calclimber · 12-02-2015, 05:06 PM

I see this post is used for reference so I thought I should follow up on my case. About 2 years ago I replaced my propane regulator. Problem solved!