Furnace not working

[dave103]

Hello,
I just purchased a 2010 390BH! The unit has 6000 miles and is very nice. Purchased it in Southern Utah and just got bach to Long Island.(2900 miles) Two issues I have questions about that hopefully I could get some help.

1st the furnace will not ignite. The fan turns on and I can hear the ignitor trying to light but no luck. The stove and hot water heater work fine. I spoke with a service tech from the dealership that the previous owner bought the unit from. He said it could be air regristictions from spiders in the intake. He recommended using compressed air to blow out same. I tried it with no luck. I feel like the intake is too wide so i am thinking of attaching a small hose to my air chuck and sending it into the intake further.

Second is the heat pump on the AC unit. We were traveling in 35-40 degree weather at times. I turned the generator on and the heat pumps. At first the air felt warm and seemed to be working. After the night went on it was getting colder and colder in the coach. Are these units made to work in these temperatures? If not, how do you heat the coach while traveling? I did not have the kids with me but they would have been very cold in the back.(It was cold in the front)

Any help would be appreciated. Thanks, Dave

[BigDTx]

Dave103,

welcome to the forum and congrats on your new purchase.

I am assuming you have plenty of propane and your batteries or generator are in good condition. Did you let the furnace try to ignite for a few cycles? there will be air in the lines that must be purged out by the gas. also you need to have power to the unit, not sure if you need 12v or 110. You may need ot let the air purge some more or there is a mud dobber or something blocking the gas flow. can yiou hear any gas or air hissing sounds while trying to ignite? is your propane alarm sounding?

I am not help with the heat pump question, my roof mounted AC is AC only no heat. MY furnace is a seperate unit entirely.

Hang in there and someonw will be along with soem more information and help.

[cfsoistman]

Heat Pumps produce heat from the heat they draw from the outside air. Basically it's air conditioning in reverse. Summer time you have the unit taking the heat from inside and transferring it through refrigeration lines to the outdoor coils then out into the outside air. Now you're taking the heat that in the outside air and transferring it through to the indoor coil to produce heat inside. Problem is the colder it gets outside the cooler the air will be coming out of the vents inside. Residential Heat Pump systems have auxilary electric heater packs to work along with the outdoor unit. Occassionally the outdoor unit must go into defrost which makes it work like an AC unit. Taking heat from inside to defrost the coils outside. Heat Pumps work fine in moderate temperatures but your propane furnace will do the job way better when the temps get below 35 degrees.

[RoamingEngineer]

In the 390BH, only the rear AC unit is a heat pump. The front one should not have come on.

On the furnace, it could be a couple things. The furnace will not run if gas pressure is low. I've had ours stop working due to low propane but the stove and refrigerator were still able to operate. I'd check your propane levels first.

The order of operation for the furnace start is as follows:

1..Thermostat calls for heat
2..Blower starts
3..After 15 seconds spark fires
4..gas valve opens
5..Sparking occurs for 7 seconds

At step 2, there is a sail switch that makes sure air is flowing through the system. If the sail switch is obstructed, you won't get any further and the fan will eventually shut down.

There is also a limit switch that makes sure the unit isn't already hot from running earlier. The limit switch prevents the heat of the unit from getting too hot.

If both these switches trip properly, you move to step 3.

If you are hearing the clicking noise, then you've got a spark and you're at step 4 then immediately at step 5.

If you are in fact making it to step 4 or 5, it could be the gas solenoid valve isn't opening. It could also be that the gas pressure is too low, so again, check the propane levels first. Check them at the tank. Don't rely on the inside panel and lights.

Check to see if voltage is coming out of module board to gas valve after the 12 - 18 second delay. Check the wires in the molex connector to be sure they're intact and making contact with the module board. Check wire from the module board to valve for continuity. Wire and connections check OK -replace module board.

If Voltage is coming out of module board to gas valve, but gas valve does not open - replace gas valve.

If you find you aren't making it to step 4, then it is probably the sail switch. It sits by the Squirrel cage fan and senses that air is flowing through the system. I had my sail switch get stuck and even though air was flowing, the furnace wouldn't attempt to light.

It isn't too hard to remove the furnace to do diagnostics. It's a self contained unit with pipes that fit inside the ports to the outside. You can remove the screen under the fridge, loosen some bolts and slide the unit into the RV enough to work on it. You don't need to remove the gas line if you're careful.

Hope this helps.

--Mike

[amarzano]

On our Berkshire - the Heat pump is only on the FRONT unit (not the rear), not sure when this change occurred.

Over the weekend - our furnance stopped - just as you described. Problem turned out to be a blown 15 amp fuse. I'm sure your dealer would have checked this - but worth a shot.. This was the #2 fuse in the third (ie far right side).

We did run the heat pump for 2 nights to heat the RV in high 30's low 40 deg temps. It heated fine - but did have to run most of the night.

Let us know what you find..

[RoamingEngineer]

Mine could be on the front too. I've only tried the heat pump once and remember that only one unit is a heat pump. I was thinking it was the rear but could be wrong.