Just learned: Furnace needs generator!

[Jim917]

I guess I'm going to need warmer pajamas.

I'm still such a newbie that every time we take the RV out, I learn a lot, including learning how much I still need to learn! I'm attempting some dry camping this weekend.

My coach has two sources of heat: furnace and fireplace. It already seemed obvious to me that I wouldn't be able to use the fireplace without the generator, since that's all electric. However, I was thinking that the furnace could run off the inverter since the source of the heat itself is the propane, and electricity is only needed to blow the heat around. But I just figured out that's not true!

So, that means there's no source of heat without the generator! At our current dry camping spot at Lake Pleasant (by Phoenix), there are acres available for parking so people are really spread out. Running the generator during the night at this location would be fine. But my understanding is that many places (understandably) have quiet hours when you can't run it. I'm realizing that I'll need to be without heat from 9:00pm to 7:00am or whatever.

It makes me wonder if there are RV furnaces that are self contained propane-only. That is, the propane somehow generates the electricity needed for the blower. I haven't heard of that, and even if it existed it might not be compatible with my rig.

Anyway, in cold locations, this is going to be a bit of a bummer. Like I said, I'm going to need warmer pajamas! And maybe a hat!

[jacwjames]

Usually a propane furnace requires a 12 volt source to operate the fans. I would be surprised if yours requires 120 volt but I may be wrong.


What is the make/model of your furnace.



Are your batteries good? If your batteries don't provide a sufficient voltage the furnace may not operate but when you run your generator it is providing charging to the batteries which in turn provides power to the furnace.

We had a Class C with only one 12 volt battery. It would not run the furnace the whole night and have enough juice in the AM to start the generator. I put a second one in with a selector switch with helped. I could run the furnace on one battery and then switch it over to start the generator in the AM.

[edge68474]

At first, I thought I had to run the Jenny in order to run the furnace. So every time we needed heat, I would start the generator first. I guess that would be good to keep the batts up, but really not needed all the time.
I've come a long way since then, thanks to this forum, but I still have a ways to go, but I enjoy learning. Like I've said. My coach is a hobby.

[wolfe10]

I agree- your propane furnace should be 12 VDC, not 120 VAC.


What is your house battery voltage, generator off, no shore power just before you try to start the furnace? Just after it turns on?


How far into the cycle does it get:


Fan starts
Hear ignitor clicking/gas valve opening
Flame start

[Old-Biscuit]

RV's are self-contained meaning appliances can run via 12VDC & propane
*water heater, fridge, stove top-oven and furnace

Course that requires 12VDC Voltage (charged battery/battery bank) and propane

**Battery voltage is first to be depleted....so means of recharging is needed


CAVEAT:
Used to be self-contained
Then residential fridges became more prevalent, Aqua Hot/Oasis Systems with AC/Diesel, Induction Stove tops, Convection/Microwaves, etc


YOUR furnace runs on 12VC & Propane.....provided you have 12VDC System in service.

[Tha_Rooster]

Originally Posted by Jim917

I guess I'm going to need warmer pajamas.



I'm still such a newbie that every time we take the RV out, I learn a lot, including learning how much I still need to learn! I'm attempting some dry camping this weekend.



My coach has two sources of heat: furnace and fireplace. It already seemed obvious to me that I wouldn't be able to use the fireplace without the generator, since that's all electric. However, I was thinking that the furnace could run off the inverter since the source of the heat itself is the propane, and electricity is only needed to blow the heat around. But I just figured out that's not true!



So, that means there's no source of heat without the generator! At our current dry camping spot at Lake Pleasant (by Phoenix), there are acres available for parking so people are really spread out. Running the generator during the night at this location would be fine. But my understanding is that many places (understandably) have quiet hours when you can't run it. I'm realizing that I'll need to be without heat from 9:00pm to 7:00am or whatever.



It makes me wonder if there are RV furnaces that are self contained propane-only. That is, the propane somehow generates the electricity needed for the blower. I haven't heard of that, and even if it existed it might not be compatible with my rig.



Anyway, in cold locations, this is going to be a bit of a bummer. Like I said, I'm going to need warmer pajamas! And maybe a hat!

I think you are confused how your Rv works.
Your RV gas furnace runs off of 12 volts.
Your inverter turns 12 volt into 110 volt.
If you not plugged in and your batteries are low you will need to run genny.

[radar]

You do not need to run your generator to run your furnace. It is 12 volts. Your inverter has nothing to do with it. It makes 120 volts from 12 volts.

My guess is your 12 volt battery is low and won’t spin the fan of the furnace fast enough to open the sail switch for the furnace. Starting your generator will usually rectify this as the genny, via the converter, will charge your 12 volt battery.

What kind of RV do you have. How many 12 volt batteries do you have.

[n2zon]

Originally Posted by Old-Biscuit

RV's are self-contained meaning appliances can run via 12VDC & propane
*water heater, fridge, stove top-oven and furnace

Course that requires 12VDC Voltage (charged battery/battery bank) and propane

**Battery voltage is first to be depleted....so means of recharging is needed


CAVEAT:
Used to be self-contained
Then residential fridges became more prevalent, Aqua Hot/Oasis Systems with AC/Diesel, Induction Stove tops, Convection/Microwaves, etc


YOUR furnace runs on 12VC & Propane.....provided you have 12VDC System in service.

One quibble:

The use of the Aquahot 120V coils is optional. While we've never had one, I think it's the same for Oasis and Hydrohot systems. We use the AH all the time when dry camping, running only on diesel and 12V power. I don't know whether it uses more or fewer amp hours than two propane furnaces would, but it doesn't drain the batteries overnight. The battery monitor is usually at or above 85% when we wake up after a full charge ending at 6-7 pm the night before and some TV before bed.

[Jim917]

Originally Posted by Tha_Rooster

I think you are confused how your Rv works.

Yes, I am absolutely confused about how my RV works! LOL. Lots of great replies here, so thanks everyone. And as multiple people have pointed out, it makes sense that I would need to run the generator if the batteries aren't charged enough. And so perhaps I can run the furnace without the generator if my batteries are charged. I'll experiment with that.

My Precision Circuits control panel has some generator control screens, and I was watching a youtube video explaining how they work. In that video they were talking about the auto-gen-start, and they said that (when enabled), the system will always auto-start the generator when any of these 3 conditions occur:
1. Batteries are too low
2. Climate control wants to run the AC
3. Climate control wants to run the furnace

That's was initially lead me to believe that I had to run the generator for the furnace, since the AGS will run the generator for the furnace.

However, I have not tried to run the furnace with AGS turned off, and with fully charged batteries. I will give that a try.

[radar]

Originally Posted by Jim917

Yes, I am absolutely confused about how my RV works! LOL. Lots of great replies here, so thanks everyone. And as multiple people have pointed out, it makes sense that I would need to run the generator if the batteries aren't charged enough. And so perhaps I can run the furnace without the generator if my batteries are charged. I'll experiment with that.

My Precision Circuits control panel has some generator control screens, and I was watching a youtube video explaining how they work. In that video they were talking about the auto-gen-start, and they said that (when enabled), the system will always auto-start the generator when any of these 3 conditions occur:
1. Batteries are too low
2. Climate control wants to run the AC
3. Climate control wants to run the furnace

That's was initially lead me to believe that I had to run the generator for the furnace, since the AGS will run the generator for the furnace.

However, I have not tried to run the furnace with AGS turned off, and with fully charged batteries. I will give that a try.

You are on the right path. If you have standard flooded 12 volt batteries make sure the water levels are up or they will never take a good charge.

[Unplanned Tourist]

To save on your batteries, try to keep power use to a minimum. That is not running your inverter so you can watch TV, turning lights off when you aren't needing them, etc.

I have a small propane heater called a "Buddy Heater" that we often use to take a chill off. You will want to have a couple of windows cracked open an inch to let fresh air in. They are rated as safe to use inside and have auto shut-off for low oxygen, but I still don't completely trust that. It doesn't use any electricity, and throws lots of heat. Just be careful and follow all the directions.

Have fun in that nice new rig.

[Jim917]

Originally Posted by radar

You are on the right path. If you have standard flooded 12 volt batteries make sure the water levels are up or they will never take a good charge.

Here's a update. With the batteries well-charged, I can run the furnace without the generator, just like you guys were saying. So, it's all good. Thanks for the help!

The trick, though, is I need to make sure that the auto-gen-start is not enabled, or it will turn on the generator when I start the furnace.

I still don't understand why the AGS is programmed to start the generator if you turn the furnace on, when that's not actually necessary. But now that I understand how it works, I can work around that.

[radar]

Originally Posted by Jim917

Here's a update. With the batteries well-charged, I can run the furnace without the generator, just like you guys were saying. So, it's all good. Thanks for the help!

The trick, though, is I need to make sure that the auto-gen-start is not enabled, or it will turn on the generator when I start the furnace.

I still don't understand why the AGS is programmed to start the generator if you turn the furnace on, when that's not actually necessary. But now that I understand how it works, I can work around that.

The generator starts when the voltage drops to a certain level. When the furnace comes on there is an immediate load on the batteries of about 7 to 9 amps. If your batteries are down at all this will make the battery voltage drop enough to trigger the generator to start. It’s not that the generator is programmed to come on when the furnace comes on, it’s just that the furnace coming on causes the battery voltage to drop enough to trigger the auto start of the generator.

Cheers.

[J Birder]

You might also look into installing a ventless heater which runs on propane, and needs no electricity at all. These come in two flavors. There the blue flame type which heat by convection, and the catalytic type which heat by radiation.



All of them will require that you keep a window cracked open an inch or so, to replenish the oxygen used to support the combustion. Otherwise, if the oxygen level is low, they will produce carbon monoxide. They will also produce a significant amount of water vapor, regardless of the oxygen level.


Some of them have a built in oxygen level sensor that will turn them off if the oxygen level is too low. This can be a nice safety feature, but there is one drawback. They will prevent the heater from operating at elevations greater than about 6,500', which may be where you are most likely to need heat. If you use a heater without a low oxygen sensor, you will have to rely on the RV's carbon monoxide detector.


I often boondock at elevations around 9,000', so I need one without the sensor. I use one of the Camco, Olympian Wave series. I have one of the smallest models, and only heat the sleeping area.


Joel