Thor Miramar furnace does not light at 8k

[djlia99]

I have seen other posts regarding the furnace not igniting and have followed some of the suggestions. The only time I have seen the furnace not ignite is at 8000 ft elevation. What is the solution? I am at 8k elevation now and could use some heat at nighttime. brrrrr. Any suggestions on how to correct the elevation issue?

[16ACE27]

Originally Posted by djlia99

I have seen other posts regarding the furnace not igniting and have followed some of the suggestions. The only time I have seen the furnace not ignite is at 8000 ft elevation. What is the solution? I am at 8k elevation now and could use some heat at nighttime. brrrrr. Any suggestions on how to correct the elevation issue?

What's your furnace manual say about operation above 4000 ft?

[djlia99]

Unfortunately we did not receive a lot of the manuals that should have come with the purchase of a new Thor Miramar in 2017. So I don't have a manual.

[ducksface]

Just a guess:
Near the flame tube end there should be a brass thing that opens and closes a slot on the tube.

Give it a hand twist.
If it's not there someone else might help.

[16ACE27]

Originally Posted by djlia99

Unfortunately we did not receive a lot of the manuals that should have come with the purchase of a new Thor Miramar in 2017. So I don't have a manual.

2 Options:


Get your VIN and create an account on the Thor Owners Resource Website and have access to all your manuals; or

Locate your Furnace Model number either from the furnace itself or the Thor build sheet inside one of your cabinets and do a web search for the manual in PDF format.

In any case you may find that a high altitude kit is required.

[djlia99]

I was able to log into the owner resources under Thor. The manual 7 pages and not much info on how to operate. Certainly no troubleshooting section and no information about elevation. I did learn the furnace is an Atwood. Atwood series AFS, AFM, AFL. So at least I have the manufacturer info and I can keep searching. If anyone else can offer any more info I'd appreciate it. Thanks all

[Ottosails]

Originally Posted by djlia99

I have seen other posts regarding the furnace not igniting and have followed some of the suggestions. The only time I have seen the furnace not ignite is at 8000 ft elevation. What is the solution? I am at 8k elevation now and could use some heat at nighttime. brrrrr. Any suggestions on how to correct the elevation issue?

After reading your post it made me think…. We have a Dometic 30,000 btu in our Magnitude SV34 that we hadn’t used above 6,000’.
* at 6,000’ it took about 2-3 minutes of firing and refiring before it would burn steady - I wasn’t sure why but then saw your post - Ah, ha moment.
* Yesterday we were at 7,000’ in flagstaff and it took about 5 minutes of firing and fire-firing before it would run steady.
* Now we are at 8,100’ in CO and it took a good 17 minutes of firing and re-firing before it was a steady burn. It was 2:am and 55° in the RV so I had nothing better to do than track, time and pray it would get steady so I wouldn’t have to get out of bed and get the electric heater… (oh my) I counted to 3 it would stop, then it would make it to a 7 count, then 20, back to 3, up to 35, back to 7 and so on - after 17 minutes of this it stayed lit and brought the temp up to 68° and kept it there the rest of the night.

So if you never gave yours some time that may help. If you have given yours time you’ll need to figure something out.

Best of luck - heat is good to have.

[JimOIB]

Check this out: https://myrvworks.com/wp-content/upl...ing-Manual.pdf

The troubleshooting section indicates that air flow inside and outside the coach is a key factor.