I need help with my furnace

[1930]

I cant find a model number, I need to understand how it works and if it dosent work how to go about making it work.

At this point Ive turned on the propane and turned on/up the thermostat and nothing happens.

This is in an 88 Camper.

Any suggestions? Im asking around on RV forums but replies can be more scarce than this forum.

Surely someone here can identify what Ive got and tell me how to make it work?

Ok I looked harder and it is an FA 7920

 

[vhol5]

Assure there are 12v going to it.

 

[kaymccampbell]

Did you connect it to 12V DC?

 

[metaldad]

it s broke
it cant be fixed
you need a new one

 

[The Cobbler]

has it worked for you before or is this first attempt?
does it have a pilot light that needs to be lit?

 

[KANSASBOY]

https://www.manualslib.com/manual/1010647/Hydro-Flame-Fa-7920.html?page=2#manual

 

[mnoeltne]

Try lighting the propane stove and let it burn for 10 or 15 minutes to get the air out of the line.

Can you hear any clicking? Is the thermostat turned to heat? As others have asked, is your 12v system working?

 

[neophyte]

My furnace recently didn’t work, and after dickering with a bunch if stuff, I realized the cut of switch between the circuit breaker and furnace was bad, so no electricity was actually getting to the furnace.
The year before this the problem was dead batteries in the thermostat.

The older furnace this replaced had issues with some of the electrical components. A plumber recomended lightly tapping the area were all the circuitry was a few times. The furnace would usually start up, and remain working the rest of the season.

The are also safety cutoffs built into furnaces nowadays.
One cutoff is for the exhaust venting to prevent carbon monoxide poisoning. If the outside vent/flu gets blocked, or wind forces the hot gasses backwards, the cutoff can get tripped. It’s apparently a major reason that furnaces sometimes shut down. It’s usually located near were the furnace gasses vent, and there might be a button to reset it if it has tripped. Resetting it would only be an issue if you have to ceep resetting it.

 

[Marctrees]

1988 model ?

Definitely time to replace..

Rotted heat exchanger, etc.

Being a Propane appliance, Just too old to risk.



Marc

 

[signcrafter]

Google "RV propane furnace" and they are only a few hundred bucks. Just replace it. I hope you tested it before you bought it and negotiated a new heater cost into your purchase price.

Otherwise its just florida, go buy a heater like this and put on an extra blanket and you will be more then fine, https://www.northerntool.com/shop/t...VtSsQBW-r5--VVAtKfioVBgVNVwPY5QRoChPAQAvD_BwE. Not like it ever gets to negative 40 there.

 

[3robert 1]

Google is your friend on this one. Just did a quick internet search and there is all kind of information on what you have. Including replacement furnaces if you need to go that route

 

[Coloshaver]

You may already have figured this out, but on my Hallmark of about that vintage, there was a switch on the bottom of the thermostat turning the system off and on. Only when "ON" did it respond to the temp setting.

 

[1930]

Google is your friend on this one. Just did a quick internet search and there is all kind of information on what you have. Including replacement furnaces if you need to go that route

I am looking for an easy to understand step by step process of how to figure out where the malfunction is, if you can show me this I love you all night long

You may already have figured this out, but on my Hallmark of about that vintage, there was a switch on the bottom of the thermostat turning the system off and on. Only when "ON" did it respond to the temp setting.

I did figure this out but thanks

 

[1930]

Seriously though I do not see a step by step process for my specific unit, it is a hydro flame FA 7920.

I have an owners manual, I have this http://bryantrv.com/docs2/docs/hydroflameold2.pdf and I have some other info but deciphering it is my problem.

Im betting its a .50 cent part and Im not gonna toss it out until I am sure its not worth fixing.

 

[MG44]

50 cent part? Can't even buy a can of soda for 50 cents

 

[Marctrees]

Google is your Friend.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

Don't blame me if you blow yourself up.

Step by Step is there for various models.

Marc

 

[Marctrees]

And get a CO detector if you're gonna use this old *** thing.

I still consider it a stupid idea.

Marc

 

[1930]

Google is your Friend.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

Don't blame me if you blow yourself up.

Step by Step is there for various models.

Marc

I appreciate it, Ive found some easily understandable direction on an R.V forum, I think Im getting it. Still testing though.

If I blow myself up than at least when I stop posting you will know what happened

 

[6768rogues]

I would replace it.
That said, here is what I try if I have to. I make sure there is propane to the furnace, it takes a while to purge the line of air. Then I make sure there is power to the unit. Then I jumper the thermostat terminals to see if it is getting a call for heat. If you are in FL, is it cold enough to trigger the thermostat? Usually the safety devices are in one circuit, so any triggered or bad one shuts down the circuit. I go through and jumper out one safety switch at a time, like the limit switches. If one that I jumper lets it light, that is probably the bad one. I never run one with a safety device overridden, it is just for diagnosis.
1988 in the humidity capital of the world? My advice is to junk it.

 

[oldmxracer]

"i appreciate it, ive found some easily understandable direction on an r.v forum, i think im getting it. Still testing though.

If i blow myself up than at least when i stop posting you will know what happened"


lol !!

 

[Hpozzuoli]

Are you sure the tank has enough propane? Did you fill the tank personally? Just this summer my tank monitor read 3/4 full propane when the tank was pretty much empty. I decided to fill it at the campground we were at and the sucker took 10gallons which is a full tank.

 

[Marctrees]

"i appreciate it, ive found some easily understandable direction on an r.v forum, i think im getting it. Still testing though.

If i blow myself up than at least when i stop posting you will know what happened"


lol !!

Reminds me of the Rain Barrell Stand thread.

Marc

 

[Marctrees]

Understand that when Heat exchangers get a rust hole, CO can possibly go into the ducted room air.

Many times, this has caused Folk to "Not wake up"

So, do not worry you could be a "Trend setter".

Marc

 

[jd_1138]

Understand that when Heat exchangers get a rust hole, CO can possibly go into the ducted room air.

Many times, this has caused Folk to "Not wake up"

Marc

Yep, I have a friend who was having issues with his gas furnace leaking gas (supposedly fixed after 3 visits from an HVAC guy). I bought him a CO detector as a gift because I knew he wouldn't worry about it. Then I told him to get another one for "belt and suspenders" since they're only like $10 and his house is pretty large.

He said: "you already bought me one; why do I need another one?" Around here in the poorer parts of the area, there are at least a few people who die every year due to gas leaks.

 

[Ole Slewfoot]

If you put all your questions about a given device in its own single thread, all the background info would already be there, and it might be easier to get useful replies.

3 questions you might ask yourself...
Are any other propane things working?
Are other electrical things working?
Did a spider or dust bunny build a nest up in my **** and prevent it from firing.

25 posts in, you havent mentioned what happens when you flip the switch.

Do you go to the doctor and just say 'I think I might be sick'? Or go to the mechanic only willing to tell him/her 'It made a noise'?

So here is how you fix it, based on your input;
Check the inputs
Check the interlocks
Check the actuators.
And because I know a thing or two about RV (info not specified int he title) furnaces.
Check the interlocks again.

 

[1930]

If you put all your questions about a given device in its own single thread, all the background info would already be there, and it might be easier to get useful replies.

3 questions you might ask yourself...
Are any other propane things working?
Are other electrical things working?
Did a spider or dust bunny build a nest up in my **** and prevent it from firing.

25 posts in, you havent mentioned what happens when you flip the switch.

Do you go to the doctor and just say 'I think I might be sick'? Or go to the mechanic only willing to tell him/her 'It made a noise'?

So here is how you fix it, based on your input;
Check the inputs
Check the interlocks
Check the actuators.
And because I know a thing or two about RV (info not specified int he title) furnaces.
Check the interlocks again.

My mistake and I may update this thread with what I have found so far, at this point Ive got a similar thread on an RV forum and I hate to just blow those people off now that they have time invested in my project.

Im prob gonna update this one though anyway cause traffic over there is NOTHING like it is here. This forum is the best and its cause of guys like you willing to help

 

[Ole Slewfoot]

I can't knock the RV guys, I might be one...More trying to suggest just rolling the 'looking at a camper' thread into a build thread with pictures and questions and answers and stuff.

 

[Kev250R]

When my GF and I first got together and I started taking her camping in my Travel Trailer she never understood why I *always* keep the window above where we sleep cracked open when the heater is on. I didn't want to scare her so I never went into much detail.

Then a friend explained CO poisoning to her

Now she keeps the window on her side of the bed cracked as well.

As others have said, get a CO detector, a smoke detector and I'll add that you should throw-away the cheesy factory Fire Extinguisher your rig likely came with and get a quality Fire Extinguisher

 

[checkthisout]

We can't be of much help.

1) check for power at furnace

2) Check for power at t-stat. Make sure t-stat actually makes connection when click is heard.

If can validate power and t-stat switching at furnnace and nothing happens then you're into relays and such.

 

[1930]

We can't be of much help.

1) check for power at furnace

2) Check for power at t-stat. Make sure t-stat actually makes connection when click is heard.

If can validate power and t-stat switching at furnnace and nothing happens then you're into relays and such.

I've got a real dumb question to ask and it has to do with a relay. I want to show pictures with the question and I can't do that for a few hours when I get home.

Please stay tuned. Thanks

 

[1930]

Im gonna start a new thread so its less confusing for people, Ill put a better title too so that maybe it will come up in a google search and help someone else down the road.

Thanks everyone and please see my new thread.

 

[Marctrees]

I recommend you put it in "Heating and AC"

Marc

 

[1930]

Hydro Flame FA 7920 furnace

This is the original furnace thats in my new to me 1988 Sunliner camper. Its not working and I know you guys will help me to either get it working or enjoy watching me blow myself up using it. Either way I welcome all comments and suggestions.

Im gonna post what I do have/know about the unit.

First I will show pictures of what Im dealing with.

 

[1930]

Re: Hydro Flame FA 7920 furnace

The furnace is auto ignition, there is no pilot light in other words that has to be lit.

Its has a thermostat that has the temp control at the top and an on off switch at the bottom.

I show a picture of the cover of the thermostat

I also show a picture of the RVs converter

I turn the temp all the way up and move the switch over to on, wait quite a few seconds and eventually I hear a very faint click, after that nothing happens.

When I turn the on/off switch off I hear the same faint click after quite a few more seconds.

This is all while I am hooked up to the house via an extension cord thats part of the RV and an adapter I bought to plug it into a standard outlet.

 

[1930]

Re: Hydro Flame FA 7920 furnace

This http://bryantrv.com/docs2/docs/hydroflameold2.pdf is a service manual I found for the unit I believe. It is above my paygrade.

 

[1930]

Re: Hydro Flame FA 7920 furnace

This http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf is a link to a very good easy to understand diagnostics deal that may be for a bit of a newer model but evidently from what Ive been told they didnt change much over 30 years

 

[1930]

Re: Hydro Flame FA 7920 furnace

This is from that link Ive just posted above and is an overview of how my furnace works

 

[1930]

Re: Hydro Flame FA 7920 furnace

Here is a picture of the wiring diagram for my furnace

 

[1930]

Re: Hydro Flame FA 7920 furnace

Im thinking that the single click I am hearing when I turn on and off is the time delay relay, I think I have confirmed that by feeling the thing jiggle just a bit when it ticks.

The relay is seen here

 

[1930]

Re: Hydro Flame FA 7920 furnace

I think by looking at the wiring diagram that I posted that the wire going to the blower motor is the top red wire I show in this picture

I am also showing the diagram again and pointing to that wire