Atwood Hydro Flame 8520, replace or fix?

[lamopar]

I have a 2011 RV with the Atwood heater. It won't continue to run and after opening up I find the burner is falling apart. I don't know if I have a problem with the board or any other parts also. When I am looking at replacement parts it shows the burner is not available but another may fit which I am checking. All in all it appears I can replace most of the replacement parts for ~ $150-$175 with new units running ~ $500. Just wondering if I replace all the valves and burner/igniter and switches do I still have an old furnace and newer unit would heat my RV much better. I hate to put a bunch of new parts in an old furnace when for a few more dollars I could get a much more efficient unit that blows air much better.

So what would you do if money was not a major issue?

Thanks, Wally

[mchero]

Combustion chamber A.K.A. Heat exchanger? If the heat exchanger is rusted thru then trash the furnace. I rebuilt two hydroflame furnaces on my 93 pace diesel pusher. Burner (rusted), sail switch and one blower motor.
Still running to this day. My rear furnace in my current rig needs new board. Think ill order a Dinosaur board for it.
7 degrees this am, better hustle.

[enblethen]

the 8531-II takes a different one. Shows as a 32811

[BFL13]

enblethen wrote:
36043 fits a wide range of furnaces. It diffuses the propane to give a good flame pattern.

The "burner" on our 8531-II is like a tongue that sticks nearly straight out. I have seen one like it but with a big angle to it, not sure what model they are for.

The replacement I got came off an 8531-III. It is the same as the II's except it had an "extra" mounting bracket/bolt I had to cut off with a hacksaw so it would go on the II ok. Same two screw holes though, so that was easy.

[lamopar]

Thanks Doug! Yep I agree I should have a larger unit. That will be another project to work on. I bet they designed the heating system based on the trailer being built in Southern California and being a toy hauler probably thought it would be used in nicer conditions. We use our for all conditions so I may need to work on it a bit.

Again, thanks for the guidance.

[dougrainer]

lamopar wrote:
The unit is the Atwood 8520 IV. It seems the unit has been replaced by another unit but many of the parts interchange. I guess one thought I had was how well it heats our trailer. I saw someone posted the 1000 BTU per foot of length as a general thought. Mine is a 36' but the furnace is only a 20K BTU. When we camp below freezing it is a challenge to keep the unit warm. We keep a dehumidifier running inside and it really helps. Anyway it seems to work so far and I assume with the destroyed burner it was not running efficiently anyway. From time to time I could smell some propane inside and the monitor would randomly go off. I believe it was incomplete combustion due to the damaged burner unit. This morning after running it for quite a while there is no smell and it is heating up pretty well.

I posted the 1000 BTU per foot. THAT is not my opinion, but both Atwood(Dometic now) and Suburban is what they stated are the guidelines. One thing that 1000 does NOT cover is the addition of slide room/s. Each slide room will need to be thought of when spec'ing BTU's. Most large RV's above 30 foot with slide rooms will have 2 Furnaces. If you have a 36 foot and a 20 BTU furnace, you do not have the size to do a good job of heating up the RV. I made Cruiser(the OEM) upgrade 2 of our customers 20 BTU furnaces to 30 BTU furnaces a few years ago, on their 28 foot Trailers as the 20 BTU could not keep up in even 30 degree weather. They were both under warranty. Doug

[enblethen]

36043 fits a wide range of furnaces. It diffuses the propane to give a good flame pattern.

[BFL13]

lamopar wrote:
It is P/N 36043 on model 8531.

Thanks. They kept changing those things over the years, so you have to get the right one. It was the "screen" on ours that had rusted away.

[lamopar]

It is P/N 36043 on model 8531.

[lamopar]

BFL13 wrote:
Hard to follow just what was replaced. "Burner assembly" was mentioned at first, but now "combustion chamber" --what exactly was replaced?

Parts list for our 1991 8531-II has a "burner box assembly" and also a "burner assembly"

Trying to understand in case it happens to ours.

For part numbers it is part number 30268. This is a metal and screen assembly that encases the area where the propane enters from the nozzle. The igniter is on the outside of the screen. I have tried to post the picture of the damaged unit but this process to do it makes no sense to me.

[enblethen]

Did you look at parts breakdown on Laurelhurst site? Note they have different numbers.

[BFL13]

Hard to follow just what was replaced. "Burner assembly" was mentioned at first, but now "combustion chamber" --what exactly was replaced?

Parts list for our 1991 8531-II has a "burner box assembly" and also a "burner assembly"

Trying to understand in case it happens to ours.

[lamopar]

The unit is the Atwood 8520 IV. It seems the unit has been replaced by another unit but many of the parts interchange. I guess one thought I had was how well it heats our trailer. I saw someone posted the 1000 BTU per foot of length as a general thought. Mine is a 36' but the furnace is only a 20K BTU. When we camp below freezing it is a challenge to keep the unit warm. We keep a dehumidifier running inside and it really helps. Anyway it seems to work so far and I assume with the destroyed burner it was not running efficiently anyway. From time to time I could smell some propane inside and the monitor would randomly go off. I believe it was incomplete combustion due to the damaged burner unit. This morning after running it for quite a while there is no smell and it is heating up pretty well.

[dougrainer]

RV Furnace Technology has not really changed in 30 years. They are not quieter or more efficient. BTU's is BTU's. As long as the combustion chamber is in good repair, just replace parts as needed, unless the newer parts are not advised by the Furnace maker. There is a REASON a Furnace maker may disclaim using certain parts when original parts are not available as Chris noted. As a Service facility, we would NOT use parts that were not approved by the Appliance maker for the older appliance. Doug

[enblethen]

What is the exact complete model number of your current furnace?
The one you have could be the updated model.