Another question about Hydroflame 8531-III furnace

melissaburn · 09-27-2023, 04:49 PM

I have a 1996-ish T 36-SS-B that I'm living in while my home is being built. The furnace worked the first year but last winter it failed and the tech who came out said it was probably the control board (we'd already repaired the fan and checked the burner, etc) He said it might not be worth fixing because I expected my home to be finished before I needed the furnace again. I relied on a Heater Buddy for the rest of last winter. Now it looks like I'll be spending another winter in the camper after all, so I want to get the furnace working again. Besides the nice heat, the floor ducts will help keep the pipes from freezing. (I put on a skirt and insulate, etc.) According to my original documentation, the replacement part number for the DSI Board is 6215. I googled 'Hydroflame furnace, 8531-III, 6215" and several boards come up that don't look exactly like mine. I don't know how to tell which ones will work and which ones are too different. Can anyone recommend a replacement board? Thanks!

**JohnB** · 09-28-2023, 05:47 PM

Hi Melissa,

It looked like you were trying to post a picture, and it did not come through. Pics for sure help in these cases, and in this case, a pic of the furnace with the outside cover off.

There are 3 ways to add pics.

1. Upload pics to a specific post, attaching them at the end of the post.

2. Linking them in from a public viewable web photo hosting service you have.

See here for 1 and 2 https://www.sunlineclub.com/forums/f...html#post86041

3. You can upload pics to the forum to your own personal photo album. Then link them to anywhere in the text of a post. See here for how to create an album. https://www.sunlineclub.com/forums/f...html#post87945

If you still need help, let us know.

I'm digging into your post now and will be back with more later.

Hope this helps

John

**JohnB** · 09-28-2023, 06:33 PM

Hi Melissa,

I'm trying to help, but I need more info to help make sure what the real issues are.

Atwood part numbers have been superseded a lot, as many parts have been discontinued. And there were a few iterations of the 8531-III furnace along the way. The 6215 does not line up with current offerings. The board has been updated several times. Let's try this.

What does the furnace do or not do now? It should do this: tell me what it is or is not doing.

1. Turn on the T-stat
2. Adjust the heat temp setpoint way up; if it is 68F in the camper, go up about 10 degrees hotter so we make sure it will be signaled to start.

3. The first thing that should happen is the fan should start running within a short period (2 to 25 seconds pending the vintage of control) of turning up the call for heat. If we have no fan, that is problem one.

4. Once the fan runs for approximately 20 to 30- seconds, the gas valve opens, and the igniter starts clicking "if" the safety devices were met for enough fan speed. If there is no clicking and no gas, then we have to sort that out; then why not? It could be the igniter board or the safeties are not met, allowing the ignition sequence to start.

It is a big step if you make it to the gas burner running. I assume yours is not doing something before this; I need help with what.

Pictures help show us what you have. As I said, the 85 rev III furnace had several iterations of fan controls, and we are still determining what someone else may have attempted to upgrade.

Post pics of:

- The T stat you have.
- A few pics of the furnace outside the camper with the white cover off of it. Need to see details and stickers. Also, try to get a picture of the control board as good as you can.

Hope this helps,

John

melissaburn · 09-28-2023, 06:42 PM

https://imgur.com/iLhedWt

melissaburn · 09-28-2023, 06:46 PM

That's the control board. I'll have to put it back in to run the test you request. Honestly, it's been so long since I tried to run it, I don't remember the symptoms so a test is in order. However, as I've said, the tech who came out to look at it checked everything and told me it was the control board. At the time, I didn't think I'd need it running because I thought I'd be out of the camper and could fix it at my leisure. But, here I am, another winter in the camper! I'll get back to you ASAP with a symptom report.

melissaburn · 09-29-2023, 09:06 AM

[QUOTE=JohnB;159322]

What does the furnace do or not do now? It should do this: tell me what it is or is not doing.
[QUOTE=JohnB;159322]

Thanks so much for asking me to test the furnace. It works!! I noticed when I removed the control board there was a LOT of crud on the back, probably bridging between some circuits. I carefully wiped that off so I could take a picture. As a result, when I put the board back in this morning, the furnace started right up and is generating heat. You saved me a bunch of money and effort with just that one request.

Thanks John!

**JohnB** · 09-29-2023, 07:20 PM

WOW, great!

And you are welcome.

Happy heating this winter.

John

melissaburn · 10-20-2023, 07:18 AM

Hi John (and others) - So, I was too quick to proclaim total success. As it turns out, there is a continuing problem with the furnace. When I use the thermostat to turn it on, it runs properly -- firing up, burning propane, and blowing hot air -- cycling on and off normally for an hour or two. Then, at some point, I hear the burner quit (no more rumbling sound) and the fan just keeps blowing cold air. I shut it off at the thermostat, wait a while, turn it back on, and the process starts over again -- working correctly for a while and then blowing cold air again. Any idea what might be going on?

**JohnB** · 10-20-2023, 10:33 PM

Hi Melissa,

Bummer on the furnace. The pattern you are describing could be a few things. Let's start with the more simple things.

1. Is the camper plugged into shore power, or are you on battery power when the furnace stops creating heat?

2. How old is the battery in your camper?

3. Are you still on your original power converter, or did it get changed along the way?

4. What brand and model power converter do you have? Can you post a few pics of the power converter?

5. Do you have access to someone with a 12-volt DC voltmeter to measure the battery's voltage? Measure the battery voltage when you start the furnace and things are going well, and then measure again when the gas burners stop working. Take both readings at the battery terminals with the furnace running. If you do, please tell us those two battery voltages. We need the data in at least one decimal place.

The way the furnace works, there is a sail switch inside the fan blower housing. The wind created by the fan has to be strong enough to blow on the sail switch to close the switch and allow the gas burner to operate. If the battery 12 Volt DC power goes too low, the fan slows down, the sail switch opens, and the gas burner will no longer work. But the fan will keep running if the T stat is satisfied or until the furnace is turned off.

The above is the first place to start and the easiest to check. It gets deeper into troubleshooting if the above all shows good. We can get to that as needed.

Hope this helps

John

melissaburn · 10-22-2023, 07:39 AM

Thanks for all the great information John!

I checked the battery and it only showed 4 Volts, so I hooked it up to a charger and it has been fully charged for about 12 hours now (it's still hooked to the charger). However, the furnace is still behaving the same -- it goes through 2 or 3 normal cycles of firing up, blowing hot air, shutting off the propane, blowing cold briefly and then shutting off. Then on the last cycle it'll just keep blowing cold air. Sometimes the period of burning propane and hot air seems pretty short, just a couple minutes but I don't know how long a "normal" cycle should last. The battery is less than 3 years old. The converter seems to be the original MagneTek.

melissaburn · 10-22-2023, 07:42 AM

Also, I forgot to mention that I'm on shore power all the time.

melissaburn · 10-22-2023, 09:35 AM

My original owner's notebook says the converter is a MagneTek 6336. Apparently, the replacement for it would be this one: https://www.etrailer.com/p-PD4635V.html

But, I don't want to order this until you tell me you think the converter is the problem.

**JohnB** · 10-22-2023, 10:23 AM

Hi Melissa,

First off, you are very welcome. Glad to help as we can.

I'm going to recap a few key things from your responses so we can clarify a few things. See the highlights in blue

Quote:

Originally Posted by melissaburn

Also, I forgot to mention that I'm on shore power all the time.

Quote:

Originally Posted by melissaburn

snip...

I checked the battery and it only showed 4 Volts, so I hooked it up to a charger and it has been fully charged for about 12 hours now (it's still hooked to the charger). However, the furnace is still behaving the same -- it goes through 2 or 3 normal cycles of firing up, blowing hot air, shutting off the propane, blowing cold briefly and then shutting off. Then on the last cycle it'll just keep blowing cold air. Sometimes the period of burning propane and hot air seems pretty short, just a couple minutes but I don't know how long a "normal" cycle should last. The battery is less than 3 years old. The converter seems to be the original MagneTek.

Here are 4 key points.

1. You are plugged into shore power all the time. This means your power converter is always powered up, which is a normal event. This also means if your power converter was working correctly, the 12-volt DC power inside the camper should have been 13.2 volts or higher in the camper to power the furnace.

2. You checked the battery, and it read 4 volts. Was the furnace running when you measured the 4 volts, or just the voltage without the furnace running, or both?

Need to clarify this, as 4 volts is part of the problem. 4 volts shows the battery is in a totally drained/discharged state to nothing (0% state of charge) when the power converter is plugged in. If everything was working correctly, it should have read between 13.2 to 13.7 volts on your older converter.

3. You said your battery was three years old. OK, understood, this is not that old; if the battery was not subjected to damage, 3 years is not a problem by itself.

4. The power converter appears to be the original.

5. You stated you hooked the battery up to a charger, which is now fully charged. It is still hooked up, but the furnace still has issues. I assume the charger has a light stating it finished charging, correct?

If I have stated anything incorrectly, let me know what and if the furnace was running or not when you measured the 4 volts.

Assuming I interrupted this correctly, here is where we are now. The 4 volts at the battery with the power converter on is an issue. The voltage should have been 13.2 to 13.7 volts DC and it is not. This points to at least two main issues; there may be others if we can surpass these first two.

1. The fuse protection between the battery and the power converter is blown. On your older camper, this fuse protection is an actual fuse or a self-resetting circuit breaker in place of a fuse located in a little wooden box on the floor at the front wall under a storage area or a cabinet. When this fuse/self-resetting circuit breaker is not working, the power converter is not connected to the battery, which does not allow the power converter to charge the battery or get power from it even if it was charged. Some older power converters need the battery to work correctly with the converter to create stable DC power. We have to confirm this fuse/self-resetting breaker is working.

2. Your old power converter is bad. These old converters have commonly failed. These can fail in a few different ways. They go into overcharging the battery or, worse, high voltage all the time, they get stuck at 13.6 volts or above 14.4 volts all the time. Since you are plugged in all the time, it is overcharging the battery, boiling out the electrolyte, and killing the battery. Then there is the failure where the voltage regulator goes bad in a low voltage mode where instead of trying to regulate 13.2 to 13.7 volts, it is below 12.7 - 12.6 volts and starts draining the battery. Some I have seen get stuck trying to maintain 8 volts and can drain a new battery, pulling it down to that low voltage. The other way the converter can fail, which is the best if it is going to fail, it stops working altogether. While, yes, it is dead, at least it did not create considerable damage to the battery in the process.

If you still have your stand-alone battery charger plugged in, suggest unplugging it. If the power converter is failing, it can affect the charger and damage it.

To help sort out if no. 1 or 2 is the problem, do this: Whoever did your first set of voltage tests should be able to A through E. We need a one-decimal place number of the voltage, for example, 12.7 VDC, not 12 or not 13. We need the decimal point; we hope your meter has one decimal place on it.

A. Unhook your battery charger.
B. Have the furnace off.
C. Have the shore power plugged in to operate the power converter.

D. Go to the battery, measure the voltage at the battery posts, and record the number.

E. Go inside the camper and measure the voltage between the big red and white cables on the right side. The red is +, the white is -. Record the number. (Note: This is not the smaller red wire on the first 15 amp fuse on the left. )

F. After doing the voltage checks, go back to the battery. Unplug the camper from shore power while you do this test. Carefully lift the caps on the battery cells; with safety glasses on and a flashlight, look at the electrolyte level on each cell. See if the lead plates are exposed. Exposed means their liquid level is at or below the plates. You are checking to see if the power converter boiled out the battery. NOTE: ONLY do this check, if you are experienced in checking a battery. The liquid is sulfuric acid and will burn if it gets on your skin and make holes in your clothes. If this check is too much for whoever is doing it, do not do test F. We can work around it.

The big red and white wires at the power converter are the battery hookup wires inside the camper, which have fuse protection between the battery and the converter. The 30 amp battery protection fuse or self-resetting circuit breaker is in the wooden box with a wood cover. See if you can find the box and photograph the inside. If the fuse is not blown and the self-resetting circuit breaker is working, the voltage at the battery and inside the power converter should be close to the same voltage; it might be 0.1 - 0.2 volts or so difference, but not much more. If the difference is a lot more, it also tells us things pending what the readings are. (Note: The box may have a green 30 amp fuse, but it can be the truck charging protection fuse, not the battery/converter protection fuse. Sunline has used fuses and self-resetting circuit breakers, a little silver cube, over the years as the battery/converter protection. So there may be 2, green fuses or 1 green fuse and 1 sliver cube)

Tell us the readings, and we can go from there. We need to get the camper voltage sorted out before troubleshooting the furnace. The main camper voltage can be or at least one of the issues causing the furnace issue.

I hope this helps,

John

**JohnB** · 10-22-2023, 10:45 AM

Quote:

Originally Posted by melissaburn

My original owner's notebook says the converter is a MagneTek 6336. Apparently, the replacement for it would be this one: https://www.etrailer.com/p-PD4635V.html

But, I don't want to order this until you tell me you think the converter is the problem.

Hi Melissa,

I spelled out some checks in my last response. They can help if the power converter is bad, and we can go from there. We can talk more about the change out pending the tests, as it seems the fuse board should also be changed.

Here is an option for the Etrailer listing for the new converter if we need to go there. I agree that Progressive Dynamics is the way to go; Best Converter worked with Progressive Dynamics to create a retrofit kit for several older converters. I have bought five of them to deal with the WFCO and American brands that failed in the newer Sunlines. See here for the Magnatek upgrade: https://www.bestconverter.com/Upgrad...llax_c_64.html

I know Etrailer also, they are a good company. Best Converter, and the owner, Randy, specializes in power converters. Their tech support is top-flight. I deal with both companies, just different items I buy from the two.

Consider comparing the two companies. Heads up on Amazon, though: there are a lot of clones out there that are not connected with Progressive Dynamics, and the warranty will not apply.

John

melissaburn · 10-22-2023, 12:04 PM

Thanks John! I should have clarified that I measured the battery voltage at 4 V while the furnace was shut off. I'll remove the recharger now and do the other things you suggested.

melissaburn · 10-31-2023, 03:07 PM

John,

Thanks so much for all the information you provided. Because of your in-depth explanation of all the things that go wrong with the converter and battery, I was able to guess that the converter was bad. What clued me in was an error code on my battery charger, which said my battery had been sulfated. I ordered the converter you identified and also got a new battery. I just installed the converter and battery today and my furnace seems to be running fine (fingers crossed). Thanks again for all your help!

Melissa in WV where it's turning cold.

**JohnB** · 11-01-2023, 07:51 AM

Hi Melissa,

First off, you are very welcome. We are here to help as we can.

Good job! Glad this all worked out. Yes, if your battery is heavily sulfated on a 3-year-old battery, the odds are high that the power converter is cooking it to death. Your new Progressive Dynamics converter has a deflate mode on it. While it may not cure a heavily damaged battery, it will maintain a working battery and can be plugged in 24/7 if needed and not harm the battery. Ensure you check the electrolyte level at least once a year and top off to the correct height with distilled water.

Thanks for reporting; your posting back helps quantify the fact these older power converters do go bad and you may not realize it until things stop working.

The cold snap, central Ohio is in the middle of it now, and we are hoping by the weekend, it breaks and goes back to a more normal, whatever that is nowadays.

Take care,

John