Propane furnace not lighting

[OhioBurner©]

Anyone have any advice?

I had a bad igniter and gas valve. Igniter glows now and new gas valve has been converted to propane and installed, seems to be working. Can here it turn on and burners light. Problem is only the first burner or two light (there are 6 burners). I've tried adjusting the gas valve setting several turns in and out, a half turn at a time but doesn't noticeably change anything.

The odd thing is the first time I fired it up all the burners lit up on the second attempt (I figure the first attempt had to purge the lines). But each subsequent attempt (like 2 dozen +) only the first one or two light up and seemingly lazy flame. My bulk tank is at 20-25% so should be good there.

I did remove the manifold and blast some air in there are all the burner tips, etc, everything seems good no obstructions. I'm pretty stumped now.

 

[DAKSY]

I'd try going back to the tank, shutting it down completely & then starting over.
Sometimes too much gas flow out f the tank will trigger the system into
thinking there is an issue at the valve or burner.
If that doesn't help, check the pressure coming INTO the valve to MAKE sure it's at the correct setting.
Then check the pressure coming OUT of the valve.
Let us know what you find...

 

[moresnow]

Does it stink while your trying to ignite? When our LP tank gets low the gas stinks. Maybe your tank gauge is incorrect? Otherwise you seemingly have a pressure/delivery (lack thereof) problem from the sounds of it. Is your bulk tank gas valve, other inline valves turned on correctly? Hate to say/admit why I ask.
Good luck. I hate working on LP furnace issues. Normally at below zero temps!

 

[blades]

20-25% that is considered border line as far as gas supply is concerned - according to my suppler. That alone could be your issue. how old is your tank? they do have a service life . I am not sure how the gauge works, but I know from past experience with my forklift tanks that strange things pop up at that point and the gauges never seem to read correctly. I have LP home furnace and hot water heaters. when mine gets to apx 30% gauge wise I call for fill.

 

[laynes69]

Had the same issue and local HVAC place came out. They took off the combustion cover on the heat exchanger after replacing a 400 dollar gas valve. Months after they worked on the furnace and still issues, it was corrosion between the gaps on the heat exchanger where it ignites. Cut a strip of sheetmetal, bent it and flossed between the orifices. After that......zero problems. Was first told a bad valve then a bad combustion blower fan and in the end it was a little corrosion! Cost me zero dollars to diagnose and fix. The first 2 burners would ignite....then when the gas wouldn't reach the rest it would turn off. After cleaning....no issues for years. Dad had the same issue with the same furnace and the HVAC company couldn't diagnose correctly. We have a 90% efficient lp furnace that now is never used. From sitting and the condensation between the basement and the heat exchanger was causing corrosion.

 

[OhioBurner©]

@DAKSY - I don't have any equipment to check pressure on a gas line, unless a regular air pressure gauge can be used?

@moresnow & @blades Its a rented 500 gallon tank. I've run it down to zero before a couple, it goes all the way to zero before it runs out, so I figure the gauge is accurate best I can tell. Tank valve is open as well as the shut off by the furnace, those are the only 2. Tank was put in 2008. I'd call for a fill but don't really want to if I can't get the furnace working. I'm really only keeping the tank for now to test the furnace to get it working, after that I'm not sure if I'll use it, just burn wood, or maybe get smaller tank/s.

@laynes69 That's interesting seems like the exact same symptoms. I took the assembly out and checked it over really good last winter but maybe its worth a disassembly again. Yeah there is lots of humidity in my basement and condensation.

Thanks fellas!

I should've mentioned it is an older furnace, Rheem I think around 1990? I'm facing the facts I might just need a new one but trying to see if I can bring this one back. In the last two years I've also replaced my water softner, well pump, sump pump, and now my hot water tank needs replaced. It feels like have to replace everything.

 

[DAKSY]

***I don't have any equipment to check pressure on a gas line, unless a regular air pressure gauge can be used? ***

No. You need a manometer to measure inches of Water Column.

 

[fbelec]

double that on the manometer. you said the burners that are working have a lazy flame then i would be looking at a regulator

 

[OhioBurner©]

Low pressure coming in makes sense to me. I looked up manometer they arent as expensive as I thought though not sure how much use I'd have for it again. Does one just use various adapters to go from barbed fitting on the manometer to the gas line?

 

[paulnlee]

Who converted the valve and how?

 

[OhioBurner©]

I did. It came with instructions for replacing the spring and cap.

 

[paulnlee]

Must be a new procedure. Normally just reverse the cap, nothing to do with the spring?

 

[DAKSY]

Low pressure coming in makes sense to me. I looked up manometer they arent as expensive as I thought though not sure how much use I'd have for it again. Does one just use various adapters to go from barbed fitting on the manometer to the gas line?

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[OhioBurner©]

Must be a new procedure. Normally just reverse the cap, nothing to do with the spring?

The valve came with stainless steel spring and silver cap screw. The propane conversion kit included a red spring and black cap screw for propane application. It included my gas valve in the list of compatible valves so I assume its all correct. I can't speak of if this is new procedure, sorry?

 

[fbelec]

who provided the regulator? if the company did they might test it for nothing. i had my regulator go on my natural gas line and they replaced it for nothing.

 

[paulnlee]

The valve came with stainless steel spring and silver cap screw. The propane conversion kit included a red spring and black cap screw for propane application. It included my gas valve in the list of compatible valves so I assume its all correct. I can't speak of if this is new procedure, sorry?

Interesting

 

[OhioBurner©]

who provided the regulator? if the company did they might test it for nothing. i had my regulator go on my natural gas line and they replaced it for nothing.

https://www.supplyhouse.com/Honeywell-VR8205H1003-Slow-Opening-Dual-Direct-Ignition-Gas-Valve
That is the valve and where I ordered it from. And the conversion kit is at the bottom of screen in related products.

Thanks for the help all! Looks like I need to order and manometer and test some pressures. I'm heading out of town for a bit, hopefully get this working next week.

 

[OhioBurner©]

OK fellas, a little more troubleshooting...

Got a manometer, it included the fitting and hose same size as the input and output pressure taps on the gas valve so I checked there... on the input side reading 12 and on the output side 9.6 (with whatever adjustment I had set in there). Supply is within the specs on the furnace. Furnace says 10" for the burners, so a little low, but should that not be close enough for it to light? I assumed it was close enough and didn't make any adjustments yet. Seems like the problem is after the gas valve so I pulled the burner assembly off. There is a lot of corrosion. Not sure if this may be the issue? Nothing is blocked or anything like that, just rusty surface. Do you guys think the rustiness is enough to prevent all but the first one or two burners lighting?

 

[DAKSY]

Pressures are good...
Are the tubes clear?
That rust shouldn't hurt anything, but I'd clean em.
How does each burner orifice look?

Might wanna go here:

HVAC-Talk: Heating, Air & Refrigeration Discussion

The #1 HVACR Community

hvac-talk.com

 

[laynes69]

The spaces in between the burners bridge the gas to ignite the next burner. Take a piece of sheetmetal and clean in between them. The rust and corrosion will stop the gas from bridging to the next burner. My father fought this issue for years and I did for a few. Once I cleaned those there were no problems. Clean in between and use some compressed air. Is this a high efficiency furnace? I ask because with burning wood, furnaces don't get a ton of use. With a high efficiency furnace the piping leading in and out of the exchanger can cause corrosion especially when not in use. From the looks of the picture, the gas cannot go to the next burner with all of the corrosion.

 

[OhioBurner©]

The spaces in between the burners bridge the gas to ignite the next burner. Take a piece of sheetmetal and clean in between them. The rust and corrosion will stop the gas from bridging to the next burner. My father fought this issue for years and I did for a few. Once I cleaned those there were no problems. Clean in between and use some compressed air. Is this a high efficiency furnace? I ask because with burning wood, furnaces don't get a ton of use. With a high efficiency furnace the piping leading in and out of the exchanger can cause corrosion especially when not in use. From the looks of the picture, the gas cannot go to the next burner with all of the corrosion.

I plan on trying that Laynes, I remember you mentioned this earlier. Was yours of a different design though? It doesn't really look like anything is passing between the burners through the rusty area on mine, its like sheet metal pressed together there doesn't seem like any gap there, I think the picture I posted makes it look more of a gap than it really is. Or does the gas really only need a paper thin gap between layers of metal? I'll see if I have something I can get in there to clean em. Some spots the rust is enough there are pinholes already, maybe they all need replaced. Does anyone know what type of burners these are called that I can look them up for replacement?

And yes, its a high efficiency. Didn't get used much, and now has not run in 3 years I think.

 

[laynes69]

No it was not a different design. Just like you mentioned.....it would light the first burner or two then shutoff. If the flame sensors sense no heat they shut down the furnace so it's not pumping raw gas. I was told a bad gas valve and told a bad combustion blower. It was neither but corrosion. If the spaces weren't necessary, you would have a igniter at each.

 

[OhioBurner©]

No it was not a different design. Just like you mentioned.....it would light the first burner or two then shutoff. If the flame sensors sense no heat they shut down the furnace so it's not pumping raw gas. I was told a bad gas valve and told a bad combustion blower. It was neither but corrosion. If the spaces weren't necessary, you would have a igniter at each.

It's working!!
Looking at it closely I could see there was an intentional gap though very thin... I could get a sheet of sand paper in there and then a broken piece of hacksaw blade, then blast with air. Reassembled and it lit off. But the corrosion was pretty bad, in cleaning and air blast I now have several burners with holes in them, in the inside corner of the cross shaped opening in my pic above, 3 of the burners now have bb size holes in these corners. Anyone know what this style is called? When I search for burners I'm seeing different shaped ones.

 

[OhioBurner©]

Oh after some searching (I can't seem to find a part number on em anywhere?) I think they're called Inshot burners and Rheem only lists two models, one which appears to be identical to mine by the pic. Pricey little buggers (x8!) https://parts.rheem.com/product/RPD-75-24001-01
Found em a little cheaper on supplyhouse.com https://www.supplyhouse.com/Rheem-7...zC9IJnLszDGVzXaEaAgZQEALw_wcB#reviews-content

 

[laynes69]

That's good news! We had multiple furnace techs over the years look at ours before we bought the house and none of them could figure it out. One day I watched it....thought about it and figured it out. Glad to hear it's working!