Bryant furnace manifold press after LP conversion

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  #1  
Old 11-27-20, 09:50 PM
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Bryant furnace manifold press after LP conversion

hi all, I have a bryant gas furnace set up as a portable heating unit. put in the LP kit. seems to work great nice blue flames. checked the manifold pressure at the test port, and the WC is about 3" not the 10" I would expect for an LP unit.

is this normal? I vaguely recall the kit just included changing orfices and adding a low pressure cutoff.
 

Last edited by diyer5; 11-27-20 at 10:07 PM.
  #2  
Old 11-28-20, 04:23 PM
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Should have been a spring for the gas valve as well. That pressure is way too low. Your risking sooting the unit up.
 
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Old 11-28-20, 04:46 PM
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Definitely needs a new spring in the gas valve.
Good video on the process..... conversion video
 
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Old 11-28-20, 07:10 PM
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kinda wanted to make sure. it has lotsa blue flame and I think the kit documentation said just bigger orfices on this model, no spring. of course I cant find it now.

its a bryant 395CAV

maybe someone has the KGANP2001ALL lp conversion kit instructions.

we followed the steps exactly.

i threw the wc gauge on there just for the heck of it and found it has around 3.5wc which is a NG value

any chance thuis unit keeps the low WC and just goes in with bigger orfices?

 
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Old 11-28-20, 07:17 PM
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No. If it has the bigger orifices it needs more gas pressure.
The pdf below is the instructions you are looking for.
It shows the kit as coming with three springs.
The spring needed depends on the gas valve used.
 
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Installation Instructions.pdf (226.6 KB, 17 views)

Last edited by PJmax; 11-28-20 at 07:40 PM.
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Old 11-28-20, 07:39 PM
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The spring is available by itself.....
for a White Rodgers valve - EF39ZW023 - Spring
for a Honeywell VR8200 valve - EF39ZW025 - Spring
 
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Old 11-29-20, 12:00 AM
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thanks I'll read the document. here is my regulator... which is it?


 
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Old 11-29-20, 12:03 AM
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A big oops, I misquoted the kit number I actually installed a KGANP4601ALL which I believe superseded the 2001...

sorry about the wrong kit number but the parts and process should be the same... I would think anyway...
 
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Old 11-29-20, 01:14 AM
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Heres the regulator valve number label, just confirming that it does need a spring and which opart number and I'll get the correct spring.

EF32CW203





 
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Old 11-29-20, 02:14 AM
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You have a White Rodgers 36F24-209. That requires the White Rodgers spring I already listed.

I couldn't post the instructions as the board limit is kicking in.
You should be able to download instructions from here.
 

Last edited by PJmax; 11-29-20 at 10:17 AM. Reason: typo
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Old 11-29-20, 08:02 AM
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yes I can,. thank u for all the assistance

btw, the label says 36F24-209 (not 509) same thing as far as spring?
 
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Old 11-29-20, 10:18 AM
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Yes.... the spring required is listed in both instruction manuals.

 
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Old 12-03-20, 08:28 PM
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installed the spring today, and got just over 9WC at max turn in. I'll check the input side next. the test port has a low pressure cutoff that was required for LP conversion

anyway, question: how can I confirm the correct orifice size for this conversion kit (Carrier KGANP4601ALL Conversion Kit)? this Bryant 395CAV is not listed....

thanks
 

Last edited by diyer5; 12-03-20 at 10:00 PM.
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Old 12-03-20, 10:28 PM
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I was watching a video on setting up the valve...... the tech said to tighten the spring..... should be at maximum. His was at 9wc. Back the setting down until the pressure just starts to drop. Now turn in 1/2 turn and lock it there.

I believe this was done so that if the main pressure rises...... that valve will still regulate at 9wc.

Looking at the conversion charts..... they want almost 11wc in the manifold. Make sure you check your supply pressure with the burner running. Your main pressure may be dropping too low

It looks like normally #55 orifices would be used. If running on slightly lower pressure it may be better running on the #54's. Make sure you have a nice blue flame.

This reply is purely speculation. The manufacturer recommends a factory trained tech install the kit and check the furnace out. I take no responsibility for the information I've supplied. It is up to the OP to confirm system operation.

 
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Old 12-03-20, 11:18 PM
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Thanks again Pete. The orifices are 55. This is used as a shop heater and running off a 20lb propane tank with a 2 stage regulator good for 160k btu. Assuming it just cant make the required pressure, what happens at 8.5 - 9 WC manifold pressure? Is it just reduced heat output? (that would be fine) The last remaining issue is that I have always smelled some faint propane/unburnt/exhaust when its running but only when running. There are no leaks between the tank and furnace regulator (I check for leaks with soap spray). Maybe the 4" exhaust stack seam or the base where it attaches? It's just weird and cant be too careful.

The flames are blue with intermittent wisps of yellow. There is no air adjustment on this. I'll attach a pic of it running:


 
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Old 12-10-20, 08:53 AM
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A 20 lb propane bottle is pretty small to be operating a furnace. A #55 orfice will flow 18,000 btu and Propane yields about 21,000 btu/lb. You won't get a lot of run time from a bottle that small.
 
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Old 12-10-20, 11:38 AM
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Thanks I know that the small tank wont last long but this is run for a short time then off.

The real question is how can I hunt down the lingering faint smell after this has been run?
 
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Old 12-10-20, 02:47 PM
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What smell are you talking about?
 
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Old 12-10-20, 03:02 PM
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At first I thought it was dampness etc, but now I know its LP either burned or unburned. If the unit is not running there is nothing. But when running its there. Not strong but there and lingers after. There are no leaks per soap test in the few places after the regulator like where the manifold screws in or at the threads of the orifices

Now Im wondering about the HX. Weird. Getting ready to remove the conversion kit and scrap the unit!

I did just find a good test for the HX integrity besides a boroscope which I do have one. Pressurize the plenum (power up the blower with furnace burners off/gas off) and see if a match flame is disturbed at each of the burner inlets.

I did learn a lot here I have to say about the pressure checks and regulator spring and orifice sizing. Very helpful.

But unless I locate this odor source, not keeping this heater.


 
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Old 12-10-20, 05:48 PM
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Try the 54 orifices in there. You're only using it in your shop.
Typically if the heat exchanger has a hole you'll see the burners flicker or change when the blower starts.
You are venting this furnace outside ?
 
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Old 12-10-20, 07:51 PM
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of course - vent pipe straight up and out a flashing.... I shouldnt smell anything
 
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Old 12-12-20, 06:42 PM
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A little progress. Ran the blower and a match flame was the same at every burner hole of the HX, no flickering or bent over flame.

I unscrewed the manifold tube and applied ptfe tape to the threads, also used LP approved dope on the jet threads and just to be extra detailed, on the spoiler screws threads. Those are the only places after the reg that there is gas until the nice blue flames.

When running, I smell lp to the right of the regulator above where the manifold tube goes in, and it is sealed and tite. Definitely have to put my nose right up to the regulator, top right side. Then its clear. No place else I can tell, just there.

Is it possible to have a regulator itself seeping lp and only while running? Like I said it's faint, but definitely there at that one place for sure.


 
  #23  
Old 12-14-20, 02:14 PM
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Found it

OK, well my new Pangaea Combustible gas detector already paid for itself,. Brought me right where my nose did (although I thought it was the reg. never would have guessed the fitting). The 1/8" NPT elbow for test port was porous china junk.





 

Last edited by diyer5; 12-14-20 at 04:26 PM.
  #24  
Old 12-14-20, 07:01 PM
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Good find. That sight is becoming all too common.
 
 

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