Heatilator GNDC33 - flame size too low

[Chuckpen]

Hello all,

My first gas FP post. We moved into a home that has two direct vent propane Heatilator GNDC33 fireplaces. Initially both had pilot and ignition issues that were tracked down to bad thermocouplers and thermopile sensors. Both entire pilot assemblies were replaced and that resolved all pilot and ignition issues. These are standing pilot light fireplaces. Both fireplaces were completely disassembled, cleaned and restored to normal. Both pilots burn strong and blue.

Now for the question:
One fireplace has a great "normal looking" fire flame. the other has a very low flame, almost like it is set to it's very lowest setting. I don't have a manometer handy to measure port pressures but can get one if I need to.

Looking at the regulator/valve assembly there is no high/low adjustment. For testing sake, I opened the pressure adjustment port (big brass flat blade screw plug" and tweaked the internal adjustment both left and right a few turns with no resulting change in the flame, then back to original position.

1. Is this asymptomatic of a bad regulator / valve?
2. Are there any adjustments that would help?
3. Do I need to check gas pressures?

All help appreciated.

/cp

 

[DAKSY]

Check your gas pressure. there are two pressure ports on the front of the fireplace's gas valve.
Check the IN port for 11"WC.
The OUT port should read 2.7" WC..

 

[murray1113]

Also, check the air shutter, I've seen cases of very low flame which just needed an air shutter adjustment. It may or may not be accessible from the controls area, you might need to take the burner off to access it.

 

[DAKSY]

Also, check the air shutter, I've seen cases of very low flame which just needed an air shutter adjustment. It may or may not be accessible from the controls area, you might need to take the burner off to access it.

I kinda doubt it's the air shutter. The OP didn't say anything about soot, & LP soots like crazy with a misadjusted air shutter.

 

[murray1113]

If the flame is small and blue then there would be no soot. It would be burning too clean.

 

[Chuckpen]

fire flame is small and blue. I found no soot when I cleaned the fireplace, either on glass front or burners. I will try to come up with a manometer to check gas pressures.

 

[murray1113]

I would try the air shutter first, a small blue flame means there's too much air, try closing the air shutter a little. Some units are very sensitive to air shutter adjustments, others not so much.

 

[Chuckpen]

Thanks for all the direction. I did move the air shuttle to the effective minimum gap of its range. I did get a very minor flame appearance change but minimal. Still very small. Also, on this LP fireplace it appears the air shuttle was wide open from the factory or last maintenance.

BTW, you do have to remove the burner pan to access the shuttle on this model.

Sounds like I need a Manometer or similar device to check gas pressure at both manifold ports. One interesting note is that when lighting the burner I noticed that maybe half the gas holes do not light immediately but do if I put a flame to them. burner pan is very clean. Seems like low pressure may be the fault.

Anyone voting for just a bad valve?

Anyone have a recommendation for a decent manometer that is cost effective for a single use?

thanks for the replies.

/cp

 

[DAKSY]

Thanks for all the direction. I did move the air shuttle to the effective minimum gap of its range. I did get a very minor flame appearance change but minimal. Still very small. Also, on this LP fireplace it appears the air shuttle was wide open from the factory or last maintenance.

BTW, you do have to remove the burner pan to access the shuttle on this model.

Sounds like I need a Manometer or similar device to check gas pressure at both manifold ports. One interesting note is that when lighting the burner I noticed that maybe half the gas holes do not light immediately but do if I put a flame to them. burner pan is very clean. Seems like low pressure may be the fault.

Anyone voting for just a bad valve?

Anyone have a recommendation for a decent manometer that is cost effective for a single use?

thanks for the replies.

/cp

If you've got time, pull the burner. Then, for grins, pull the burner orifice (1/2" wrench).
Push a Q-tip swab into the gas tube behind the orifice & swirl it around.
See if you pick up anythingon the swab...just might be a spider's nest in there, that's
partially blocking gas flow.
If that's not it, I'm willing to bet on the pressure.
Are both units fed from the same gas feed?
What diameter pipe is feeding them?

 

[Chuckpen]

DAKSY nailed it. I pulled the orifice and gave it a good look over. I could see light through but trying to blow through felt restricted. No spiders but just a crust that seemed to coat the sides of the exit orifice hole. Anyway cleaned it, and now blowing through was as expected. Set the air shuttle back to full open for Propane. What I found after lighting was that the flames were now big and as expected but were making a ripping sound so I set the valve outbound gas by ear, dropping the pressure until the ripping sound went away, the flame was not jumping off the burner and the flame still held a nice size and color. Poor man's manometer I suppose. I have a manometer on order and will check / set both fireplace valves when it arrives.

Big thanks to everyone that lent their talent and wisdom to my repair. As I get better at this I will pass the knowledge along. Great group here!

best,
/cp

 

[DAKSY]

DAKSY nailed it. I pulled the orifice and gave it a good look over. I could see light through but trying to blow through felt restricted. No spiders but just a crust that seemed to coat the sides of the exit orifice hole. Anyway cleaned it, and now blowing through was as expected. Set the air shuttle back to full open for Propane. What I found after lighting was that the flames were now big and as expected but were making a ripping sound so I set the valve outbound gas by ear, dropping the pressure until the ripping sound went away, the flame was not jumping off the burner and the flame still held a nice size and color. Poor man's manometer I suppose. I have a manometer on order and will check / set both fireplace valves when it arrives.

Big thanks to everyone that lent their talent and wisdom to my repair. As I get better at this I will pass the knowledge along. Great group here!

best,
/cp

Glad to be of assistance. That's what they pay me the BIG bucks for.