Propane fireplace problems... Poof, no eyebrows!

[MatBirch]

Trying to help a friend here. He was recently "re-issued" his house post-divorce. While he was away, the existing gas fireplace died, so his ex and a friend bought a used one, and attempted to install it. The story I got was of a 12' ball of fire into the living room. I went to investigate. I found no leaks with my testing, so very carefully, I lit the pilot. All was well, but the burner would not light. I got it to light with a lighter, although a little sluggishly. I reached under to adjust the valve and WHOOOSH! No more arm hair and a 12' ball of flame. We shut down and began to investigate further, and still could not find a leak. I test lit it again, even more carefully this time. Ultimately, it gave me a similiar result, although expecting it, I was able to keep what hair I had left. Time to throw in the towel. We removed the fireplace and brought it to the shop. I have disassembled it and began testing it further with air instead of gas. (Figured it was a bit safer). I still cannot find a leak, but did learn something. If the pressure is above 3-31/2psi, it will bleed off through the pilot circuit, ONCE THE PILOT KNOB IS PUSHED IN AS IF LIGHTING. once it drops of to 3psi or so, it will seal up.
The valve assembly appears to be - SIT 820 NOVA mV. The sticker reads "For Natural Gas Only". However, the flame adjustment valve attached to it reads- "For LPG only. Pout 10 "W.C. Temp range 32f to 225f

How can I know if this is setup for propane? With the symptoms, I am doubting it. With propane being heavier than air, and the valve sticking open at higher pressure, it stands to reason that the gas would build under the firebox, and cause me that big poof. Is this how a nat gas unit might act if connected to propane?
That pilot light sort of seems to be acting like a pop off valve you'd find on an air compressor tank. I can sort of pull against the spring and help it seal before it gets down to 3psi, but it won't hold on it's own.

Any help is greatly appreciated!

 

[DAKSY]

First off, what MODEL fireplace is this?
It sounds to me like the regulator head has been changed,
but what about the pilot & burner orifices?
How far open is the air shutter?
Is the burner exactly aligned with the burner orifice?

 

[Phoenix Hatchling]

Maybe the ex has booby trapped it?

 

[MatBirch]

First off, what MODEL fireplace is this?
It sounds to me like the regulator head has been changed,
but what about the pilot & burner orifices?
How far open is the air shutter?
Is the burner exactly aligned with the burner orifice?

There is no info of any kind with regard to brand or model. I believe it may be something that was sold in Canada, as we are very near the border, and the warning labels are also in French.
The burner tube was in very good shape, and does not appear to have been moved out of alignment. Everything was in very good looking shape.
You'll need to forgive me a bit, as I don't neccessarily know what it is that I'm looking at with regards to component names. I consider myself quite skilled as a repairman of tools and compressors, bicycles, motorcycles, cars, home repair, etc. I work as a fabricator/electrician/plumber building large scale generator modules for power generation, primarily for North Slope oil companies. I have the skills for this, just not the hands on knowledge of these particular parts. I understand most of the theory and practical application, just not the details.

so... "regulator head"...??
as for the orifices, I have little to go off. The burner orifice measures around .0700, I haven't opened up the pilot one yet.
I don't know where to find the air shutter, sorry.
Here are a couple of pics of the valve assembly. You can see the two different labels that read propane only and nat gas only... I can take more if needed.

Thanks a bunch for the help!

 

[DAKSY]

Looks to me like the valve has been converted from NG to LP.
The regulator head (HI-LO knob) is just above the sticker in the first picture.
Pout = Pressure Out = 10" W.C. (Water Column). Measured with a manometer
at the "OUT" port above the OFF-PILOT-ON Knob in the 2nd pic.
The air shutter is on the burner tube, usually located near the burner orifice.
It is a mechanical device that regulates the ATF mixture.
For LP is should be wide open.

 

[MatBirch]

All righty! Thanks for the help, after hours of testing, trying, cleaning and figuring, I did finally find a leak and get it fixed. It is now sealed and holding pressure indefinitely. I put everything back together to test on the bench, but now I have some more questions with regard to the wiring. Not knowing much about this setup, how does it work?? What I mean is- It's a millivolt system, but it has to get that signal from somewhere, right? I have two long wires that each connect to TH terminals. They each have a spade connector on them. I'm guessing they went to a T-stat. or switch of some kind. Being used to "regular" electrical though, if those are just connected as if closing a switch or t-stat, there is just a loop... no introduction of power??
Then there is the thermopile connections. (learned that with a quick google search). One wire connects directly to the TH terminal, one jumpers around through some sort of a small disc type thermo switch?? mounted up near the "flue" outlet, and back to the TP terminal.
Again, nowhere is power brought in to play.
There is a 115V AC connection for the fan, which is the least of my worries...

What turns this thing on and off? I'm ready to test fire with a small propane tank, just want to keep the hair that has grown back on my arm since last time!

 

[DAKSY]

The "Power" Is created by the pilot flame.
There a electromagnets in the valve, on both the PILOT side
and on the BURNER side. The thermocouple & the thermopile
are considered millivolt generators. The thermocouple generates
enough DC voltage (28+/-mV) to keep the electromagnets OPEN
allowing fuel to flow to the pilot side. The thermopile generates enough
DC voltage ( 325+mV) to keep the electromagnets OPEN allowing
gas to flow to the burner side. TH terminals are for the THermostat (or switch).
You can jump these two ternimals to allow gas to flow to the burner, IF your
thermopile is generating enough mV to keep the e-mags open.
TP & TP-TH (or TH-TP) connectors are for the ThermoPile.
If you hook 110VAC household voltage to the valve, you will SMOKE it.

 

[MatBirch]

Got it! Thanks!
It functions as it should now. I still need to trouble shoot the blower fan, but that I can handle. I assume there is a thermo switch that is stopping it at the moment. On my own unit, the fan doesn't not kick on for a few minutes after the burner lights.

 

[MatBirch]

All systems GO!

Thank you very much for all your help!!

 

[DAKSY]

Any time!

 

[MatBirch]

got another question, sorry.
We got everything hooked back up and working great, but now we are curious about the vent connection. The connection of the pipe (chimney) to the box is a slip fit rectangle to round fitting that slides onto the top of the fireplace as you slide the fireplace into the wall. The front of this area is open to the room, and does not appear to be just a missing piece. I don't know if it's supposed to be this way and creates a draft, or if it's a problem.

The area in question is the uppermost space where the two wires cross to the thermo switch. There are the two holes that are indicative of something mounting there, but those two flanges are angled down. That would make for a quite complex brake to have a piece fit in there. All we can find with the parts that came with the unit, is the louvered grill trim piece.
The lower space is the outlet of the fan's air.

 

[DAKSY]

OK. Looking at the latest pics, I'm thinking you have a fireplace INSERT, not a FIREPLACE.
Many inserts have the feature shown, so that the venting can be disconnected
& the unit can be removed without pulling the co-linear liners out as well.
I believe the two holes in the brake-bent tabs are for the wire-type handle used for pulling
that feature OFF the insert for removal from the fireplace, or for pulling that feature ONTO
the firebox to position the venting after it is installed IN the fireplace. That handle may have
been removed & placed in the manual bag for future usage.

 

[MatBirch]

Thanks again! Yes, it's an insert and I did know that. Sorry for the mix up. I tend to agree with your assessment, but the actual slip fit joint is behind, on top of the part in question. I can't get a better pic, so here's a quick crude drawing of how it's laid out.

at this point we're kind of assuming that it is similiar to a gas water heater exhaust, in which there is definitely a space that is open. Possibly it needs fresh air to mix with hot exhaust gas to create the draft??

 

[DAKSY]

Hmm. I have never seen a set up like that. Single vent pipe points
towards a B-Vent rather than Direct Vent, but ALL the B-Vents I've
seen, are sealed AFTER the firebox, where the byproducts are released.
Combustion air is introduced near the front of the firebox, so that it can
mix with the fuel burn. I see there's a snap disk to shut the unit down,
but that's a safety feature in case of an excessive heat build-up in that area.
Gonna need Heatsource or on of the other gas guys to chime in at this point.
Sorry.

 

[barmstrong2]

That's the draft hood. It's there to prevent the flame being lifted off the burner by the convection of the vent, just as you described on a water heater.