Heatilator GDST5244IL premature combustion starting problem

[adrenarush]

Hello all,

We have a Heatilator "see through" propane fireplace which came in home we recently purchased. It is very difficult to get started and I would like to see if anyone here at the Hearth.com forums has the expertise to show me how I might be able to remedy the situation. I like to think I am a pretty capable DIY guy, but this one has me a bit perplexed.

Model # is GDST5244IL and this unit includes an Intellifire pilot system with a standard wall switch.

The symptoms I'm experiencing are as follows. Upon switching on the fireplace, the pilot lights, but immediately combusts with a small and somewhat unnerving "boom". After the small explosion, the pilot stays lit, but eventually after 1 minute, the pilot extinguishes and the fire never starts.

My workaround currently is to turn the fireplace on, letting this precombustion explosion happen, then immediately turn the switch off for around 10 seconds, then turn it back on at which point the pilot light will relight and the fireplace will subsequently fire properly and burn fine for the evening. It is not exactly reliable with this workaround, but I can almost always eventually get it started after multiple attempts. And once it is started it works great.

My theory is that the main gas valve is leaking very slightly when the unit is off and thus causing a buildup of gas to accumulate in the burner grate which is what causes the initial explosion upon pilot lighting. This theory does not explain why the fireplace doesn't light after the initial explosion as I would expect it to because the pilot is still going for that minute and I would expect it to heat the thermocouple and open the main valve.

Does anyone have any thoughts on how I can best address this so that I can have this fireplace working flawlessly? If it is the main valve, are they repairable or would this require new parts?

I realize this may be pretty hard to understand so please post your questions and I will try to clarify anything that does not make sense. I have included links to PDF docs for the fireplace below, but I was unable to find anything like this in their troubleshooting instructions.

GDST5244 Brochure


GDST5244 Install Manual

Any help or ideas are greatly appreciated.

 

[ashthree]

First thing I'd be checking is to make sure you have no "glowing embers" around the ports which are close to the pilot assembly.

I find that causes a fair bit of explosive ignion, especially with the ST models.

Other than that I'd be chasing the pilot tube back to the valve from the pilot head and making sure that there is no leaks in that (soapy water or sniffer)

 

[DAKSY]

One question. Have you tried the tech switch UNDER the unit? Do the same
symptoms appear? If not it may be a faulty wall switch... Otherwise,
with the wall switch off & the unit cool, take the glass off & see if you can detect
the smell of propane anywhere in the firebox. That will tell you if the valve is
leaking - which I sincerely doubt. I would check the pilot assembly itself, focusing
on the brass fitting with the hex nut that holds the pilot orifice in place. It would
seem the there is a small amount of "puddling" which is typical of LP gas as it's
heavier than air & when the pilot ignites it also ignites the "puddle" below the pilot
assembly. The "puddling" could be caused by that brass hex being loose or a small
crack in the pilot tube...