Heat n Glo Modell 6000 GDV won't stay lit

[HRK]

We have an older Heat n Glo unit, it will light but the flame goes out after a minute
then it won't relight after a few tries, local company replaced several parts and no joy,
the same problem of initial light then eventually not able to light it recurs.

It is an LP unit, the tank is full, there are no gas feed problems per the tech.

When the tech opens the glass front window the flame will stay lit, if you seal the
unit back up, the flame extinguishes itself.

The presumption is that we have a restricted or no oxygen flow into the area with
the gas logs, so it will light, burn up the oxygen and the flame will go out. Open up
the glass and allow air in and it will light. So it's not a gas problem

Does the unit draw air from the outside through the exhaust vent and then exit out the same port,

I'm presuming that something has crawled into the exhaust vent and built a nest
and blocked the air passage.

Thanks

 

[Fingerlakes Fireplace]

The vent is either restricted, or leaking. The exhaust vent can leak into the intake, causing issues like you are describing. But I would guess blocked vent.