CM Heating Completed fireplace diagnostic. Pilot is not staying lit due to a failed thermopile. However due to the age (1990) and condition of the fireplace. I recommend replacement of entire fireplace over any needed repairs. The average lifespan of a fireplace is around 15 to 20 years, the reason for this is all of the parts in the fireplace are aging at the same rate and generally fail back to back and you end up putting more money in it than it's worth. Also the firebox has rust throughout and the metal is starting to peel off. The fireplace is built in and would most likely have to be removed from the back. With the siding currently off of the building it may be a perfect time to consider replacement. I recommend setting up a free consultation with cm heating to replace fireplace. Included are estimates for various parts just for reference of price. Also, if you replace the unit with us, today's diagnostic fee will go towards the price of the new unit.