I have an old Lennox space heater in my warehouse. The standing pilot valve has malfuctioned and would like to repair it. I believe the part number is V5114-100 or 15AGAC1. I am having difficulty find a replacement part. What are my repair options?

Depending how old it is you might be able to use a generic replacement valve. Older units are not that specific. You might be able to go to a local HVAC company and sort through their discards, I've picked up a few older units that way and was able to retro fit.