I’m curious if you guys can help me. A few years ago I built this monolithic forge. Used firebrick and then a layer of clay on top of that and then fero cement on top of that. It has two burners coming in at the top that are Plummed together with a valve on each. There is one single opening at the front with a sliding door. I can only use one burner at a time or both start to stutter and flame out. I’ve pulled both burners out and run them in tandem in open air with no problem. I kinda think I’m not letting enough oxygen in to run both burners in the forge. Both burners have plenty of fuel, and when at temperature more than enough heat, however if I flip the 2nd burner on both putter out until I kill one or the other. Kinda thinking of adding a fan or pump to force more air into the forge. As it’s the only variable in the combustion triangle that I can think of that may be out of wack. Thoughts?