Crud in combustion chamber

timmm

Is there anything that will dissolve the crud (see picture) that was in the combustion chamber of this lochinvar knight whn110 running on propane? It was supposedly serviced annually, but I suspect it wasn’t cleaned out properly. I physically removed all I could, but there are remnants down inside that remain

EdTheHeaterMan

That is a byproduct of combustion mixing with the metal surfaces of the heat exchanger, we commonly refer to them as coffee grinds. they can be vacuumed out with a shop vac and a thin enough crevasse tool. sometimes i need to make one out of a small piece of tubing that can be flattened to fit in different tight areas. Then wrap duct tape around the tube until it is boilt up enough to fit snugly into the vacuum hose.

timmm

I vacuumed all I could, and carefully used a dental pick while vacuuming to get all of the “coffee grounds” inside the tubes that were within reach, but some has fallen down further inside and likely restricts gasses from flowing through. That’s why I was hoping there was some type of solvent that would dissolve it without damaging the stainless steel.