Joel Hollingsworth wrote:Sorry if this is a stupid question, but do you suppose water is condensing in the exhaust pipes? Have you provided for removing that water?
Erica Wisner wrote:General comments on rocket heaters:
Water does condense in the pipes on other RMH systems, but not to the point where it would pool and do damage. Earthen masonry is pretty forgiving up to moisture levels around 13-15%, and cob both absorbs and evaporates water readily.
My gut is that any condensed water gets evaporated out again once the fire dies down. Some amount of cooler, drier air flows through the warm pipes as the fuel load diminishes, especially if you aren't tending the fire super-closely and let it burn out completely before shutting the burn door.
The time when RMHs tend to be really drippy is just after building them, especially if you build it in the fall when the weather is cold and wet. Water comes out everywhere - the cob faces, the pipes, the drainage underneath.
We do try to orient the cleanouts so that water can drain down and out.