Thank you for your thoughtful reply. Tomorrow afternoon at 4 pm a chimney mason is coming to check if the flue is safe enough to continue to use. Is a chimney mason using mirrors the right person for this type of check? Will he be able to answer both questions: whether the chimney is sound structurally and whether it leaks? My guess is that he says it is structurally sound or he wouldn't be doing the mirror work, right?
We will be getting natural gas service in this area within two years. If there is a way to use the existing chimney for about two years (i.e., it's safe enough), I'm thinking that we might install the metal liner kit if necessary and flash the existing chimney now, finish the current siding job, wait until gas comes and then install a new direct vent gas boiler that is designed for both radiant and floor-panel heat (we have about 1/2 and 1/2 in the house). What do you think of this plan?
The chimney mason said that the chimney is probably not strong enough to stand in the long term and therefore not worth repointing. He used a light and mirror and looked down the inside for interior damage and found damage only to four tiles at the top of the chimney but the lower part was ok. He said he thought it would be usable for two years if I did the minor repairs he suggested--holding the loose bricks at the top together with mortar and creating (from mortar) an angled slope from the top of the ceramic flues down to the edge of the chimney to better drain rain water away from the chimney bricks (done, see attached photo). This will protect the siding workers from falling bricks. He also suggested putting silicone into the visible cracks alongside the chimney (purchased but not yet done). I offered $100 and he took $50 for coming to look.
Since we'll be getting natural gas in the area in two years, I plan to convert the Buderus to natural gas, change it to direct vent, remove the chimney from the top down to a point that is no higher than the existing roof, and side over the chimney to prevent water from seeping into the house. Do you think it is reasonable to direct vent the Buderus after being adapted to a gas burner?
Alternatively, since about 1/2 of the house is radiant heat and the other 1/2 is baseboard hot water, I've been advised to spend $9000 when gas comes to town to install a high-efficiency direct vent modulating condensing gas boiler with a cost of about $9000. Your thoughts about this? I just dodged a $5000 bullet by not tearing down and rebuilding the existing chimney so maybe that is the best?
Below are photos in very large format, first of the damaged interior of the top of the flue, then of the repaired top of the chimney, and then of the damaged seam between the chimney and the exterior wall without siding (for some reason the last photo lies sideways with the top of the chimney on the left). Your comments about the photos are of course welcome.
Attachments are only available to registered users.