Post by downunderdave on Jul 26, 2021 21:10:16 GMT
The fixing of the anchor plate presents some problems. Don’t use plastic plugs they’ll melt and burn. Normal steel plated or even galvanised fixings are also inadequate. Use stainless, maybe dynabolts. The high heat in that area accelerates corrosion. The second problem is that metal fixings, being more conductive than the brick or refractory that surrounds them, will expand first creating extra pressure around the holes. Thirdly drilling holes is inviting cracking around the holes. If using a fireproof caulk high temp silicon is inadequate in that position from my experience. My solution is not to use an anchor plate at all, but fabricating the surrounding refractory such that the pipe is a slightly loose fit to allow it to expand without placing pressure on the cast flue gallery that supports it. I cut three tabs in the base of the pipe and bend them out 90 degrees. The pipe is then supported higher up with 5:1 vermicrete that is slightly flexible. The outer shell then covers the vermicrete higher up the pipe and supports the pipe with a high temp silicon sealto cope with the pipes expansion. Being higher up the pipe is slightly cooler and the high temp silicon copes ok. This is only one solution there are other ways of doing it.
Post by hiddenspringvineyard on Jul 27, 2021 11:52:32 GMT
Thanks Dave. I am thinking of setting a firebrick box above the arch thats 45cm x 45cm to mount the anchor plate (40 x 40cm) (I've bought it so determined to use it!!). The sleeve anchors seem the best option so I'll increase the holes in the anchor (there is one in each corner) to allow for the M6 bolt diameter but to allow for expansion maybe make it an extra mm or so in diameter - as long as the bolt holds it. Then I was going to use refractory mortar to cover the edge of the anchor to the edge of the bricks or maybe most of the way in to the twin wall mount in an attempt to create a slope for any water to flow down (it rains alot here in England). Do you recommend mixing vermiculite for the filling to the flue mount?
I am debating trimming the anchor plate as 40x40cm seems huge and forcing me to have a very large mounting box...