Brackets and wall fixings
Everything that hangs on a wall: an outdoor unit, a tank, a boiler, a shelf, an awning. What they share is that the anchor holds them rather than the item, and that what gets calculated is not the weight but the overturning moment from the reach.
How a bracket is built
A bracket is a shelf, a brace and a plate with anchors. The shelf carries the weight, the brace turns the overturning moment into compression, the plate spreads the force into the wall. Take the brace away and the whole load lands on the top anchors, whose pull-out force is three times the weight of the unit.
Two details left out of the cheap version. Anti-vibration pads — the compressor runs at 50 Hz, and without them the vibration goes into the wall as into a membrane; the neighbours hear it better than the owner. And the fall: 2° away from the wall is what sends condensate to the drain instead of letting it pool under the unit.
What kinds there are
For a tank or a cylinder you size for the full volume, not the empty one: a 100-litre cylinder weighs two hundred kilos full. For a boiler the holes come out of the manual — the maker put them where they are for a reason, and "I'll drill it on site" ends in a skewed heat exchanger.
The awning is the odd one out: its load is wind rather than weight, and it works in uplift. That is why it has more anchors than seems necessary and why its braces point the other way.
Household oddments
A letterbox, a number plate, a flagpole, a hose holder, a cylinder stand, a fold-down table. All of it is an hour of welding, and all of it is held not by what was welded but by what it was bolted with.
The cylinder stand deserves a word. It is not there for stability — the cylinder stands up by itself — but so that it cannot be knocked over or carried off. The chain or clamp in the design is not decoration: it is a requirement for storing gas in cylinders, and it does get checked.
Where to go next
Gazebos, greenhouses and yard oddments are in yard and garden. Stainless for kitchens and food plants is in stainless equipment. Fixings for different substrates, price and lead time are in how ordering works.
Frequently asked questions
Why is a bracket sized for overturning rather than weight?
Because the load is applied not at the wall but out on the reach. A 50 kg unit on a bracket with a 600 mm reach puts about 150 kg of pull-out on the upper anchors — three times its own weight. That moment is what gets calculated, not the mass, and it is exactly why a bracket has a diagonal brace.
Why does an outdoor unit need anti-vibration pads?
Because the compressor runs at 50 Hz and that vibration goes into the wall as into a membrane. The neighbours on the other side hear it better than the owner does. Rubber pads between the unit and the shelf take out nearly all of it; they cost about as much as lunch and go on in five minutes.
Can a bracket be hung on aerated concrete?
It can, but not with an ordinary expansion anchor. Aerated concrete does not hold an expansion fixing: it wants a chemical anchor with a mesh sleeve, or a through-bolt with a plate on the other side. The same question for every substrate is set out separately — the article on ordering has a section through six kinds of wall.
Does an outdoor unit need a canopy over it?
It does unless it hangs under a balcony. The issue is not snow on the casing but icicles off the roof: they punch through the grille and bend the fan. A canopy overhanging the unit by 100–150 mm settles it, and costs a tenth of the repair.
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