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Ten feet from somebody else’s bedroom
There is no association on this island to referee anything. There is a four-foot gap and a person on the other side of it. This page is about doing the job without starting something.
Three things worth understanding before any of the detail.
One: heard and felt are different problems. Airborne noise travels through the air and is about placement, distance and what is between the unit and the listener. Structure-borne vibration travels through the building and is about mounts and fixings. They need different fixes, and money spent on the wrong one does nothing. Vibration is also the one people find hardest to live with, because it is felt in a room rather than heard from outside it.
Two: the conversation is cheaper than the dispute. Telling a neighbour what you are planning, before it happens, converts a complaint into a discussion. It costs ten minutes and it is the single most effective thing on this page. It is also the thing people most want to skip.
Three: we will not interpret your city’s rules. Noise limits and setbacks are the city’s to state and they differ between them. We will give you the manufacturer’s published figures and the measured distances, which is what anybody ruling on it will ask for. What those mean under a particular ordinance is not ours to say.
Pick the job and how close the buildings are. Everything below is written out in full.
A machine bolted to a wall that two households share does not have to be loud to be unbearable. Vibration passes directly into the structure and arrives in the next room as a low hum that is felt rather than heard — the kind of thing somebody notices at two in the morning and cannot locate, and which a sound meter outside the building may not register at all.
What actually addresses it. Not screening, and not moving the unit two feet. Isolation at the fixing: proper anti-vibration mounts rated for the weight, a pad that is actually doing something rather than a strip of foam, and — best of all — not mounting to the shared wall in the first place. A unit on its own stand on the ground, or on a bracket on a different wall, solves at source what mounts only reduce.
Two things that make it worse. Rigid pipework clamped hard to the same structure, which carries vibration further than the unit itself does. And a unit that has loosened over time — fixings work slack, and a machine that was fine for three years can start transmitting without anything having “broken”.
And one thing to check first if this is already happening: whether anything has loosened. We have resolved complaints that had run for months by tightening and re-isolating a mount, which costs almost nothing compared with what everybody had been assuming.
Putting in cooling for the first time
The best position, because everything is still a choice.
Work out where it can go before you decide what to buy. On a narrow lot there are usually only two or three possible positions, and each has consequences — clearance for the machine to breathe, service access, distance to the nearest window, whose window it is, and how the line set gets there. A unit crammed into the only spot that was convenient will run hot, cost more and annoy somebody.
Tell the neighbour. Before it happens, in person, with a rough idea of where and when. It converts the whole thing from something done to them into something they knew about. People who are told are people who wait a week before mentioning a noise; people who are surprised ring the city.
And decide about mounts now. Isolation fitted at installation costs very little. Retrofitting it means taking the unit off the wall, which costs a great deal more.
Replacing what is there
People assume this is neutral because nothing new is appearing. It is not, in two specific ways.
New equipment is often physically bigger, particularly taller, which changes what is visible over a fence and how much clearance is left in a gap that was already tight. It is worth measuring rather than assuming the new one drops into the old spot.
And it is the cheapest moment there will ever be to move it. If the current position has always been slightly wrong — too close to a window, too tight to service, on the shared wall — a replacement is when that costs least to correct. Once the new one is on the old brackets, it is there for fifteen years.
Modern equipment is usually quieter, which helps, though a quieter machine badly mounted on a shared wall is still a vibration problem. The mount matters more than the model.
Moving a unit somewhere better
Usually the right instinct, and worth understanding what it does and does not solve.
Distance helps with airborne noise and it helps in a fairly ordinary way — further is quieter. Getting a unit away from directly under a window, or round a corner so the building is between it and the listener, makes a real difference.
Distance does almost nothing for vibration if the new position is on the same structure. Moving along a shared wall changes very little; moving off it changes everything.
What it costs. A longer line set has manufacturer limits and may need the charge adjusting. Condensate has to go somewhere from the new position, and on a narrow lot “somewhere” is frequently a neighbour’s path. Electrical has to reach. None of it is exotic; all of it needs planning rather than improvising on the day.
And if the move is because of a complaint, say so to the neighbour. A move made in response to them is worth a great deal more than the same move made silently.
It is the neighbour’s unit
The hardest one, and the one where we are least use and most likely to be asked.
What we will not do. We will not come and assess somebody else’s equipment on your behalf without their knowledge or consent, and we will not produce a report intended to be used against them. That is not squeamishness — it is that we work on this island and so do they.
What is usually true, and worth knowing before you escalate. Most of these situations are a mounting problem rather than a bad machine, and most are fixable cheaply. A unit transmitting into a shared wall, a fixing that has worked loose, a pad that was never there. The owner is frequently unaware there is a problem at all, because in their house it is at the far end of the building.
The sequence that works is boring and it works: tell them, specifically — which hours, what it sounds like, which room you notice it in. That is far more useful to whoever eventually looks at it than “your air conditioning is too loud”. If nothing changes, your city has a process, and that is the right next step rather than a contractor.
If they ask us to look at it, we are glad to, and we will treat it as their job and not yours.
Somebody has complained about ours
Take it seriously and take it early. Almost every one of these we have seen was fixable, and almost every one that became difficult did so because the first response was defensive.
Establish which problem it is. Ask them which room they notice it in and at what times. A complaint about a sound heard outdoors in the evening is airborne and points at placement and screening. A complaint about a hum felt in a bedroom at night, through a wall, is vibration and points at the mounts. Those are different jobs and the question takes thirty seconds.
Check the obvious first. Fixings that have loosened, a fan blade out of balance, a pad that has compressed, something resting against the casing. We have resolved months-old complaints with a spanner.
Then the real options, cheapest first: re-isolate the mounts; add or improve a screen if it is airborne; change the schedule so it is not running at the hours that matter most; and, if none of that is enough, move it. That order is also the order that shows willingness, which matters more than any of the individual measures.
What we will not do is tell you it is within the limit and they should live with it. Even where that is true, it is not a solution to living next door to somebody.
A narrow gap between two houses
The standard Alameda situation, and the one with the most levers.
The gap is a problem twice over. It puts the machine close to somebody, and it reflects sound between two hard parallel walls, which makes a unit in a gap louder at the far end than the same unit in the open. That is why a position that looks marginally worse on a plan is sometimes much better in practice.
What helps here: getting the unit out of the narrowest section if there is any choice, keeping it away from directly under either window, leaving genuine clearance so it is not fighting for air, and a screen that absorbs rather than reflects if one is needed.
And clearance is not optional. A unit squeezed into a gap with less air than it needs runs hotter, costs more and fails earlier. That is the argument to make if somebody is proposing to fit one into a space that will not take it.
A shared or party wall
See the note above, which is the whole of it: this is a vibration situation, and the answer is isolation or — better — not mounting to that wall at all.
The one thing to add is about the pipework. Refrigerant lines and condensate clamped rigidly to the same structure carry vibration a surprising distance, and a beautifully isolated unit on a badly clamped line set is still a problem. It is an easy thing to get right at installation and a fiddly one afterwards.
Somebody lives above or below
The mixed-use case, common on the commercial streets here, and it adds a dimension the others do not have: hours.
A cafe’s equipment starting at five in the morning is a different proposition from an office system running at two in the afternoon, and no amount of isolation changes when it runs. Timers, staging and a schedule that matches the actual business are often worth more here than hardware.
Mounting on old fabric matters more too. A bracket on a hundred-year-old wall in a building with a flat above transmits everything. Isolation at the fixing is not a refinement in that building, it is the job.
And extract is part of the picture. A kitchen hood running with no make-up air pulls air out of the whole building, including the flat upstairs. That is a comfort problem for them, a cost for you, and it is frequently the actual complaint underneath a complaint about noise.
A garden or yard between you
The most comfortable position, and worth not wasting.
With real distance, airborne noise falls off quickly and vibration is not in the conversation at all, because nothing is shared. The decisions become ordinary ones: clearance, service access, sun on the unit, and keeping it away from the part of the garden anybody actually sits in — including your own.
The one thing people get wrong is putting it where it is least visible rather than where it is least audible. A unit tucked behind a shed against a fence is out of sight and reflecting straight over it. Ten feet of thought at installation is worth years.
Next step
Decide the position before the equipment, and tell the neighbour before the installation. Those two, in that order, prevent most of what this page is about.
Next step
Measure the new unit against the old position rather than assuming it fits, and treat the replacement as the cheapest chance you will ever get to move it somewhere better.
Next step
Work out whether you are moving away from a sound or off a structure. They are different journeys, and only one of them is solved by distance.
Next step
Tell them specifically: which room, which hours, what it sounds like. That is far more useful than a general complaint, and it is what any contractor they call will need. If nothing changes, your city has a process.
Next step
Ask which room and what time, then check whether anything has loosened. Those two steps resolve a surprising share of these, and both happen before anybody spends money.
What we will not do
We will not claim a noise level. We will quote the manufacturer’s published rating and say where it came from. What it sounds like at a particular window depends on the buildings, the surfaces between them and the hour, and anybody giving you a number for that has not measured it either.
We will not interpret your city’s ordinance. We will give you the published figures and the measured distances. What they mean under a particular rule is for the city.
We will not assess a neighbour’s equipment on your behalf without their knowledge, and we will not write a report intended to be used against them.
And we will not install something into a position that has no clearance, however much you want it there. It will run hot, cost more and fail early, and we would rather lose the job than be the reason.
The twenty minutes with a tape measure
A visit, the possible positions measured, the windows either side noted, the published sound figures written down, and an honest answer about which position will cause you the least trouble over fifteen years.