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What actually happens to your heating when the ground moves
Five pieces of equipment, crossed with the four kinds of building they sit in. What is worth securing, what it does not protect you from, and the situation where the honest answer is that this was never a heating question.
Three things that apply to every answer below
- Afterwards: do not shut the gas off unless you have a reason to.
The standard advice from utilities and emergency agencies is narrower than most people believe. Shut the gas off at the meter only if you smell gas, hear gas escaping, or see obvious damage suggesting a leak — and then leave the building and call from outside. Once it is off, only the utility should turn it back on, and after a large event that can take a long time, which is precisely why turning it off without cause is not the safe default it sounds like. Know where your shut-off is and keep a wrench near it. Do not use it for practice.
- Securing an appliance protects the appliance and its connections. Nothing else.
Strapping a water heater, bolting a furnace down and fitting flexible connectors are cheap, quick, genuinely worthwhile and among the best value work in this trade. They reduce the chance of a gas line being torn off something that moved. They tell you nothing at all about whether the building will stand up, and anybody who lets you conflate the two is doing you harm.
- We install it. We do not certify it.
We fix equipment down to the manufacturer’s instructions and to whatever the code official requires, we fit connectors that can move, we photograph the work and we write down what was done. Calculations, sign-off, and anything an insurer, a lender or an inspector will rely on belong to a structural engineer. We are a mechanical contractor and that line is not blurry.
Work out what is worth doing
Pick the equipment and pick the building. Every answer below is on this page whether you pick anything or not — the picker only narrows it down.
We will say this plainly because it is the most useful sentence on the page. In an older house that still sits on an unbolted foundation, or on a short stud wall between the foundation and the floor that has never been braced, the building is the question and the furnace is a footnote. A house that moves off its foundation takes its gas line with it regardless of how well the appliance was strapped. That is a structural retrofit — a licensed contractor’s work, on an engineer’s detail where the house needs one — and there are grant and rebate programmes in California that exist specifically for it. We do not do that work, we are not paid by anybody who does, and we are not going to pretend that bolting the water heater down is a version of it. What we will still do, and what is still worth doing: strap the tank, fit flexible gas and water connectors, secure the furnace to what it stands on, and make sure you know where the shut-off is. All of that is cheap, all of it helps, and none of it is the retrofit. Do the retrofit.
Check that it is fixed to something that will still be there, and that the gas connector can move.
A furnace in a crawl space or a basement is usually sitting on a platform, a plinth or a pair of blocks that somebody built at some point. The two questions are whether the appliance is actually attached to that, and whether the platform is attached to anything. After that, the connector: a rigid gas pipe into an appliance that can shift is the failure everybody is trying to avoid.
What we look at, and what it costs to put right
- The stand. Whether the furnace is fastened down, and whether the thing it is fastened to is itself fixed or simply stacked. Concrete blocks dry-laid under an appliance are extremely common down there and are not a mounting.
- The gas connector. Flexible connectors of the right length and rating, without a rigid run straight into the appliance. Where an old rigid connection exists, replacing it is a short job.
- The flue. Vent connectors that are properly fastened rather than pushed together, because a separated flue is a carbon monoxide problem and separations are what movement causes.
- The condensate and the electrical. Both want enough slack to move without tearing.
- What is stored around it. The single most common finding in a crawl space is that the appliance is fine and there are four boxes and a bicycle leaning against its flue.
None of this is expensive and most of it is an hour or two. It is also the easiest thing in the world to leave undone for thirty years, which is why it is usually undone.
The appliance is in the wall. The questions are the gas line and the flue, not the appliance.
A wall or floor furnace is built into the structure and it is not going anywhere the wall does not go. What can fail is the connection to it and the vent above it, and a separated flue on an appliance people go on using is a genuine carbon monoxide risk.
Wall and floor furnaces, honestly
There is a persistent idea that these appliances are inherently unsafe and should all be replaced. That is not true and it is frequently said by people who would like to sell you a system. A wall or floor furnace that passes a combustion analysis, vents properly and has its clearances respected is a working appliance, and a great many Berkeley houses are heated perfectly well by one.
What matters after movement is the vent. These appliances vent through a flue that runs up inside the wall or the roof space, in sections, and sections separate. If the building has moved at all, that flue wants looking at before the appliance is used again, and it is not something you can check by looking at the front of it.
The other item is the connector and the shut-off, which on older installations is sometimes rigid and sometimes seized. Both are short jobs.
And the genuine limitation, which is a comfort point rather than a safety one: a wall furnace heats the room it is in. Whether that is acceptable is a decision, not a fault, and it is one we will price either way.
Strap it, top and bottom, and put flexible connectors on the gas and the water. Cheapest worthwhile job on this page.
A full water heater is heavy, tall and narrow, and it is the appliance most likely to fall over. When it does it takes the gas line and the water line with it. Two straps and two connectors is an hour’s work and it is required by California code for new and replacement installations, which tells you what the state thinks of the risk.
What a proper job looks like
- Two straps, not one — upper and lower third of the tank — anchored into structure rather than into plasterboard, with the correct clearances from the controls.
- A flexible gas connector of the right rating, and a flexible water connector on the supply.
- A temperature and pressure relief discharge pipe that is intact and terminates where it should, which is frequently the thing we actually find wrong.
- Combustion air and clearance respected, and nothing stored against the appliance.
- A working carbon monoxide alarm in the house. If there is not one, we fit one.
There is a version of this sold as an earthquake service that consists of one strap and a photograph. That is not what a job looks like, and it is worth asking anybody who offers it what exactly they are anchoring into.
Bolt the unit to its pad, bolt the pad to something, and leave the line set a service loop.
An outdoor unit standing loose on a pad is the easiest fix on this page and one of the most commonly missed. The refrigerant lines are the vulnerable part: a unit that shifts even a little can work a brazed joint until it leaks, and a slow refrigerant loss is expensive and takes months to be noticed.
Outdoor units, pads and line sets
Three things decide whether this goes wrong. Whether the unit is fastened to the pad, which on a great many installations it simply is not. Whether the pad is anything — a poured pad tied to the ground behaves differently from a plastic tray on gravel. And whether the line set has slack: a gentle loop before it enters the wall absorbs movement that would otherwise go straight into the joint.
Wall-mounted and bracket-mounted units, which are common on the narrower lots here, need the bracket checked as well as the unit — and the bracket wants to be into structure, not into siding.
The electrical disconnect and the whip want enough slack for the same reason. And on a hillside property, whether the ground the pad sits on is itself stable is a question for somebody who reads soil reports, not for us.
The curb attachment and the gas riser are the two items, and both want somebody who can see the structure.
Rooftop plant is heavy, high up, and connected to gas, refrigerant and electricity. Whether it is properly fastened to its curb, and whether that curb is properly part of the roof, is a real question, and on an older building it is one nobody has asked since the unit went in.
Rooftop and platform plant
What we check and correct: whether the unit is mechanically fastened to the curb rather than resting on it; the condition of the curb itself and its flashing; whether the gas riser has a flexible section and an accessible shut-off at the unit; whether refrigerant lines and electrical whips have slack; and whether vibration isolators are still doing anything, because a perished isolator is both a noise problem and a restraint problem.
Platform-mounted plant at ground level, which is common behind buildings here, raises the same questions plus one: whether the platform is braced against racking. That is a structural detail and where it looks doubtful we will say so and stop.
On any building where the plant is large or the structure is old, this is a conversation that should include a structural engineer. We are happy to be in it. We are not going to be the only ones in it.
An older house that has never been retrofitted
Read the note above first, because it is the substance. Everything on the equipment side is still worth doing and we will do it, quickly and cheaply, and it will still be true that the building is the larger question by a long way.
The practical order we would suggest: strap the water heater and fit flexible connectors now, because it is an hour and it removes one of the likelier fire risks. Fit a carbon monoxide alarm if there is not one. Find your gas shut-off and put a wrench beside it. Then get a structural assessment, and look up what assistance exists — California has run grant programmes for exactly this kind of retrofit and they change, so check the current position rather than relying on what somebody told you in 2019.
One more thing, said plainly. If a contractor arrives to do heating work and tells you that securing the equipment makes the house safe, that is either ignorance or a sale. It is neither true nor close to true.
A house that has been bolted and braced
Then the building work has been done and the equipment is genuinely the next item on the list, which is a better position to be in than most houses in this city.
Worth checking: whether the retrofit included anything on the mechanical side, because it frequently does not. A contractor bolting a sill plate has no reason to look at the water heater strapping, and the two jobs are often years apart. We find unstrapped tanks in retrofitted houses regularly.
Also worth doing, since somebody has been under there: ask for the documentation from the retrofit and keep it with the equipment records. If we have ever measured your system, that sheet belongs in the same folder. When a house is sold, the folder is worth more than any single item in it.
An apartment building
Then most of the equipment is not yours and the useful thing is to know which part is. A water heater inside your own unit is typically within your control; a shared plant room, a rooftop unit or a central boiler is the building’s. We will tell you which is which on a first visit and that costs nothing.
Where the building owns it, a measurement with a date on it is the most effective thing you can have. “The water heater in the shared closet is unstrapped” is a sentence a managing agent has to act on; a general concern is not.
We will not work on common parts, shared plant or a building’s systems on one resident’s instruction. That needs the owner or the association, and we will say so rather than start and stop. And on soft-storey buildings — a living floor over an open parking level — the structural question is the whole question, and several Bay Area cities have required work on exactly that. Ask the owner what has been done.
A commercial building
Then the plant is larger, higher and more of it, and the restraint question is genuinely part of a mechanical survey rather than an add-on. We include it: how each unit is fixed, whether gas risers have flexible sections and accessible shut-offs, whether isolators are perished, and whether lines and whips have slack.
Two things worth having in writing. First, where the shut-offs are and who is authorised to use them, on a drawing, somewhere that is not only in one person’s head. Second, what is expected of whom under the lease, because plant restraint is precisely the sort of item that falls between a landlord’s structure and a tenant’s equipment and gets done by neither.
Where the building is old, large, or has plant that is heavy relative to its structure, we will recommend a structural engineer and we will not proceed as though our fixings answer a question they do not.
Where this page stops
We will secure appliances to manufacturer instructions, strap water heaters properly, fit flexible gas and water connectors, check flues and connectors for separation, leave slack in refrigerant lines and electrical whips, photograph all of it and write down what was done. We will fit a carbon monoxide alarm where there is a gas appliance and none. All of that is ordinary mechanical work and it is worth doing this month rather than eventually.
We will not certify seismic restraint, perform or advise on a structural retrofit, tell you your building is safe, or let equipment work stand in for building work. If you smell gas at any time, leave the building and call the utility from outside — that is the one thing on this page that does not wait for anybody, including us.