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How high your equipment sits, and what that actually protects
Written for League City, Clear Lake and the Bay Area. It goes through the four parts of a heating and cooling system that water reaches, what happens to each one, what can honestly be dried out and what cannot, and how to find out where you stand. There is nothing to buy at the end of it.
Why this page exists
We are asked the same question in two forms. Before a flood: “does the height of the outside unit really matter?” After one: “can this be saved?” The honest answers are yes and usually not, and both of them are worth knowing in advance rather than afterwards.
League City sits low and flat between Clear Creek and Galveston Bay. Water that arrives drains slowly, parts of the area have subsided measurably over decades, and a system installed at a sensible height thirty years ago may not be at a sensible height today. None of that is a reason for alarm; it is a reason to know the number.
What we are not. We are a mechanical contractor. We do not determine flood zones, issue base flood elevations, write elevation certificates, or carry out drainage, grading or pump work. Those belong to FEMA, to the City’s floodplain administration, to a licensed surveyor and to other trades. What we do is set equipment at a height, and tell you plainly what height we think it should be at.
Work out where you are
Pick the situation you are actually in and the part of the system you are asking about. Everything below is written out in full either way — the picker only narrows it.
Before you replace an outdoor unit at the same height, read this
A condensing unit is a sealed compressor, a fan motor, a contactor and a control board sitting in a sheet-metal box that is open at the bottom. It is built to stand in rain. It is not built to stand in water.
What this means in practice: if a unit has been submerged once and the replacement goes back on the same pad at the same height, the replacement is exposed to exactly the same event. The equipment was never the weak part. The height was.
The options are three, and the first one is usually enough. Put the new unit on a taller pad or a fabricated stand, above the level water has actually reached in that yard — which the owner nearly always knows more accurately than any map. Or relocate it to higher ground on the plot, if the line set run allows it. Or accept the exposure deliberately, knowing what it costs, which is a legitimate choice on a low-value unit near the end of its life.
And the one we will not do: drop a new unit onto the old pad without mentioning it, and let you find out next time. If you have been flooded before, the height goes in the quote.
It ran afterwards, which is encouraging and not conclusive
A system that restarts after being submerged has not proved it is undamaged. It has proved that nothing has failed yet. Water leaves three things behind: silt in places air is meant to move through, corrosion starting on terminals and laminations, and moisture inside insulation that takes a long time to leave.
The failures that follow are therefore delayed and look unrelated — a contactor that welds shut months later, a fan motor bearing that goes dry, a board that fails in the next humid spell, a compressor whose winding insulation has been quietly degrading. Each gets diagnosed as its own fault, and the common cause goes unrecorded.
So the useful thing is to write down that it happened — the date, and how deep. That one note turns three mystery failures into one explanation, and it changes whether repairing the fourth one is sensible.
It did not restart, and that is usually the end of it
We would rather say this plainly than be asked to try. Submerged electrical equipment with sealed windings, a control board and a hermetic compressor is generally not economic to recover. It can sometimes be made to run. Making it run is not the same as making it safe or making it last, and the second failure tends to arrive without warning.
There is also an insurance point that costs people money: a loss is easier to document before anybody has worked on the equipment. Photograph it, note the depth and the date, and get the claim opened before a technician starts dismantling things. We will wait.
What we would do: establish how deep the water actually got, which parts of the system were in it and which were above it, and quote only what genuinely needs replacing. Often the indoor side is fine and only the outdoor equipment and its electrical are gone. A quote that replaces everything by default is not a careful quote.
A yard that holds water is the warning, and you have it in time
This is the best position to be in, because the decision is still cheap. If the street or the yard stands in water and the house does not, the margin you are relying on is whatever your slab and your pad happen to give you, and nobody has measured it.
So measure it. How high is the top of the condenser pad above the lowest point of the yard, and above the highest point water has reached? Where is the disconnect box? How high does the line set enter the wall? Those four figures take ten minutes, and once they are written down you never have to guess again.
What usually comes out of it: either the equipment is already high enough and nothing needs doing — a perfectly common answer — or it is low, and the fix costs a fraction of the equipment and gets done at the next replacement anyway.
You are at the only moment when height is nearly free
At replacement the pad is already coming out, the line set is already being handled and the electrical is already being touched. Adding height here costs a modest amount of steel or concrete and no extra labour worth mentioning. Doing the same work as a separate job later costs several times more.
The constraints are real but manageable: refrigerant line set length and rise, service clearances around the unit and above it, airflow that must not be choked by what the unit now stands on, how the unit is fixed down for wind, and whether a taller stand creates a hazard in a walkway. All of those are worked out at the quote, in the yard, not on the phone.
And the honest limit: height protects the equipment. It does nothing for the building, and we will not pretend otherwise. If water in the house is the concern, the people to speak to are a drainage contractor and the City, not us.
You can see most of it before you own it
A general home inspection will usually say the system is operating. That is not the same as telling you what it has been through, and the difference can be a five-figure one in the first two years.
What is visible on a walk round: how high the condenser sits relative to the yard, whether the pad or stand looks original or added later, a silt or stain line on the unit casing or on the fence behind it, corrosion on the disconnect and the whip, the age from the data plate, and in the attic whether there is a secondary pan and a float switch and whether the ceiling below shows a repaired stain.
What to ask directly: has this equipment ever been in water, and when was it installed. The answer may be no, and if so you have lost nothing by asking. Flood history for the property itself is a separate matter, and it is a question for the seller’s disclosure, the City and your insurer rather than for us.
The outdoor condensing unit
The most exposed and the most expensive single item. Inside the casing: a hermetic compressor, a fan motor, a contactor, a capacitor, usually a control board, and on heat pumps a reversing valve and defrost control. The casing is louvred and open at the bottom, so water does not have to get past anything to be inside it.
- What survives rain: all of it. These units stand outside for twenty years.
- What does not survive submersion: the contactor, the capacitor, the board, the fan motor bearings, and over time the compressor windings.
- What silt does separately: blocks the condenser coil from the inside, which is not cleanable from the outside, and the unit then runs permanently hot.
- What height fixes: all of it, for the cost of a stand.
The indoor furnace or air handler
Where this sits decides everything. In most League City houses it is in the attic, which means it is the part of the system least at risk from rising water and most at risk from its own condensate. In a few houses, and in a lot of older commercial buildings, it is in a closet or a ground-level plant room, and then it is as exposed as anything outside.
- In the attic: rising water is not the threat. The primary drain, the secondary pan and the float switch are, because they stand directly above a ceiling.
- In a closet or at ground level: treat it like outdoor equipment. A submerged gas furnace is replaced, not repaired — the gas valve, the ignition control and the safety circuits are not components anyone should gamble on.
- What is salvageable after water: sometimes the cabinet and the coil. Rarely the controls. Never the gas train.
- What height fixes: a platform in a closet installation, if there is headroom. Often there is not, and relocation is the real answer.
The ductwork
The part people forget, and the one that causes the longest-running trouble. Flexible duct is an inner liner, fibreglass insulation and an outer jacket. Once water is inside that insulation it does not come out, and the duct is now a permanently damp enclosure with air blowing through it into every room.
- Attic ducts: normally untouched by flooding, which is the one advantage of putting them up there.
- Ducts under a raised floor or in a crawl space: if they have been submerged, they are replaced. Not dried, not cleaned — replaced. This is the one we are argued with about most, and the one we hold to.
- Metal trunk in a slab: under-slab duct that has taken water is a serious problem with no cheap answer, and the honest options are abandonment and rerouting rather than remediation.
- What height fixes: nothing retrospectively. This is a design decision made when the house was built.
We are not a remediation contractor. Where there is visible mould growth the sequence is remediation first, then us.
Electrical, disconnect and line set
The cheapest part of the system and frequently the lowest. There is no point raising a condensing unit two feet if the disconnect box stays at ankle height, and we see exactly that more often than you would expect.
- The disconnect: a box with live terminals in it. Submerged, it is replaced. It is inexpensive and it is not worth an argument.
- The whip and conduit: water travels inside conduit and stays there. Where it has, the run is renewed.
- The line set penetration: the point where the refrigerant lines pass through the wall is a hole into the building, and if it is below the water line it is also a route in. Sealing and height both matter.
- Scope: we work on the equipment side of the disconnect. Anything upstream of it — the panel, the circuit, the service — is for a licensed electrician, and we will say so rather than reach into it.
Inspect it properly once, then leave it alone
One thorough visit is worth more than watching and waiting. We would open the outdoor unit and look for a silt line inside the casing, check the contactor and capacitor rather than assume them, measure amp draw against the data plate, read pressures and superheat, inspect the disconnect and whip internally, and look at the coil for silt packed between the fins from the inside. Then we would write down the date of the event and the depth, and give you the readings.
After that, nothing unless something changes. We would not recommend pre-emptive replacement of a system that is working. We would tell you what the readings mean for its remaining life, so you can plan rather than react.
Document, then replace only what is gone
First, before anything is dismantled: photographs, the depth, the date. If there is a claim, it is far easier to support now than later.
Then we establish the water line and work out what was above it. Frequently the attic air handler and the attic ductwork are untouched and only the outdoor unit and its electrical need replacing, which is a very different quote from a whole-system job. Where the indoor and outdoor units are of different ages or capacities we will tell you what that means for efficiency and for matching, without using it as a lever to sell you more.
And we take the height decision at the same time, because the new unit has to stand somewhere and this is the moment it costs almost nothing to stand it higher.
Measure the four heights and write them down
A short visit, often alongside a maintenance call. We measure the top of the condenser pad above the lowest point of the yard, the bottom of the disconnect box, the line set penetration, and — where you can tell us — the highest level water has actually reached. Four numbers on one sheet.
Then one of two answers. Either the equipment is already above anything the yard has seen, in which case we say so and you have a record. Or something is low, and we tell you what raising it would cost and whether it is worth doing now or at the next replacement. On a unit with years left, waiting is often the right call, and we will say that even though it means no work for us today.
Decide the height in the yard, before the order goes in
Height is part of the quote, not an afterthought. On site we look at where water has stood, what the line set run will allow, what clearances the unit needs for airflow and for service, how it will be fixed down against wind, and whether a taller stand gets in anybody’s way. Then we put a figure in the quote with the reason next to it.
At the same visit we deal with the parts that usually get left at the old height: the disconnect, the whip and the line set penetration. Raising the unit and leaving those low is half a job.
And if the honest answer is that the existing height is already fine, the quote says so and costs you nothing extra.
Look at it before you exchange, not after
A pre-purchase look at the mechanical system specifically: age from the data plate, condition of the outdoor unit including a look inside the casing for a silt line, the height it sits at, the state of the disconnect and whip, the attic platform, secondary pan and float switch, a static pressure reading if the system can be run, and refrigerant pressures to see whether it is performing or merely operating.
What you get is a plain statement of what the system is, what it appears to have been through, and what it is likely to need in the next few years with rough figures. That is a negotiating position, or a reason to walk, or — often enough — reassurance.
Flood history for the property is not ours to establish. The seller’s disclosure, the City and your insurer are the places for that, and they will tell you more than any inspection of the equipment can.
Where to look things up yourself
None of this is our information to give, and you should not take a flood answer from a contractor’s website. It is all public and it is all free.
- Your flood zone and the maps — FEMA’s Flood Map Service Center at msc.fema.gov, searchable by address.
- Base flood elevation and local requirements — the City of League City’s floodplain administration. They deal with this daily and they are the authority on it, not us.
- An elevation certificate for your property — a licensed surveyor. If one already exists for the house, the seller or the City may have it.
- What your policy actually covers — your insurer, in writing. Whether outdoor mechanical equipment is covered, and on what basis, varies and is worth knowing before you need to know.
- What height your equipment is at right now — a tape measure, or ask us at the next service visit and we will record it.
If you want the four heights measured, say so
It takes a few minutes on a visit we are making anyway. Call and describe the property, and we will tell you on the phone whether there is anything worth looking at.
Mon–Fri 7am–5.30pm