Water Heaters installation: a permit and a plumber, by design.
A water heater is the one appliance on this site we describe only so you know what the installer is doing. A tank holds 40 to 80 gallons at 120°F under house pressure, with a relief valve whose discharge line is a code item, an expansion tank where the city requires one, and either a gas burner with a flue or a 240V element circuit. Most cities require a permit and an inspection for a replacement. A licensed plumber owns this install from the first shutoff to the first hot tap.
First use: what is normal
A new machine can do things on its first run that look like a fault and are not. Here is what the makers say is normal, what to do first, and where the line is.
Normal the first time
- Air sputtering at the hot taps at first, until the lines clear.
Do this first
- 1Never power or light it before the tank is full. An element burns out almost at once in a tank that is not full.
- 2Open a hot tap and let it run until the flow is steady, then turn it on. An electric one takes at least an hour to heat.
Where the line is. A dripping relief valve is not normal, and neither is a gas smell or water on the floor: shut it off and text us.
What is typically not in the box
Surplus inventory — open box, cancelled order, overstock, minor scratch & dent — is priced for exactly this: a unit can arrive without the small items that ship with a sealed machine. Have these on hand before install day.
The temperature-and-pressure (T&P) relief valve's discharge pipe — rigid pipe run to the manual's and the code's termination.
The water connectors, dielectric nipples or unions, and the gas connector or the 240V whip.
The expansion tank where the house has a check valve or a pressure-reducing valve (most newer houses).
The drain pan and its drain line where the heater sits over a finished space.
The vent connector, the draft hood or the PVC venting on a gas unit; the condensate neutralizer on a condensing one.
The printed manual — download it by model number.
Power, water, gas, venting, space
What the room has to have before the appliance comes through the door. The manual gives the exact figures for your model; these are the shapes to check.
Most jurisdictions, Jefferson City and Columbia among them, treat a water-heater replacement as permitted plumbing work. The permit is the plumber's; the inspection is what proves the T&P line, the venting and the connections.
A dedicated 240V circuit sized to the plate — 30 amps on most residential tanks — hardwired to the heater's junction box. A hybrid heat-pump heater has the same circuit plus the manual's air volume around it.
A gas line with a sediment trap and a shutoff, a new connector, the right venting for the unit — atmospheric to a chimney or B-vent, power-vented or condensing through PVC — and combustion air per the fuel-gas code.
Cold in with a shutoff valve, hot out, dielectric fittings between copper and steel, an expansion tank where required, and the T&P valve's discharge piped down to within inches of the floor or to an approved drain — never capped, never reduced.
Level floor, the manual's clearances, a drain pan with a drain where a leak would damage the floor, and in a garage the burner at least 18 inches off the floor unless the unit is rated otherwise.
The install, step by step
An overview of the manufacturer's own sequence, so you know what a good install looks like whether you watch one or do one. The manual's page for your model is the authority on every figure.
- 1
The plumber shuts off and drains the old heater
Water, then gas or power, then the tank drained through a hose to a drain, then the old connections cut and the old heater out.
- 2
The new heater is set and connected
Level in the pan, the cold and hot lines connected with new fittings, the expansion tank on the cold side where required, the T&P discharge pipe run, and the gas connector or the 240V whip made up.
- 3
Venting
The vent connector, draft hood and flue on an atmospheric gas unit pitched up and secured; PVC intake and exhaust on a power-vent or condensing unit run and terminated outside per the manual.
- 4
Fill before power
The tank filled with a hot tap open until water runs steady and the air is out — an electric element powered dry burns out in seconds, and that is the one install mistake the warranty names.
- 5
Light or energize, and set the temperature
The gas unit lit per the label and the draft checked at the hood; the electric breaker on. The thermostat set to 120°F, which is the standard for scald safety and the tank's own life.
- 6
Inspection and the leak check
Every joint checked with the tank at pressure, the gas joints with soap solution, and the city's inspection scheduled on the permit.
The diagram
Drawn by us, schematic on purpose: the shape of the connection with every part named. Your model's wiring and hookup page in the manual rules on the details.
Mistakes that look like a broken machine
Most first-week calls are one of these. Each is an install item, not a fault — and each is the reason we ask for every function to be tested before the installer leaves.
An electric heater powered before the tank is full — the upper element burns out dry on day one.
The T&P discharge line capped, run uphill or reduced — the relief valve has nowhere to go; this is the inspection's first look.
No expansion tank on a closed system — the T&P valve weeps every time the heater runs, and the tank's life is shortened.
A gas vent that back-drafts — soot at the draft hood, and carbon monoxide in the room; the draft is checked at the first firing.
Set at 140°F or more — scald risk at the tap and faster sediment; 120°F is the standard.
When a licensed installer is the standard
We recommend professional installation for every appliance we sell. On a water heater these are the parts of the job that the code, the permit or the manufacturer's warranty place with a licensed trade.
Every water-heater installation is a licensed plumber's job under permit — the T&P line, the expansion tank, the venting and the connections are inspected code items.
A gas water heater's connection, venting and combustion air are a licensed gas fitter's or plumber's job under the fuel-gas code.
An electric heater's 240V circuit, or a hybrid's dedicated circuit, is a licensed electrician's job.
Asked at the counter
Can I install a water heater myself?
Most cities require a permit and an inspection for the replacement, and the manufacturer's warranty and the code both expect a licensed installer. We describe the install here so you know what the plumber is doing, not as a how-to.
What is the T&P valve and why the pipe?
The temperature-and-pressure relief valve opens if the tank overheats or over-pressurizes; the discharge pipe carries that scalding water safely to the floor or a drain. It is required on every tank, never capped, never reduced.
Do I need an expansion tank?
If the house has a check valve, a backflow preventer or a pressure-reducing valve on the main — most newer houses do — yes. The plumber knows from the main's fittings.
Why 120°F?
It is the standard for scald safety, it slows sediment and scale, and it costs less to hold. The dishwasher heats its own water from there.
What your receipt says about installation
Installation & testing
Apex Sales does not perform installation, and we strongly recommend professional installation. Moving or installing an appliance without the proper steps — transported upright and secured, every connection checked, and the unit leveled — can loosen parts or cause problems, and improper installation can void the manufacturer warranty. Have a licensed plumber, electrician, or appliance installer test every function of the unit before they leave, so any issue can be reported right away. Damage caused by improper installation is not covered.
Condition & warranty
All units are surplus inventory (open box, cancelled order, customer return, overstock, or minor scratch & dent). Every unit includes the manufacturer's full factory warranty. Please inspect thoroughly in person before purchasing — cosmetic imperfections or missing accessories are possible.
These pages are a general reference for the appliances we sell. They do not replace the manufacturer's installation instructions, the local building, electrical, plumbing, gas and mechanical codes, or the judgment of a licensed installer. Apex Sales does not perform installations and is not responsible for installation performed by the customer or by a third party. Damage caused by improper installation, transport or connection is not covered by the manufacturer's warranty or by Apex Sales.
When it's not a DIY moment
Everything on these pages is safe to look at with the machine unplugged or the gas shut off. These three are not a look — secure the appliance and call.
Gas smell
Close the appliance's shutoff valve if you can reach it safely, open a window, leave the room, and call the gas utility from outside. No switches, no flames.
Burnt smell, a melted plug, arcing
Shut the breaker off, not just the appliance. A scorched cord, plug or outlet means an electrician looks before anything is plugged back in.
Water that will not stop
Close the supply valve at the appliance first (washer, dishwasher, fridge line, water heater cold inlet), then unplug. Mop before you diagnose.
Text us the model number and what it's doing — we'll point you at the next step.
A fix, a part, or a warranty call — the plate's model and serial plus one line about the symptom is all it takes to tell which.
These pages are educational. Every appliance is a little different — follow the manufacturer's manual and local code, and leave gas, water heater and 240V work to a licensed installer.