Water heater replacement quote checklist: 12 items plumbers forget to price

A water heater swap looks like the easiest job to price: the tank, the labor, done. Then you're on site and the shutoff won't close, the vent is the wrong size, and the inspector wants an expansion tank. Each item is small. Together, they're the profit on the job.

Use this checklist before you send the price. Walk it on the first visit, or ask the customer for photos of the heater, the vent and the shutoff if you're quoting by phone.

Codes differ by state, county and city, and they change. This list tells you what to check and price, not what your local code requires. Your local code and inspector (the authority having jurisdiction) have the final word.

1. Permit and inspection

   Do you need a permit to replace a water heater? In many places, yes, even for a like-for-like swap. Check with your local building department. Price the permit fee, the time to pull it, and the trip or wait for the inspection. If the customer asks you to skip it, put the decision in writing.

2. Expansion tank

   Does a water heater need an expansion tank? When the water system is closed, for example by a check valve, a backflow preventer or some pressure-reducing valves, the plumbing codes used in most of the US require a way to control thermal expansion. An expansion tank is the usual answer. If there's one already, check that it isn't waterlogged and that its air charge matches the house pressure. Either way, it belongs on the quote as a line or an option.

3. Water pressure

   Put a gauge on a hose bib. Common US codes call for a pressure-reducing valve when static pressure is over 80 psi. High pressure shortens the life of the new heater and can trip its relief valve. Price a PRV, or a new one if the old one has failed.

4. Drain pan

   Where a leak would damage the building, such as an attic, an upper floor or above finished space, codes commonly require a pan with a drain line to a safe place. Check whether there's a pan, whether it's the right size for the new tank, and where its drain goes.

5. Temperature and pressure (T&P) relief discharge

   The new heater comes with a new relief valve, but the discharge pipe is yours. It should be full size, run downhill, end in a safe, visible spot that meets your local code, and have no threads on the end. Many old installs don't. Price a new discharge line if this one fails.

6. Venting (gas)

   Check the vent size, slope, connections and clearance from combustibles. A new heater with a higher input, or a different height, can need vent work. A power-vent unit needs a new vent path and an electrical outlet. A high-efficiency condensing unit needs a condensate drain. Any of these turns a simple swap into a bigger job. In parts of California, Utah and Colorado the replacement also has to be an ultra low NOx water heater.

7. Gas supply

   Plan a new flexible connector, an accessible gas shutoff at the appliance, a sediment trap (drip leg) where your fuel gas code requires one, and a leak test. Make sure the gas line can supply the new heater's input.

8. Electrical (electric heaters)

   Check that the breaker and wire size match the new heater's element ratings, and that there's a disconnect where your code requires it. Bigger or faster-recovery units can need electrical upgrades, which may mean an electrician.

9. Shutoff valve and supply connectors

   An old gate valve that won't close fully is a common surprise. Price a new quarter-turn cold-water shutoff and new connectors as standard, or at least as an option. Watch for corrosion where dissimilar metals meet.

10. Seismic straps

    In earthquake areas, California among them, water heaters must be strapped to the wall. Check the existing straps and price new ones if they don't fit the new tank.

11. Location, clearance and access

    New tanks are often taller or wider than the old ones. Measure. Check the clearances the manufacturer and your code require. In garages, gas appliances often have to keep their ignition source raised off the floor (commonly 18 inches) unless the heater is listed as flammable vapor ignition resistant (FVIR), as most modern gas heaters are. Price extra labor for attics, crawlspaces, tight closets and stairs. Our guide to water heater code requirements lists the IRC, IPC and UPC section for each item.

12. Haul-away and disposal

    Draining, removing and disposing of the old tank takes time, and some areas charge a disposal fee. Give it its own line so it's never forgotten, and so the customer can see what it covers.

Plumbo's Quote Guard runs this kind of check on every water heater quote: it asks about the expansion tank, the drain pan and the permit before the price goes out, and adds what you pick from your own price book. Watch it catch a missing expansion tank →

Put the checklist into your price book

The easiest way to stop forgetting these items is to give each one its own line in your price book, with a set price: expansion tank, PRV, drain pan, T&P discharge line, shutoff valve, gas connector, seismic straps, haul-away, permit, attic access. Then quoting a heater is a matter of ticking the lines that apply. Our guide to building a plumbing price book shows how.

Quick reference