Why tankless is not a drop-in swap
A tank heater keeps 40 or 50 gallons hot and uses a small burner to hold it there. A tankless unit heats water on demand and has to deliver a full flow of hot water at once. That takes a large burst of gas or electricity, which is why the supply side matters so much.
Most problems we see on tankless jobs trace to the planning stage. The gas line was too small, the vent run was too long or the water supply was not set up for service valves. Fixing those after the unit is on the wall costs more than doing it right at the start.
The steps of a tankless install
- 1
Check gas or power capacity
A gas tankless needs a line sized for the unit and any other gas appliances. An electric one needs a high-amp circuit.
- 2
Choose a location
Outside wall mounts, garages and closets each have clearances and venting rules.
- 3
Run the vent
Venting must follow the manufacturer limits on length, turns and terminations.
- 4
Connect water and drain
Isolation valves let you flush the unit later. Condensing models need a condensate drain.
- 5
Test and commission
We check combustion, flow, temperature and safety devices, then show you the controls.
Gas line sizing is the hidden cost
Tankless gas units draw many times more gas at once than a typical tank. If the existing line was sized for a tank, it may be too small. Upsizing a gas line can mean opening walls or running new pipe from the meter.
Ask your plumber to measure the existing line and tell you in writing whether it works. If it does not, you want to know before you buy the unit.
Want your gas line checked first?
Call and we will talk through your setup. A short visit can save you from buying the wrong unit.
What to ask before you buy
| Question | Why it matters |
|---|---|
| Is my gas line big enough? | An undersized line limits output and can cause error codes |
| Where will it vent? | Vent length and turns are limited by the model |
| Does it need a condensate drain? | Condensing units produce acidic water that must drain properly |
| Are service valves included? | They make flushing simple and extend life |
| Who pulls the permit? | A permit means the work is inspected |
Permits and licensing
The City of Bothell Permit Center says replacing a water heater requires a permit. A tankless install is a bigger change, so expect a permit and an inspection. The Washington plumbing code, based on the Uniform Plumbing Code with state amendments, covers venting, relief piping and gas connections.
Washington requires plumbing contractors to be licensed. You can check a contractor on the state Department of Labor and Industries lookup. Ask for the registration number and verify it before work starts.
What the finished job should look like
When the install is done, you should see isolation valves on both water lines with a port for flushing, a gas shutoff within reach, a sediment trap on the gas line, a vent that follows the manual and a relief line that terminates safely. Labels and clearances should match the unit instructions.
Ask the installer to show you the controls, the display and what the common error codes mean. A short walk-through at handover saves a service call later.
Care after the install
A tankless unit needs a little attention. Flush the heat exchanger on the schedule in the manual, clean the inlet filter and keep the area around the unit clear. Condensing models also need the condensate neutralizer checked.
Skipping that care is the most common reason tankless units fail early. Put the date of the first flush on the calendar when the unit goes in.
Handover checklist
- Isolation valves installed and labeled
- Gas line size confirmed in writing
- Vent route matches the manual and passed inspection
- Condensate drain tested on a condensing unit
- Temperature set and tested at the farthest fixture
- Manual, warranty paperwork and permit copy handed over
Gas service and tankless in Bothell
Gas in much of the area comes from Puget Sound Energy, though service differs by address. Before you commit to a gas tankless unit, make sure your home has natural gas service and that the meter and regulator can supply the added load. A call to your gas utility can answer the meter question.
If you smell gas at any time, leave the house and call 911 from outside. See our tankless water heater page for service and flushing, and water heater installation for a standard tank. We also serve Kenmore and the towns on our service areas page.
Tankless installation questions
Replacing a water heater requires a permit according to the City Permit Center, and a tankless install is a larger change. We confirm what applies to your address.
Usually not. Tankless units need venting that matches the model, and the old tank flue is often the wrong size or material.
It depends on whether the gas line and vent need work. A simple swap in the same location is faster than a relocation with a new gas line.
Yes. Check your manual for the interval. Bothell water is soft, but a flush is still part of normal care.
Permit and licensing rules vary, so ask the Bothell Permit Center and the state Department of Labor and Industries first. Gas and venting errors can be dangerous.
Sometimes, for smaller loads. Electric units need a high-amp circuit and may require a service upgrade.