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Free template · updated November 3, 2026

Tankless water heater instructions for guests (template)

A tankless heater never runs out of hot water, but guests still message about it. The water takes a few seconds to heat, a tap on a trickle may stay cold, and two showers plus the dishwasher at once can make the water lukewarm.

This template explains how it works in plain words, a couple of habits that help, and what to do if a code appears on the display. Fill in your model's display location and settings.

The template

Replace anything in [brackets] with your own details.

How it works

  • This home has a tankless water heater. It heats water as it flows, so it won't run out the way a tank can.
  • When you turn on a hot tap, it takes [Number] seconds for hot water to arrive.

Getting good hot water

  • Please turn the tap on at least half way. On a trickle, the heater may not switch on and the water stays cold.
  • Running two showers and the dishwasher or washer at the same time can make the water cooler. Spacing them out helps.
  • If the water goes cold for a moment and then hot again in the shower, that's normal when someone turns another tap on or off.

Temperature

  • The heater is set to [Temperature setting]. Please test the water before getting into the shower or bathing children.
  • Please leave the setting on [Display or control location] as it is.

Where it is

  • The heater is at [Location, e.g. on the wall in the utility room / outside wall by the deck].
  • [Gas model: it has a vent outside at [Vent location]; please keep it clear of snow, furniture and barbecues].

Safety

  • [Gas model: if you smell gas, leave the building without touching switches, and call [Gas company emergency number] from outside].
  • Carbon monoxide alarm: [Alarm location].

If something goes wrong

  • No hot water at all: check the display for a code and turn the hot tap on fully. [Reset step, e.g. press the power button off and on once].
  • A code shows on the display: please send us a photo of it at [Host phone].
  • During a power cut, the heater won't work, even on gas, as it needs electricity to run.
  • Still not working: text [Host name] at [Host phone]. Please don't open the cover.

Tips

Put it on one guest page instead of a binder

Keegix turns your welcome book into one link and a QR sign by the door. Upload the binder you already have and AI drafts the page in about a minute, or paste this template in. Free forever for one property.

Questions

Why does a tankless water heater go cold for a few seconds?

The heater needs a moment to fire up when flow starts or changes, so a short cold burst can happen. It usually settles quickly.

Can a tankless water heater run out of hot water?

Not in the way a tank does, but it has a maximum flow. Too many taps at once can make the water cooler.

Does a gas tankless water heater work in a power outage?

Most don't, because the fan and controls need electricity. Check your model's manual.

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https://keegix.com/house-manual/tankless-water-heater/