The short answer
A tankless water heater heats water as it flows through the unit. Available flow depends on the model and required temperature rise; “on demand” does not mean unlimited simultaneous hot water or instant arrival at every tap.
Make the busy-hour list
Tell the designer which fixtures operate together and how the current system falls short. Ask for a selection based on actual demand and the manufacturer’s performance information. A marketing headline is not a flow assessment for your property.
Assess the whole gas route
For a gas model, provide the appliance specification and a list of other gas equipment. Ask the gas fitter to assess meter, regulator, available pressure and downstream piping together. Do not assume the existing tank’s connection is sufficient for a different appliance.
Check the location and ongoing access
Discuss the proposed vent route, drainage where required, service clearance and access for maintenance. Ask what water-quality or maintenance requirements apply to the selected model. A compact cabinet may still need substantial surrounding access.
Understand the delivery and quote
Ask how the design addresses waiting time at distant fixtures and whether any circulation arrangement is proposed. Confirm the equipment, related trades, approvals, old-system removal and homeowner handover in writing. For a strata, resolve common-property work before installation is booked.
Prepare for your assessment
- Fixtures used at the same time
- Model under consideration
- Existing gas appliances and route sketch
- Distance to farthest regularly used fixture
Common questions
Does tankless mean instantly hot water at a tap?
No. Water still travels through the distribution piping; discuss the actual layout and delivery expectations.
Can I size it by the number of bathrooms alone?
No. Simultaneous demand and required temperature rise matter alongside the equipment’s rated performance.
Continue planning
Sources & further reading
Speak with Robert Hamilton at BeeWarm about your property and confirm availability, qualifications and the accepted scope. Find your Lower Mainland service area.
Published October 8, 2026 by BeeWarm. General planning guidance, not an installation procedure. Exact requirements depend on the equipment, property and authority.