Diamond Home Services logo
Diamond Home ServicesServing Toronto & the GTA
24 HOUR RESPONSE GUARANTEED

Tankless Water Heater in Oshawa

Tankless water heater installation, service, and repair in Oshawa.

Call (437) 475-2233
24 hour response
Licensed & insured
OEM parts on the truck

Tankless water heaters give homeowners in Oshawa endless hot water, real energy savings, and a fraction of the mechanical-room footprint of an old tank. That efficiency comes at a price: these units need proper install sizing, annual descaling, and real service knowledge when something goes wrong. We install, service, and repair every major tankless brand — Rinnai, Navien, Noritz, Rheem — and quote the job before we swing a wrench.

Why tankless water heater matters in Oshawa

Endless Hot Water

Properly sized units deliver hot water on demand, forever. No more cold showers when the last kid goes in in Oshawa.

Real Efficiency

Condensing tankless units run at 94–96% efficiency, meaningfully lower than a tank's standing losses.

Space Savings

A wall-mounted unit frees up floor space and lets you rework the mechanical room around it.

Our tankless water heater process

  1. 1

    Sizing Assessment

    We measure your peak demand — showers, kitchen, laundry — and pick a unit that hits it in the coldest month of the year in Oshawa, not the average one.

  2. 2

    Install Or Descale

    New installs include venting, gas line sizing, and condensate drainage done to code. Existing units get a full descale on the annual visit.

  3. 3

    Combustion And Flow Check

    Every service call ends with a combustion reading and a flow test at multiple fixtures.

  4. 4

    Repair When Needed

    Flame-sensing, ignition, flow-sensor, and control-board faults are the common failures, and we carry all of them on the truck.

  5. 5

    Documentation

    Every install and service call comes with a written report and warranty paperwork.

Common findings in Oshawa

  • Scale buildup on heat exchangers in hard-water areas
  • Undersized gas lines starving the burner at peak demand
  • Failed flow sensors causing intermittent cold sandwiches
  • Corroded flame rods from long service intervals

What you get

Lower Gas Bills

Real-world savings of 20–30% versus an aging tank, especially in low-usage homes.

Reliable Hot Water

Annual descaling means the unit performs the way it did the day it was installed.

Better Warranty Position

Documented service keeps your OEM warranty valid — a real dollar value on a 15-year-life appliance.

Tankless Water Heater reviews in Oshawa

4.9 average from 743 verified customer reviews
A real person answers the phone
No call centre, no chasing. Booked in two minutes and got a text when the truck was on the way.
Ryan K. - Mississauga - 2026-02-28
Documentation on everything
Photos, readings, and a written summary after every visit. Makes it easy to keep records for the house file.
Doug T. - Burlington - 2026-01-11
Bundled two services, saved the trip fee
Had the chimney and the dryer vent done on the same visit. Cheaper and half the disruption.
Farah N. - Markham - 2025-12-27
Reliable across three jobs
Used them for a sweep, a dryer vent, and a fireplace service. Same standard every time and the same technician twice, which I appreciated.
Helena B. - Toronto - 2026-04-17

FAQ

How often should a tankless be serviced?

Annually, or every 18 months in soft-water areas.

Can any home switch to tankless?

Most can, but venting and gas line size need to be checked first. That's the sizing visit.

What brands do you install?

Rinnai, Navien, Noritz, and Rheem primarily.

Book your tankless water heater today

24 HOUR RESPONSE GUARANTEED — call now to lock in a slot in Oshawa.

Call (437) 475-2233

More Oshawa services

Tankless Water Heater in Oshawa neighborhoods

Tankless Water Heater in nearby cities