Hayes Plumbing handles tankless water heater installation in Ajax, plus repairs and descaling for units that are already on the wall. We work across town, from Pickering Village and Downtown Ajax to Discovery Bay, Westney Heights, Applecroft and Nottingham, with plumbers driving in from our shop at 448 Ritson Rd. South in Oshawa, normally 20 to 30 minutes away. A tankless heater warms water only while it flows through the heat exchanger, so there is no tank of water losing heat between uses. To deliver on that, the unit has to be sized, vented and maintained correctly, which is why we look at your hot water habits and the installation space before quoting. The quote is free and in writing.
What We Check Before Quoting
A tankless installation is more than hanging a unit on the wall. Before we price one, we look at five things:
- Peak demand: which showers, taps and appliances are used together at the busiest time of your day.
- Gas supply: whether the existing line can feed the unit or needs upsizing, which tankless units often require.
- Venting: where a dedicated vent can leave the house. A condensing unit produces acidic condensate that needs a drain, and it vents through PVC or other specialized pipe; a non-condensing unit is vented in stainless steel.
- Location: wall space close to the gas, water and vent routes, with isolation valves fitted so the unit is easy to flush later.
- Water quality: whether a softener is installed, which changes how often descaling will be needed.
Sizing for an Ajax Winter
Water reaches Ajax homes from the Region of Durham's Ajax Water Supply Plant, which draws from Lake Ontario through an intake extending about 2.5 kilometres into the lake, at a depth of roughly 18 metres. The water arriving at the house is much colder in midwinter than in late summer, and a tankless unit has to make up that whole temperature difference while the water passes through it. A unit that seems ample in summer can struggle in winter, so we size for cold-weather inlet water and for the fixtures your family uses together.
Natural Resources Canada cautions that a family running several showers together can outstrip what a single tankless system delivers. If back-to-back showers with the dishwasher going are normal in your house, we will tell you plainly whether one unit will cover it.
Gas Safety and Permits in Ajax
Ontario law, as TSSA explains it, allows only TSSA-registered contractors to maintain fuel-fired appliances such as a gas tankless heater, and those firms have to send gas technicians who hold TSSA certification. You can look a company up on the TSSA website before you book. Should you smell gas near the unit, get everyone outside before calling Enbridge Gas's emergency line, 1-866-763-5427, or 911.
On the permit side, plumbing permits in Ajax are applied for through the Town's online portal or by emailing buildingpermits@ajax.ca, and inspections are requested on 905-619-2529 at least 24 hours ahead. Ajax's permit page adds that a building permit and an ESA (Electrical Safety Authority) notification are two separate things, and some work needs both. Check with Building Services about permit requirements for your conversion before an installation date is set.
Tankless Water Heater Maintenance in Ajax
The Region lists the Lake Ontario water supplied to Ajax at a hardness of 125 mg/L. When that water is heated, calcium and magnesium come out of solution and crust the heat exchanger. The crust insulates it, makes the burner work harder and eventually narrows the flow path. Our maintenance guide also suggests keeping a record of each service, since many manufacturers ask for proof of regular descaling under their heat exchanger warranties. A full service visit covers:
- A descaling flush, circulating a mild acid solution through the heat exchanger by way of the isolation valves.
- Cleaning the cold-water inlet screen, which catches grit and can trigger low-water faults when it clogs.
- Clearing and checking the intake and exhaust, the condensate drain and its neutralizer, and the outside vent terminations.
- Checking the burner and combustion on gas models, testing temperature and flow, and reading the stored fault history.
- Fitting isolation valves if the unit was installed without them, so later flushes are quick.
Tankless Water Heater Repair in Ajax
Tankless heaters tend to give warning before they quit, and scale on the heat exchanger is behind many of the symptoms, so a descaling flush is often the first fix we try. If the problem continues afterwards, we look further at the inlet screen, the flow sensor, the venting and the controls. Signs that a unit needs attention:
- Mid-shower, the water dips from hot to lukewarm.
- Hot water takes longer to arrive, or the flow at the tap is weaker than it was.
- The unit knocks or whistles while firing.
- A code appears on the display, particularly one for scale or flow.
- White mineral crust builds up around the fittings.
- The unit switches on and off even though a tap is running steadily.
Pricing a Tankless Installation
Our hot water tank replacement article puts a complete tankless installation at $3,000 to $6,000, while a standard tank comes to $1,200 to $3,500 installed. The difference reflects the extra work a conversion often involves, such as a larger gas line, a dedicated vent and a condensate drain. Our 2026 Oshawa plumbing cost guide gives water heater installation as $500 to $1,500 and notes that this covers tank or tankless, depending on model and installation complexity. Repairs and descaling are quoted once we have seen the unit, and all figures are in writing before work begins.