John Wood is a Canadian water heater brand that belongs to A. O. Smith. It came with GSW, the Fergus, Ontario manufacturer that A. O. Smith acquired in 2006, which makes GSW and A. O. Smith its sister brands. A. O. Smith's Canadian head office is still in Fergus; water heater manufacturing there ended in 2013, so a newer John Wood was built at another A. O. Smith plant.
Check ownership before anything else. Look on the jacket for an Enercare or Reliance sticker and look for a rental charge on a monthly statement. If either is there, call the rental company: they own the tank and repair it without charge. Owned tanks and bought-out tanks are ours to work on, and our water heater rental buyout page explains how a buyout is done.
What fails depends on the type. Power-vent John Wood tanks, the ones with a blower on top and a plastic vent through the wall, fail at the blower and the pressure switch. Atmospheric gas tanks lose their pilot, and electric tanks burn out the lower element.
Lake Ontario water in Halton and Hamilton is hard, and a John Wood that has never been flushed carries a layer of sediment on the tank floor. It rumbles on recovery, heats more slowly and runs the steel above the burner hotter than intended. A tank in that state at 10 years is a replacement candidate even when the failed part is cheap.
John Wood lines we install and service
The standard gas tank that vents up a chimney or B-vent with no fan and no power cord. These are flammable-vapour ignition resistant (FVIR) designs: combustion air is drawn through a screened intake at the base, and that intake has to stay clear of lint.
Tanks with a blower that pushes flue gas out through plastic pipe in the side wall. Power direct vent models also draw their combustion air from outdoors through a second pipe. These are the usual choice in houses built without a chimney, and they need a wall receptacle to run.
John Wood's high-efficiency gas line, in power vent and power direct vent versions. They are serviced like other power-vent tanks, with closer attention to the venting and, on condensing versions, to the condensate drain.
Two-element electric tanks on a 240-volt circuit, common in condos, townhouses and rural properties off the gas main, including parts of rural Caledon and Flamborough. Each element has its own thermostat, and the upper thermostat carries the red reset button.
What goes wrong on John Wood equipment
Power vent: noisy or failed blower motor
A power-vent John Wood that has started to whine, rattle or grind at the top is telling you the blower bearings are worn. When the motor stops, the burner cannot fire and there is no hot water. The blower assembly is specific to the model. The repair falls within the $150–$800 band, and on a tank past 10 years we quote a replacement beside it.
Power vent: pressure-switch lockout from a blocked vent
The blower runs, nothing lights and the control locks out. The pressure switch is refusing to prove airflow, usually because the vent termination outside is blocked by snow, ice, leaves or a nest, or the vent has sagged and is holding water. Clear the termination and reset the heater once. If it locks out again, see why a power vent water heater runs but does not ignite and book a visit.
Atmospheric gas: pilot outage
The pilot will not light or will not hold. On older John Wood tanks the cause is a failed thermocouple, $150–$300 to replace, and on newer tanks with an electronic gas control it is a weak thermopile. On any FVIR tank, a lint-blocked air intake at the base starves the burner and trips the thermal cut-off. Laundry rooms are the usual setting, because dryer lint settles at floor level around the tank.
Electric: burned-out lower element or failed thermostat
A short burst of hot water and then lukewarm means the lower element has failed and only the upper is heating. Element replacement is $200–$400. No hot water at all, with the breaker on, points to the upper thermostat or its tripped reset button. A reset that trips again is a fault and not a nuisance: see electric water heater repair.
John Wood warranty: what to know
- The warranty term for a John Wood is printed on the tank's label and warranty sheet. The tank and the parts have separate terms.
- A rented John Wood is the rental company's equipment. The warranty and every repair belong to them for as long as you rent.
- After a buyout, do not assume manufacturer coverage came with the tank. Have the serial number checked with A. O. Smith's Canadian office before counting on it.
- John Wood's website has a tool for checking the age of a heater from its serial number. Age decides most repair-or-replace questions, so look it up before you call.
- The manufacturer's warranty covers the tank or the part. Labour, disposal and any water damage are not included.
Parts availability in the GTA
John Wood shares its platform with GSW and A. O. Smith, so parts for one usually serve all three, and support in Canada runs through A. O. Smith's office in Fergus. Thermocouples, thermopiles, gas control valves, elements, thermostats, relief valves and anode rods are everyday stock at plumbing wholesalers in the GTA and Hamilton. Power-vent blower assemblies and pressure switches are matched to the model, and on older tanks a superseded part number may have to be traced first. Send a photo of the rating label when you book so the right part comes on the first trip, and if a blower for a 12-year-old tank is priced close to half of a new tank, we will tell you before ordering it.
A. O. Smith Water Heater Error Codes Explained — what each one means and whether it is safe to keep running.
Common questions
Can ZK Mechanical repair my rented John Wood water heater?
No: a rented tank belongs to the rental company, which is responsible for repairing it at no charge, and outside work can breach the rental contract. Call the number on the sticker. We work on tanks you own, tanks you have bought out and replacements for rentals you have returned. If the rental has stopped making sense, we can explain the options.
Should I buy out my rented John Wood or replace it?
Compare the buyout figure with a new tank at $1,200–$2,500 installed. Rental fees of $25–$45 a month keep coming until one or the other happens. As a rule, buying out a tank more than 8 years old makes little sense, because you pay for equipment near the end of its life. See buy out or replace a rental water heater.
Are John Wood, GSW and A. O. Smith water heaters the same?
They share an owner and a platform. A. O. Smith acquired GSW and its John Wood brand in 2006 and sells all three names in Canada, with many models differing in little more than the label. Parts and service information cross over. Our A. O. Smith water heater page covers the wider range, including hybrid heat pump models.
Is a noisy John Wood power vent blower an emergency?
Not yet, but it has a deadline. A blower that has become loud still vents safely while it turns. When it seizes, the heater shuts itself down and you have no hot water. Book the repair while it is still running, and install a carbon monoxide alarm near the mechanical room if there is not one already.
My electric John Wood trips its reset button. Can I keep pressing it?
Press it once. The red button is a high-temperature cut-off, and it trips when a thermostat sticks closed or an element shorts to the tank. Repeated resets leave a tank that can overheat. Turn the breaker off and have the thermostats and elements tested; electrical connections to the heater fall under the Electrical Safety Authority's rules in Ontario.