Thermostats and controls in West Hill, Ontario
A thermostat does not change what a heating system can do. It decides when the equipment runs, which stage it runs at, and when backup heat is allowed to help — and getting those wrong costs more than most people expect. Metropolitan Heating and Air Conditioning has wired and configured controls on all makes and models since 1979, and serves West Hill from our shop on Venture Drive in Scarborough.
Call (416) 283-5698, Monday to Friday 8:00 AM to 4:00 PM.
Power comes first: the C-wire
An old mechanical thermostat had one job — close a contact — and needed no continuous power. A modern control runs a display, a radio and a processor around the clock, and that needs a permanent supply.
The common wire is the return leg that completes that circuit. Some houses have a spare conductor already sitting in the thermostat cable, and it is then a matter of landing it at both ends. Others have four conductors with nothing spare, and the choice becomes new cable back to the equipment or a power-extender module at the board.
Controls advertised as needing no common wire usually draw a trickle through the call itself. On some equipment that is fine. On others — particularly ignition boards sensitive to leakage current — it produces intermittent false calls or short cycling that then gets blamed on the furnace. Worth establishing before the thermostat is on the wall.
The control has to know what it is driving
A two-stage furnace has a low fire covering the bulk of the season and a high fire for cold snaps. A modulating furnace adjusts continuously. A variable-speed blower can circulate at low speed between calls. None of it happens automatically — the thermostat has to be configured for the equipment it is connected to.
Set up as single-stage, a two-stage furnace tends to be driven straight to high fire on every call: shorter, harder cycles, wider temperature swing and more noise, from equipment bought specifically to avoid all three. Configured correctly it spends most of the winter on low fire. The same applies to a two-stage air conditioner and to blower speed.
Heat pump changeover is where it gets consequential
A heat pump is not a furnace with extra terminals, and this is the mismatch we see most.
The reversing valve needs its own output, energised in heating or in cooling depending on the manufacturer — O or B. Wire it to the wrong convention and the system heats when you ask for cooling. Auxiliary heat and emergency heat — the EM HEAT setting on the thermostat — are separate stages with separate rules the control has to hold apart.
Then there is balance point: the outdoor temperature below which backup heat may assist, and the conditions under which the compressor alone should carry the load. A control that energises electric backup the moment the room falls a degree behind setpoint runs resistance heat far more than the house requires, and resistance heat is the expensive way to make it. Configuring changeover properly is most of the value in a heat-pump-capable control. For the equipment itself, start at heat pumps.
Scheduling, setback and recovery
Setback works for a simple reason: a building loses heat in proportion to the difference between indoor and outdoor temperature, so a cooler house loses less. The saving comes from hours spent at the lower setting.
Two things complicate it. Recovery from a deep setback on a heat pump can pull in backup heat and cost more than the setback saved, which is why heat-pump-capable controls use gradual recovery. And remote sensors only behave as intended if they are configured — one left averaging with a sensor in an empty hallway holds a temperature nobody is sitting in.
What an installation involves
Location is decided first, because a thermostat controls the temperature at the thermostat. Mounted in direct sun, on an exterior wall, above a lamp, near a supply register or in a stairwell draught, it reads a temperature the rest of the house is not at — and the system then does exactly what it was told, to a number that was wrong. Relocating a control is often a cheaper fix for uneven comfort than anything done to the equipment.
From there: power isolated, existing wiring identified and photographed before anything is disconnected, then the control mounted. Equipment type, stage count, changeover convention, backup heat rules and cycle rates are set, the control is joined to your network, and every mode is run through to confirm the intended output energises. We then walk you through the schedule, because a control left on its factory programme is the commonest reason people conclude it did nothing.
Everything else we do in West Hill
Beyond thermostat installation we cover heating, air conditioning, HVAC repair, indoor air quality and water heaters. Licensed and insured, all makes and models, installing Carrier, Lennox, Napoleon, Trane, Bosch and Daikin, with financing through Vista. West Hill is on our service areas list.
Book a controls visit
Call (416) 283-5698 weekdays 8:00 AM to 4:00 PM, or tell us what the thermostat is wired to.