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Power outages

When the power goes out: heating and cooling in a shutoff.

In the hills, planned power shutoffs and storm outages are part of life. Here is what your heating and cooling can and can't do without power, and how to restart it safely.

What needs power

Almost every modern system needs electricity — including gas furnaces, which use it for the blower, the igniter and the controls. What differs is how much. The bars below are a rough, illustrative comparison of typical running loads, not measurements of any particular unit.

Older wall furnace
Some older models with a standing pilot run without any power at all. Many newer ones need a little.
Gas or propane furnace
Needs power for the blower, igniter and controls — a modest load a correctly installed backup can often carry.
Ductless heat pump
A single indoor head is a moderate load; several heads add up.
Central heat pump or AC
The largest load in most homes, especially at start-up. Needs a backup sized for it.

Illustrative only. The real figures are on each unit's nameplate; we can read them for you.

Before

Before an outage

Know where your furnace switch and the HVAC breakers are, and label them.
Replace thermostat batteries once a year — many keep their settings on batteries.
Test your carbon monoxide alarms.
If you plan to use a generator for heating, have an electrician install a transfer switch or interlock first.

During

While the power is off

Set the thermostat to Off, so the system doesn't start the moment power flickers back.
Keep doors and curtains closed to hold heat (or coolness) in.
Close off rooms you aren't using.

Never heat the house with a gas oven, a barbecue or an outdoor heater, and never run a generator in a garage, carport or near a window. All of them produce carbon monoxide.

After

When the power comes back

Wait a few minutes for the power to settle before turning the system back on.
Set the thermostat back to Heat or Cool and check the time and schedule.
If nothing happens, check the breaker once. If it trips again, leave it off and call us.
Some heat pumps have a start-up delay after a long outage. Give them time before assuming a fault.

A wall thermostat in a softly lit hallway, daylight coming from a nearby window

Backup power

Portable generators, standby generators and home batteries can all keep some heating or cooling running — if they are sized for it and connected properly. The connection is electrical work: it must be done by a licensed electrician with a transfer switch or interlock, so power can never flow back into the utility lines.

Our part is the heating and cooling side: we read your equipment's nameplates, tell the electrician what it needs to start and run, and check the system afterwards.

A wooded hillside road at dusk with overhead power lines running through the trees

For businesses

After a long shutoff, rooftop units and ductless systems usually restart on their own — but not always, and not always with the right schedule. Server closets heat up quickly once the cooling stops. We can check a building before opening day and set restart settings so equipment comes back in order.

Arrange a visit (650) 659-2229