Furnace Running But the House Still Feels Cold?

Stony Plain Winter Troubleshooting Guide

When it dips well below zero in Stony Plain, your furnace has to work a lot harder. But if it seems like it’s running non-stop and your house still feels cold, something isn’t right.

At Over the Top Heating, we see this all the time in Stony Plain, Spruce Grove, Parkland County, and Edmonton—especially on those long cold snaps. The good news: there are some common causes, and many of them are fixable before things turn into a no-heat emergency.

In this guide, we’ll cover:

• Why your furnace might be running but not keeping up

• Simple checks you can safely do yourself

• When it’s time to call in a professional

1. Your Furnace Filter Is Plugged

This is the #1 issue we find.

A dirty filter chokes airflow. When there’s not enough air moving across the heat exchanger:

• The furnace can overheat and cycle on and off

• Your registers feel weak or lukewarm

• Some rooms never seem to warm up

Quick homeowner check

• Turn off the furnace at the thermostat

• Slide the filter out and hold it up to the light

• If you can barely see light through it, it’s time to replace

In Alberta winters, it’s not uncommon to need a new filter every 1–3 months, especially if you have pets, renovations, or a lot of dust.

2. The Furnace Is Undersized or Just Tired

Older homes around Stony Plain and Spruce Grove often have:

• Older mid-efficiency furnaces

• Equipment that was sized for a milder climate, or

• A furnace that was already borderline and now struggles on the coldest days

Signs your furnace may be too small or at the end of its life:

• It runs almost constantly on cold days

• Certain parts of the house are always cold

• It’s 15–20+ years old

• Your gas bill is high, but comfort is poor

You might get by with tweaks and maintenance, but at some point it’s worth talking about a properly sized, high-efficiency replacement to actually heat the home comfortably and efficiently.

3. Leaky or Poorly Designed Ductwork

Even a perfectly good furnace can’t fix bad ductwork.

Common duct issues we see:

• Disconnected or leaky ducts in basements, crawlspaces, or mechanical rooms

• No return air in main living spaces

• Long runs with undersized ducts feeding far rooms

• Closed or crushed flex duct

These cause:

• Big temperature differences room-to-room

• Weak airflow at certain registers

• Furnace working harder than it should

A duct inspection and some adjustments (sealing, adding returns, resizing certain runs) can make a huge difference in comfort.

4. Thermostat Problems or Bad Location

If your thermostat isn’t reading the house properly, the furnace can’t either.

Issues we often find:

• Thermostat installed:

  • In direct sunlight

  • Right above a supply register

  • Near a drafty door or window

• Thermostat set to the wrong mode or schedule

• Older thermostats that are simply inaccurate

Homeowner checklist

• Make sure it’s set to Heat, not just “Auto” or “Cool/Off”

• Check the temperature setting and schedule (no big night setbacks if the house can’t recover)

• If the thermostat is in a weird spot, mention it to your technician—relocating can help a lot.

5. Poor Insulation, Drafts, and Old Windows

Sometimes the furnace is doing its job, but the house just can’t hold the heat.

Common building issues:

• Little or no attic insulation

• Older single- or double-pane windows with drafts

• Gaps around doors, hose bibs, dryer vents, and electrical penetrations

• Unheated additions or poorly insulated rooms

You’ll notice:

• Certain exterior rooms are always freezing

• Cold floors, especially over garages or crawlspaces

• Strong drafts near windows and doors

No furnace can fully “overpower” a very leaky house. Fixing insulation and drafts is often the cheapest long-term comfort upgrade you can make.

6. Blocked or Frozen Vents and Intake Pipes

On high-efficiency furnaces with plastic venting, winter can cause some specific problems:

• Snow or ice blocking the exhaust or intake

• Frost building up at the end of the vent

• Vent pipes too close to grade, downspouts, or windy corners

When this happens, the furnace may:

• Start and stop repeatedly

• Show pressure-related error codes

• Fail to keep up or shut itself down for safety

A quick visual check outside for ice/snow on vent terminations is a good homeowner step. If anything looks buried, iced over, or questionable, that’s a good time to call a tech—especially if you’re seeing error codes as well.

(Note: don’t chip away aggressively at frozen venting; you can damage the pipe or joint.)

7. Lack of Regular Maintenance

A furnace is like any mechanical piece of equipment—it needs regular attention.

During a professional tune-up, we:

• Clean and inspect burners, flame sensor, and heat exchanger area

• Check venting and combustion air

• Verify temperature rise and airflow

• Inspect drain lines and traps on high-efficiency units

• Confirm electrical connections and safety controls

When a furnace hasn’t been looked at in years, small issues stack up. The system may still “run,” but it performs poorly and struggles during the coldest weather.

What You Can Safely Check Yourself

Here are some safe homeowner steps before calling us:

• Check your filter and replace if dirty

• Make sure all supply and return vents are open and not blocked by furniture or rugs

• Look at exterior vents for snow or loose debris (if it’s safe to do so)

• Confirm thermostat settings, including schedules and temperature setpoint

If you’ve checked these and the home is still uncomfortably cold, it’s time for a professional diagnosis.

When to Call Over the Top Heating

You should call a licensed technician if:

• The furnace runs constantly but room temperatures never reach the setpoint

• Parts of the house are extremely cold compared to others

• You see fault codes or flashing lights on the furnace

• The furnace is older and you’re wondering if it’s worth repairing again

• You suspect venting, ductwork, or sizing issues

We can:

• Inspect and test your furnace properly

• Check ductwork, airflow, and venting

• Give honest feedback on whether a repair, duct fix, or replacement makes the most sense

• Help you plan a comfortable, efficient system for Stony Plain winters

Local Help for Stony Plain, Spruce Grove & Parkland County

If your furnace is running but your Stony Plain home still feels cold, you don’t have to guess what’s wrong.

? Serving Stony Plain, Spruce Grove, Parkland County, and Edmonton
? Call or text 780-870-4328
? Book online through Over the Top Heating

We’re a small, owner-operated company, so when you call, you’re dealing with real technicians—not a distant call centre. We’ll help you figure out why your furnace can’t keep up and get your home comfortable again.