Most people wait until their HVAC system completely fails before considering a replacement. Long before that happens, your furnace will begin showing signs of giving up the ghost. Here are a few things that might indicate your unit is on its way out.

#1. You’ve encountered much higher heating costs

Furnaces tend to become less efficient as they age. Near the end of their lifespan, you might notice a drastic drop in efficiency, leading to heating bills that are much higher than normal. You may also observe hot and cold spots, or need to set your thermostat a few degrees higher than normal. A newer, high-efficiency model will help you lower costs and could allow you to recoup your investment within five years.

#2. Strange noises are coming from your HVAC system

All heating and cooling systems make some noise. However, when those sounds become unusual or especially loud, this could indicate you have a more serious issue going on. Loud noises are usually accompanied by major repairs or a complete breakdown of your system. Consider a replacement if you notice clanging, popping, squeaking, screeching, squealing, or any other strange sound.

#3. You have a carbon monoxide problem

If your pilot light is yellow rather than blue, this indicates your furnace is producing carbon monoxide. You might also notice a rotten egg smell or excess soot building up next to your furnace. Carbon monoxide leaks are most often caused by cracked heat exchangers, which in themselves can be very expensive to replace. There is no safe level of carbon monoxide inside a home, so do not be fooled into thinking you can continue running your furnace until it breaks down.

#4. Dust is being spit out into your home

Your furnace is supposed to filter dust particles before blowing air out of your vents. So long as your filters are clean, you should not notice clouds of dust coming out of your unit when it kicks on. If you see thick layers of dust on your furniture or observe it spilling out of your registers, this is a sign that your HVAC system can no longer perform its intended function.

#5. Your furnace blows out cold air rather than warm air

If you notice cold air coming out of your vents, this is a sure sign that your furnace is not working properly. In many cases, cold air is accompanied by sweating or excess moisture near your registers. This has the potential to damage hardwood floors, and leaves your home more susceptible to developing mold. In other words, you could be on the hook for more extensive repairs unless you go ahead and have your furnace replaced.

It might also be time for a replacement if you are constantly needing repairs or encounter a single repair that is more than half the cost of a new unit. Consider the age of your furnace and the exact nature of your problem to determine when a new HVAC system is in order.