Odorless Smoke In House – Is It Something To Worry About?

If you have found yourself confronted with an odorless smoke in your house you may be confused about the cause. Smoke typically has a smell so what is this phenomenon, and where does it come from?

The likely culprit is your air conditioning unit. It can create the right conditions for an odorless smoke to develop in your home which can be quite unsettling when you don’t know what it is.

Often the reason is a clogged drain hole leaving excess water in the heater box.

Reasons For Odorless Smoke In Your House

It’s rare, but you might find a strange haze appearing in your home without any obvious cause. We were definitely worried when we first located odorless smoke in our home! It can cause immediate panic, especially if you have children or pets like us. 

This ‘smoke’ is odorless and doesn’t appear to be from any kind of fire, so what could be the cause?

Excess Water In AC Heater Box

The ‘smoke’ or more correctly, water vapor that you’re seeing is coming from the air conditioner’s heater box and is caused by an excess of water there. 

It is normally a sign that the drain hole from which condensation would normally escape has become clogged and blocked. This is a feature of older air conditioners. Newer models collect the condensate in a pan and reuse it to keep the components cool. 

Older air conditioner models have a condensation drain hole. When the hole gets blocked the water inside comes into contact with heat and turns into steam. This steam pours out of your air conditioner and creates odorless ‘smoke’ in your house. 

It’s a good indication that the unit needs a good clean or possibly to be replaced with a newer, more efficient model. 

Cold Dry Air Meeting Warm Air

Another potential cause for odorless smoke in your home is when the cold air hits the warm air. This creates a fine mist. It happens when the air conditioner temperature is below its dew point. The water vapor condenses in the air as water droplets. 

When the indoor humidity is higher than usual this makes the problem more obvious. A low fan speed and clogged up air filters will add to the situation. With reduced airflow the cold is exposed to the moist air for longer and makes the problem worse. 

To avoid this you should make sure that the air filters are always kept clean. You should also run your air conditioner on high speed which will cool the indoor air a lot quicker. 

Regular inspections of your air conditioner will keep it working properly, and you can avoid this issue altogether. 

When The Smoke Is Odorless

As long as the ‘smoke’ coming from the AC unit is odorless then there is not normally a serious problem. In these cases the issue is one of humidity and condensation. 

However, if you were to smell burning wire then this might indicate mechanical or electrical problems. 

AC units are filled with electronics and wiring. If it begins to blow out smoke that emits a strange smell then you’ll need to take action. Turn off the unit and call a professional repair person. 

Many times these issues are caused by overheating which in turn is caused by clogged air filters. Without proper ventilation the unit will overheat and may catch fire if not serviced properly. 

Is Odorless Smoke A Health Threat?

Odorless ‘smoke’ is actually condensation or water vapor and does not pose any health risks. It also isn’t a serious problem for the operation of your air conditioner. 

However if the smoke is accompanied by an acrid burning smell then you need to call a professional HVAC technician. 

If smoke with a strange odor is coming out of your air conditioner then this is not good for your health. You should immediately switch it off until you can have it repaired. 

How To Avoid A Smoking Air Conditioner 

There are a number of things that you can do to make sure your air conditioner doesn’t start smoking. One of the most important steps you can take is to schedule an annual maintenance check for your unit. 

A HVAC professional will inspect your air conditioning system for any signs of wear and tear, blockages, or component failings. This helps to get these issues sorted out before you need to run your AC at the hottest time of year when it will be under the most pressure. 

You should check your air conditioner regularly and carry out your own maintenance too. If you replace the air filters on a regular basis it should stop any potential problems from happening in the future. 

A common mistake for many homeowners is having the wrong sized air conditioner for the space. Units that are too small for the room will need to work harder to keep the space cool and this can lead to parts overheating and wearing out prematurely. 

An oversized AC unit can cause something called intermittent air conditioner operation. This causes the unit to turn on and off too often which can add to the humidity levels in your home. 

Having the right sized air conditioner for the size of your home is much less likely to cause problems of this kind. 

Final Thoughts

Summer is when your air conditioner has to work the hardest so make sure it is ready for action. Book a maintenance appointment every year with a HVAC specialist. 

That way you know that your air conditioner will be in good working order when you need it most. Hopefully without any odorless smoke appearing in your home.

Frequently Asked Questions