Looking at some condo gas furnace installations in compartments or closets above the ceiling makes me laugh, cry, and scream at the same time. I can’t even imagine what the installer of the furnace was thinking … or if he was thinking at all.

In HVAC trade, just like in any other, there are some basic rules that anyone performing the job should follow. Not because somebody wrote them down, but because there’s a reason to follow them. Many of the rules are common sense. Some must be just taken for granted, but all should be followed if you (the installer) are being paid for it.
This short story is just another proof that Chicago’s new condos are rarely (if ever) inspected by the city building department inspectors.

• The access to the furnace closet, located directly above the bathroom ceiling, was quite comfortable and served as an air combustion supplying port – this is the good part and where it unfortunately ends.

• The condo furnace had been suspended from the ceiling in a far corner of the closet space. It had been positioned in such way that any attempt of servicing it would require a person to levitate horizontally in approximately 16” of clearance between the furnace front panel and the chimney wall. It appears that furnace installation was performed before the bathroom ceiling drywall went up – set it and forget it…

• For the furnace to vent efficiently, its vent pipe must be pitched up at least ¼” per linear foot of an entire run – this one drops down a few inches before connecting to the chimney. Another basic requirement for the gas appliance vent pipe installation, and an important safety issue.

• The gas supply line at the furnace had been installed without the required drip leg (this is Chicago, and it might not be required in all jurisdictions), and the flexible CSST pipe was missing straps along its run.

• Protective drip pan under the furnace and A/C coil had been plumbed together with the coil main condensate drain pipe – two separate lines are requires to provide drainage in case one of them fails.

Another option is to install a drip pan condensate overflow safety switch which disconnects power to the air conditioning system in case the drip pan condensate level approaches overflow (not everywhere approved as a replacement for the drip pan separate drain pipe).

• Furnace service door was missing.

• No air filter installed.

It wouldn’t take much effort and time to make this condo furnace installation work from the beginning. It’s just pure stupidity and a waste of time to whoever did it and will ever have to service.

Is your gas furnace installed above the condo ceiling? Look up there, and imagine yourself crawling and performing any type of maintenance on it.

Related posts:

1. Chicago Condo Furnace Installation Most Common Problems This chapter of the Chicago new condo inspection covers most...
2. Chicago New Condo Laundry Room Inspection Chicago new condo laundry room electrical You can start your...
3. Top Ten New Condo Safety Issues & Defects Fitting New Condo Safety Issues and defects into the Top...

Making seasonal inspections of your furnace and air conditioning system makes sense, and I’d highly recommend having it done on a regular basis on any age furnace and AC units.

The question is – do you trust your HVAC guy?

Most people do, because they are always very happy to announce at the beginning of a home inspection that their heating and air conditioning system was JUST serviced by a professional, and it is in a perfect condition.

This statement always makes me suspicious of some hidden issues, and in most cases, I end up delivering a rather unpleasant message to the home owner …that he just dumped a $100.00 HVAC checkup fee into the drain.

This has happened many times already and I always feel sorry for the homeowner, but in a particular home inspection, I finally got proof that I can present to you. In this case, the HVAC guy taped his invoice to the front of a 20 year old furnace with an explanation of his work.

“Check furnace and A/C and found no problems, I cleaned the evaporator coil + drain. Tested operation – Good.
Unit look good for its age and operates normal.”
$89.00

The appliance was a direct vent forced air furnace with a cooling unit, everything in one box. It was installed in a townhouse utility room with its back compartment open to the building exterior. I’ve seen many of those units, usually in condominiums, and I know from my experience that heat exchangers in this particular type of a direct vent furnace / AC combo often fail within 15 years, and 20 is a significant stretch.

There are usually two service panels: one gives you access to the air conditioning coil and air filter, the second is for the burners. The filter and AC coil behind the first panel looked OK, but the condensate pan and condensate drain tubing was leaking, there was standing water on the floor underneath the coil / floor heavily contaminated, and black mold covered the air return compartment – old stuff, something that accumulated there over the years.

I already had a huge headache, because my sinuses suffer in a moldy environment, so I moved over to the furnace’s second compartment to finish the job. Unfortunately, it took a while to remove screws holding this access panel (one was severely corroded) and I’m 100% sure that nobody even attempted to open it for a long time (certainly not 3 days ago).

As I expected from this 20 year old direct vent furnace, areas around the burner chambers showed severe corrosion but no visible holes or cracks.

• Direct vent type furnaces utilize air from the house exterior for combustion (gas burning process) purposes. Because exterior air usually contains more moisture than conditioned air from the house interior, it accelerates corrosion of the furnace internal components – heat exchanger.

• The gas furnace heat exchanger – it is a metal separator between two areas inside the furnace. One area is where the fire is burning; the second area is where the air stream is pushed by the blower fan into the air ducts and registers (some very old furnaces operated without blowers). When that separating piece of metal cracks, Carbon Monoxide, which is a bi-product of an incomplete combustion, might leak into the air stream … and cause your death.

The good thing about most of those direct vent type furnaces is that you can easily access the heat exchanger for evaluation – as long as you can remove all of the corroded screws holding the furnace heat exchanger compartment access panel.

It was not easy, but I was finally able to lift the panel a few inches and take some pictures from the furnace heat exchanger interior. No surprises there, corrosion and several cracks along the edges of the metal tubes that serve as the heat exchanger.

Lets summarize our findings and compare them with the verdict from the HVAC professional:

1. Furnace / AC compartment contaminated with potentially hazardous mold, distributed through the house every time the system is turned on – visible from the furnace air filter access panel / no comment from the HVAC service person
2. Heavily leaking condensate drain pipe, water accumulating on the floor inside the air return compartment, water soaked framing of the compartment – HVAC professional claims cleaning the AC coil condensate drain pipe, not mentioning leaks and standing water
3. Furnace heat exchanger severely corroded and cracked in many places – potential life threatening hazard / possibility of Carbon Monoxide poisoning – there’s not even one word in the HVAC service description mentioning severe corrosion and dangerous cracks of the furnace heat exchanger …

And the owner paid almost $90.00 for a statement that everything is OK

Before you hire a contractor:

• do some research on the internet to find out the basic “How To” for whatever type of service you need
• ask friends for recommendations
• check credentials of the contractor
• ask if there’s any warranty to cover performed work
• follow the servicing person if possible (not invading his work space of-course)
• ask him to explain what is he doing.

This poorly performed furnace / AC inspection is not just a single accident, it happens very often, and remember – it’s your money that ends up in somebody else’s pocket.

Related posts:

1. Condo Furnace Above the Ceiling – The Unprofessional Way In HVAC trade, just like in any other, there are...
2. Drip Pan Under the Attic Installed Air Conditioning Coil The following industry standards apply to locations where accumulating /...
3. Chicago Condo Furnace Installation Most Common Problems This chapter of the Chicago new condo inspection covers most...

Musty smell from heating system air ducts could have many sources. Although, it is always associated with moisture presence, eliminating it in some cases requires total redesigning of the forced air heating system.

This particular case applies to the houses with a forced air heating system metal air ducts embedded into the concrete slab (scroll to the bottom for a couple of other scenarios). With a plastic or cement air distributing pipes this is rarely a case, unless some water leaks develop on pipe connections or cracks start appearing due to uneven settlement.

So if you have a forced air heating system, your house is build on concrete slab with no basement or crawlspace underneath, and air registers are located on the floor or along the baseboards – the following might answer your concern about some musty smell coming from heating system air ducts.

Depending on your house location, water table, drainage system around the property, whether you have a sump pump or not, the air ducts embedded into the concrete slab might be acting as a drain tile.

They could pick-up water from the ground through the pipe connections and forced air heating system would distribute moisture through the house.

Over time, those metal air ducts corrode under the concrete slab when exposed to moisture and slowly disintegrate. All kinds of insects might enter through the holes and contaminate your property. Mold will usually start growing in that dark, moist environment and its spores easily distributed with the circulating air contaminate your house.

Musty smell in your house.

Solution to that musty smell caused by heating system air ducts embedded into or installed under the concrete slab without ruining your house floor:

• Single story house with an attic and a forced air heating system installed on the floor level.

Furnace air supply side would have to be disconnected from the floor opening and extended into the attic, new air ducts distributed through the attic area with registers open into each room previously supplied from the floor. This might not be that easy if you have a downflow type forced air furnace and no room for the side or rear air duct that would run into the attic. New furnace might be the only solution, still cheaper than cutting the concrete floor and replacing those old, corroded air ducts.

• Two story house with lower level partially or fully supplied from the floor registers.

Disconnect section of the air duct entering concrete slab… the rest depends on the house layout. You’d have to find the easiest way to install air supply for the house section that was using floor vents.

The cheapest way to block those disconnected forced air heating system registers, would be to pour some concrete into each opening.  You could also use expanding foam and top it with concrete after it dries out.

Musty smell from a forced air heating system ducts installed in a crawlspace or attic area

• If you are experiencing this musty smell from the heating system air ducts, and part or entire forced air heating system is located in the crawlspace or attic, your answer will be most likely in one of those areas. There might a mold-contaminated attic and gaps in the return air ducts or filter compartment are acting as a vacuum, pulling musty air with mold spores into the air circulating system.

• Same condition applies to the area under the floor of your house. You could have a flooded crawlspace , humid / contaminated with mold, and musty smelling which would be picked up by loose, separated forced air heating system ducts, gaps around the floor penetrations, etc.

Musty smell in your house should be always treated as a warning sign.

Now, pick up that floor register cover, look into the attic, open the crawlspace hatch – get rid of that nasty, musty smell in your house!

Related posts:

1. Heating System Issues This post, concerning heating system issues, is my fourth in...
2. Air Filters in Forced Air Heating / AC Systems We notoriously forget to replace air filters in our forced...
3. Furnace Air Return in Forced Air Systems Poorly designed or older forced air heating, and air-conditioning systems...

Without a regular maintenance your whole house humidifier unit might become a perfect mold distribution device. If your furnace is located in a crawlspace or house attic area you might not even know that you have a whole house humidifier installed. Please, check it or if you can’t, have someone else do it for you. Those areas are always full of surprises…

Whole house humidifier basic maintenance tips:

Furnace humidifier maintenance #1. Check your humidifier unit visually on regular basis. If the humidistat is located somewhere close to the humidifier, turn it to OFF position and than back ON to the higher setting while listening for a “click” like noise from the unit itself (flow through type humidifier / check all whole house humidifier types).

If it clicks, the solenoid valve should be operating. After you hear that click listen for the water running through the plastic tubing. If the humidistat is on a different floor, ask someone to turn it, and listen for the solenoid valve to click – this test requires furnace to be ON / operating.

For the whole house humidifiers equipped with a float valve, you have to remove the humidifier enclosure cover and slightly push the float valve down to see if the water starts flowing.

Wick type whole house humidifier needs to be removed from the furnace air duct in order to evaluate it.

Furnace humidifier maintenance # 2. Make sure that there’s no water dripping from the whole house humidifier itself and any of its components (water supply line, drain line, shutoff valve, enclosure, area underneath the unit, or furnace itself)

Furnace humidifier maintenance #3. Replace the whole house humidifier water pad / evaporator pad / filter / foam on seasonal basis (or more often if required, e.g. with private well water). Make sure that you re-assemble everything correctly to prevent water leaks

Furnace humidifier maintenance #4. Clean the whole house humidifier components contaminated with mineral deposits after the heating season ends – it will be much easier to do it when everything is still wet and soft. You can use 50/50 vinegar-water solution for heavier contaminated components. Just soak them for 15-30 minutes (or longer if necessary) and that should help with cleaning

Related posts:

1. Whole House Humidifiers Types, Performance and Tips A whole house humidifier or furnace mounted whole house humidifier...
2. Rotary Disc Humidifier by Desert Spring Review It’s been almost one month since I’ve finished the installation...
3. Anytime House Maintenance | Small, Preventive Repairs Always Help Anytime house maintenance explains a few of the house components...

It’s been almost one month since I’ve finished the installation of my Rotary Disc Furnace Mount Whole House Humidifier by Desert Spring. I was a little hesitant before buying it and concerned with the other not-so-happy owners, but have finally come up with some answers I hope will help.

Let’s start from my environment:

• House sq footage – 2200
• House type – 2 story colonial, on slab (no basement or crawlspace)
• Furnace type – New American Standard, high efficiency down-flow, 80000 BTU
• Difficulty of the Rotary Disc Humidifier installation – easy with right tools, as it is most likely with every type of the whole house humidifiers

Rotary Disc Humidifier design flaws – overall design is very clean, parts easily accessible and removable for maintenance purposes. The only thing so far that I don’t like is the float switch assembly height adjustment. To achieve maximum performance from the Rotary Disc Humidifier, its plastic disc’s outer ring has to be fully submerged in water. However, there is a vertical slot in the plastic basin where the floating switch is attached, which allows for a small adjustment of its height.

For a properly installed / leveled Rotary Disc Humidifier, this level will never change, and the position of the floating switch is in the top section of the slot. In such an installation, the rubber float seal installed on the Rotary Disc Humidifier basin exterior wall does not provide a watertight seal. Almost every time the basin starts filling up, water finds its way under the rubber float seal bottom section and drips on … whatever you have underneath.

It’s easy to overcome this problem by installing another washer (same shape as the rubber one) made out of thin plastic on the floating switch side of the basin. Placing the rubber seal on that inner side of the Rotary Disc Humidifier basin doesn’t work too well because of the basin slot and float valve design. You can also use a small piece of an aluminum duct tape. Just tape the slot on the basin inside wall and cut a little opening for the floating valve assembly on the upper section of the slot.

Rotary Disc Humidifier motor – there are 3 possible ways of controlling the humidifier motor operation.

1. The humidifier comes equipped with a 24VAC plug-in type transformer
2. You can use a furnace 24VAC transformer to supply the Rotary Disc Humidifier’s power – follow the furnace manufacturer instructions
3. You can connect a Rotary Disc Humidifier motor and humidistat directly to the furnace control board in which case the appliance will operate only when the furnace burners are on – same as above, follow the manufacturer requirements.

Rotary Disc Humidifier motor burnout – I believe that it occurs in the first two wiring options, and the reason is very simple. This is only based on my own observations – I was running the Rotary Disc Humidifier with its own transformer plugged into the electrical outlet for 3 days. Prior to this installation, my house humidity level was controlled by one portable humidifier, running constantly, and it never went over 36% at 69°F on second floor (humidifier installed on second floor), and about 34% on the first floor (it’s been a cold / dry winter in Illinois).

I set the humidistat to 50% humidity hoping to get to at least 40% and turned the furnace blower to ON position for a little more dramatic … instant effect. It seemed like during the first 10 hours, the humidity level went up by 2%. Unfortunately, it stayed at that 2% for the remaining 3 days – with the Rotary Disc Humidifier’s motor and the furnace blower running constantly, and furnace burners turning ON at an average 15 minute intervals (exterior temperature in the 15°-20°F range).


So, with the furnace blower either ON or OFF, your Rotary Disc Humidifier will run almost constantly, eventually burning the motor, because it will rarely reach (if ever) the 50% setting. In my house, it never went over 38%…

The optimal performance of the drum or disc style humidifiers is achieved with a hot furnace heat exchanger, when water particles are vaporized before they actually hit the heat exchanger. The problem with running the blower and the Rotary Disc Humidifier (besides burning up the humidifier motor) is the moisture that will not evaporate on a cold furnace and will accelerate heat exchanger corrosion. So, I personally don’t like the setup with the direct transformer power feed.

The third option for the Rotary Disc Humidifier connection, which turns the disk’s motor only when the furnace burners (and the blower) are on, would be perfect, but for some reason the appliance doesn’t perform as expected.

At first, I thought that my humidity-measuring device is malfunctioning, so I went and purchased another one, then I borrowed a third one from my neighbor… same results, between 35%-38%

Rotary Disc Humidifier efficiency – I’m pretty sure that water usage is very low (this part I didn’t measure), so this is most likely right at the manufacturers description.

Rotary Disc Humidifier cleaning – this will depend completely on your water type, source, and filtering devices – like every type of humidifier, this one also needs maintenance. I’m very close to Chicago and on Lake Michigan water, which should be very well purified. What you see on the picture is after 24 days of running the humidifier and draining the basin every 4 days.


Rotary Disc Humidifier final thoughts

• Part of the humidifier’s performance problem might be caused by my high efficiency furnace, and its two heat exchangers … However, the Rotary Disc Humidifier manufacturer, Desert Spring, does not specify that this product should not be used or may not perform as described with a high efficiency furnace.

• I would most likely install a steam whole house humidifier by Honeywell but because of my furnace setup, this is not possible.

• Maybe with a different furnace type, its layout, and a smaller house, Rotary Disc Humidifier would work much better.

I’m working on a whole house humidifier installation tutorial, based on the Rotary Disc Humidifier installation. However, if you decide to purchase and install some different model, the installation procedure will be almost identical.

Fill free to share your experience, ask questions, and … another humid summer is on its way to Chicago …

Related posts:

1. Whole House Humidifier Maintenance Without a regular maintenance your whole house humidifier unit might...
2. Whole House Humidifiers Types, Performance and Tips A whole house humidifier or furnace mounted whole house humidifier...
3. Whole House Fan ShutterCover Review There are three reasons for which I put together this...

All types of fuel burning appliances in our homes require air to properly burn that fuel. It is called Combustion Air and it actually has three functions:

1. It  is required to properly burn fuel
2. To dilute exhaust gases that are being vented to exterior
3. To vent and cool appliances

The most popular fuel used in our homes is of course natural gas. For every one cubic foot of gas, there are 10 cubic feet of air needed for clean burning in addition to dilution and ventilation air.

There are two products out of a perfectly balanced gas combustion – carbon dioxide and water vapor, which are perfectly safe. However, if we limit the amount of air for the combustion process, there might be a third bi-product, unfortunately a deadly one – Carbon Monoxide.

Example:

Imagine a gas water heater in a small closet, behind the solid door and without any openings in walls providing that necessary combustion air. After using all of the closet’s air for its combustion process, the air pressure in the closet will become lower than the one inside the water heater vent flue pipe.

The water heater closet will pretty much act now like a vacuum and the exhaust gases may be sucked back into the closet space instead of being discharged to the exterior. Since the oxygen starving combustion process is now producing that deadly Carbon Monoxide, it will eventually leak through the gaps around the closet door into the house…

The areas designated for fuel burning appliances are described as confined space and un-confined space.

The water heater closet from my example could be a confined space – an area with a closed, solid door, and walls / ceiling that create a barrier between the appliance and the rest of the house.

A confined space is a room that has less than 50 cubic ft of air volume for every 1000 BTU/hr of appliance input .

If the water heater has a 40 000 BTU/hr rating, the room would have to have over 2000 cubic feet of volume to provide enough air (without additional sources) for proper combustion process.

Un-confined space is a room that has more than 50 cubic ft of air volume for every 1000 BTU/hr of appliance input (BTU/hr input should be on the appliance label / information tag).

Assuming that our example water heater closet itself is a confined space, and it is located in a room being an un-confined space, we would require two openings in the closet door or wall. One opening should be located within 12” from the floor, and second within 12” from the ceiling of the enclosure.

Openings between confined space and unconfined space must have at least 100 sq. inch area each and provide at least 1sq. inch of a free airflow area per 1000 BTU/hr of the appliance input (1/4” min. or larger mesh screen if installed over the openings, metal grills and louvers provide 60%-75% of their net free area, wood louvers only 20%-25%).

With the 40000 BTU/hr water heater input, the combustion process would require only 40 sq. inches of an opening at top and bottom, but you still have to obey the minimum 100 sq. inches per each opening.

Combustion air opening sizes between confined space and un-confined space (inside of the house air)

Up to 100K BTU/hr – 100 square inch openings
125K BTU/hr – 125 square inch openings
150K BTU/hr – 150 square inch openings
…

More about combustion air coming soon.

Related posts:

1. Chicago Condo Inspection & Combustion Air Requirements This part will cover Chicago condo inspection combustion air requirements...
2. Solid (Wood/Coal) Fuel-Burning Stove Chimney Venting As with every fuel-burning appliance, proper venting is always critical,...
3. Water Heater PVC Vent Pipe and Power Venting Water heater PVC vent pipe information below does not apply...

A whole house humidifier or furnace mounted whole house humidifier is just another example of an extremely neglected component of our house – on top of a brick chimney, an attic, and a crawlspace, which fall into the same basket.

If you’re not going to maintain it, it’s probably a bad idea to get a whole house humidifier. Since it is attached to a forced air heating system that constantly circulates air throughout the house, poor maintenance can create environment attracting mold growth and help reproduce of dust mites.

Properly operating and maintaining a whole house humidifier helps us relieve many physical discomforts associated with cold / dry weather, including respiratory problems and dry skin and lips. It also lowers or completely eliminates static electricity, cosmetic wall trim separations, cracks in finishes, separating hardwood floor boards, etc.

The trick is to balance the amount of moisture in your home at such a level, which will benefit your health, living environment, and save energy instead of creating conditions which sometimes cause mold or other biological organism growth (excessive moisture could do that).

For a proper humidity balancing, you either have to observe and monitor your environment, or purchase an electronic device which will do it for you. In general, the humidity in your house should not exceed 50% (35% – 50% is the most comfortable).

Higher levels will usually create condensation on windows, sometimes on walls and ceiling surfaces, or possible mold and mildew growth.

No matter how advanced the whole house humidifier system installed on your property is – it will require regular maintenance because it won’t work properly or at all without it. The truth is – I rarely see one properly maintained or even operating at all.

There are basically 5 types of whole house humidifiers:

Flow-Through (bypass) Whole House Humidifiers (passive and fan assisted) – they use a so-called water pad made out of foam, expanded aluminum, and some other materials. The water drips on top of the square pad and the air from the heating system flowing through the pad picks up the water particles and carries them through the air ducts and around the house. The remaining water (whatever wasn’t picked up by the air) drains through the base of the whole house humidifier.

A whole house humidifier’s water pad has to be replaced once a year before every cold season to perform efficiently and to prevent mold growth. For the homes utilizing private well or other sources with high levels of minerals, cleaning might be required more often.

For every gallon of water evaporated into humidity, Whole House Flow-Through Humidifiers waste between 5-8 gallons down the drain.

Drum Whole House Humidifiers – they have a drum shaped rotating frame (powered by a small, low voltage motor) and a foam or fabric sleeve pulled over it. The bottom section of the drum is always submerged in water which keeps the rotating foam / fabric moist and allows air flowing through the drum to pick up that moisture.

The foam / fabric and the water in a small reservoir under the drum require regular maintenance! If you leave that water standing in an unused humidifier (for example during the summer), and then just start the whole house humidifier unit without cleaning it first, I guarantee that you’ll be spreading mold spores through the entire house.

Wick Type Whole House Humidifiers – assembled out of a small reservoir and a filter (wick) that absorbs water from it. The entire humidifier is mounted inside the air duct, and in order to inspect it, you have to unscrew the cover plate and remove the entire unit – I don’t recommended it, very cheap and easy to install, but there’s no device (humidistat) to control humidity level.

Spray Mist Whole House Humidifiers – as the name suggests, they spray water mist into the air duct and the mist is picked up by the flow through the air duct. Don’t even consider this type if your house’s water supply is a private or community well – it will contaminate the spray head immediately. Those are one of the cheapest and easiest to install types out of all the whole house humidifiers.

Steam Whole House Humidifiers – being the most expensive to purchase / install and not that cheap to operate, it consists of advanced technology and complicated designs. Steam whole house humidifier might operate with or independently from your system heat cycle.

Whenever the humidity drops below the setting, they will activate your furnace blower and get the humidity to the right level independently from the thermostat settings. One of the known problems associated with this type of the whole house humidifier is that the water distributed with cold air (with operating furnace blower only / no heat) does not completely evaporate.

Condensing on the air duct cold walls might sometimes cause bacteria and mold growth. If you like new gadgets and don’t mind spending some serious money for it – go ahead – but it sill does require maintenance. One more type of a Flow – Through type humidifier but this time almost 100% efficient (as claimed by the manufacturer).

Rotary Disc Furnace Mount Whole House Humidifier by Desert Spring: To be honest with you, I can’t say much about it except for relaying information from the manufacturer’s website, forums, and discussion boards. It sounds great because it is (as claimed by the manufacturer)

• the most effective furnace-mount humidifier on the market
• 100% efficient – 1:1 conversion of water to humidity
• uses only 4 Watts/hr of energy
• drain-less system – there’s no need for a drain in your utility room / furnace location area
• very little maintenance with Auto-Flush accessory (you can do it manually every few days, depending on usage, minerals would only need to be removed every month or two in most regions of North America)
• never needs filters or pads replacement – uses self cleaning polycarbonate discs (non-absorbent plastic)

As with every product, there are those who love it and hate it. I’ll show you how to install one of those units… at least I’ll try, and by clicking on the picture or link below, you can find out about its performance.

Rotary Disc Humidifier by Desert Spring Review

Just like with every type of equipment, whole house humidifiers require regular maintenance – follow this link for details furnace humidifier maintenance.

Related posts:

1. Whole House Humidifier Maintenance Without a regular maintenance your whole house humidifier unit might...
2. Rotary Disc Humidifier by Desert Spring Review It’s been almost one month since I’ve finished the installation...
3. House Exterior Maintenance Tips – Fall House exterior maintenance performed during the last days of summer...

Poorly designed or older forced air heating, and air-conditioning systems often have only a single air return compartment. With a single story home, such furnace air return installation is still popular, simply because it saves money and material.

However, single furnace air return configuration might not be as efficient as the one with individual air return ports installed in every room. You should also remember to have doors in all rooms undercut approximately 3/4″ above the finished floor surface to provide proper air circulation.

Sometimes, carpet installation over the hardwood floor completely eliminates this necessary gap under the door bottom edge. Single furnace air return systems are also noisier (noise from air returning to the furnace through only one opening) than the ones with returns distributed evenly through the house.

Single furnace air return in two-story residences, usually installed on first floor becomes little more problematic. Such designs are very common in older houses, built when air conditioning wasn’t yet popular or available. For heating purposes it almost works, warm air naturally raises up, so upper floor should be warmer…, and as long as your house is not too “air tight” this is true.

However, if you notice that temperature on the second floor appears to be dropping, slightly open the window to release air pressure, and you’ll be OK. Over the years, air conditioning units were added to those air forced heating only systems.

Most of the time without any concern about proper sizing of ducts, and installation of an additional furnace air return on the second floor. That extra furnace air return would significantly help to optimize performance of the entire system.

Forced air systems AC/heating duct work is designed primarily for cold air distribution, because more cold air is necessary to lower room temp., than hot air to raise it.

Therefore, summer time on the second floor, and without the furnace air return duct, might be painful (you can always open the window to release pressure). The easiest way to improve this condition is to use part of the first floor closet, or any wall corner space, to install return duct between the basement furnace and the second floor area.

One more furnace air return condition – this time a safety hazard, is an installation of air return in close proximity to any source of combustion (process of burning fuel). Because each floor (including basement), should have at least one furnace air return port for proper circulation, such ports are often installed next to the furnace enclosure, on the furnace air return duct.

By code, and for safety reasons, furnace air return (in forced air systems) should not be placed closer than 10′ from any area of combustion, or should be located in a separate room. This condition doesn’t apply to high efficiency systems, and regular efficiency furnaces with sealed combustion chamber which often (not always) use combustion air from exterior.

Another furnace air return compartment safety issue – an item often forgotten by the furnace installers, and at the same time required by the furnace manufacturers is a bottom closure panel. Furnace enclosures are sometimes shipped with an open bottom for return duct attachment.

However, installation location might require return duct to be attached on the furnace side or rear, in which case special metal plate (bottom closure panel) must be installed – same hazardous condition as in previous paragraph – might cause bi-products of combustion, Carbon Monoxide to mix with and contaminate the circulating-air.

Go and check your furnace air return right know!

Related posts:

1. Air Filters in Forced Air Heating / AC Systems We notoriously forget to replace air filters in our forced...
2. Musty Smell From Heating System Air Ducts | Forced Air Heat Musty smell from heating system air ducts could have many...
3. Chicago Condo Furnace Installation Most Common Problems This chapter of the Chicago new condo inspection covers most...

• We notoriously forget to replace air filters in our forced air heating / air conditioning systems… Air flow starts deteriorating through the house, system seams to be operating, but it takes significantly longer to achieve desired temperature …

• The solution might be simple – clogged air filter, or missing air filter, and in that second case, you might have a contaminated evaporator coil (part of air conditioning system). Air filters, usually come in two groups: electronic/electric and passive (reusable, electrostatic or disposable).

electronic/electric – reusable filters, click on link for detailed information and maintenance instructions (this one is for American Standard Inc. brand, but principal is the same for most of them) – use caution when performing all maintenance tasks, parts of those filters require extremely delicate handling.

Operation of some units might be noisy and resembles sounds from mosquito / bug zapper (device with fluorescent, blue light that you hang on your back-yard)… which some people don’t like and replace electronic cells with regular, disposable filters.

Passive (reusable, electrostatic or disposable) – depending on type, should be cleaned or replaced anywhere between 1-4 months Location of filter varies significantly, but common areas to look for one are:

• furnace blower compartment (depending on setup, it might be top, bottom or any side section of the furnace) – access requires compartment service cover to be removed – be very careful! - by removing blower compartment cover, safety switch located underneath should be activated and turn off the furnace / disable blower.

However, some older furnaces have no such device installed, or it could be broken / removed, compromised by taping it in constantly closed position, bypassing, relocating from designated position – in such case furnace / blower will not stop when you remove the cover, or might start turning during filter replacement.

Therefore, for your safety, before changing filter (s), turn the furnace off by switching thermostat from “on” to “off” position, and / or by turning off service switch, usually located in close proximity to the furnace (if you don’t feel safe, you can also disconnect power to the furnace by turning off the breaker or unscrewing fuse in the main electrical panel – assuming it’s been properly marked).

compartment located next to the furnace enclosure

narrow slot installed next to blower compartment, sometimes with a cover

• house air return grill – usually installed on one of the walls or ceiling, might contain filter behind its door (usually secured with screws or small latches)

• in some of the attic installed heating / AC systems you might actually have to claim up to the attic in order to replace air filter – be careful!

Related posts:

1. Furnace Air Return in Forced Air Systems Poorly designed or older forced air heating, and air-conditioning systems...
2. Musty Smell From Heating System Air Ducts | Forced Air Heat Musty smell from heating system air ducts could have many...
3. AC Wall Units // < ![CDATA[ // < ![CDATA[ // < ![CDATA[ //...