Replies

1. 
   DaveRicheson | Mar 21, 2008 05:40pm | #1

   I have cleaned them annually in commercial and sometimes more in industrial work.

   You will extend the life of the blower motor considerably by keeping it and the squirrel cage fan clean. The same holds true for exposed burners on older 80% gas furnaces. You also get an inspection during the cleaning. The tech will use a bottle brush and mirror to clean the inside of the heat exchangers and will note if there are any holes. Same thing with the vent inspection. He will also look for any frayed wiring or signs of arcing that would indicated a loose connection.

   On 90+ model gas furnaces the inspection will also include checking all the safeties and switches as well as cleaning out the slime that builds up  in the condensate bowl.

   If the unit has central air the A-coil will be inspected and cleaned with a rinse less foam cleaner.

   All in all cleaning is a good idea. Most furnaces just set in a basement, closet, crawlspace, or attic just chugging along, doing their job for years, with nothing more than a filter change when the HO happens to think about it. It is not so much neglect that does them in as the slow accumulation of grime that builds up over years.

   Getting a good job at a reasonable cost is another matter. There are a few companies that use furnace cleaning as a profit builder. As with anything, hiring a reputable contractor is important.

   FWIW, when I sold my last home the home inspector ask DW what was wrong with the furnace. She told him nothing and then ask why he ask. His reply was that in 30 years as a builder and then 10 years of inspecting he had never seen a 15+ year old furnace that looked almost like new.

   Once you see how one is cleaned you will likely save yourself some money and DIY the next time.

2. 
   rich1 | Mar 21, 2008 06:06pm | #2

   I agree with everything that Dave says, other than normally most A-coils and heat exchangers that we see don't need cleaning. 

   For us the first priority is making sure the venting is safe.  Most co problems are a venting/combustion air issue.

   Then is the fan/air filter in good shape.  Lack of air flow is probably the number one  killer of systems.  And don't forget the filter during the cooling season.

   Once those two are good, we check for operation of the system.  Operating and safety controls.  Temp rise within specs, and manifold pressure.

    

3. 
   user-204835 | Mar 21, 2008 06:10pm | #3

   Oil fired furnaces should be cleaned once a year from my experience. The cleaning includes removal of all soot from inside the heat exchanger and firebox. I have a PEERLESS furnace and it has to be cleaned once a year, or it will "soot up" and flood the basement with smoke.

   Otis

4. 
   roger g | Mar 21, 2008 06:14pm | #4

   A lot depends on your lifestyle. I've cleaned furnaces that hadn't been cleaned in a few years and still were fine yet I've cleaned furnaces that should have been cleaned every month.
   Get the best filter you can buy and clean it every month and it will solve most of your dirt problems. The better the filter the more dirt it catches so it must be cleaned more often. If you don't want to clean filters, put in some chicken wire and it will keep out chickens and raccoons but the filter will look new all the time.
   ANY dirt on the vanes of the blower impedes air flow. A good look by a professional should be done every couple of years. The high tech one really should be given a once over and not left too long.
   ALWAYS HAVE A CARBON MONOXIDE DETECTOR!!!!
   roger

1. 
   DaveRicheson | Mar 21, 2008 11:18pm | #7

   yet I've cleaned furnaces that should have been cleaned every month.

   Sounds like a few of our power plants.

   We had a few units in a couple of our plants that got the treatment weekly. Even at that we were lucky to get five to seven years out of them.

   Jeeze I'm glad I don't do those anymore

5. 
   Piffin | Mar 21, 2008 08:54pm | #5

   Nothing bogus about it!

   You change oil in your vehicle don't you?
   You change your socks and underwear now and then, right?
   I'll bet you even mop the floor occasionally...

   The burner nozzle needs cleaned and adjusted mix. The fuel filter needs changing if you burn oil. The heat exchanger must be inspected to keep you from breathing CO gasses. The blower motor lasts longer when it runs clean and the filter itself must be changed from one to three months depending...

    

    

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6. 
   rjw | Mar 21, 2008 09:24pm | #6

   I recommend using an HVAC contractor who is certified in combustion analysis and carbon monoxide analysis.

   http://www.nationalcomfortinstitute.com/ has a contractor locater.

   BTW, you cannot tune a furnace by eye, you need a combustion analyzer (and know how to use it.)

   ---

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   ---

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7. 
   DanH | Mar 22, 2008 12:47am | #8

   An oil furnace needs to be cleaned regularly. A gas furnace doesn't require it so long as you use good filters and change them regularly, and your house isn't incredibly dusty. Really isn't much in a typical gas furnace that's accessible for cleaning anyway.

   Getting a gas furnace "checkup" every 2-5 years may be worthwhile, but any cleaning they do will be purely cosmetic.

   If your view never changes you're following the wrong leader
1. 
   Biff_Loman | Mar 22, 2008 12:51am | #9

   It's a natural gas furnace.

1. 
   Piffin | Mar 22, 2008 06:24pm | #20

   I was thinking oil since that is all we have around here. gas does run much cleaner without sooting 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   catfish | Mar 22, 2008 12:59am | #10

   When I finally claened my unit, a gas pack, I got enough dog hair to make a coat. 

1. 
   DanH | Mar 22, 2008 03:44am | #11

   Sometime examine a standard gas furnace/AC (at a HD display or whatever, if you don't have one). There is no way to access the heat exchanger or the A coil without totally disassembling the unit. The fan can be accessed, but removal likely requires significant disassembly (and it's impossible to effectively clean the fan without removing it).The fact that a gas furnace is not designed to be cleaned should make it obvious that cleaning isn't a necessary activity. (However, changing filters IS a necessary activity.)
   If your view never changes you're following the wrong leader

1. 
   catfish | Mar 22, 2008 04:13am | #12

   I keeep clean filters, but didn't realize that wasn't enough.  After cooling didn't seem to work my neighbor advised cleaning coils and the blower  The entire top had to be taken off 4' x 4' or so.  3 times the airflow after cleaning what I could.

2. 
   roger g | Mar 22, 2008 06:01am | #13

   Actually a lot of stuff in a gas furnace is accessible. Just takes time. The burners usually come out as an assembly. The heat exchanger we usually blew out with a vacuum cleaner but the secondary was left alone. I have taken them apart and always found them clean because gas is such a clean burning fuel.
   The whole blower assembly slides out where you can access the blower and clean the vanes with an old toothbrush (or your wifes). Several of the failsafe switches were also tested.
   Of course having said all of the above, lots of furnace cleaners don't do it.roger

1. 
   DanH | Mar 22, 2008 06:11am | #14

   Both on one of our old furnaces and on our new one the fan will not come out without major disassembly. You can't get at the A coil without cutting open the ductwork. You'd have to at least remove the electronics, the induction fan and burner to access the primary on our new unit. All that disassembly is more likely to cause problems than any cleaning is apt to cure.
   If your view never changes you're following the wrong leader

2. 
   roger g | Mar 22, 2008 06:37am | #15

   The coil usually isn't any great problem to remove. Most cases there is an access panel which was used to put the coil in the first place. We used to carry pieces of sheetmetal in our service vehicles so if we had to cut into a plenum to move a coil, again no big problem. Cut a big hole. Pull out the coil and try not to kink any lines. Clean coil. Check inside to top of heat exchanger. Put back coil and screw in new piece of sheetmetal. It was very rare not to have an access panel.
   If the coil was placed high enough in a furnace plenum we used to cut an access hole and look under the coil (or at least feel it) to see how dirty it was. If it wasn't high enough we used to pull them.
   I've never seen a blower that wasn't designed to come out. Sure sometimes circuit boards and/or boxes have to be moved out of the way but they were designed to be moved out of the way without disconnecting anything. I never said it was easy but you got used to seeing the same brand over and over again and you knew the procedure that had to be done. Some manufacturers really made it tough to service them.
   Service procedures are with the customers/install handbook that came with the furnace. Sometimes we would come across a brand we had never seen or a new model and we needed the book.roger

3. 
   DanH | Mar 22, 2008 04:47pm | #17

   No service procedures in our book.On one of our old furnaces the only way to remove the blower was to remove the side of the furnace. But it was tight up against the ductwork of the other furnace. Neither old nor new furnace had/has access port for the A coil.
   If your view never changes you're following the wrong leader

4. 
   roger g | Mar 22, 2008 05:09pm | #18

   Get your tin snips out and start cutting. It may seem like you are doing something you shouldn't but it IS the way to do it:) Two minutes snipping and you are in.
   I'm not sure if you realize but when I'm talking of removing the blower I'm talking about the whole assembly, not just the blower wheel or motor. Once the assembly is out, only then can you get out the blower wheel (squirrel cage)roger

5. 
   DanH | Mar 22, 2008 11:10pm | #21

   I realize you're talking about the whole assembly. On the old furnace I dearly wish I could have removed it, since I had to replace the bearings, and ended up doing it as orthoscopic surgery because the blower would not come out.
   If your view never changes you're following the wrong leader

6. 
   catfish | Mar 22, 2008 05:40pm | #19

   My unit is a large square box outside the house.  Heat exchanger for the ng and the AC and the blower are all in the box.  Take the top off and presto! there it all is.

7. 
   DanH | Mar 22, 2008 11:14pm | #22

   That's not the norm by any stretch. Standard indoor furnace has the A coil stacked on top of the furnace and then the plenum above that, all crammed into a closet or at least jammed into a corner in the utility room, with the return duct blocking access to the "open" side. So the only access is from the front.
   If your view never changes you're following the wrong leader

8. 
   catfish | Mar 23, 2008 12:27am | #23

   My house was built in '52.  The return is where the old furnace was, thats why it collects so much trash.

   a lot of people in this neighborhood build a closet over the furnace hole and run duct in the attic.

8. 
   JeffBuck | Mar 22, 2008 07:31am | #16

   The DW is wondering if there's any benefit

    

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