Replies

1. 
   junkhound | Oct 25, 2002 05:45pm | #1

   Have had one for 25 years, but seems the regular filters picks up most of what's in my house. If you're a smoker electrostatic will help. Electrostatic need to be cleaned almost weekly to function at peak capability - which may be why mine doesn't pick up as much as the folded fan type filter elements <G>

1. 
   Dogdazed | Oct 26, 2002 04:49pm | #2

   Thanks junkhound (great user name  ;)

   The house has a gravity type system, and it always seems like dust is a problem. I know that just having forced air with a regular filter will help, altough at start-up it may be a dust storm.    

1. 
   maneyj | Oct 27, 2002 01:01am | #3

   Look at the 3M  1 inch disposable filters. They make them in several grades.  The best are a little pricey for a disposable filter, but they actually do a better job of filtering then the electric powered filters. 

   No equipment to buy or install, and no maintenance except replace them as frequently as the 50 cent filters.

2. 
   MarkH128 | Oct 27, 2002 03:29am | #4

   I have one of those coal conversion gravity furnaces. Dust is terrible. Many years of dust, mouse turds, dead bugs and dog hair is in the furnace. I wouldn't spend anything on the furnace itself other than a good cleaning. A filter would probably upset the airflow anyway. Maybe you could use a portable air cleaner instead.

1. 
   rjw | Oct 27, 2002 02:39pm | #5

   Fow those old gravity feed systems, a good duct cleaning might help. too, although I'd be careful to make sure there isn't any asbestos inside the ducts before letting the duct guys go at it.

   FWIW, I'm not aware of any likelyhood of asbestos wrap or tape having been used inside the ductwork, but think it's a possibility to be accounted for.

1. 
   MarkH128 | Oct 27, 2002 03:14pm | #6

   Asbestos inside the ducts would be a real bummer. Mine does have exterior asbestos which is troubling me. I just haven't had the money to replace it. It's inefficient, but fairly comfortable and quiet heat.

2. 
   TLRice | Oct 28, 2002 04:24pm | #7

   DD,

   Yes and no, and it depends. They are very effective if maintained well. If you have or generate lots of dust, you would be better off with a good pleated filter. I recommend the AprilAire 2200, or the Honeywell EnviracAire Elite. Get the 20x25 size. If you get one of these types (I have the AA 2200) you can use standard filters in the housing to clean-up or during construction and use 1, 2, or 4" thick commercial grade filters, all of which are less expensive than the filter media that "goes" with the housing. The filter cartridges that the manufactures offer are very effective for a long period of time under "normal" conditions. Once a year change, as opposed to once a month (recommended) for regular filters.

   I don't know exaclty what you mean by "plenum return air filters". You'll have to explain further.

   Bottom line, I would (and did) buy the high efficiency mechanical filter over the electrostatic and save the electricity to operate the clean blower.

1. 
   Dogdazed | Oct 30, 2002 04:08am | #8

   Tim,

   Thank you for the information.  I was looking at a filter that sounds similar to the one you mentioned.  It comes with a 5" filter, but could be retro fitted to an electrostatic unit (electro-air F808-0708).  

   I said return air plenum, what I mean is the return air duct where it enters the furnace cabinet.

   Thanks for the input!

   J

1. 
   rjw | Oct 30, 2002 05:02am | #9

   I said return air plenum, what I mean is the return air duct where it enters the furnace cabinet.

   Same thing, isn't it?

1. 
   Dogdazed | Nov 03, 2002 07:27pm | #10

   Bob,

   It is the same as far as I'm concerned, but I must have confused someone....

   J

2. 
   TLRice | Nov 05, 2002 12:05am | #11

   To answer your question; no, they are not the same.

   I asked because a plenum is an entirely different thing from a return duct or return drop, which is what he was describing.

   An example of a plenum is: a building with a dropped accoustical tile ceiling, using only grilles in place of tiles throughout the building to return air back to the unit, without return ducts. Not common residential practice.

   Technically, in a house that has a single return in the hallway, the hallway is a plenum, which is illegal in all but residential construction.

1. 
   rjw | Nov 05, 2002 08:00am | #12

   Tim,

   Thanks.  I was thinking what you describe as the "drop" (which I am guessing ios the last section of return that typically runs down parallel tot eh furnce casing on an updraft furnace) was the plenum, but see that's wrong.

   So many terms in so many trades and an ever increasing learning-resistent brain!

2. 
   LarKor | Nov 05, 2002 08:41am | #13

   Both terms are correct.  The word plenum is used in HAVC to reference the following

   Cold Air Return Plenum

   Hot Air Plenum

   Plenum Ceilings

   Plenum Floors

   Items #1 & 2 refer to the metal cavities of the furnace return and supply, where the ductwork is attached to distribute the conditioned air.

   Item # 3 is found in Commercial buildings, where the return air flows thru ceiling grills and above a ceiling (without ductwork) back to the HVAC unit (roof top or suspended above the ceiling).  The heated or cooled supply air is still distributed by ducts to areas of the building. 

   Item #4 is rare to find as many codes today prohibit utilizing the airspace between joists of a residential floor as the means to return air to the furnace.

   There is also Plenum-Rated communication cables (NEC type CMP).  These are used where low voltage wiring (computer, PA system, etc.) is permitted to be run in plenum airspace above ceilings.  The plenum cable outer jacket and insulation around the wires are designed to be low-smoke, low-spreading in the event of a fire.  Without plenum cables, the air movement above the plenum ceiling would be like blowing on a small fire to make it burn better.... 

3. 
   Dogdazed | Nov 12, 2002 05:36am | #14

   Lar,

   Sounds good to me :~)

   That's the great thing about this site, always a learning experience.

   It seems like the consensus is a good pleated filter would be the best.

   J