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Thread: From a H.Owner
06-28-2005, 03:17 PM #1Regular Guest
- Join Date
- Nov 2004
- Atlanta, Ga. burbs
First of all last week I dreamed I was in an HVAC class at a local Tech. School. Woke up in a cold sweat, an old man, trying to install HVAC equipment. Oh my aching back.
The real reason I am posting:
Really confused about the kind of filter to use on the air handler for a heat pump. Some of you pros. say to use a standard one inch blue filter to just protect the equipment. I have been using the 3M filterete brand and change every three months.
Never used or intend to use an electrostatic filter based on what you all have said.
Is there a correct answer?
06-28-2005, 03:40 PM #2
The 3m's can restrict your airflow......blue is better.If everything was always done "by the book"....the book would never change.
06-28-2005, 03:42 PM #3Professional Member
- Join Date
- Sep 2004
The pleated filter low micron filters and electrostatic filters are great if used in a system where the use does not restrict the return airflow to a point where the unit is affected. This means you have to closely follow unit manufacturers recommendations for return air duct size and filtermedia face sizing calculated using the intended filter media flow rate. The problem with these restrictive filters is that people are buying them and installing them on systems with return duct that is undersized and way undersized grille face areas (marginal systems) this will typically drop the unit performance off a cliff and can cause coil/suction line/accumulator freezing and possibly create a dead compressor in the near future due to liguid slugging. A extra return may need to be added or a return box added to the existing opening that will allow a larger filter face area to reduce the affect of the more restrictive flow. I have seen industrial uses where a 6ft x 6ft plenum box bank of HEPA filters are used to supply a 18 x 18 return air duct, it takes that much filter surface area to get the static down to a acceptable level with the HEPA's. Have a reputable company come out and check your install they can calculate the needed face area and check your return duct sizing plus take actual static and CFM readings with the unit in operation for a small fee, well maybe a medium to large fee LOL I always suggest opening the trash can placing the restrictive filters in and stomping them real hard. Go with the cheapo fiberglass babies unless the system is set up for the others IMO