Furnace Filters

[Duffyjr]

We get free filters from the guy that installed our new system a few years ago and they are always MERV 10. We also have a UV light installed, my wife says she can really tell the difference in the air quality. A while back she told me she thought it had stopped working so we had the guy come out and sure enough the bulb was bad.

 

[JohnnyG]

We get free filters from the guy that installed our new system a few years ago and they are always MERV 10. We also have a UV light installed, my wife says she can really tell the difference in the air quality. A while back she told me she thought it had stopped working so we had the guy come out and sure enough the bulb was bad.

I use a UV light in our heat pump too. I just get them off the internet and change them once a year. That's about maximum effectiveness for the "UV-B" part of the bulb, the part that does the actual "cleaning" work.
On that note, 3M Filtreet filters are the only ones that the UV light destroyed. I have used many other brands without issue, but the 3M filter disintegrated in the presence of the UV light.

There is a lot of talk on this thread about airflow. According to our local power company (FPL), whenever any vents are closed in an effort to "balance" a system, it has the same effect as a dirty or plugged air filter.
They claim that to maintain maximum efficiency on your system, all vents should remain open.

 

[PWMDMD]

5" filters FTW. They even make ones that will fit standard return sizes that were originally designed for 1" filters - there is a 1" lip that fits the original sized return opening and then the other 4" of depth are slightly smaller and extent up into the duct. These are much less restrictive due to the increased surface area but can still filter well.

 

[alarmguy]

5" filters FTW. They even make ones that will fit standard return sizes that were originally designed for 1" filters - there is a 1" lip that fits the original sized return opening and then the other 4" of depth are slightly smaller and extent up into the duct. These are much less restrictive due to the increased surface area but can still filter well.

Yes, these are what I use, called Return Grill Filters They fit in the place the standard 1 inch filters fit assuming you have 5 inches of room behind the filter. Technically they are called 5 inch but closer to 4 inch and lately Honeywell has cheapened it down to 3 inches (or something like that)

 

[Hall]

Our current furnace has a filter slot and a filter in it, but I just don't see how it actually does anything. I think it just draws in all the air from the bottom of the furnace itself.

Find your "cold air return" and take a piece of tissue or toilet paper and lay it on the grate. Notice how it's sucked onto it ? The furnace draws air in, filters it, then recirculates it.

 

[TheLastWord]

You need to be careful when switching to Marv rating filter since the vast majority of ducks are undersized. To do it safely you need to check the air flow and if needed adjust it.

So you have undersized ducks in your ducts?

 

[PWMDMD]

Yes, these are what I use, called Return Grill Filters They fit in the place the standard 1 inch filters fit assuming you have 5 inches of room behind the filter. Technically they are called 5 inch but closer to 4 inch and lately Honeywell has cheapened it down to 3 inches (or something like that)

But still claim just as good as 5"....lol

 

[CDX825]

When it comes to HVAC air flow is more important than filtration. The filter is only there to protect the equipment. Its really not intended to filter the air in your house. If you have a 1" filter the last thing you want to do is stick a high merv filter in and cause air flow restriction.

If you want better filtration you need to go to a 4 or 5 inch air filter setup. They offer better filtration with less restriction than the standard 1 inch filter.

 

[oilcandave]

When it comes to HVAC air flow is more important than filtration. The filter is only there to protect the equipment.

...such as the evaporator coil...once clogged its a pain in ass to clean usually..

 

[Fitter30]

A furnace filter is only as good as the air flow. A vacuum sweeper only picks up what it runs over. Not 2" away not 2 ' same with a furnace filter. Look at total blower run time if blower cycles with burner vrs fan on.
Blower running 24/7 cold drafts and still not a100% of the air is turned over. Look at the dust in the air on a sunny day. Old style electronic air filter will catch more than 4" pleat.