best value furnace air filter?

[RustyShackleford]

I use a "permanent" electrostatic and I AM religious about cleaning it
(hose it down about once a month).

But ever since I installed it, I've worried that maybe it restricts airflow
too much (that was 11 years ago, I guess I wasn't THAT worried).

I'd like to do the measurement procedure detailed above, but not sure
how to access the duct system so near the heat exchanger, not what sort
of temperature probe to use.

 

[OAG]

I use a "permanent" electrostatic and I AM religious about cleaning it
(hose it down about once a month).

But ever since I installed it, I've worried that maybe it restricts airflow
too much (that was 11 years ago, I guess I wasn't THAT worried).

I'd like to do the measurement procedure detailed above, but not sure
how to access the duct system so near the heat exchanger, not what sort
of temperature probe to use.

I have absolutely no knowledge of this subject, but I did get a good nights rest so here goes: Get two of those temperature things they stick in meat to check cooking temperature, drill little hole in duct near where the air come out (at top), drill another hole where the air returns (at bottom). After checking just put some tape over the hole (or it may whistle at you).

Someone will be along shortly to "fact check" me, but it seems it would work fine. Unless it is way off base, I plan to do that shortly; got me curious.

 

[ERD50]

A little update on my earlier measurements, and a few more tests to do yet. With the cheap, basic fiberglass mesh filter, I reported above that I was seeing temperatures that indicate a good flow (I have not tried those calculations yet, I will).

Then I put in the relatively cheap pleated paper filter, and the temps only increased a few degrees, so that doesn't seem bad.

It may have been the washable type filters that were causing my flame to shut down - I thought the pleated did it too, but I might be mistaken about that. I'm going to do this measurement with the washable filters in and see.

-ERD50

 

[ERD50]

- the filtrete we got supposedly is good for 3 months so I have some time to figure it out -

I wouldn't go by the calendar. It depends on the season, ours was barely run this summer we probably had a 3 month period with near zero usage. And of course, how much dust/dirt is in your house - I imagine pets could add dramatically to the load with shedding hair.

I check my filters after about 6-8 weeks of being into the heating season - usually fine, I let them go another few weeks.

My brother mentioned that his digital thermostat keeps track of the ON time, and lets you know when to change the filter based on hours of use. Better than time alone, but it still is dependent on many toher factors.

-ERD50

 

[travelover]

I've always kind of wondered what would happen if you never changed the filter. I got my answer from a co worker who said his furnace wouldn't heat the house any more, so he called a furnace repairman in. Turns out he had not changed the filter in 18 years. Guy was Asian born, just didn't know furnaces had filters. Bet that filter was about 4" thick with dust and lint.

 

[samclem]

I've always kind of wondered what would happen if you never changed the filter. I got my answer from a co worker who said his furnace wouldn't heat the house any more, so he called a furnace repairman in. Turns out he had not changed the filter in 18 years. Guy was Asian born, just didn't know furnaces had filters. Bet that filter was about 4" thick with dust and lint.

CFB (peace be upon his bunniness) posted a story several months ago about a guy who had a visit from a furnace repair guy because his furnace wasn't working right. The repairman asked how often he changed the filter, and the customer said something like he just put a new one in whenever the old one was gone. He never saw the old ones, never took them out. As it turned out, the filters would get so full of junk that the negative pressure would become sufficient to collapse them and they'd get sucked into the ductwork. At that point he'd see the filter was gone and install a new one.

You do have to wonder how some people function in a modern world.

 

[RustyShackleford]

I have absolutely no knowledge of this subject, but I did get a good nights rest so here goes: Get two of those temperature things they stick in meat to check cooking temperature, drill little hole in duct near where the air come out (at top), drill another hole where the air returns (at bottom). After checking just put some tape over the hole (or it may whistle at you).

Someone will be along shortly to "fact check" me, but it seems it would work fine. Unless it is way off base, I plan to do that shortly; got me curious.

The drilling of a diny hole sounds good - maybe there's even a plug
there already (sealing a tony hole).

Not sure about the meat probe. There's probably something meant for
this. I have a nice Fluke multi-meter, maybe something that would
plug into it ?!?

 

[ls99]

Not sure about the meat probe. There's probably something meant for
this. I have a nice Fluke multi-meter, maybe something that would
plug into it ?!?

Meat probe will work fine. No need for gnat's a$$ accuracy.
Thermocouples, range converters, adapters, are pretty expensive. $$$.

 

[jazz4cash]

I only have to change it once per month ......

Another cry for help!

 

[samclem]

Quote:
Originally Posted by samclem
I only have to change it once per month ......

Another cry for help!

I guess I need to get off the cough syrup! I should have written that I only have to change the pleated media filter once per year. I'd sooner go without a filter than spend $30 on one every month.

Thanks for the catch!

 

[ERD50]

Quoting myself for an update

A little update on my earlier measurements, and a few more tests to do yet. With the cheap, basic fiberglass mesh filter, I reported above that I was seeing temperatures that indicate a good flow (I have not tried those calculations yet, I will).

Then I put in the relatively cheap pleated paper filter, and the temps only increased a few degrees, so that doesn't seem bad.

It may have been the washable type filters that were causing my flame to shut down - I thought the pleated did it too, but I might be mistaken about that. I'm going to do this measurement with the washable filters in and see.

-ERD50

Yes, it was the washable/re-useable type filter that was causing my flame to shut down. I took that one, washed it out well and the flame would shut down after 4 minutes, and the temp had only reached 115F in the duct. It would shut down for a minute, and keep cycling like that.

But the pleated seemed fine for me.

I still question the importance of any filtering beyond basics, since ~5 months of the year we pretty much have the windows open and/or no HVAC running, and those window screens are a lot courser than even the cheapest furnace filter.

-ERD50

 

[NW-Bound]

The repairman asked how often he changed the filter, and the customer said something like he just put a new one in whenever the old one was gone. He never saw the old ones, never took them out. As it turned out, the filters would get so full of junk that the negative pressure would become sufficient to collapse them and they'd get sucked into the ductwork. At that point he'd see the filter was gone and install a new one.

You do have to wonder how some people function in a modern world.

Umm... He probably read somewhere that furnace filters are "consumables".

So, how many were stacked in the duct, I wonder.