Ducted Heat Pump Return Filter Longevity

[PWMDMD]

I have a 4-ton ducted heat pump that runs year around. It has two returns sized at 14x14 and 14x30. I'm using 4" MERV 11 filters changed at 30 days/720 hours of run time. I just changed them and while they certainly have some dust and the new filters make less noise than the old, they don't look that dirty. I have the unit serviced every Spring and the tech always says the coils were clean.

Is there a rule of thumb as far as run time and filter size? I do have a cat and dog and there are five people living here. I'm happy to spend the money if needed but these filters are getting hard to find with lots of places out of stock and they're not cheap.

 

[bugeye]

Google is your friend to purchase online in the size and MERV rating you want. Have the service technician measure the airflow with the filters when your are ready to change to assure your HVAC unit is not low on airflow. I use a FARR 3030 which is a MERV 8. I also use a woven fiber pre-filter and follow the Farr with an electrostatic cleaner. Once the children grew and the old carpet was changed, the filters last 6 months. Your needs sound more demanding

 

[Racer4]

I use a 1” pleated in both of my heat pumps I blow them out every 30 days or so and change them about every 90 days or so. I believe the 4” filter you use is good for 90 days plus.

 

[RhondaHonda]

I use the cheapest 3M see through filters. When these systems require replacement I’ll go with a 4” filter. Mine stay in for 4-5 months and don’t hardly have anything on them except some calcium or whatever from the humidifiers…..probably because it’s all stuck to the coil!

We have a dog and 3 kids. The house gets cleaned weekly and we don’t live by a busy road or near any dust, maybe that helps slightly.

I’d think a 4” filter would be good for much more than 30 days.

 

[alarmguy]

I have a 4-ton ducted heat pump that runs year around. It has two returns sized at 14x14 and 14x30. I'm using 4" MERV 11 filters changed at 30 days/720 hours of run time. I just changed them and while they certainly have some dust and the new filters make less noise than the old, they don't look that dirty. I have the unit serviced every Spring and the tech always says the coils were clean.

Is there a rule of thumb as far as run time and filter size? I do have a cat and dog and there are five people living here. I'm happy to spend the money if needed but these filters are getting hard to find with lots of places out of stock and they're not cheap.

Change no less than every 90 days that would be a more than acceptable time frame for that kind of filter captivity involving 4 inch filters.
90 days is what I would recommend.
Merv 11 is acceptable but never higher than that.
Merv 8 is a better choice but I used both, when buying online.
I actually preferred 8 but price ruled when buying online so at times the 11 was around the same price. I used to prefer one 8 and 11 in the other.
You do not want to restrict air flow so stay at 11 or less.

Keep In mind HVAC systems were never intended to be used as air purifiers the filters are to protect the coils

I had 4 filters in our systems 2 separate units each with a 14x14 and 20x20

Main floor used to get dirtiest and changed those 4 inch filters every 6 months to one year.
Second floor was almost always clean so 6 months using one inch filters


30 days way, way to soon

 

[RhondaHonda]

I just went and looked. My East side main level unit only has 350 hours of run time from Jan 1-Jun 30. The west side has 643 hours in that same window. Upstairs has 411.

Is 720 really accurate in 30 days? With 2 filters and returns I think you’d be able to go longer either way.

 

[brianl703]

Is 720 really accurate in 30 days?

It is if you're running with the fan ON all the time.

Not recommended because it can increase the humidity in the house by helping to evaporate water off the coil that remains after a cycle.

 

[RhondaHonda]

It is if you're running with the fan ON all the time.

Not recommended because it can increase the humidity in the house by helping to evaporate water off the coil that remains after a cycle.

Yeah I could see doing that in heating mode but that was my understanding as well when cooling.

 

[PWMDMD]

I just went and looked. My East side main level unit only has 350 hours of run time from Jan 1-Jun 30. The west side has 643 hours in that same window. Upstairs has 411.

Is 720 really accurate in 30 days? With 2 filters and returns I think you’d be able to go longer either way.

30 x 24 = 720 hours. The thermostat keeps track of runtime hours but makes you set the change filter based on "runtime days". The 30 days = run time and not calendar days.

 

[PWMDMD]

Change no less than every 90 days that would be a more than acceptable time frame for that kind of filter captivity involving 4 inch filters.
90 days is what I would recommend.
Merv 11 is acceptable but never higher than that.
Merv 8 is a better choice but I used both, when buying online.
I actually preferred 8 but price ruled when buying online so at times the 11 was around the same price. I used to prefer one 8 and 11 in the other.
You do not want to restrict air flow so stay at 11 or less.

Keep In mind HVAC systems were never intended to be used as air purifiers the filters are to protect the coils

I had 4 filters in our systems 2 separate units each with a 14x14 and 20x20

Main floor used to get dirtiest and changed those 4 inch filters every 6 months to one year.
Second floor was almost always clean so 6 months using one inch filters


30 days way, way to soon

That's "30 runtime days" or 720 runtime hours and not 30 calendar days. It's a Bosch thermostat and it keeps track of runtime hours but makes you set the change filter length in runtime days. The filter gets changes ~ twice per year at 30 runtime days.

 

[PWMDMD]

Google is your friend to purchase online in the size and MERV rating you want. Have the service technician measure the airflow with the filters when your are ready to change to assure your HVAC unit is not low on airflow. I use a FARR 3030 which is a MERV 8. I also use a woven fiber pre-filter and follow the Farr with an electrostatic cleaner. Once the children grew and the old carpet was changed, the filters last 6 months. Your needs sound more demanding

Seems 4" filters in this size are not easy to come by and I pretty much have found a single source. All other sources say out of stock.

 

[Chevyc10]

The 4” filters can be run much longer than 30 days. I change mine once a year. But I also have return air filter grills with 1” pleated MERV 13 filters too. I change the 1” filters every 90 days.

 

[Cujet]

You could install a water manometer and measure restriction. Then change based on that.