HVAC Air Filter Needs to Be Replaced Every 3 Weeks

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TrippWest

New Member
Jan 28, 2021
14
Detroit
I had a Napoleon EPI3C Oakdale Series Cast Iron Wood Insert installed in September and have been burning wood every day all day since. When the stove is not in use, I have to replace the air filter in my HVAC system once every 3 months. Now, I am finding that I need to replace it every three weeks. Is this normal, or could this be a problem with my installation?

I run the fan in my HVAC system for 30 minutes every hour to try to spread the heat throughout the house. (I have trouble getting the back of the house warm.) I am not particularly good about turning the HVAC fan off when I restock the fire in the morning, and I have to keep the door open a crack for a half an hour or so to give the logs enough oxygen to get a good burn. I think that may be allowing some ash to escape.

Also, my ash emptying technique could improve.

But is this enough to be running through airs filter in the HVAC this fast, or should I get the system checked out?

FYI, I also bought an air purifier for the room. Thanks for the help.

Air Filters.jpg
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,484
central pa
I had a Napoleon EPI3C Oakdale Series Cast Iron Wood Insert installed in September and have been burning wood every day all day since. When the stove is not in use, I have to replace the air filter in my HVAC system once every 3 months. Now, I am finding that I need to replace it every three weeks. Is this normal, or could this be a problem with my installation?

I run the fan in my HVAC system for 30 minutes every hour to try to spread the heat throughout the house. (I have trouble getting the back of the house warm.) I am not particularly good about turning the HVAC fan off when I restock the fire in the morning, and I have to keep the door open a crack for a half an hour or so to give the logs enough oxygen to get a good burn. I think that may be allowing some ash to escape.

Also, my ash emptying technique could improve.

But is this enough to be running through airs filter in the HVAC this fast, or should I get the system checked out?

FYI, I also bought an air purifier for the room. Thanks for the help.

View attachment 273039
Is there an air return vent near the stove?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,484
central pa
Welp, that die is cast.
It is against code for a very good reason. The dirty air filter is an annoyance. The risk of pulling CO out of the stove late in the burn process distributing it through the house is a very real danger
 
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brenndatomu

Minister of Fire
Aug 21, 2013
6,397
NE Ohio
and I have to keep the door open a crack for a half an hour or so to give the logs enough oxygen to get a good burn.
Sounds like you do not have dry fuel...or your chimney has very poor draft...something. No way you should have to leave the door open that long...normally you should not need to leave the door open at all.
Make sure you have working CO detectors!
 
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brenndatomu

Minister of Fire
Aug 21, 2013
6,397
NE Ohio
CO detectors in place. Firewood has had 15-18% moisture.
How is it being tested? (details please)
15-18% wood takes off almost as good as gun powder...your's is burning more like 25-30% MC wood...or like I said, some real chimney draft issues there!
 

Corey

Minister of Fire
Nov 19, 2005
2,594
Midwest
I would back up for a second and look a bit further up in the process. What is causing you to change the filter? Some pressure sensor / warning light? Air flow indicator? Other indication? Changing it just by 'eye' or because it is dark colored? (The last option might not be the best indicator of when to change.)

If you are getting some type of 'sensor' indication to change that often, is the filter media the actual one called for in the system? If you've upgraded to a much higher MERV rating, that could trigger much more frequent changes... especially since it looks to be only a 1" thick filter. Typically a higher filter rating would need greater fan capacity and/or a deeper filter media to give approximately equal filter life and performance.

On the stove side, keeping the door open for half an hour to get a fire going, and worrying about ash coming out seems to suggest a very weak draft. That might also be worthy of an investigation. Flue size / height? Insulation? Last cleaned? Flue cap plugging? Appliances / vent fans moving air out of the house? ..all things to look into.
 
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TrippWest

New Member
Jan 28, 2021
14
Detroit
I'm tipped off about the air filter because my Ecobee thermostat starts "recalibrating" and shutting itself off and turning on again. Checked the Ecobee website and sure enough, a clogged air filter can cause that to happen. This problem has only started since I started using the fireplace.

The installation was just in September, so I haven't had a first cleaning yet. No appliance fans running aside from the HVAC system fan.
 

TrippWest

New Member
Jan 28, 2021
14
Detroit
How is it being tested? (details please)
15-18% wood takes off almost as good as gun powder...your's is burning more like 25-30% MC wood...or like I said, some real chimney draft issues there!

I have a moisture meter. I can tell the difference between the way the wood burns when I first get the cord delivered and as I get towards the end of the cord -- definitely lights easier. But there are some days when it lights easier than others and I haven't been doing this long enough to get a good feel for all the factors that affect it.

Filter has a MERV rating of 8. I just had a new AC installed, and when they did that, they almost doubled the size of the HVAC supply duct, said it was undersized.

Flue liner is about 25' tall, 6" diameter.
 

moresnow

Minister of Fire
Jan 13, 2015
1,783
Iowa
I had a Napoleon EPI3C Oakdale Series Cast Iron Wood Insert installed in September and have been burning wood every day all day since. When the stove is not in use, I have to replace the air filter in my HVAC system once every 3 months. Now, I am finding that I need to replace it every three weeks. Is this normal, or could this be a problem with my installation?

I run the fan in my HVAC system for 30 minutes every hour to try to spread the heat throughout the house. (I have trouble getting the back of the house warm.) I am not particularly good about turning the HVAC fan off when I restock the fire in the morning, and I have to keep the door open a crack for a half an hour or so to give the logs enough oxygen to get a good burn. I think that may be allowing some ash to escape.

Also, my ash emptying technique could improve.

But is this enough to be running through airs filter in the HVAC this fast, or should I get the system checked out?

FYI, I also bought an air purifier for the room. Thanks for the help.

View attachment 273039
Have you actually checked heat register/room air temps in the far parts of the house with, and without the HVAC fan running. Success is normally minimal. At best. Most times it does zero good in my experimentation as the heat is lost in the ducting.

The trouble starting a fire may be explained because you are putting your stove draft up against your HVAC system head to head competing for available combustion air. How well does the fire start when the HVAC fan is turned off? If you still have very slow starts I would naturally suspect wet fuel.

I would not be using the HVAC fan in your setup. No way.

If you need to move air, set a floor fan in the cold part of the house gently encouraging dense cold air towards the stove room for circulation. Mucho safer!

Good luck
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,484
central pa
I'm tipped off about the air filter because my Ecobee thermostat starts "recalibrating" and shutting itself off and turning on again. Checked the Ecobee website and sure enough, a clogged air filter can cause that to happen. This problem has only started since I started using the fireplace.

The installation was just in September, so I haven't had a first cleaning yet. No appliance fans running aside from the HVAC system fan.
Was it installed by a professional? If so that is scary that they ignored this serious safety issue. Again don't worry about the filter the intake needs to be relocated
 

TrippWest

New Member
Jan 28, 2021
14
Detroit
Yes, the insert was professionally installed. (The fireplace and return were obviously already in place. Also, separate HVAC guys were just here to install the AC and as part of that, they increased the size of the supply duct. Neither one mentioned this.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,484
central pa
Yes, the insert was professionally installed. (The fireplace and return were obviously already in place. Also, separate HVAC guys were just here to install the AC and as part of that, they increased the size of the supply duct. Neither one mentioned this.
I personally would go back on them both. This can potentially be a serious problem
 

BrianVA

New Member
Oct 28, 2020
48
Central VA
I have a moisture meter. I can tell the difference between the way the wood burns when I first get the cord delivered and as I get towards the end of the cord -- definitely lights easier.

Sorry if you are already doing this, but just to make sure...

When you use the moisture meter, are you splitting a piece and putting the prongs against the fresh split side? Technically it should be around 70 deg, but the more important part is the fresh split.

I ask because it is very unlikely that you are getting a fresh delivery of 18% MC firewood. But maybe you have a really awesome firewood guy.
 

TrippWest

New Member
Jan 28, 2021
14
Detroit
Sorry if you are already doing this, but just to make sure...

When you use the moisture meter, are you splitting a piece and putting the prongs against the fresh split side? Technically it should be around 70 deg, but the more important part is the fresh split.

I ask because it is very unlikely that you are getting a fresh delivery of 18% MC firewood. But maybe you have a really awesome firewood guy.

I am not. I will see what happens when I do.
 

BrianVA

New Member
Oct 28, 2020
48
Central VA
I am not. I will see what happens when I do.

Gotcha. Yes, it is very important to check fresh splits. You need to know the MC on the inside. If you're wood is 18% on the outside, and you're keeping it covered, it is probably much higher on the inside.

I usually pick a few of the bigger pieces, and once those are good, I can be pretty sure the rest of the stack is ready as well. For me, I burn mostly oak. It generally takes 2 years to get it fully seasoned. Most firewood guys are delivering wood that is 6-12 months. Which means you generally need to buy it a year in advance (or cut your own).
 

TrippWest

New Member
Jan 28, 2021
14
Detroit
Gotcha. Yes, it is very important to check fresh splits. You need to know the MC on the inside. If you're wood is 18% on the outside, and you're keeping it covered, it is probably much higher on the inside.

I usually pick a few of the bigger pieces, and once those are good, I can be pretty sure the rest of the stack is ready as well. For me, I burn mostly oak. It generally takes 2 years to get it fully seasoned. Most firewood guys are delivering wood that is 6-12 months. Which means you generally need to buy it a year in advance (or cut your own).

Thanks, that's helpful. This is my first year with the insert, so I did not buy wood in advance. But the leftover firewood that I got at the beginning of the summer for the backyard firepit went up super easy.
 

brenndatomu

Minister of Fire
Aug 21, 2013
6,397
NE Ohio
You need to know the MC on the inside. If you're wood is 18% on the outside, and you're keeping it covered, it is probably much higher on the inside.
This!
It generally takes 2 years to get it fully seasoned. Most firewood guys are delivering wood that is 6-12 months. Which means you generally need to buy it a year in advance (or cut your own).
At least a year...if not 2!
 

moresnow

Minister of Fire
Jan 13, 2015
1,783
Iowa
First year! The learning curve is a bit flat for most. You have come to the correct spot for accelerating the curve :cool:

Select a handful of random splits from your wood stash. Bring them indoors for a full day and night to get them up to room temp 70ish. Then take them outside and re-split them. Take them back inside and press the moisture meter prongs firmly into the freshly exposed inner face of the split. This should give you a reasonably accurate measure of your moisture content.

Testing the outside of splits that have been sitting in a stack for days, weeks or months means virtually zero. You must re-split for accuracy. Many if not most meters are calibrated to be accurate around 70F. Hence the required warm up period before re-splitting/testing.

Testing cold splits will give you low inaccurate readings.

Food for thought. Let us know what you find.