Water Softeners and Air Filtration Systems - When To Replace Media Filter
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rjordan392
12-27-07, 01:36 PM
Hello,
I read with interest past responces by others about these 4 inch media filters being too restrictive. I can imagine that a filter that is not changed in a timely manner would be.
I have a new heating and ac system with the manufacturers best thermostat which tells me when to change it. It also tells me how much in percent of the use of the filter. But this reminds me of those idiot lights that were in stalled on our vehicles.
The reading on the condition of the filter indicates 20 percent used. It was installed in August.
So I put my furnace through two separate tests that records data at the thermostat with the filter in place and without the filter. Do you see anything in this data that may need further investigation?
With the media filter in place:
Furnace Heat Low Furnace Heat High
Airflow CFM 712 Airflow CFM 1033
Blower RPM 681-689 Blower RPM 990
Static Press. 0.23-0.24 Static Press. 0.48-0.49
With the media filter removed:
Furnace Heat Low Furncace Heat High
Airflow CFM 712 Airflow CFM 1033
Blower RPM 663 Blower RPM 959-965
Static Press. 0.19-0.20 Static Press. 0.42-0.44
What I only see in these numbers is that the airflow does not change when the filter is removed. I believe I should get more airflow through the supply side. Do you agree?
I read with interest past responces by others about these 4 inch media filters being too restrictive. I can imagine that a filter that is not changed in a timely manner would be.
I have a new heating and ac system with the manufacturers best thermostat which tells me when to change it. It also tells me how much in percent of the use of the filter. But this reminds me of those idiot lights that were in stalled on our vehicles.
The reading on the condition of the filter indicates 20 percent used. It was installed in August.
So I put my furnace through two separate tests that records data at the thermostat with the filter in place and without the filter. Do you see anything in this data that may need further investigation?
With the media filter in place:
Furnace Heat Low Furnace Heat High
Airflow CFM 712 Airflow CFM 1033
Blower RPM 681-689 Blower RPM 990
Static Press. 0.23-0.24 Static Press. 0.48-0.49
With the media filter removed:
Furnace Heat Low Furncace Heat High
Airflow CFM 712 Airflow CFM 1033
Blower RPM 663 Blower RPM 959-965
Static Press. 0.19-0.20 Static Press. 0.42-0.44
What I only see in these numbers is that the airflow does not change when the filter is removed. I believe I should get more airflow through the supply side. Do you agree?
airman.1994
12-27-07, 08:05 PM
Hard to say when to change them! But the rule is every 6 months to a year. I have a 5 year old and a 1 year old and a cat so mine get changed every 6 months. Now my neighbor are retired and except for my kids going over their for a couple of hours a week their is not a lot of activity. We slide his out the other day after 6 months and I slide it back in and told him he is good for about another 4 months. Id change it by static pressure. I would not let it go above 55. You don't have a lot of room to play with. Your duct must be causing a lot of SP.
rjordan392
12-27-07, 08:48 PM
Thanks,
I'll check the static pressure each month. I think the reason for the high static pressure is that all the 90 degree turns in the ducts are abrupt (box shape) unlike as those in an elbow. When the house was built in the early 50's, it had a gravity type furnace. So at that time square ducts were placed in the walls with no consideration for static pressure when no blower fan was involved.
I'll check the static pressure each month. I think the reason for the high static pressure is that all the 90 degree turns in the ducts are abrupt (box shape) unlike as those in an elbow. When the house was built in the early 50's, it had a gravity type furnace. So at that time square ducts were placed in the walls with no consideration for static pressure when no blower fan was involved.