Space Guard Air Filters?

[Woodtourer]

We have one of these but and I understand they are quite efficient but do they tend to reduce air flow a considerable amount?

[fredhargis]

I had one for years, and it probably does reduce air flow. But mine was installed with the furnace I had at the time, and they set up the blower speed to compensate for the filter. Since then, I've had other similar filters installed with the furnaces and they always checked the air flow.

[daddo]

I've been installing them for 30 years with no issues except with 5 ton systems which is marginal- just keep it changed every 6 months in a 5 ton system instead of a year.