This may be a dumb question, but can the MERV rating on a filter be TOO high. I have used Nordic Pure filters in the past and they all have a MERV of 12. I have a new Coleman Echelon 100,000 BTU furnace and need to get new filters and don't want to adversely affect performance. I couldn't find in my manual what was recommended.
It is more important to look at you duct sizing then your furnace, but if your old furnace handled these nordic's, then the new coleman would as well. The only concern about having a higher merv rating (generally speaking a higher arrestance value,) is that you may need to change it more often to keep the system from having to overcome the pressure drop. But in general, a merv 12 would not be too much for a system.
What's your superheat?...."uh....it's good."
What were your pressures?...."uh, they were fine."
If I never here this again, I will die a happy man.
Do you have a VS blower, or a standard multispeed blower.
Did they do a load calc, or just install teh same size furnace that teh old one was.
Newer furnaces, require more air flow.
Are talking about a 4" media filter, or a 1" MERV12 rated air filter.
The 1" will restrict the air flow.
You need to have your contractor test the ESP(external static pressure) of your system,and advise how restrictive of a filter you can use without damaging the equipment.
Anything else is just a guess.