Seven questions to ask before you buy a furnace
The answers separate a contractor who will do it properly from one who is guessing. Ask all seven, and ask them of everyone who quotes.
Ryan DeRue · September 14, 2026 · 1 min read
Replacing a heating system is one of the larger purchases most people make for a house, and it is bought from a stranger, under time pressure, usually in the cold. These seven questions sort out who is worth listening to.
1. Did you do a load calculation?
Sizing from the old unit repeats whatever mistake was made last time. A Manual J load calculation accounts for the actual house: insulation, windows, orientation, air sealing. If the answer is "we will match what you have", keep looking.
2. Did you measure static pressure?
New equipment on bad ductwork performs badly and fails early. Somebody who has not measured static pressure does not know what they are connecting the new system to.
3. What is the full price, and what is not in it?
Permit, inspection, removal and disposal of the old unit, thermostat, condensate management, any venting changes. Get the exclusions in writing, because that is where quotes quietly diverge.
4. Are you pulling a permit?
A permit means an inspector checks the work. A contractor who skips it is skipping the one independent check on their own installation, and the missing permit will surface when you sell the house.
5. Who registers the warranty?
Manufacturer warranties usually need registering within sixty days. If nobody does it, a ten year warranty can quietly become five.
6. Is the indoor coil matched to the outdoor unit?
A mismatched pairing costs less and never reaches its rated efficiency. If you are replacing air conditioning at the same time, the coil matters as much as the condenser does.
7. Who actually turns up on the day?
Your own staff, or a subcontracted crew nobody has met? It is a fair question, and the answer tells you a great deal.
And one thing to ignore
A discount that expires at the end of the visit. A real price does not evaporate because you wanted to think about it overnight.
Read it and still not sure?
Describe what the system is doing and we will tell you whether it is a five minute fix, a real repair, or a replacement conversation. That costs nothing.
Quick answers
How many quotes should I get?
Three is plenty. More than that and you are comparing noise. Compare what is included rather than the headline number, because the cheapest quote is usually cheapest because something has been left out of it.
Is a higher efficiency furnace worth the extra?
In this climate, usually yes on a system you intend to keep. The payback on going from 80% to 95% is real in Michigan winters. Going from 95% to 98% rarely pays for itself.