Replacing or upgrading a furnace or air conditioner is an expensive prospect for a home owner. How can we know what kind of unit we need or what brands are best? New Hampshire’s Jack Harrison has the answers. Use his site to find the best HVAC system for your home, whether it be central heating, a boiler, or even a wood furnace. Harrison also offers advice about working with an installer and repairing air conditioning units. We can use his site to get estimates from local contractors.