what size furnace ??

Question

I have a 30 x 50 ranch home in ny and was wondering what size furnace is needed to heat this home,,an extention may be added in the future ...if the home is zoned will it make a difference in sizeing the furnace. I will be useing propane with radiant floor heat

Answer 1

You use the term furnace, but if you have radiant floor heat, which is hot water, you have a boiler. Furnaces heat air, boilers heat water. If you do install a furnace, you will not be able to use it on radiant floor heat.

The size of a boiler is given in BTUs. To determine what size you need, you should have a heat loss calculation performed. The analysis will consist of the size and construction of the building, ceiling heights, insulation, doors, windows and climate region. The calculation will tell you how many BTUs per hour your home will lose in the winter. Your boiler is sized to replace the BTUs lost. Definitely include the addition in the calculation. Multiple zones is a good thing - that way you can keep unused sections of the home cooler than the constantly occupied sections.

Your HVAC contractor, or plumbing/heating supply store will usually perform the calcs no charge if they get your business.

Check the insulation R values in your house. Consider adding to the insulation, which will result in savings on your heating bills. Many new homes in NY have a minimum R49 insulation in the attic, and R19 or better in the walls.

Answer 2

Sizing a furnace properly includes more than just size. It is also based on the number of windows and doors and other heat robbing sources. Get a home heating inspection and make sure the company does all the equations needed to compute your needs. Knowing there may be an addition later will help with sizing ducts to prevent the need for more extensive rework later.