01/24/2014
Lots of stories going around of frozen pipes, burst pipes, furnace is balking, or the furnace just can't get the house warm. I copied this from a discussion that we were having about frozen pipes and not enough insulation.
Furnaces are all different sizes in BTU's per hour. How do you know which one is the right one for your house? The furnace size depends on the heat resistance of the outside of the house. A bigger house does need a bigger furnace, unless it is insulated much better. So after an analysis of your house is completed and we assume a base temperature of 2F in Onondaga County. Which means everybody who had furnace that wasn't 20% oversized is probably not keeping their house at their normal thermostat setting. So if my furnace has to produce enough heat to keep my house at 68F when it's 2F outside that number becomes the heat load. Most contractors oversize this number because of a few factors that are hard to predict and in case it gets really cold like today.
My house at -5F outside my furnace will run about 50 minutes an hour. Today at -18F the furnace ran about 55 minutes out of the hour. My furnace can maintain the desired 68F in the house despite the fact that the house is continually losing heat and loses it faster at colder temperatures than warm.
If you felt cold , it could be from your furnace not being able to maintain the temperature at which you set the thermostat. The furnace is too small or inefficient.
The wrinkle in the math is that my 80,000BTU furnace at 90% efficiency puts out 72,000BTU an hour so my house has to lose less than 72,000BTU's an hour for me to stay warm. Now if I have an old furnace, it might be only 60% efficient and it would put out 48,000BTU and I would be cold on a very cold day.
What to do? Get an energy audit done on your house. Contact me, an Energy Star contractor, or if you qualify get an EmPowerNY energy audit completed on your house. The auditor should look at the insulation, the appliances, the air leakage in the building and test your combustion appliances.
If anyone is following this thread, and is considering buying a new furnace, it is imperative to be certain that the ductwork (both cold and hot) allows sufficient air flow in cubic feet per minute to provide adequate cooling of the heat exchanger. I bought a 60 thousand btu 92% efficient furnace to replace a 70 thousand btu conventional furnace, and when I did the math to check the airflow capability I actually had to create two new cold air ducts to reach minimum airflow to cool the heat exchanger. The higher efficiency furnaces are not as forgiving about overheating as the old units were.
And now for the information you've been waiting for:
We do energy audits, we only do audits, if you want the information and the coaching on doing the work on your house, we can do it. If you want to find out what you need before a contractor tries to sell you something, we can do it. You can find us here: https://www.facebook.com/TowpathHouseTechs
If you income qualify and own your own home, you will want to start here for EmPowerNY which is a free program: https://www.nyserda.ny.gov/.../Eligibility-Guidelines.aspx
You can also look at all income based programs here: https://www.nyserda.ny.gov/.../Low-Income-Assistance.aspx
If you don't qualify for those, there are two more programs, Assisted Home Preformance, see the link directly above, and Home Performance with Energy Star. You can find out more about those programs here: https://www.nyserda.ny.gov/.../Existing-Home-Renovations...
If you just want a friendly explanation or a quick question answered, just ask.
