Friday, January 18, 2008

Heating your House

This is Minnesota and everyone seems to talk about the weather. We are in for a cold stretch.. I thought I would talk about furnaces. Here's our boiler. It hangs on the wall. You can see the blue hot water storage tank next to it. The storage tank is about the size of a water heater. More about that later.

The most popular kind of furnace around here is the forced air furnace. They are the least expensive and they provide air flow which, among other things, allows you to have air conditioning. A home inspector will tell you that a forced air furnace has a life expectancy of about 20 years.

In an older furnace the heat exchanger could develop a crack. This is bad because carbon monoxide from the burning of natural gas or propane can enter your home through the crack. Every year when there is a cold spell there are carbon monoxide deaths in the news.
You should have a carbon monoxide detector in your home and have your furnace checked before each heating season. I recently sold a home with a 50 year old forced air furnace, which did actually looked old. I'm sure it was not very efficient.

A twenty year old forced air furnace can look like new, they haven't changed much in that time. High efficiency furnaces are becoming more common. A standard furnace may be 85% efficient whereas the newer high efficiency models may be more than 95% efficient.

Higher Efficiency models are more expensive, but they pay for themselves over time.. High efficiency models capture so much heat from the burning process that very little goes out with the exhaust.. You can identify a high efficiency furnace because instead of a metal pipe going up and out the chimney, they have a white PVC pipe that vents out the side of your house.

Believe it or not, water is one of the byproducts of burning natural gas. In older furnaces the water vapor escapes out the chimney. In high efficiency furnaces there is a condensate tube that drains the water from the furnace. If the tube clogs the bottom of your furnace could fill with water if the furnace is working hard.

Another common type of furnace is the boiler. Residential boilers are hot water systems, not steam. In older systems the radiators are used to distribute the heat. Starting in the 1950's or 1960's they started to use baseboard units which don't take up as much space. More recently, in floor heat has become popular.

Boilers are more expensive than forced air furnaces and they should last longer. There are advantages to hot water heat. Instead of blowing dry winter air around your house warmth radiates from a warm radiator or floor. I've been told this type of heat feels warmer and you can keep your thermostat lower. I'm not sure how to judge that.

In floor radiant heat is very nice, especially in a tile bathroom or basement floor. We put a new cement floor in the basement of our previous old house. The plumber talked us into putting radiant heat in the floor. He told us it was okay to run water from our water heater through the pipes instead of putting in a boiler. It worked fine that way. Our whole home felt warmer and our basement family room with warm floors became a favorite spot for everybody.

When we built our new house we put in both in-floor radiant heat and forced air. The boiler hangs on the wall in the utility room. The high efficiency boiler supplies both domestic hot water and heats the water that keeps us warm. Unlike our old system, the water that heats our home is in a closed system and is different than our water for showers etc.We also planned for an outdoor wood boiler which circulates water in the same way as the main boiler but the heat source is outside.

We envisioned saving lots of money by burning wood. We haven't put in the wood boiler yet because it is expensive and we have discovered that our house is very easy to heat. It would take a long tome for the wood boiler to pay for itself. That's all for now.

J. T.

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