The solution problem 3: heating and heat transfer

In theory, heat transfer systems in homes with wood burners are a good idea. The huge Achilles heel is they have a net cooling effect on the home.

This is mainly due to minimal insulation around the long runs of ductwork that supply warm air to distant bedrooms.

Ducting is typically installed on top of ceiling insulation. Warm air from the fireplace exits the thermal envelope for the journey to the bedrooms, losing warmth the whole way, then re-enters the thermal envelope considerably cooler. While the air in the lounge ceiling may be 30°C+, it can fall to as low as 10-20°C as you get further away.

Insulation

Fortunately, retrofitting insulation around ducting is quick, easy, and inexpensive. Where the ducting in our ceiling lay flat, I covered it with R 3.6 blanket insulation. Where it connected to a suspended fan, I double wrapped each side with polyester under-floor insulation and taped it up like a whiskey barrel.

The difference in performance for us was immediate and substantial. The old Kent fireplace used to heat just the lounge. By improving our home’s thermal envelope using insulation, and super-insulating the heat transfer system, it now easily heats the entire house. For a typical home, the savings in firewood over one or two winters would probably pay for the upgrade, a 50100% return on investment.

A modern wood stove

We rarely need to light the Kent these days. That’s because we installed a Wagener Fairburn wood stove in the kitchen for cooking, hot water, and space heating.

Here, we made another small choice that’s had a big effect, opting for a heat saver-type flue rather than a standard flue.

To keep the outside of a standard flue cool, there’s an air gap between the flue and the flue casing. Air is drawn in from the room, fills the gap, and is expelled. This hugely inefficient system means large volumes of newly warmed air are sucked outside.

For not much more money, newer eco or heat saver flues draw cool air from the ceiling cavity or outside, so all the warm air stays inside.

The results

The entire family is happy with the way the house feels and performs. My nine-year old daughter loves lighting the fire, and her younger brothers enjoy playing in a warm bedroom.

I’m getting ready to order more glazing panels for the last couple of windows. That means, after 7+ years, the job might be… almost done.