New furnaces offer better fuel efficiency

Hey there, time traveller!
This article was published 02/10/2005 (7314 days ago), so information in it may no longer be current.

QUESTION — We live in a 2,007-sq-ft., two-storey house, with a 30-year-old 128,000 BTU furnace. When we had an energy audit done in 1999, the inspector said that our furnace was 70 per cent oversized for our house and recommended a 78,000 BTU furnace when replacing it. I know that we are living on borrowed time with our present furnace, as the blower motor is making strange noises, and I would like to upgrade to a higher efficiency furnace and need some advice.

I am looking at Trane furnaces and have had two quotes. One contractor is suggesting installing an 80,000 BTU Trane XV90, approximately 92 per cent efficiency, which comes with a variable speed blower motor and five-year parts and labour warranty. The other contractor suggested a 100,000 BTU mid-efficient Trane XL80 furnace. With the same motor and a combustion air intake duct installed, we are looking at very close to the same price with a five-year parts and one-year labour warranty.

It looks to me like the high efficiency furnace is by far the best deal, but I have also heard that they are more costly to repair and some may have reliability problems. I also understand that the vent to the outside should be graded but I am not sure why. Is the high efficiency furnace the way to go and is an extended warranty on a high efficiency furnace something we should seriously consider?

–Michael S. Nayler, e-mail

ANSWER — The decision to choose between a mid-efficiency and high-efficiency furnace is a very common question. It is a difficult decision and varies depending on the home and other circumstances, but either will provide much better and more energy efficient heating than your old unit. I will offer my advice and some background information, which I hope will help with your decision.

The first thing to address is the comments of the energy auditor on the size of your original furnace, which I would disregard. While it is true that many older standard efficiency furnaces were oversized, I doubt it was anywhere near 70 per cent too large. The estimates for the size of the newer furnaces, which are considerably more energy efficient than the old one and subsequently have a lower BTU rating, appear to be more in line. The energy auditor may not have been properly trained to size heating systems or may not have had the proper tables to refer to. Licensed gasfitters are trained to do calculations on homes and refer to the appropriate charts and tables in the codes to size furnaces.

You are correct that many older versions of High-E furnaces had problems with high maintenance costs of repair and replacement of complicated controls and electronic components. These costs largely ate up or exceeded the savings in energy input. Most of these issues have been rectified. This is due to the use of computer circuitry in almost all new furnaces, mid or high-efficiency, that reduces the need for many of the older electronic control components. If this computer circuitry fails, it may be very costly to replace, but that is much less likely than with the controls on older units.

This costly circuitry may be the reason that an Extended Warranty on a new furnace is a good investment. If a circuit board is defective or fails after the initial warranty period, it can cost hundreds of dollars to replace, which may be a substantial percentage of the original cost of installation of the furnace. Care should be taken, however, to inquire about specific conditions and limitations of any warranties. An extended warranty is only as good as the company backing it up and may become void if you fail to service the furnace regularly.

The added savings in natural gas input of approximately 5 per cent to 10 per cent between these furnace types may be well worth the added cost of the High-E furnace. The benefits to the environment may be even greater. With global warming and the Kyoto protocol very much in the news and in the mind of the government, reducing emissions from fossil fuel burning appliances is admirable. Manitoba Hydro has incentive programs for High-E furnace upgrades, and the federal department of Natural Resources has grants available through their Energuide program for efficiency upgrades to homes. You may have been given details about these programs when you had the Energy Audit done on your home, but if not you can find out more at www.energuideforhouses.gc.ca or call 1-800-387-2000.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors – Manitoba (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.

trainedeye@iname.com