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New super-efficient boilers give best overall comfort

Question - Our furnace is old and should be replaced. I am considering a new super-efficient hot water heat system (boiler) for better comfort. Does hot water heat offer any advantages, and which boilers are best? - K.L.

Answer - New super-efficient hot water boiler systems (hydronic) provide the best overall comfort (especially "warm feet" floors) with low heating bills. These extra-quiet hydronic heating systems are installed in many of the most luxurious houses built today.

If you have an old boiler replacing it with a new high-tech model can cut heating bills by 40%. Switching from electric heat to an oil or gas direct vent boiler (no chimney needed) is easy and the savings are significant. Adding a water heater coil can lower domestic hot water costs, too.

A key advantage of hydronic heating is the simplicity of zoning a house for efficiency and comfort. It also simplifies adding features like warm floor heating, ice-melting driveways - even heated bathroom towel racks. Since hot, dry air is not blowing around, fewer allergens are airborne.

The most efficient gas and propane boilers use condensing heat exchangers just like new high-efficiency forced-air furnaces. The most efficient (up to 95%) design uses an evaporative re-cooling tower and heat recovery unit to preheat the incoming outdoor combustion air.

Another condensing design uses the pulse combustion principle where the fuel burns in rapid intense bursts instead of in a slow standing flame.

Both of these design technologies use quiet sealed combustion with no chimney. The combustion air and flue gases vent horizontally through a plastic pipe.

In areas with frequent outdoor temperature swings, consider a two-stage (low/high heat output) non-condensing gas boiler. In all but the very coldest weather, the burner operates in the lower output mode. This provides greater overall efficiency and improved indoor comfort.

Super-efficient condensing and two-stage models use low-mass heat exchangers for rapid heating. Some of these small low-mass boilers are light enough to be mounted on a wall. Old style but durable (some with lifetime warranties) cast-iron models are good for boiler replacements.

Several sealed direct sidewall venting oil boilers are now available.

These are quiet and do not require a draft inducer fan. Trianco makes one with a unique efficient low-mass steel counterflow heat exchanger for rapid heating.

To heat domestic hot water, some boilers use a new technique that provides instant heat for the house too. Instead of having a domestic water heating coil in the boiler, the coil is located in a separate insulated buffer tank.

Write for or instant download ( Update Bulletin No. 737 buyer's guide of 14 super-efficient gas and oil boilers, efficiencies, sizes, venting method, warranties, features and a savings/payback chart.

Please include $2 and a business-size SASE. Write: James Dulley, Deseret News, 6906 Royalgreen Drive, Cincinnati, OH 45244.

Question - Our concrete patio has developed cracks. I plan to build a solar greenhouse with a concrete floor, and I do not want it to crack, too. Are there any tips for the new floor and for fixing the patio? - H.D.

Answer - The primary cause of cracked concrete is soil movement underneath it. Most cracking occurs within months of construction. Wait until it stops getting worse. Then you'll have to call a professional to repair it.

At your proposed site, make sure that the soil is stable and not subject to excessive water drainage flows. When the concrete floor is poured, there should be control joints every eight to ten feet to handle some movement.