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Dear Jim: We often run out of hot water for morning showers, and one room is always chilly. How effective are the combination hot water-space heating units, and will they lower my utility bills? -- Mary J.

Dear Mary: Combination water-space heating is feasible with new high-output water heaters. It is an excellent system for both mild and cold climates. These super-efficient water heaters produce 125 gallons of hot water per hour -- enough for the entire Green Bay Packers team on Sunday.

It really does not make sense to use two expensive heating appliances (a water heater and a furnace) when a single new water heater can do both jobs. A combination system reduces maintenance costs, noise and overall utility bills.

There are complete water-space heating combination systems integrated into one unit. There are also modular systems that circulate hot water from the water heater through a coil installed in the furnace blower or in a new air handler (blower). To warm just one room, install a small in-the-wall blower unit.

Vent-Aire makes a unique air handler with built-in fresh air heat recovery ventilation. In addition to bringing in fresh air efficiently, it does not scorch the air, as in a gas or oil furnace. Heat exchangers in these furnaces get hot enough to break down synthetic lint and dust into gaseous chemicals.

This air handler includes one heating coil from the water heater and another cooling coil from the air conditioner. If you have a well, you can use the well water to cool and dehumidify your house for free in the summer. It also uses a new efficient smart General Electric ICM motor.

For large houses or ones that are not extremely efficient (need a lot of heat), several companies make high-output efficient gas water heaters. These gas water heaters use the same condensing technology as used in the most efficient gas furnaces on the market.

A condensing system vents outdoors horizontally through a small plastic pipe. It is ideal for converting from costly electric heat to natural or bottled gas. This improves efficiency and minimizes drafts.

Combination systems are very simple and require little maintenance. When your wall thermostat calls for room heat, a small, quiet pump starts circulating hot water from the water heater to the coils in the furnace blower. The blower starts to comfortably warm your house.

As the water temperature drops in the water heater, its burners come on to reheat the water. The return water from the furnace coil back to the water heater is about 120 degrees, still hot enough for showers.

Write for Update Bulletin No. 618, a list of 15 manufacturers of combination heating systems, new air handler units, super-efficient water heaters and a size estimating chart. Please include $3 and a business-size, self-addressed envelope, and send your request to James Dulley, The Buffalo News, 6906 Royalgreen Drive, Cincinnati, Ohio 45244. Or instant download at

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