Dear Jim: I am adding two rooms to my house for my parents’ apartment. I have heard boilers make comfortable heat, especially for the elderly. Are they efficient and can I also use one for the rest of my house? – Kathy M.

Dear Kathy: Hot water heat was very popular years ago. It went out of favor somewhat when central air-conditioning became commonplace. Since central air-conditioning required a duct system, forced air furnaces were usually installed.

Today, with the high cost of heating homes, hot water boilers are becoming more common again in all climates. This is partly due to the comfort and efficiency of a hot water system. Within recent years, technology improvements in gas and oil boilers have made the equipment as efficient as forced air systems.

For cooling during the summer, there are several central air-conditioning alternatives to a standard ducted forced air system. The most common are mini-split ductless systems and mini-duct, high-velocity systems. The mini-duct system can also be used for heating your home.

Boilers are available in many sizes (heat output capacities), so you should be able to find one small enough to efficiently heat just two rooms. Most of the residential models are also available up to 200,000 Btuh heat output, which is enough to heat a very large house in the coldest climates.

As with gas and oil forced air furnaces, you can get a $150 federal tax credit if the efficiency (AFUE) of the boiler is 95 percent or above. In order to meet this requirement, many of the gas boiler manufacturers have slightly modified their designs to meet or exceed this requirement.

There are only a few oil boilers that also are in the 90-plus efficiency range. For the highest efficiency which qualifies for the tax credit, a boiler uses a condensing heat exchanger. This condenses the water out of the flue gases to squeeze out more heat before they are exhausted outdoors.

A condensing boiler design is ideal for your room addition because it does not require a chimney. The flue gases are exhausted through a small plastic pipe.

These high efficiency boilers use a low-mass heat exchanger, usually made of stainless steel. A few use specially-coated aluminum. Low-mass heat exchangers heat and cool quickly so the system can adapt quickly to changing heating needs of your house. Noncondensing models often use high-mass cast iron heat exchangers. They are less efficient, but very durable.

The typical heat delivery options are baseboard radiators, infloor radiant tubing and/or a heat exchanger with a blower. Since your parents are older, infloor heating would be an efficient, comfortable choice.

The room temperature reacts slower to thermostat changes, but your parents may not tolerate a nighttime setback well anyway.

Write for (or instantly download, at www.dulley.com) Update Bulletin No. 490 – buyer’s guide of 15 efficient gas and oil boiler manufacturers (29 models), listing efficiencies, sizes, venting methods, warranties, features, and a savings-payback chart. Please include $3.00 and a business-size SASE.

Dear Jim: My house has brick veneer over insulated stud walls. I am going to build a raised deck off the second-floor bedroom. It will be supported by four posts. Should I attach the deck floor to the house wall? – Scott E.

Dear Scott: It is probably better if you do not attach it securely to the house wall. With tall wooden posts, the deck surface may move up and down more than the house wall throughout the seasons. This can stress the materials. To provide a more stable feel to the tall deck, screw steel angles to the house wall. Screw another set of angles to the deck several inches below the other ones. Connect them with long bolts that allow some vertical movement.

Send inquiries to James Dulley, Bangor Daily News, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.