Home repair: Don’t expect big savings from tankless heater

Q. I look forward to your column every week in the Daily Herald. We’re looking into changing to a tankless water heater when our current tank heater dies. There are four in our family, including two teenage girls. We now have a 40-gallon natural gas water heater. I am wondering if 1) you recommend a tankless heater over a tank; 2) if yes, what brand would you suggest; and 3) can a tankless heater be self-installed, as I am pretty handy?

A. Tankless water heaters are gaining popularity in the U.S. They are used almost exclusively in the European countries with which I am familiar, and probably in many others.

For tankless heaters to be satisfactory, the right size must be selected. However, you may want to check Consumer Reports’ review of them. In short, although they save energy in daily use (about $70 a year), Consumer Reports states that, because they are so much more expensive than tank heaters to buy and install, it can take up to 22 years to recoup the additional cost. The expected life of a heater is 20 years on most models.

Tankless water heaters may need upgraded gas lines and additional electrical connections, as well as more expensive venting systems. They cannot deliver hot water during power outages. Inconsistent water temperatures also have been reported. They do not deliver instant hot water, as often claimed; it takes time for the water to be heated. Calcium buildup is also a potential problem requiring expensive service calls from licensed plumbers.

Some well-regarded brands are Rinnai and Bosch, among others.

I am sure a skilled DIY’er can handle the water connections. But I can’t recommend a do-it-yourself installation considering there needs to be a gas connection, and perhaps an upgrade in it, as well as add-ons to the electrical system. The risk is too great.

Q. For many years, my wife and I have had the vent hose from the clothes dryer directing heat and humidity into our home to reclaim the lost energy. We have put pantyhose, held on by a vehicle radiator hose clamp, over the end of the hose to trap any lint. The benefits have been terrific, and since we used the electricity anyway, it provides double duty to us.

A. Discharging a dryer’s heat and humidity into the house instead of outdoors became somewhat popular after the energy crisis of the mid-1970s. It was an interesting way to capture what otherwise would be wasted heat (in the winter, at least) and to add moisture in the houses of the time, because most were too dry.

But any house built to today’s standards has a tendency to have too high a level of relative humidity (RH). Some even need air-to-air heat exchangers to keep the relative humidity at a healthy level.

Q. When I had my fireplace chimney cleaned several years ago, the sweep inspected the other side of the chimney, which is the vent for the oil furnace, and said I needed a new liner. Now I have to have that liner cleaned every year to maintain the warranty. What dangerous materials accumulate in the liner from an oil furnace? Would it be an equivalent danger to creosote on the wood-burning fireplace side?

A. Did the sweep tell you why you had to have a new liner? Most oil-fired furnaces and boilers vent in clay-lined chimneys without need for a metal liner.

A well-adjusted, oil-fired heating appliance, serviced yearly, will coat a chimney with only a light-brown ash that does not represent a danger requiring annual maintenance — certainly nothing like the creosote deposits from efficient wood-burning stoves that are not equipped with catalytic converters or treated with ACS, an anti-creosote preventer.

Wood-burning fireplaces do not usually suffer significantly from creosote buildup because so much air flows through the chimney that the combustion gases are greatly diluted.

Q. We live in a 1920s, two-story house with basement and finished attic. It is a Pittsburgh-area brick house with an old dependable boiler. The attic is not heated. There are three old radiators on the first floor and four on the second. The problem is the radiators on the second floor don’t get hot. One gets warm, and the other three don’t even do that.

Oddly, the house stays pretty comfortable with the thermostat set at 68 to 70 degrees. We have to leave the bedroom doors open on the second floor for those rooms to stay warm, except the master bedroom, which is over the living room that has the hottest of the radiators. This room and radiator are right above the boiler, so it’s not surprising.

I can’t help thinking that we could be turning down the thermostat and maybe saving money if the upstairs radiators threw some heat. Our natural gas bills are not out of the ordinary. The radiators have been bled for air, which seems not to make a difference.

A. It sounds as if one of two scenarios is possible. Either the filter screen in the fast-fill valve is clogged with sediment (and should be replaced), or the pressure is set too low to deliver hot water to the second floor. If this is the problem, the pressure valve setting needs to be raised to deliver 18 to 20 pounds of pressure to be able to deliver hot water to the second floor. Too low a pressure results in one of the radiators upstairs only getting warm, while the three that are fed after it get no heat.

You should have a licensed plumber check out your system. While you are at it, you may want to consider replacing an 80-plus-year-old boiler, in spite of its dependability, with a new, more efficient one. This would be the best way to save on your heating bills.

Q. We had a vinyl sliding door installed on our addition that leads out onto a deck. They put wood trim around the inside and vinyl trim outside and caulked both. When it rains, we get leakage inside along the top where the wood trim meets the vinyl door. It’s not leaking from ceiling to door — the water seems to start behind the door trim and runs onto the door.

We’ve checked the gutters. We’ve had new flashing installed where addition meets original house. That’s when the leak started. You’re great at solving problems. Hope you can help me.

A. You haven’t given me much information to go on. Where is the door in relation to where the addition is tied to the main house? This is important to know since you think the leakage is related to the new flashing.

From your description of where the leak is occurring, it is possible that when the addition was built, the contractor used a housewrap under the siding and cut an “X” in it at the door opening instead of cutting it horizontally at the top. When an “X” is cut, the top flap is folded over the framing and any flashing is installed over the housewrap instead of under it. Since most sidings, especially vinyl siding, are not watertight, any water penetration behind the siding is directed inside instead of to the exterior. Caulking is never a permanent answer to this poor practice, even if done well, which under the circumstances does not appear to be the case, since the leakage developed so soon after construction.

Q. What are some of the best methods and products to insulate forced-air ductwork? Is it necessary to insulate the cold air return line?

A. If the ducts are inside the heated building envelope and not used for air-conditioning, there is no reason to insulate them, unless the runs are so long that you can’t get warm air at the end of them. If you have air conditioning, insulating the ducts protects them from the potential of condensation in climates with high summer humidity.

There is special insulation for metal ducts, which you should be able to purchase in big box stores or plumbing supply houses.

There is no need to insulate return ducts.

Q. Last summer, we had a local specialty contractor build a four-season sunroom onto the back of our 10-year-old home, using the existing pressure-treated deck as the floor structure for the new room. The builder, whose reputation spans several decades, insisted that the existing deck platform was in satisfactory condition and had been built with proper framing techniques and allowances for the new application, after the addition of a few extra support joists underneath and new flooring underlayment above.

My question primarily concerns the foundation for the new sunroom. The builder elected to replace the existing two, 4-by4-inch pressure-treated support posts with five, 6-by-6 pressure-treated posts, which I was told were of specially treated “foundation grade.” He claimed this would allow him to bury the posts themselves to the full depth of the post holes (4 feet), after driving multiple galvanized nails into the bottom foot of each pole (to reduce frost-heaving) and encasing each base in 18 to 24 inches of concrete. In other words, he did not use what I believed to be the customary method of support, in which a concrete footing is poured to the full depth of the post holes, and the pressure-treated posts are then bolted to the footings, with all wood being above ground.

I questioned this approach extensively, but the builder insisted he was using sound engineering principles. Have I made a mistake in allowing him to use this technique? My wife and I are most anxious to clarify this issue and to understand what our options and future expectations might be.

A. There are two schools of thought on this subject. Years ago, a pressure-treated foundation system for the entire house was tested and publicized as the wave of the future. It was particularly aimed at the South. It is still used in certain locations.

The advantage of what your contractor did is that there isn’t the weak “knee” connection that is present when metal hardware is used to connect wood posts to cylindrical concrete tubes. The disadvantage is that the type of treatment of the posts is crucial. It should be at least 0.4 CCA for in-ground use, and even that has only a 20-year life.

If you call any lumberyards around, you will be told that the 6-by-6 posts used are OK, but no one will be able to tell you the rate of penetration of the chemical treatment used. It should be rated UC4A at a minimum and preferably UC4B or C.

The method the contractor used to anchor the posts against frost heaves is questionable, as the galvanized nails will eventually corrode from contact with the concrete, the moist soil and the chemicals in the posts.

There are better ways to protect wood posts and concrete piers from frost heaves. It would also have been better to pour concrete pads in the bottom of the holes and set the wood posts on them to ensure solid bearing when the galvanized nails eventually corrode.

At this point, it does not seem there is much you can do about the situation except perhaps to insist that the contractor give you a written warranty for 20 years against settlement, since he has been around for several decades and has a good reputation. But he will probably laugh in your face.

You could also check with a structural engineer to get a second opinion on my comments.

Q. I have water leaking behind my siding, I believe, and into the foundation of my house when it rains. I have had this problem for quite awhile. I just had a new roof put on, so that cannot be the problem. I am at a loss as to where the water is coming from.

A. How long is quite awhile? Is the leak all around the foundation or in localized places? If the latter, what is above the leak — windows, doors? What type of siding is on the house? Any roof overhang? Two-story house or ranch-style? On which walls does the leakage occur: gable or front or back walls? Any gable vents?

As you can see, I need a lot more information to be helpful.

Ÿ Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at henridemarne@gmavt.net. His book, “About the House,” is available at www.upperaccess.com and in bookstores.

© 2012, United Feature Syndicate Inc.