Circulating Solutions for Those in a Hot-Water Hurry

By Jeanne Huber
Special to The Washington Post
Thursday, November 9, 2006

Q Every morning, I get frustrated at how long it takes for hot water to arrive at my bathroom sink. Is it worth installing an instant water heater in the cabinet underneath?

A If you need hot water only at the sink, a small instant water heater might be a solution, but you'll probably need a 220-volt circuit or a gas line, so the fix could wind up being quite expensive. Some small instant water heaters do run on a typical 120-volt household circuit, but they can't raise the temperature enough to make the water very hot in the winter, and they deliver only half a gallon per minute. Most people want the flow to be twice that. Plus, in most houses, an under-sink water heater doesn't address the other half of the problem: the wait for hot water in the shower.

There is a way to get hot water more quickly at both the sink and the shower, however, assuming the pipe run between them is short, as it is in most houses. Install an on-demand recirculating pump, sold under several brand names that all use the word "D'Mand" in the product name.

Using the fittings that come in the package, you connect the pump between the hot and cold pipes under the sink. When you want hot water, you press a button, and the device shoots the once-warm water in the hot-water pipe into the cold water line. It's like opening the tap and waiting for hot water, except that instead of sending the water down the drain, the pump pushes the water backwards in the house's piping loop. In effect, the once-warm water becomes the supply source for the water heater.

The pump operates at full throttle, so hot water arrives much more quickly than it does when a low-flow faucet regulates the water's speed. Because water isn't being wasted, you can use the minute or so of delay to do something else, such as picking out a fresh towel for your shower. When hot water arrives, the pump shuts off. You open the tap, and hot water flows instantly.

It's important to get an on-demand recirculating pump, not one that runs continuously or on a timer, because the always-on types waste energy. One on-demand model is the Metlund D'Mand S-50, suitable for homes where the water heater is within 50 feet. It costs about $240 at and comes with all necessary fittings for copper pipes.

You'll need a few extra parts if your house has plastic or galvanized piping. You'll also need a standard 120-volt outlet. If that doesn't already exist, extending a line from a nearby outlet should be a fairly simple task. Installing the pump itself usually takes about an hour. If you're handy, you can probably do the job yourself.

What's the best time of year to paint the exterior of your house?

Assuming your house has wood siding, you want to paint when the relative humidity is about average for the year. That's also the point at which the wood will be about its average size.

Paint and good construction should keep the siding from absorbing copious amounts of liquid water, but water vapor still gets through. On a humid summer day, the wood will absorb moisture and expand, mostly across its width. On a crisp, cold winter day, the moisture level in the wood will drop and the wood will shrink.

To stay attached, paint must expand and contract along with the wood. Painting mid-size wood minimizes how much the paint must stretch, so the paint job lasts longer.

The best conditions tend to occur in the spring and in the fall, so you could theoretically pick either season. However, since theory and reality often turn out to be different things, it often makes sense to plan for a spring job.

If you're hiring the work out, that gives you more leeway in case the contractor you pick doesn't show up in time. And if you're doing the work yourself, it builds in extra time in case some of the preparation steps take longer than you expect. If you wait until fall, you risk working on days that are too short or too cold for the paint to dry properly.

In spring, just be sure to wait for a few clear days before you begin painting, and don't paint on days when rain is expected within 24 hours.

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