But now consider a hot water boiler. Most operate at six times the pressure of the typical steam boiler, yet most have no protection against a dangerous low-water condition. Some hot-water boilers have that crucial protection, but these are the larger boilers, 400,000 BTUH and higher. Why boilers of this size? Because it's the law. Contractors usually install these boilers in multi-family housing and commercial buildings - places where there are lots of people.

But what about smaller hot water boilers? You know, the kind you find in single-family homes. Plenty of people living there, but they don't have low-water cutoffs, do they? Why? Because in most states, there's no law that says you have to install them.

What's causing this shift in policy? We suspect it may have to do with the rapid growth of hydronic heating in certain areas of the United States.Did you know that the radiant-floor-heating market has been growing at a steady rate of about 30% a year for several years now? Many newer hydronic heating systems include at least some radiant floor heating. And when all or most of your system piping wind ups up below the boiler, it's time to start thinking seriously about potential system leaks, and about the people who are going to live in that house.

Even a simple baseboard-loop system can have several feet of piping that dips under a concrete slab to clear a doorway. That piping is out of sight and prone to corrosion and leakage; in most homes, there's nothing to protect the boiler from a low-water condition. Maybe you're thinking the feed valve will protect the boiler if something goes wrong? If you are, consider this situation. Suppose the burner locks into the firing position and doesn't drop out when it should. Anything from a stuck-open gas valve to a faulty control can cause this problem. Once the burner locks in and keeps firing, the temperature and pressure inside that boiler will build until the relief valve opens.In most homes, this happens at 30 psi.

So the relief snaps wide and unloads a furious blast of steam. Once the immediate danger passes, the valve quickly seats itself. In most homes,they seat at about 26 psi. But remember, the burner continues to fire.

And then in a few moments, the relief valve roars open again, dumping even more steam into the boiler room. Unless someone notices, this will continue until there's little or no water in the boiler.

Now consider this. While this is happening, the system pressure never drops below 12 psi. Because it doesn't, the feed valve can never feed. And if the feed valve shot water into the boiler, there's no telling what could happen.

Take it a step further. Suppose the burner is behaving and things are working as they should, except there's a leak in a buried pipe, and the system is losing water constantly. Since the system pressure is below the feed valve's setting--which is, say 12 psi--the feed valve will feed. It will allow in gallon after gallon of fresh, cold water. When the boiler heats that raw water, the system will receive a massive injection of oxygen, and before long, the ferrous parts of the system will corrode and fail. The fuel bills will also soar, and if the water in your area is hard, the boiler will fill with lime, and it too may fail. Your customer will have no warning that this is happening.

Can you see how low-water cutoffs are in the best interest of your hot-water heat customers? It's to your great advantage t o mention them to your customers, especially if you're replacing their boiler. When they realize a low-water cutoff is in their best interest, most home owners say,''Sure, install it!'' This is especially true when you're replacing their boiler, because the cost of the low-water cut off seems modest compared to the cost of the complete job.

Think about it. If you mention it to them as an option, explaining the facts about feeders and boiler protection, they might just say Yes! And if they do, you'll make more money on that job while you're protecting that family from potential danger. And if they say No, you're still better off. You've raised an issue with a solution that's in their best interest. You've shown you care about their safety.

When you sell with your customers' best interests in mind, you separate yourself from other contractors in a big way. This caring approach and awareness of the workings of hydronic systems make you more professional in the customer's eyes. And the best part: you'll probably increase your profit on every job you do.