AS OF THIS SPRING, I have been working on hydronic heating systems for a third of a century; 33 years is a long time to be hanging out in boiler rooms.

I've seen boilers as large as a bedroom. These actually had a man door the size of a regular door to get into the combustion chamber, and they were equipped with a blower/burner assembly the size of a small car. I still wonder about the seasonal efficiency of that boiler, which was serving the needs of a large hotel.

I've also seen boilers small enough to be shipped via UPS and handled and carried by one man. Most recently, a new class of hydronic heat source has made an appearance on our shores. This new technology has actually been in service and proving itself in Europe for almost 20 years, so although it may be relatively new to us, it is considered old hat in Europe.

At present, more than 300 different brands and models of condensing boilers are available in Europe, and no less than a dozen modulating-condensing boilers/appliances are available here. Rumor has it that about that many "new" boilers will be on the domestic market within the next few years. Key features of these new appliances include an on-board diagnostic/programmable computer, outdoor reset, the ability to modulate their burner outputs and the capability to condense the flue gas resulting in significant increases in thermal efficiencies.

I've seen fuel  consumption reductions  between 30% and 50%.

Six or seven years ago, we would have received a call from a customer on a Monday telling us he had no hot water or heat over the weekend, and, when we showed up, we would reset the boiler's power switch. When it caught and took off, we really had no idea exactly what "issues" the physical plant had experienced, nor what had caused it to lock out.

With this new class of appliance, we now have the ability in most cases to take a portable laptop computer to the jobsite, plug it into the appliance's onboard computer and find out exactly what caused the loss of operation. This feature, in and of itself, is a significant improvement, and it has the ability to make trouble-shooting a breeze. No more inadvertent parts replacement programs.

You may have noticed that I refer to these efficient beauties as heating appliances and not boilers. To call these units boilers is a misnomer, and many of them are not certified under the rules that boilers are certified under. Many of them are certified as "water heaters" and, as such, may not be allowed in commercial installations requiring the use of a certified boiler. The rules, however, are quickly changing, and most manufacturers are in the process of getting their appliances approved as boilers under the present boiler code. Just make sure that the appliance is properly rated before you venture out into the commercial hydronic heating world with one of these appliances tucked under your arm.

My home is a beta testing site for new hydronic products. At present, I have a modulating/condensing appliance that is made of a carbon composite material. The appliance has a stainless steel heat exchanger in direct view of the combustion process, but the rest of the appliance's water ways and flue gas ways are made of a carbon composite plastic material. If someone had asked me 10 years ago if I ever thought we would be dealing with plastic boilers, I would have laughed in his face.

My "laboratory" has a flow meter on the hydronic side so that I can see exactly how many gallons per minute I am circulating through the appliance, a flow meter on the gas side to show me how many BTU per hour I am putting into the appliance, digital recording thermometers to log temperature differentials across the whole system, and I am capable of determining thermal operating efficiencies to within a tenth of a decimal point. I have personally witnessed my current "testee" at peak thermal efficiencies approaching 99%. The lowest thermal efficiency I have seen approached 88%, and that was seen during exceptionally high temperature (180° F).

Obviously, the key to high thermal performance is to maintain low operating temperatures. However, even if it is considered for a retrofit application, such as replacing a boiler that was typically operated at 180°, the system can be reset based on outside air temperatures. This will keep the appliance in the sweet condensing mode for the majority of the time it is operating.

I have personally witnessed fuel consumption reductions between 30% and 50% when systems are retrofitted with one of these extremely efficient appliances. In my own home, I replaced an existing forced-air heating system with a complete hydronic heating system and reduced my annual energy consumption by about 67% — and I have increased the overall comfort factor significantly to boot.

If you have not yet done due diligence and investigated these new appliances, do yourself and your company a favor and get comfortable with the technology. I can see a day in the near future when the consumer is going to demand that we install these appliances. The new wave has landed firmly on these shores, and it is time for all hydronic heating contractors to jump in and test the waters.

Come on in, the water is warm and ultra efficient!

Mark Eatherton is a Denver-based hydronics contractor who writes a monthly column on hydronics for CONTRACTOR. He can be reached via e-mail at markeatherton@comcast.net or by phone at 303/778-7772.

More articles on hydronics by Mark Eatherton