Heat computers do more than reduce energy and water bills.

The ability of fuel computers to reduce fuel, electric and water bills by up to 40 percent or more is widely recognized by owners and managers of multifamily buildings. By round-the-clock monitoring of inside as well as outside temperatures during the heating season, and permitting boiler cycling only when apartments actually need heat, these systems eliminate overheating of apartments - the major cause of fuel waste.

Less widely known but equally important are the ways that fuel computers can help diagnose the true causes of heating and/or water system malfunctions and eliminate unnecessary maintenance. Here are a few examples:

Return Line Leaks

A leak in the condensate return line in a steam-heated building can result in the loss of thousands of gallons of water in a 24-hour period. These leaks can go undetected because return lines are often buried under concrete, so there is no visible sign of a leak; and the boiler water is automatically replenished with cold water, which is constantly reheated, thus wasting fuel. Computerized monitoring detects these leaks promptly.

High Stack Temperatures

Excessively high stack temperatures (the normal range is 360 to 600 degrees Fahrenheit) reduce heating efficiency, resulting in higher fuel bills. They can be due either to a dirty boiler or an improperly adjusted burner flame. All too often, they are dealt with preemptively by regularly scheduled boiler cleaning when, in fact, on^Ey a boiler flame adjustment is required. This information, needed for an accurate diagnosis, is available in buildings equipped with fuel computers.

High Hot Water Temperatures

Often, an excessive rise in domestic hot rarer temperatures becomes evident when building supers replace washers because of leaking faucets. But the replacement washers don't last long unless the underlying cause of their failure - a mixing-valve problem - is corrected. By monitoring the minimum and maximum temperatures of the water from the mixing valve, the fuel computer indicates whether the valve should be readjusted or replaced. Without this aid to diagnosis, mixing valves often are needlessly replaced.

Low Hot Water Temperatures

Tenants' complaints about hot water not being hot enough or inadequate heat may or may not be justified. If the complaint is about low hot water temperature, the problem may be due to dirt on water coils or some other cause. Formerly, the only way to find out was to physically remove the coil and inspect it - a big, costly job, and a waste of time and money if the coil is actually clean. By monitoring the temperature of the water in the boiler and the water coming out of the water coil, a fuel computer indicates whether the coil really needs cleaning. The system even logs the highs and lows of the water temperature, the length of time the temperature falls below a set point, and the time of day it happens. Without this detailed information, all too often mixing valves and/or coils are replaced when only one or the other, or neither, is bad.

Centralized Monitoring

Fuel computers make it possible for an owner or manager to program 24 hourly set points and monitor the performance of the heating, domestic hot water and cold water systems in all of their buildings right from their offices. A complete fuel computer system includes indoor and outdoor temperature sensors and a full complement of sensors that monitor stack temperatures: pressure time; hot-water temperatures at the boiler, coil and mixing valves: unauthorized system overrides and other parameters: Windows 98-based telecommunications software; and an in-office dedicated printer that produces reports when the fuel computers are polled by telephone, in case of tenants' complaints to the city, these reports are evidence of compliance with municipal codes. The fuel computers can be equipped with an emergency dial-out function that phones building managers or a designated repair service in case of an emergency that requires immediate attention.

Management Tool

From the time they were introduced in the early 1970's, fuel computers have been conceived as part of a total energy management program developed by U.S. Energy Controls. To further implement this concept, the company now provides busy managers with engineering support, including interpretation of the abundant data provided by fuel computers: diagnosis of problems; recommendations for cost-effective solutions; and, upon request, names of suppliers qualified to solve them.