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On average our units pay for themselves within 6-18 months of operation and are capable of running nearly maintenance-free for more than 25 years!


“While our boiler requires yearly service and maintenance, the condenser requires no maintenance. It just sits on the floor next to the boiler and gives us free heat.”
Jim Bajema
Smith Gardens, Inc.


Our Exclusive Guarantee:
"You will be 100% Satisfied with the Money Saved, CO2, Reduced Water Conserved, and our truly exceptional Service, or I'll buy the unit back from you - period.
Sid Abma, Owner


SRU Series Condensing Waste Heat Recovery Units

OK…so here are some of the technical details about our Sidel Condensing Economizers that explain how they can help you meet your energy efficiency goals and provide your organization with the greatest ROI possible. If after reading this information you would like more details or have any questions, we invite you to call Sid Abma at 800-668-5003. There’s never any charge or obligation when you call and we would love to hear from you, so be sure to contact us today with any questions or comments you may have.

The SRU FLUE GAS CONDENSING ECONOMIZER heat recovery unit is designed to recover almost all of the waste energy from the forced draft heating unit, and turn it into usable heat. The waste flue gases from the heating appliance are redirected through the SRU flue gas condenser unit, which is placed beside the boiler or heating unit or alongside the unit's chimney. This is done to ensure that no condensation can get back inside the appliance, and cause corrosion. The SRU recovery unit is designed to cool the flue gases to the point where the sensible as well as the latent heat is recovered.

The SRU FLUE GAS CONDENSER is a DOUBLE WALLED finned tube heat exchanger. The hot waste flue gas is diverted into the bottom receiver of this unit which then flows upward through a series of specially designed stainless steel and aluminum finned tubes. The water that is being heated flows on the inside of these stainless steel tubes. The SRU series is designed so that waste flue gas temperatures can be lowered well below the water dewpoint (58°C - 136°F) temperature.

Each pound of natural gas has a heat value of approximately 22,000 BTU. When natural gas is combusted, each pound of gas produces about 2 pounds of moisture (steam) with a heat value of 2400 BTU. Therefore the BTU lost during combustion of a pound of natural gas is about 11%. 2,400 BTU/lbs = 11% loss 22,000 BTU/lbs.

For a typical 100 HP natural gas fired boiler. operating with an exhaust gas temperature of 410°F and 15% excess combustion air the efficiency is approximately 80%. The fuel input is 4.2 million BTU/hr, and 20% of the fuel's total energy is available for recovery. By incorporating a SRU waste heat recovery system to produce 104°F water, about 15% of the fuel's original energy can be recovered. If the boiler operates for an equivalent of 6,000 full load hours per year, and natural gas costs $1.00 therm, the annual savings realized from a SRU waste heat recovery system would be: 4.2 M BTU/HR x 15% x 6,000 hrs/yr x $ 10.00/M BTU* = $ 37,629 *1 M BTU = 10 therm

The key to the successful application of heat recovery is the ability to put the recovered heat to use. Two primary uses for recovered heat are domestic water heating and space comfort heating. Other uses include laundry wash water, industrial process water and district heating systems. Potential Applications include: Hospitals and Health Centers - Food Processing Plants - Schools and Universities - Laundries - Breweries - Hotels - Wineries - Government Buildings - Swimming Pools - Textile Plants - Pulp and Paper Facilities and Greenhouses.

Condensation is created from the flue gases when this temperature is cooled to below the dewpoint. Naturally the lower the flue gases can be cooled, the higher the performing efficiency of the Sidel SRU waste heat recovery unit. When the temperature of the waste flue gas is lowered beyond 133F condensation occurs. The SRU condensing economizer is designed for natural gas or propane fired equipment only. When the heating appliance is required to operate on oil or other fuels, the flue gases will have to be bypassed from the Sidel waste heat recovery unit. The vertical construction of the SRU waste heat recovery unit provides for the best possible use of available space. This design also allows the condensate to flow down from the top rows of tubes in the recovery unit, providing a complete self-cleaning action of the aluminum fin tubes.

The SRU waste heat recovery unit has a large gas-side heat transfer surface of aluminum fin tubes, with the fins and the tubes formed as one piece. Pure aluminum is a very good heat conductor; is it also exceedingly resistant to the mildly acidic flue gas condensate. The aluminum fin tubes are fitted around a stainless steel tube. Stainless steel is used to prevent corrosion on the waterside surface. Compared to other materials, stainless steel will not allow the build-up of iron particles, which would act as an insulator on the tube surface.

Because of the high conducting properties of aluminum, the fins on the heating tubes are very thin. This allows more room for the flue gases to pass through. The result is an optimal ratio of the flue gas flow with respect to the fin surface area, which keeps the resistance on the flue gas side low. Because there is only a small increase in the flue gas back pressure, in most cases the heating unit is still capable of using its existing blower fan.

Standard sizes are available for equipment with inputs from 2 to 42 million BTU per hour, with larger custom designed units to 350,000 lb/hr. All units are constructed in accordance to the ASME codes.

BENEFITS Various Benefits include: Increased system efficiency (typically 90-95%) - Energy savings typically 10-15% - Short payback - Easy installation, low maintenance - Reduced particulate, water vapor and noxious gas emissions - Reduced stack noise emission - Operates over a broad range of equipment conditions - Computer-aided design (to ensure optimum sizing) - Computer-aided investment analysis - 7-year limited guarantee

Want to find out how much money we can save you?
Contact us today for your FREE, No-Obligation Savings Analysis. With a little technical information about your heat source and potential energy application, we can show you just what a SRU waste heat recovery unit can do to reduce your company's operating costs. There’s nothing to lose and so much to gain, so be sure to call, email or fax us right away! Click here>>