Aerco Design Tips

AERCO Gas-Fired Heaters and Hydronic Boilers

Design Choices and Design Tips

Physical Layout
Look at position and access relative to other equipment and piping.
Consider positioning heater to minimize length of flue vent.
Ensure separation from source of chlorine or corrosive chemicals.
Check wall, overhead and service clearance.
See boiler application guide for minimum space requirement. For ease of maintenance, use more than the minimum clearance between units.
Install external regulator at least 3 ft. upstream of heater.
Review gas regulator specification to see if horizontal installation is required.
Do not block access to heater with gas pipe, air duct, or wiring.

Flue Gas Venting
Choose side wall or vertical discharge.
Specify Heat-Fab AL 29-4C vent pipe which will give extended service life.
Slope horizontal vent pipe down toward boiler/heater for condensate drainage.
Consider effect of condensation at vent exit. Do not locate vent discharge over walkways, windows, or paved areas, if possible
Insulate vent pipe up to about 7 ft. height for personnel protection.
Insulate flue piping through walls & floors, or specify recommended clearances.
Multiple units:

Vent individually, if possible.

Allow 3 ft. center to center spacing for roof or wall vents.

If common vent header is required, contact C. J. Michelson Company for recommendations.

CAD drawings of vent pipe system are available when Heat-Fab is specified.

Flue Gas Condensate
Use polypropylene tubing to an appropriate drain. Clear tubing will show condition of condensate.

Combustion Air Ducting
Choose sealed combustion or wall louvers. Consider:

Additional fuel savings with sealed combustion.

Need to isolate gas-fired heating equipment from refrigerant gases, or bear cost of refrigerant sensor/burner shutdown device.

Building aesthetics.

For sealed combustion, specify inlet air adapter for each unit.

Water Piping
Contractor must thoroughly flush system before start-up.

Gas pressure
For new gas service, install the meter as closely as possible to appliances to minimize user piping costs.
Learn range from user or gas company.
Gas pressure to inlet side of AERCO supplied external gas regulator must be no greater than 14" W. C. with standard Maxitrol regulator, or up to 10 psi with optional regulators. A minimum of 11" W. C. gas pressure to the regulator at maximum firing rate is required for proper operation.
Note that the Maxitrol RV-81 regulator can be mounted only in the horizontal position.
Vent each regulator individually as required. Regulator vent line sizes vary by model.
Specify only AERCO approved regulators. Contact us for selection assistance for gas pressures above 14" W. C.
Engineering specifications and drawings should indicate the design gas pressure to the AERCO supplied external regulator.

Pressure Relief Valves
Available ratings: 30, 50, 75, 100, 150 psig

Ohio Power Piping Code:
If over 30 psig, a fee plus 2% of project cost is payable to State of Ohio for inspection.

Boiler Nameplate Data
If 30 psig boiler, AERCO will stamp boiler "Boiler designed for 30 psig, and tested to 150 psig".

Interface of Boilers with Building Automation System
Decide whether the BAS will simply enable the AERCO boilers or whether a 4-20 ma signal will be sent from the BAS to provide either a supply header setpoint temperature for the boilers or a firing percentage for each Aerco boiler.
AERCO is BACnet compatible with RS-485 twisted pair communications (Master Slave / Token Passing). Drivers must be written for BAS.

Control Wiring
Specify which contractor will install wiring from Outside Air Temperature sensors(s), Building Management System, fault sensor, power level output, etc.

Variable Speed Pumps
A low flow limit should be programmed for the variable speed pumping system, based on minimum boiler flow times number of boilers.

Multiple Boilers
Use AERCO “Boiler Management System” for 3 or more boilers to obtain maximum efficiency and minimum cycling.
Use individual outdoor sensors and standard controls for indoor/outdoor reset on 2 boilers or less. Consult C. J. Michelson Company for discussion of operation.

Multiple Domestic Water Heaters - Sequencing
Use differential set points to eliminate short cycling on low load. As an example, set one heater to operate with 124 F setpoint. and second heater with 120 F setpoint.

If differential setpoint approach results in the temperature swing being too wide, then use customized control system. Contact C. J. Michelson Company for information.

AERCO Technical References

Benchmark

GF-2030 Gas Components and Supply Design Guide BMK-2.0 (9/98)

GF-2050 Venting and Combustion Air Guide BMK-2.0 (9/00)

GF-2060 Electrical Power Wiring Guide BMK-2.0 (9/98)

GF-2070 Boiler Application Guide BMK-2.0 (9/98)

KC-1000

GF-1030 Gas Components and Supply Design Guide (12/90)

GF-1050 Venting and Combustion Air Guide (5/94)

GF-1060 Electrical Power Wiring Guide (2/90)

GF-1070 Boiler Application Guide (2/91)

GF-1080 Commercial Laundry Sizing Guide (8/92)

(Date in parentheses is printing date as of September 2000)

Please contact C. J. Michelson Company if you need a current version of any bulletin.