Tips for Steam Maintenance, Operation & Conservation
These tips can help you keep your heating and cooling systems operating safely and efficiently. If you choose to pursue any of these measures, we recommend that you review them with a qualified engineer to assure that they are properly implemented.
Make sure that condensate removal equipment, such as steam traps and drain valves, are installed at appropriate points in your steam pipe system. A steam trap automatically removes condensate from the pipe system.
To ensure a safe and reliable steam system, check the steam trap regularly to make sure it is working properly. Drain valves are used to remove condensate from lines before turning on the steam after there has been an extended outage.
Condensate can be used to preheat domestic water through a heat exchanger. This not only offsets steam consumption, but also reduces the amount of water used to temper the condensate before it is discharged into the sewer. As a result, the total amount of water drained into the sewer is also reduced. As shown in the sketch below, this method requires a water to water heat exchanger, piping, and possibly pumps.
How to Avoid Condensate Build-up
Make sure that condensate removal equipment, such as steam traps and drain valves, are installed at appropriate points in your steam pipe system. A steam trap automatically removes condensate from the pipe system.
To ensure a safe and reliable steam system, check the steam trap regularly to make sure it is working properly. Drain valves are used to remove condensate from lines before turning on the steam after there has been an extended outage.
Consider Using Condensate to Preheat Domestic Hot Water
Condensate can be used to preheat domestic water through a heat exchanger. This not only offsets steam consumption, but also reduces the amount of water used to temper the condensate before it is discharged into the sewer. As a result, the total amount of water drained into the sewer is also reduced. As shown in the sketch below, this method requires a water to water heat exchanger, piping, and possibly pumps.
Make Sure Pipes are Properly Insulated
Insufficient pipe, valve, or fitting insulation causes excessive heat loss, pipe temperatures that can cause burns, and condensate build-up that can result in pipe failure.
Isolate Unused Steam Lines
Energized steam lines, even if insulated, lose heat to their surroundings. To minimize this lose, any steam lines not in use should be isolated, and condensate from those lines should be drained. For example, piping that supplies steam to steam-driven chillers should not be energized in the winter if the chillers are not in use over an extended period.
Minimize Heat Loss Through the Building Envelope
Locations of thermal losses through the building envelope should be identified using techniques like thermography. Ensure that the outside air dampers are not leaking air when closed and seal any leaks you find.
Consider Installing and Operating High-Efficiency Steam-Based Chillers
Customers can take advantage of our high-pressure steam by installing two-stage absorption chillers, and turbine-driven chillers, which require approximately 40% less steam than low pressure steam absorption chillers to meet the same cooling load. Also, if you have an all-electric plant, it may be cost effective to replace one of the existing electric chillers with a steam chiller.
A steam chiller may be operated during electric on-peak times to shave electric demand and realize operating savings. Con Edison and the New York State Energy Research and Development Authority offer economic incentives to promote the installation and operation of steam-based cooling equipment. Please call the Steam Business Development Group at 212-460-2011 for information on available incentives for steam air conditioning and free operating and economic analysis of a chiller plant in your facility.
We also have an air-conditioning program available for large steam customers. The company already supplies 700,000 tons of steam air conditioning (A/C) load. We offer a reduction of $2.00 per thousand pounds from our summer rate for usage in excess of the first 50,000 pounds of steam for residential customers and the first 250,000 pounds of steam for commercial customers. The city and your business receive an added benefit because our existing steam air conditioning customers reduce the summer electric peak load by approximately 400 megawatts
Protect The Inside Steam Service Valve
The inside steam service valve is to be closed only in an emergency. To prevent use by unauthorized persons, we wire-seal the valve and attach a metal warning tag which lists all emergency restrictions. It is possible that condensate may build up behind the inside service valve if it is closed. For this reason, you must arrange to have Con Edison reopen the valve by calling 1-800-914-9112 or 1-212-683-8830.
You should always follow the necessary safety measures whenever you need to close an inside steam service valve during an emergency.
Avoid Delay in Service Turn-on After Repair
If you plan to change or modify your steam pipes, replace pressure reducing valve(s) or station(s), change pipe flange(s), and/or perform any repair requiring welding, please call 1-800-914-9112 or 1-212-683-8830. Steam Distribution Services will return your call to discuss the scope of work to be performed before work begins. At your request, we will arrange the shut-off of the steam service to the building. We will also advise you about New York City Building Code requirements for high pressure steam piping work, including any radiographic examination (X-ray) requirements for welding or weld repairs.
We will review all repair work and associated documentation, such as radiographic examination reports for welding, before restoring steam service to your building. Failure to meet Building Code requirements to provide an acceptable radiographic examination report(s) will result in delays in restoring your steam service.
Please refer to the NYC Buildings Department rules on High Pressure Steam Piping Systems in the NYC Building Code, Appendix A, Chapter 20, Section 20-02. A copy of the rules will be provided upon request.
If asbestos abatement is performed, it shall be done in compliance with federal, state, and city environmental rules and regulations. We require an air clearance report(s) issued by a third party NYS-certified ELAP (Environmental Laboratory Approval Program) laboratory showing fiber count and volume of air collected. This must be done before steam service can be reactivated. This report is required for all abatement work, regardless of project size, conducted inside steam rooms or areas that require Steam Distribution personnel to enter to restore service.
During normal business hours, air clearance report(s) should be faxed to Steam Distribution Operations at 1-212-253-8910.
For more information, call 1-212-338-4470. During off hours, weekends, and holidays please provide hard copy reports to the steam supervisor or crew, at the time of service turn-on.
Vent lines from condensate collection vessels, such as a dilution and/or flash tank, must be kept unblocked to prevent pressure from building up. If you are a seasonal customer, please make sure that your steam equipment is thoroughly inspected before arranging for turn-on. All inspections, adjustments, and repairs to your steam piping system should be done by a qualified operating engineer or heating contractor.
Occasionally, we may have to interrupt your service to make repairs to the steam distribution system. If this happens, Con Edison will notify you in advance of the outage.
If you plan to do work on your steam system during the outage, please let us know immediately by notifying the Con Edison representative who arranged the outage, or by calling either of these Con Edison emergency numbers: 1-800-914-9112 or 1-212-683-8830. As a safety precaution, we will verify that your work is complete before reactivating steam service when our repairs are finished.
Periodically Test Steam Traps
All steam traps should be tested or inspected for proper operation on a schedule recommended by the manufacturer. A clogged trap or a trap that fails in the closed position may cause harmful water hammer, which could result in property damage and/or bodily injury. On the other hand, a trap that fails in the open position, not only wastes energy but also creates a heat condition. A failed open trap with an equivalent 1/8" size orifice could result in the loss of approximately 52,000 lbs of steam at 100 psig dry saturated condition per month, or approximately $1,500 per winter month. The balance of steam system components (such as valves and fittings) should also be tested or inspected periodically to promote safe and cost-efficient operation.
Minimize Steam Leaks
Inspect steam lines periodically to ensure that pressure relief valves and steam traps are not leaking. Also, make sure there are no visible steam leaks into the building spaces.
Apply Outdoor Temperature Reset
If your building uses circulating hot water for space heating, resetting the water temperature supply set point based on outdoor air temperature will not only improve comfort conditions, but will also reduce steam consumption during the mild winter days.
Instead of having constant water temperatures regardless of the outdoor air temperature, water temperature should be higher on cold days and lower on mild days.
If you are already resetting your water temperatures, consider shifting your reset schedule down for increased steam savings.
Adjust Domestic Hot Water Temperature
Check domestic (or service) hot water temperature at taps to ensure that it does not exceed 120°F. Any higher may not be safe and can waste energy.
Install Thermostatic Radiator Valves
Thermostatic radiator valves provide individual zoning control at the radiator level. The occupant can select and set different temperature set points to meet individual comfort levels within each room. Since the valve operation is controlled by the thermostatic element within the valve, once the settings are selected and set, there is no need to manually open and close the steam supply valve to control temperature. Installation of these valves in overheated rooms will eliminate discomfort and may provide significant savings.
Maintain Vacuum in the Steam System
Vacuum operation helps reduce steam consumption and ensures that condensate is drained properly. Typical reasons for the loss of vacuum include poor maintenance of steam traps, leaks in piping, and vacuum pumps that are not working properly.
Install a Programmable Building Management System
A programmable computerized building management system may not only help improve comfort conditions in your building, but may also reduce energy consumption. These systems make it possible to monitor and trend operational data. They also allow you to automate various control strategies to reduce energy consumption, enabling operating personnel to concentrate on other tasks.
Reuse Condensate for Cooling Tower Makeup
The use of condensate as cooling tower makeup decreases the amount of city water that is used to temper the condensate and for cooling tower makeup. The total amount of water drained into the sewer is also reduced.
Grey Water System
A grey water system may use condensate water in non-potable sections of the building’s plumbing system (e.g. toilets), thereby reducing city water consumption and drainage into the sewer. Re-plumbing existing risers may be cost prohibitive. This method may be attractive for new buildings under construction.