23 21 00 HYDRONIC SYSTEMS
23 21 00 HYDRONIC SYSTEMS
.01 General Requirements and Design Intent
Summary: Section includes basic design requirements for hydronic heating and cooling systems in HVAC applications.
General: Professional shall design each hydronic system for optimal operating efficiency throughout capacity range, reliability, flexibility, and ease of maintenance with the lowest life cycle cost.
Comply with 23 00 01 Owner General Requirements and Design Intent.
ASHRAE/IESNA Compliance: Comply with applicable high-performance building requirements in ASHRAE/IESNA 90.1 or ASHRAE 189.1 per 01 81 13 Sustainable Design Requirements.
Follow the Hydronic Heating and Cooling System Design guidelines in current edition in current edition of ASHRAE Systems and Equipment Handbook.
Strive to keep systems simple to understand and operate.
Systems Design Criteria:
Design for low flow, high temperature differences and variable flow distribution systems to minimize pump energy.
Selection of cooling coils in typical HVAC applications is recommended with a minimum 14-16°F rise at peak conditions.
Terminals shall be “right-sized” for both part load and partial load performance.
Minimum full load design flow at any terminal device shall not be less than 0.5 gpm for effective flow measurement and heat transfer.
Shut-Off Valves: Design and indicate positive shut-off valves throughout the distribution piping system to facilitate shutdown and draining of smallest segment as practical for repairs while keeping the rest of the system operational.
Clearly show locations of all shut-off valves on construction drawings to be able to properly isolate the systems for service.
Locations: Shutoff valves shall be installed at:
All locations required by the current building Mechanical Code.
Each piece of central or terminal equipment. All valves shall be installed such that valve remains in service without shutting down system when downstream piping or equipment is removed for service, alterations or repairs. Provide arrangement of unions or flanges and removable sections of pipe at final equipment connections to allow easy dismantling and pulling of associated equipment past remaining pipe assemblies without cutting pipe or breaking sweat or press-joint fitting connections.
Secondary / tertiary loops off of primary/secondary piping systems.
Pipe mains at points exiting mechanical rooms, located accessibly within the mechanical room.
Any pipes at points exiting the building or running under slab or underground, located accessibly within the building interior.
Base of each riser.
Each horizontal branch takeoff of each riser.
Each branch takeoff serving groups of multiple terminals arranged to create hydronic modules to achieve strategically divided sections that can be isolated for service, modifications, and troubleshooting while the rest of system can remain in service.
Main or branch strainers or filters (on entering and leaving sides to allow for pulling screen).
Any thermal control zone, (i.e. perimeter finned tube zones controlled by exterior orientation0).
Any 3 valve bypass around devices as required maintaining continuous flow for critical applications while servicing device.
Tees for future connections. Review with OPP – in some cases valves might be unnecessary and/or undesirable.
Pipe expansion compensating devices that would otherwise require extraordinary effort for system shutdown and drainage to be able to service or replace. Review with OPP.
Refer to section on Shut-Off Valves for types.
Bypasses:
Three valve bypasses shall be installed around control valves and pressure-reducing stations serving critical areas. Areas deemed to be critical shall be reviewed with the Project Manager. No other equipment is to be provided with a bypass unless approved by the Project Manager.
In all applications, use ball valves for shut-off purposes and globe valves for throttling purposes in the bypass line.
Gate valves may be used for shut-off purposes in large line sizes.
Ball valves equipped with “characterizing discs” may be used for throttling purposes in lieu of globe valves.
Freeze Protection:
Hydronic systems subject to freezing conditions shall be protected with separate piping loops with antifreeze solution, heat exchangers, pumps, expansion tanks, as required to prevent freezing in the event of extended electrical power outage and to minimize and isolate portions of systems requiring antifreeze from the main hot and chilled water loops.
Glycol anti-freeze systems shall be considered when outside air at a temperature below 20 degrees exceeds 50% of the total air stream. However, the professional shall not specify Glycol systems until specifically approved by the University.
See 23 25 00 for more information.
.02 Flow Balance and Differential Pressure Control
General: Professional shall design the layout and components of each hydronic distribution system to deliver the specified comfort level using minimal energy with optimal operating stability, serviceability, and future flexibility with the lowest life cycle cost.
To enable systematic balancing with absolute minimum pressure drop result, distribution piping must be subdivided into hydronic modules within a hierarchical tree.
At any node between multiple units, consider the direction of the larger flow and place a flow balancing / DP control device on the lower flow side.
Do not use multiple self-regulating DP controllers in series. For example, do not use a DP controller at a main, riser, or branch and then also use a pressure independent control valve at individual terminals.
Isolation and Flow Measurement:
General: In all hydronic systems, provide combination positive drip-tight shut-off and precision flow measuring devices at heat transfer terminals as required for service isolation and means to quickly, conveniently and accurately measure flow.
Combination shut-off/balancing valve shall provide multi-turn 360° adjustment with precise position indicators located on the ergonomically designed handwheel. Valves shall have a minimum of four full 360° handwheel turns. Valve handle shall have hidden memory feature, which will provide a means for locking the valve position after the system is balanced. Valves shall have P/T ports for connecting standard differential pressure meter, extended type as required to be accessible without having to remove primary finished insulation. 90° 'curcuit-setter' style ball valves are not acceptable.
Optional: Provide manufacturer's optional insulation covers with a flame spread rating of 25 or less and a smoke development rating of 50 or less. Coordinate installation with piping insulation installer to ensure that complete vapor barrier is maintained on systems operating below ambient dew point.
Install in accordance with manufacturer's recommendations of upstream and downstream pipe diameters from any fitting. Install with flow in the direction of the arrow on the valve body. Locate with easy and unobstructed view and access to the valve handwheel, position indicator, and metering ports for adjustment and measurement. Mounting of valve in piping must prevent sediment build-up in metering ports.
Acceptable Manfacturers:
Armstrong CBV
Tour Andersson STA series
Constant flow applications:
Generally use only for smallest systems (under 300,000 Btu/h output capacity) – verify and conform to most stringent of current Energy Conservation Code, ASHRAE 90.1 and ASHRAE 189.1 High Performance Building Standard.
Exceptions: Limited modifications to existing systems. Review with OPP.
The Isolation/balance valves shall be:
Throttled as little as possible.
Always fully open at terminals at ends of hydronic modules.
Consider potential for future conversion to variable flow systems if part of a larger facility. Include provisions for main, riser or branch Adjustable Self-acting Differential Pressure Controllers as discussed in variable flow systems below.
Variable flow applications:
Generally use on most systems to minimize energy usage.
The Isolation/balance valves are intended primarily for isolation and flow diagnostics. They shall be:
Fully open, except for very minor balancing of a group of terminals in a balancing “module” downstream of a shared dynamic pressure independent control device.
Always fully open at terminals at ends of hydronic modules.
Used on individual coil modules in stacked coil configurations for flow equalization to each coil. One in common to all the coils is not required for total flow measurement.
Differential Pressure Control: Maintain differential pressure within acceptable range to achieve stable operation of automatic control valves in most energy-efficient and lowest-life cycle cost effective manner.
Control valves of circuits subject to high pressure differentials and thus susceptible to overflow will tend to short cycle. This dramatically reduces their actuator life. Therefore differential pressure across control valves must not vary too much.
Avoid cavitation: Ensure control valves are selected to avoid cavitation due to combination of low static pressure in the system, large pressure drop across valve, high fluid temperature and/or poor valve design.
Cavitation causes vibrations in the valve, wears down cone and valve seat in a very short time.
Rule of thumb to prevent cavitation at control valves: Static pressure at valve inlet > 2 times pressure drop across control valve.
Maintain superior control valve authority range for stable operation, close temperature control, and actuator longevity.
Control valve authority: a ratio that indicates the relationship of the pressure drop of the fully open control valve at design flow vs. the overall differential pressure in the system at that point with the control valve fully shut. Its value indicates how effectively the control valve can reduce the flow while it is closing. The lower the authority, the larger the pressure differential variations on the control valve and the larger the distortion of the valve control characteristics.
In a variable flow distribution, the authority of the control valve is variable. Therefore dynamic differential pressure stabilization may be required depending on the system operating characteristics.
Evaluate differential pressures throughout hydronic system between minimum and maximum operating ranges. To achieve good control performance, select control valve and DP control device to ensure design control valve authority of at greater than or equal to 0.5, and minimum authority of at no less than 0.25.
Strategically locate self-regulating differential pressure controllers throughout distribution system, only as needed, to stabilize wide variations in differential pressure. Determine the most cost effective combination that will ensure recommended control valve authority at all operating conditions. Depending on size and complexity of system, various pressure independent control components may be applied:
On large mains or risers (greater than approximately 220 gpm):
Adjustable Self-acting Differential Pressure Controller: Similar to:
Tour Andersson DA 50 Series
Combine with manual balance valves for terminals downstream.
On Branches serving multiple similar terminals (up to total of approximately 220 gpm):
Adjustable Self-acting Differential Pressure Controller: Similar to:
Flow Design DA516
Tour Andersson DA516
Combine with manual balance valves for terminals downstream.
On smaller individual terminals (up to approximately 100 gpm, 2” and under):
Pressure Independent Characterized Control Valves (PICCV).
For specifications and acceptable manufacturers, see Div 25 - Building Automation Systems (BAS) Guidespec.
For selection criteria, see Div 25 - Pressure Independent Control Valve Selection
These combination valves are more costly than regular characterized control valves and are not needed at the more hydraulically remote parts of system. Use them strategically only as needed to maintain control authority criteria based on careful analysis of anticipated pressure differentials throughout the system.
Control valves must be characterized ball type. Globe style control valves are not permitted.
On larger individual terminals (greater than approximately 100 gpm):
Adjustable Self-acting Differential Pressure Controller same as above for DP stabilization, with separate regular characterized control valve. See Div 25 Building Automation Systems (BAS) Guidespec for control valve.
No more than 2 paralleled PICCVs (for up to approximately 200 gpm). Or,
Medium or Large Pressure Independent Control valves with internal mechanical pressure regulator in addition to the characterized disk control valve. Similar to:
Flow Control Industries, DeltaPValve.
These combination valves are more costly than regular characterized control valves and are not needed at the more hydraulically remote parts of system. Use them strategically only as needed to maintain control authority criteria based on careful analysis of anticipated pressure differentials throughout the system.
Valves using flow sensors controls to reposition the characterized ball or disk without a mechanical pressure regulator are not acceptable.
Maintain proper balance of flows in primary (production) loops vs. secondary (distribution) loops.
Correct Method: When using primary/secondary pumping, ALWAYS ensure secondary loops are designed, balanced and controlled to have less flow than primary to avoid mixing of secondary return with primary supply and thus secondary supply temperature degradation.
Ineffective methods:
Increasing secondary flow beyond primary only increases the flow imbalance and therefore mixing worsens making the condition worse.
Producing colder primary chilled water or warmer hot water can compensate only a little but at a higher energy cost. Mixing will still occur, only shifted slightly.
Miscellaneous Coordination:
Minimize pump energy with Optimized pump DP reset based on terminal heating/cooling requests. Coordinate with BAS sequence of operations.
Locate system remote DP sensor on the most probable index branch/circuit, prior to any self-regulating DP controller or PICCV.
Never place remote DP sensor for pump speed control downstream of any self-regulating DP controllers or PICCVs in the system.
Ensure each control valve/actuator combination has sufficient close-off pressure rating for application within distribution system.
.03 Air and Dirt Elimination
All closed loop hydronic systems shall have effective means for elimination of air and dirt that are safe and convenient to access and service.
Primary air eliminator shall be located at the point of lowest solubility in the system main, that being where the pressure is the lowest (on suction side of main pumps) and the temperature is the highest.
Primary dirt separation on discharge side of main pumps is best. That will allow constant blow down through a side-stream bag filter using pump pressure.
For primary air eliminator and dirt separator, refer to 23 21 13 Hydronic Piping.
Manual vents shall be installed at high points to remove all air trapped during initial operation. Manual vents are standard but automatic vents will be considered in special situations and locations. Shutoff valves should be installed on any automatic air removal device to allow servicing without draining the system. Where vent location is high or otherwise inaccessible, install valve at vent chamber, then extend 3/8" tubing to nearest janitor sink or mechanical room floor drain and terminate with ball valve.
If pumps and primary air/dirt eliminators are not at the bottom of the system, provide additional dirt separator(s) as required to collect and remove sediment at the bottom of the system.
System Cleaning and Flushing Bypass assemblies:
Provide bypass valve and piping assemblies at all central plant heating and cooling sources and at all distribution terminal units. The purpose is to be able to isolate all equipment and bypass around it to prevent circulating dirt through equipment strainers, control valves or heat transfer surfaces while performing main piping system cleaning and flushing.
Bypasses shall be of adequate size to achieve the minimum velocities required to effectively clean and flush system mains and branches out to each piece of equipment.
Provide bypasses at ends of main risers and branches as required on new or existing systems to achieve the minimum velocities required to effectively clean and flush system main risers and branches without having to rely on flows through small runout branches.
.04 Hydronic Plant Design
Makeup Water Systems:
Use automatic makeup assembly to maintain positive pressure at the highest point of at least 4 psig for system operating temperatures up to 210°F.
Exception: Cold water make-up piping is not to be directly connected to any system that utilizes glycol. Refer to 23 25 00 HVAC WATER TREATMENT for mix and fill tank assembly for automatic makeup in lieu of direct makeup water connections on glycol systems.
Reduced pressure principal back flow preventers shall be installed on all make-up water lines.
Make-up water connection shall be located along with the expansion tank at the point of no pressure change and pumps shall pump away from that point. Keep pressure drop low between pump suction and make-up water/expansion tank connection location.
Install water meter on makeup water lines. Tracking makeup water use is needed to correctly maintain chemical levels and to detect leaks.
For closed-loop hydronic systems containing no glycol, provide a make-up water meter equipped with a transmitter for BAS monitoring. The contractor providing the water meter shall also furnish the BAS transmitter and coordinate its installation.
Pulsed meter output shall be monitored by BAS to detect slow leaks.
Analog meter output shall be monitored by BAS to detect large leaks.
Refer to Division 25 Standards for further implementation requirements on domestic water metering and leak detection.
For closed-loop hydronic systems containing glycol, provide make-up water meter with only a mechanical display.
Refer to HVAC WATER TREATMENT standard for additional requirements.
Primary Heating and Cooling Production Equipment:
Ensure primary production equipment is circuited and piping system is arranged to achieve maximum efficiency.
Ensure the manufacturer’s recommended range of water flow through equipment is maintained.
Connect piping so that all return water and any water from a bypass are thoroughly mixed before any of the water enters production equipment. After the tee, there should be at least 10 pipe diameters to the nearest unit. This is to help avoid the possibility of having stratification in the primary return line, which can lead to unmixed water to the nearest unit. This can lead to control cycling.
Arrange piping such that all production equipment obtains equal return water temperature.
Exception: in systems where “backloading” or “preferential” loading of chillers is advantageous by design to maximize the operating performance of different types of chillers.
Pumping Arrangement and Configuration:
General: Refer to 23 21 23 HVAC Pumps.
Chilled and Condenser Water Systems:
In general, arrange pump assemblies to pump into chilled water heat exchangers, chiller evaporators, and condenser bundles.
Locating the chilled water pump and associated air separator on the building chilled water return provides the warmest temperature along with the lowest pressure for most effective air removal. This location also helps to minimize potential pump cavitation problems resulting from pressure buildups in fouled strainers or heat exchangers.
Hot Water Systems:
In general, arrange pump assemblies to pump away from low pressure, low temperature heating sources (low pressure boilers or gasketed-plate water to water heat exchangers).
Locating the hot water pump and associated air separator on the leaving side of the heat source provides the warmest temperature along with the lowest pressure for most effective air removal.
However, specify pump construction and seals to be rated for a minimum of 250°F to improve the longevity of the useful life at higher operating temperatures.
Provide strainer on return of each heat sources to prevent system dirt from collecting in low velocity inner heat transfer surfaces of heating equipment. Also, a sediment dirt leg with blow down valve is recommended as near to inlet as possible (local low point).
Steam to hot water heat exchanger systems:
Controls on steam heat exchangers have a higher risk of routinely overshooting supply water setpoint. By placing the pumps on the return side, the advantage is that lower operating temperatures on the pumps will better ensure and enable longer useful life on pump internals such as seals.
The difference in solubility of air in water due to the entering hot water return temperature vs. leaving supply temperature is relatively minor with respect to the difference due to pump pressure differential. With the air removed by the air separator on the suction side of the pump (lowest pressure point), the solubility after the pump will be much higher so air will not come out of solution as it is heated going through the heat exchanger.
Pumping into heat exchangers also allows the pump strainer and system dirt eliminator to be before the heat source to better protect it without having to add an additional strainer.
Primary-secondary systems:
The system must be piped and controlled so that water never flows in the reverse direction in the decoupler bypass during normal operation.
The supply tee connecting the building supply distribution loop to the primary loop shall be arranged such that the secondary loop is the side branch and the bypass is the straight through direction. This directs the primary loop water’s energy into the decoupler bypass and requires the secondary loop to pull the water out of the tee.
The return tee connecting the secondary return loop to the primary return shall be arranged such that the bypass is the side branch and the secondary return to the primary return loop is the straight through direction.
The secondary loop return must not be connected too closely to the supply pipe with a bullhead tee in which the velocity head rams into the decoupler bypass which can encourage migration.
Although in theory there should be no pressure drop in the decoupler, in order to avoid thermal contamination in actual systems the decoupler should be at least 10 pipe diameters in length (per ASHRAE Systems Handbook). Longer decouplers tend to increase the pressure drop.
Size decouplers for the flow rate of the largest primary pump. This may be more than the design flow rate of the largest individual piece of production equipment if overpumping is being considered. The pressure drop should not exceed 1.5 ft. As the pressure drop through the decoupler increases, it tends to make the primary and secondary pumps behave like they are in series.
.05 Building Automation System Performance Monitoring
Return Water Temperature – Heat Transfer: Provide return water temperature transmitters at individual terminals and in main building return to continuously monitor heat transfer performance and alarm abnormal conditions when adequate temperature differential is not maintained.
Energy Consumption of Water Distribution: Provide flow, temperature difference and watt transmitters to measure operating parameters, programming and trending/reporting to continuously monitor pumping system effectiveness through the BAS and alarm abnormal conditions. Include pump system efficiency ratios based on system type (such as kW/100 tons for chilled water and kW/1000 MBH for hot water).
.06 Ground-Coupled Heat Pump Well Field Systems
The University encourages the use and application of equipment that reduce the energy consumption of building systems. However, the installation of ground-coupled or geothermal wells have groundwater contamination risks that must be addressed prior to design of any geothermal or ground-coupled systems.
Prior to the start of design, the Design Professional shall review any proposed geothermal or ground-coupled systems at any University location with the Office of Physical Plant, Engineering Services and obtain written consent to proceed prior to any further design development or installation. No geothermal or ground-coupled systems shall be installed at any University location without written approval of the Office of Physical Plant, Engineering Services.
Where approved, well systems shall be designed and constructed in accordance with 23 81 00.03 and 33 20 00.
23 21 13 HVAC Service Piping
.01 General Requirements
Hydronic Piping Design:
General: Follow the Hydronic System Pipe Sizing guidelines in current edition of ASHRAE Fundamentals Handbook.
Design to keep system pressure drop low to minimize pump energy and long-term operating costs.
Use pipe fittings with low pressure drop characteristics such as long radius elbows, 45° laterals and Tee Wyes in main branches, tapered concentric/eccentric reducers, and bell-mouth inlets.
Do not use fittings with abrupt changes that cause high pressure drops such as non-tapered reducing flanges or couplings, or bullhead tee connections (either two streams connected to each end of a tee with the discharge on the branch, or the main flow coming into the branch connection and discharging at each end).
Pipe sizes shall be indicated on the plans at each change in direction and at all branch take off locations.
Minimum distribution pipe size shall be ¾”, except ½” runout piping may be used after shut-off valves to individual terminals.
Piping systems shall be designed and installed with adequate pitch to permit all sections of the system to be properly and fully drained. All supply water piping shall be graded up and return graded down in the direction of flow. Provide sediment leg and hose end ball drain valves at all low points of systems, at bases of riser, and at lowest points at equipment runouts, typically on downstream side of shut-off valves.
Avoid running piping in such a way that will create air traps at local high points or tend to accumulate dirt legs at low local low points. If otherwise unavoidable, provide automatic air vents at high points and blow down drain valves on dirt legs at low points.
Differential pressure control of system pumps shall never be accomplished at the pump. The pressure bypass shall be provided near the end of the system.
All piping run within the building shall be run concealed in the finished portions of building in pipe spaces, ceilings or furred chases and exposed only in mechanical rooms and where shown on the drawings.
No pipe shall pass in front of or interfere with any openings, door or window. Head room in front of openings and doors shall in no case be less than the top of the opening.
Piping shall not pass exposed through electrical rooms or be erected over any switchboard or other electrical gear.
Provide 2-inch clearance between insulated piping and other obstructions.
Hydronic Piping Materials:
Grooved pipe fittings (Victaulic and similar) are not permitted on any portion of a hydronic heating system.
Plastic piping is not permitted on any portion of a hydronic heating system.
Hydronic heating systems generated from Campus Steam Distribution systems are subject to elevated temperatures occasionally exceeding 250 degrees due to superheated campus steam and the relatively high probability of control malfunctions. Therefore, in those applications, the piping system including all associated material selections (gaskets, O-rings, pump seals, flexible connectors, valves, resilient seats, etc.) shall be rated for the maximum temperature that the system could see while pump system is operating (the associated temperature at the pressure relief valve setting).
Unions:
No union shall be placed in a location which will be inaccessible.
Unions shall be installed adjacent to all equipment for repair and replacement.
Electrolysis Control:
Electrolysis control between dissimilar materials shall be achieved through the use of dielectric nipples and a non-dielectric union.
Dielectric unions are prohibited.
Sleeves:
All pipes passing through wall or floor construction shall be fitted with sleeves. Each sleeve shall extend through its respective floor, wall or partition and shall be cut flush with each surface unless otherwise specified. Sleeves shall be two pipe sizes larger than the pipe when un-insulated and of sufficient size to allow for the insulation without binding. Floor sleeves in mechanical rooms shall extend 4 inches above finished floor, all other spaces minimum one inch above finished floor.
Sleeves in bearing walls, masonry walls, masonry partitions, and floors shall be standard weight steel pipe finished with smooth edges. For other than masonry partitions, through suspended ceilings and for concealed vertical piping, sleeves shall be No. 22 USG galvanized steel.
Where pipes pass through waterproofed floor or walls, design of sleeves shall be such that waterproofing can be flashed into and around the sleeves.
Sleeves through exterior walls below grade shall have the space between pipes and sleeves caulked watertight.
Install one-piece chrome-plated escutcheon plates with set screw at sleeves for all pipes exposed in finished areas.
The annular space between sleeves and pipe shall be filled with fiberglass insulation and caulked in non-fire rated situations.
Where pipes pass through fire-rated floors, walls, or partitions, the use of a UL approved system for through penetrations is required. The annular space around the pipes shall be packed with mineral wool or other noncombustible material and sealed at each exposed edge to maintain the rating of the system in accordance with the through penetration sealant manufacturer's recommendations.
System and Equipment Drains:
Where sectionalizing valves are installed, a drain shall be installed on downstream side of valve to drain that section of the system.
All cooling tower drains and overflow are to be piped to sanitary system (not onto roof).
All system and equipment drains are to be piped to a floor drain.
Welding:
All welding shall be done in accordance with the AWS.
All boiler, pressure vessel, and hydronic piping welding must be done by certified welders must be done by certified welders as required by applicable codes.
All welding must be done with portable welding machines.
Pressure Tests:
Tests shall be in accordance with Guide Specification.
All piping must be tested prior to receiving insulation.
Pressure tests must be witnessed and acknowledged in writing by a University representative.
Without exception, no air pressure testing shall be permitted for chilled water, hot water, steam, steam condensate, domestic water, sanitary, wet sprinkler, or plastic pipe installations.
For specialized cases where air testing is required, such as dry sprinkler pipe, fuel lines, refrigerant piping, or medical gas, approval shall be required from the Penn State OPP Project Lead. In these cases, appropriate safety measures shall be coordinated with the OPP safety office on a case-by-case basis.
Installers shall follow the applicable section of the OPP Piping Pressure Tests Requirements.
Piping System Cleaning:
All hydronic systems shall be chemically cleaned after all items of equipment have been connected to the system and all piping has been complete. Cleaning shall be done prior to installing chemical treatment of glycol, and prior to acceptance by the University. See 23 25 00 for more information.
Notify the University at least one week in advance of the date and time that system cleaning is to take place. The University shall observe the system cleaning process.
.02 Gauge Piping
All gauge piping on hydronic systems shall be extra-strong IPS red brass piping federal specification WW-P-351, Grade A, with threaded joints.
For high pressure steam systems, pressure gauge connections shall be suitable for the maximum allowable working pressure and temperature, but if the temperature exceeds 406°F, brass or copper pipe or tubing shall not be used. The minimum size syphon shall be 1/4" inside diameter. For low-pressure steam systems, all gauage piping shall be ono-ferrous.
Provide gauge cocks (low pressure or gate valves (high pressure) for isolations.
.03 Cooling Coil Condensate Drain Piping
Refer to Guide Specifications
Condensate drain piping shall not be less than 1" in diameter.
Provide cleanouts at traps and other locations as required.
.04 Guide Specifications:
Design Professional shall carefully review and edit the guideline specifications below, adapting them as needed to achieve application-specific, fully developed specifications for each project.
These shall be edited using the process described in the instructions contained at the beginning of the document. Proposed modifications shall be reviewed with OPP staff.
Finalized version shall be included in the project contract documents. Use of other specifications is not acceptable.
23 21 16 Hydronic Piping Specialties
.01 General Owner Requirements and Design Intent
General Requirements:
Professional shall design each hydronic piping application with all the required specialties to achieve the functional intent of effictive and safe operation, high reliability, and minimizing maintenance costs on those systems.
Construction documents shall include all drawings and specifications necessary to clearly define the scope of work for the contractor to furnish and install all the hydronic piping specialties required to meet the functional intent above.
Ensure details comply with manufacturer’s installation instructions.
Locate in safe and convenient area and provide convenient means for frequently inspecting and cleaning. Maintain manufacturer's recommended clearances.
Coordinate requirements between Specifications and Drawings.
Hydronic piping specialties work includes the following:
Special Purpose Valves
Pressure Reducing/Regulating Valves
Safety Valves
Combination Shut-off /Balancing Valves
Differential Pressure Control Valves
Packaged Coil Hook-up Sets
Air Vents
Manual Air Vents
Automatic Air Vents
Expansion Tanks
Air and Dirt Removal Devices
Air Separator
Dirt Separators
Strainer
Side Stream Water Filters
Open Systems Solids Separator Systems
Flexible Pipe Connectors
Applications and Selection Criteria:
Flow Balancing Valves
Refer to guidelines in 23 21 00 HYDRONIC SYSTEMS, .02 Flow Balance and Differential Pressure Control.
Balancing valves shall be sized to allow accurate and reliable measurement for the specified flow rates, which may not necessarily be the same as the line size.
Packaged Coil Hook-up Sets
Piping system longevity is important, so hard piping is required. Flexible neoprene/EPDM hoses are not to be used due to much shorter expected life of resilient material failing due to combination of effects of heat, chemicals, and dry rotting of rubber.
Air Eliminator and Dirt Separators:
General: Refer to guidelines in 23 21 00 HYDRONIC SYSTEMS, .03 Air and Dirt Elimination
High Performance Coalescing type air eliminator and dirt separators shall be installed in each closed hydronic system.
The following types of air separator units shall NOT be used:
Tangential type that depend on vortex action
In-line type that depend on internal weir
Units using PALL rings
Units with strainer type screens requiring routine removal and cleaning.
Select units at the point of peak efficiency per the manufacturer’s recommendation. Units shall be selected for low system pressure drop, not to exceed maximum of 4 feet of head at maximum design flow rate.
Dirt separator only and combination air/dirt separator units shall include removable bottom and mounted with sufficient clearance for accessing, pulling media and cleaning of interior of unit.
Include detail and specifications to require a separate ball isolation valve of same inlet pipe connection size as auto air vent .
This may not be a standard feature offered by manufacturers. However, auto air vents have float and small orifice mechanism that can clog or stick (especially with glycol fluids). These isolation valves are an important OPP requirement to enable quick and cost effective repair or replacement of auto air vent without shutting off and/or draining the main system.
Refer to Guideline Details descriptions later in this section and select the best fit for each specific application. Review and coordinate application with OPP Engineering Services and Water Treatment Supervisor.
Exception: If main piping distribution system uses all non-ferrous piping materials, then a single combined air and dirt eliminator model installed prior to the pump is recommended.
Do not retrofit coalescing air eliminators to existing air control type systems with open (air cushion in direct contact with water) type expansion tanks without also upgrading the expansion tank to closed, pressurized type (bladder or diaphragm).
Strainers:
Strainers shall be strategically applied as necessary to protect system elements, but sparingly and with screens/mesh size appropriate to the location in the system to enhance energy efficiency.
Piping systems shall be designed in a way to most effectively trap the bulk of the particles coming from the main and large branches of the piping distribution system in as few strainers as practical (particularly during cleaning and flushing operations) and to minimize the need for continually servicing individual strainers while still providing adequate protection of terminal coils and control valves.
In general, subdivide the branch piping to serve groups of terminals that do not exceed 2” (the typical upper limit for use of copper pipe sizes) and provide a strainer assembly in the branch supply pipe with mesh size to protect each group of terminals downstream.
Coordinate and combine the branch strainer with self-regulating pressure regulator as applicable for subdivided branches serving hydronic modules of similar terminal loads. Refer to 23 21 00 HYDRONIC PIPING AND PUMPS, .02 Flow Balance and Differential Pressure Control for additional information.
The individual strainers at each heating/cooling terminal unit shall still be installed. They are required to protect the small orifices in terminal unit characterized control valves that are susceptible to trapping any soldering flux or other small debris that would initially be in the piping downstream of the branch strainers during cleaning and flushing operations. However, the intent would be to remove the screens after the system has been properly cleaned and flushed but kept with the strainer body to reinsert if/when needed for future system chemical cleaning/flushing.
Include a flushing bypass valve assembly across the terminal runouts of each device protected by strainers and at the branch strainer assemblies to allow for main system chemical cleaning/flushing circulation without clogging downstream device or strainer assemblies with materials intended to be removed by the process back at the central plant dirt removal equipment. Coordinate with requirements in Water Treatment Standards and Guidespec sections.
Coordinate these requirements for Branch strainers for groups of multiple small terminal units with the Guidespec and well-defined drawing plans and details.
Do not apply fine mesh strainers in suction side of pumps serving open cooling tower condenser loops or other open systems that can quickly clog.
Not only will pressure drop quickly increase, dropping performance in increasing energy cost, but cavitation will occur which will quickly damage equipment.
Side Stream Water Filters
Refer to HVAC Water Treatment design standard 23 25 00 and guidespec section to coordinate requirements.
Open Systems Solids Separator Systems
Solids separator systems (similar to HVAC options offered by LAKOS) that minimize maintenance and reduce energy, water and chemical consumption and that do not impose a varying pressure drop to the primary loop shall be engineered for each open application for lowest life-cycle cost.
Include automatic means to purge solids while minimizing makeup water requirements.
Coordinate with Water Treatment for Open Hydronic Systems.