The VP140 reduces energy spend and improves tenant comfort
Why your test and balance company does not want you to know about pressure independent control valves.....
If you look at how we do systems today, you can see why the test and balance folks are threaten.Reaseach by our friends at Belimo explain the cost of doing it without pressre independent control valves:
Time Consuming Balancing
According to its flow design each control valve requires a balancing valve to adjust the hydronic circuit. The balancing procedure dictates the quality of the system and requires highly skilled technicians and tools. During the balancing all control valves must be in their open position. However, as soon as the system is running, depending on different cooling or heating load requirements in the building, valves are permanently closing and opening which results in a dynamic system pressure. Balancing variable flow systems is time consuming and can be conducted only under “static” design conditions.
In a conventional system, if terminals are added the whole system needs to be rebalanced because some existing terminals must be throttled back.
Or imagine a 10-story-building where every 2 months one floor is being remodeled in which balancing of the whole system is required after finishing each floor. Of course this applies also to buildings with changing tenants or new utilization of spaces.
Poor Valve Authority
Only 1% of the time is a building typically running under design conditions. The other 99% the hydronic system needs to provide an average load of 50%. Thus flow is reduced to 20% and differential pressures across control valves increase. Since the CV-rating of the valve was sized for design conditions, the valve authority decreases and the modulating valve is downgraded to one acting open or close only. This makes hunting expected.
Potential Spreading of Control Problems
Control circuits are interactive. Therefore when one control valve closes, the differential pressure on other circuits increase and the associated control valves must close to compensate. So when one or more loops are instable, control problems can spread to other control valves.
If flow is higher than required, ΔT will decrease and result in a cooling plant with lower return temperatures to the chiller and reduce the efficiency. If a chiller cannot run at peak efficiency it is more likely that the next chiller in a series will be forced to start sooner than required causing additional electricity and maintenance costs.
The opposite happens in a condensing boiler where a higher return temperature can avoid the condensing process when the dew point of the exhaust gases cannot be achieved.
The same phenomenon can happen in coils. In a heating coil for instance, overflow will result in a lower ΔT and decrease the coil’s performance which can result in discomfort due too a low room temperature.
Is a Pressure Independent Control Valve Like the Johnson VP 140 Right for you?
Here is what the extra money you pay up front get's you:
There is no CV calculation required and after the flow calculation the appropriate valve can be selected. If the flow is 8.7 GPM the correct selection is a 9.0 GPM valve. Generally the next bigger valve should be selected. However, an adjustment in the field is always possible considering the adjustable flow range.
Hydronic Balancing Simplified.
Pressure Independent Control Valves make circuits independent and they literally decouple circuits or terminals from the system. There is no balancing procedure required and for commissioning, a simple check of ΔT or flow is enough.
To measure flow, pressure independent control valves are available with pressure ports to gage pressure differential. A valve specific chart may then be used to locate the matching flow from the gage pressure differential.
Plants can be commissioned in a step-by-step approach. Individual zones can be setup and no rebalancing is required which simplifies adding to the system or remodeling.
One Piece Installation
The compact pressure independent valve incorporates the control valve and the balancing valve. Thus, the valve saves 50% of labor costs during installation and investment for the balancing valve. Additionally about 2/3 of the installation space (pipe length) is saved.
Reduces Pumping Costs
These valves assure that each terminal, depending on its load, obtains the required flow and that overflow can be prevented. Therefore, the total flow will be lower than in systems without pressure independent valves. The pump head follows a similar behavior and thanks to the automatic dynamic balancing the required pump head is substantial lower. The maximum required pressure across these valves is 3 to 5 PSI, compared to a control valve and a balancing valve where the minimum pressure drop with the balancing valve fully open is approximately 5 PSI (4 PSI control valve, 1 PSI balancing valve). However, depending on the systems dynamic as soon as the balancing valve is throttled back the pressure drop for instance may increase up to 20 PSI.
Pressure independent valves are ensured to have the designed flow for full or part load situations. Therefore, the calculated ΔT will be accomplished which will then lead to higher efficiency of chillers, condensing boilers, coils or heat exchangers.
Prevents Overflow or Underflow
At morning start-up in a plant most control valves will drive fully open. In a conventional plant overflows have been experienced and less favored terminals do not receive enough flow, which increases the time by which all rooms achieve their setpoint.
Each terminal is receiving a proportional flow and the start-up procedure is parallel. The Pressure Independent Control Valve can save up to 2 hours of start-up time every day and can reduce energy costs by 4 to 6% in a cooling plant.
It seems to me like the extra upfront cost is well worth the investment.
More on the Johnson Controls VP 140 Pressure Independent Control Valve
The new Compact Axial VP140 Series Pressure Independent Control Valve, adds to the existing ball valve model line, by offering a small footprint valve with extremely robust performance for a long life of accurate, pressure independent control. The new models are available in 1/2″ and 3/4″ size, with or without an assembled actuator.
The new Compact Axial models offer the following advantages:
• Performance – a patented dirt free cartridge provides superior performance even as
water quality declines
• Compact size – ideal for applications with tight space constraints
• Maximum flow setting adjustable without the use of special tools
• Linear or Equal % characteristic curve with the same valve
• Integral test points – pressure ports included on all models to verify pressure drop
• Higher pressure applications – working pressure of 360 psi and close-off pressure of 100 psi
• Field serviceable – clean or replace the pressure regulator if it is ever damaged, without special tools or the need to replace the entire valve
• Convenience and cost savings
• Free brass tagging
• Free factory pre-setting if desired (valve schedule required at time of order)
• Quality and peace of mind – 5 year warranty
Features of the Compact VP140 Series Pressure Independent Valve (PICV)
• Patented pressure regulator design maintains flow control accuracy and pressure independence, even in contaminated water conditions.
• Provides energy savings by reducing pumping requirements and lowering demand on heating or cooling systems. These energy saving advantages help building owners realize the full benefit of variable flow pumping systems.
• Reduces installation and operating costs by eliminating:
• Material cost of a separate balancing valve, piping and associated installation labor.
• Labor required to adjust or balance the hydronic circuit during system commissioning.
• Future labor costs of rebalancing the system if new circuits are required for system expansion or a facility remodel.
• Selection is easy, based on the gallon per minute (GPM) requirements of the coil. Calculations for Cv or pressure drop are not needed.
• Maximum flow adjustable without a special tool covers a wide range of applications with fewer part numbers.”