Heating and Ventilating

 

Valves - key to the future of sustainable buildings

Solar power, biomass and heat pumps are some of the key technologies when project managers think of developing an energy efficient building. However, the benefit of this renewable technology is multiplied when deployed in an energy efficient heating or cooling system. Stephen Hart of Frese says the use of Pressure Independent Control Valves (PICVs) to regulate the indoor climate have been shown to be one of the most effective designs to improve the efficiency of heating and cooling systems
Pressure independent control valves (PICVs) are becoming an increasingly popular way of cutting energy costs in buildings by simply controlling the heating and cooling system more accurately. Such valves used in the right way can cut energy costs for a large-scale commercial or residential building by up to 50 per cent.

At Frese we've been refining the PICV for the last 25 years and this technology has been used in some of the UK's landmark commercial projects, from schemes on Canary Wharf to the London Olympics Athletes Village and one of London's most exclusive residential projects, 3 Merchant Square.

The valves work by precisely managing the flow of fluid and pressure in a heating system, which is vital to how efficiently it warms a building and how much work the actual boiler and pump has to do. This is primarily the reason why they are becoming popular in large-scale projects because the flow of pressure in a system for a huge commercial building or high rise can be a huge headache. PICVs are an easy way of solving this. In addition the control they give on a system cuts the energy circulating pumps need to use and this leads to a reduction in the energy bills.

PICVs are quite a revolution in heating system management. If you take your traditional heating and cooling system it typically consists of a plant room and circulating pumps to distribute heated or chilled water through pipe work to heat exchangers. Until recently water flow through a coil in these heat exchangers was usually controlled by a three port temperature control valve that modulated water flow through a bypass to regulate power output from the heat exchangers. Valves were then manually balanced by the installer to ensure that each heat exchange receives enough heated or chilled water to maintain indoor air temperature.

The limitations to such traditional systems are numerous. Conventional systems that include manual balancing valves require a commissioning specialist to proportionally balance the system so it works effectively. This can be a lengthy process and the end result is a system that can still suffer significant energy wastage and is difficult to adjust if the system is subsequently modified.

This is where PICVs show their advantages. PICVs can easily establish the right pressure in a system and turn a heating system into a far more efficient animal. They are basically a self-regulating valve which react independently to changes in system pressure to maintain flow rates. The Frese Optima dynamic balancing valve is a leading PICV and includes an automatic temperature control valve, flow limited balancing valves and differential pressure valve, all in a single valve body.

This three-part mechanism allows the valves to self regulate and react independently. It's through this self regulation that optimum heat and flow in the system is maintained, the valves do away with the need to manually balance the system and provide a greater level of control than a traditional system, using basic valves. While the PICV technology can be used on any system of any scale, it's really larger residential or commercial projects where it pays dividends. Some of the projects we've done recently are leading to major energy savings. Three Merchant Square for example. Here we installed valve assemblies to fan coil units in each of the 201 apartments and combine pressure independent control, drain, flushing and isolation valves with an integrated flow measurement device. These valves ensure precise control of heating and cooling systems in the building and lower the flow and pump pressure through the apartment block. Through this system we are expecting to deliver considerable energy savings over the coming years, while the system is low maintenance and easy to change and extend if necessary. PICVs can retrofitted onto existing systems, but they give the most impact on newer variable flow heating systems which use inverter pumps, pressure sensors and two-port control valves.

It's on systems such as these that they'll cut the energy a circulating pump consumes by as much as 50 per cent and lead to a major reduction on energy bills.

// The author is the UK managing director of Frese //
11 March 2014

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