HyPerformance Upgrade in a University Project, UK
The University of York’s Biology department wanted to improve the efficiency of its cooling system, which in the summer months was not able to meet the temperature requirement of its lab spaces.
The University of York’s Biology department wanted to improve the efficiency of its cooling system, which in the summer months was not able to meet the temperature requirement of its lab spaces. Expert commissioning support from the IMI team in the UK, helped to achieve optimal system performance and better energy efficiency without having to replace expensive plant equipment.
The Project
The University of York’s Biology department conducted a large renovation project to improve the efficiency of the cooling system. The proposal was to optimise the chilled water network supplying the existing chillers which in turn provide cooling to a large range of buildings and critical lab space. The primary goal of the project was to increase energy efficiency while addressing the issue of the research labs not being able to reach the required indoor temperature during summer months. The project was delivered in two phases spanning over about a year.
As part of the project, the primary and secondary pumps were changed to pressure-controlled self-modulating pumps. To ensure the best energy savings options the proposal from the M&E designer was to convert the control valves at the chillers from 3 port to 2 port. This would take advantage of the pumps ability to modulate and therefore reduce the pump speeds at times of low demand, saving energy. Therefore, all the AHUs' 3 port control valves controlling the flow to the cooling coil were replaced with 2 port PICVs from IMI Hydronic engineering.
The Hydronic Challenge
The original system struggled to deal with cooling loads at peak demand due to a combination of oversized three port control valves at the chillers and insufficient differential pressure control within the piping network. Too much water was simply passing around the bypass circuits at the chillers nearest the pumps, which meant that some circuits could not receive the required load during summer months, even though the chiller units had the capacity to deliver.
Under the new proposal with variable volume conditions using PICV’s, each circuit would not have any bypass capability to serve minimum pump turn down, which would lead to pumps acting against closed circuits potentially causing them to malfunction and eventually fail.
The system was unbalanced and had never performed satisfactorily. This is when the customer reached out to IMI HE to support further.
The Solution
Firstly, our technical engineering team investigated the hydronic network and working closely with the University of York’s Estates Department were able to identify all the issues aforementioned. IMI HE’s engineering services department then drew up the schedules based upon these initial investigations.
The next step was to provide expert support to re-commission the valves and actuation. During phase one of this process, we were also able to identify and size the remaining PICVs required to complete phase two of the project. A bypass strategy was devised, in some cases using a correctly size three port control valve and a PICV used as a constant flow regulation valve was utilised, and in another case a dedicated bypass comprising of a reverse acting differential pressure control valve was the solution.
After on-site training was delivered by IMI HE’s technical team, commissioning was done using the TA-Scope measuring device with engineers from The University of York Estates team and the installation contractors.
It is not always necessary to replace every piece of critical equipment, simply optimising what is already there can bring about significant improvements to efficiency and thermal comfort.
As of mid-2022, the system is running well, supplying proper cooling to the critical lab spaces. Even during peak summer season in 2022, none of the AHUs that had IMI HE’s PICVs fitted experienced issues controlling the air temperature. In fact, in most areas, the valve positions were not more than 50% open even when external temperatures were upwards of 40 degrees and the AHUs were trying to reach setpoints of 18 degrees. This is in stark contrast from the previous years, where the system frequently experienced issues reaching the needed temperature for the key licensed research labs during the summer months. This demonstrates that although the system was probably oversized to begin with, the optimization project has been a resounding success.
The valve upgrades, together with proper system balancing and pump optimization will greatly improve system performance and contribute to energy savings, which the customer is measuring to evaluate the payback time. The critical success factor to this project was using high quality correctly sized valve solutions and proper commissioning, IMI HE's support was invaluable in achieving this.
IMI's specialist expertise in hydronic systems makes them the perfect partner for complex projects such as this. Working closely alongside contractors, designers, and building owners ensures the right products are selected, proper commissioning is done, and there is a clear understanding of how the system works. Involving them from the beginning can save months of setback later on. So, reach out to IMI today!