Compiled by Eamonn Ryan
The Internet of Things (IoT) is transforming the way contractors manage HVAC systems in both industrial and commercial settings – by helping manufacturers, contractors and end users monitor their performance and detect issues before they become major outages.
A DN250 Danfoss AB-QM PICV valve and actuator, 1 of 6 installed at a data centre in Centurion. Image credit: ACS
The basics any HVAC&R installer and engineer should understand when installing and specifying are pipes, fittings and gauges. These each relate to the nature of what individual components convey from plant all the way along to indoor spaces, according to the standards that exist. These components are there to protect the health and safety of people in the building as well as prevent damage that ensues when pipes leak, or wrong fittings are used or blocked pipes cause dangerous situations in buildings or create waste energy.
The opportunity and challenge posed by the inevitable digitisation of HVAC, with gauges and some valves likely to be dominated by sensors and smart technology.
Pipes: what material?
HVAC technology has changed enormously since its earliest inception. Alongside that, the materials used to make air conditioning units’ piping has evolved as well. The effectiveness of the piping gets influenced by the materials used to make it, with copper and steel being the two major types of metals used for HVAC piping.
Copper is used mostly for smaller piping, transporting water in a/c units as the use of copper is expensive compared to other materials available. Steel on the other hand is much cheaper and is used for larger sizes. The latter can withstand higher pressure than copper and is ideal for both hot and cold water. It usually allows for a range of temperatures and pressure.
A DN150 Danfoss AB-QM PICV valve and Danfoss NovoCon BACnet actuator also installed at a data centre in Johannesburg on a bypass line. Image credit: ACS
Copper.org explains that copper’s high-quality performance has allowed it to remain a standard part of air conditioning construction. Copper can be the ally of a licensed HVAC service provider: it is easy to work with, yet extremely durable once installed. A copper pipe is, “[S]o ductile that it can be formed – frequently right on the job site – to fit most design configurations”, says the site 1. The material is also versatile enough that it can be used in a wide variety of HVAC jobs, from single buildings to large scale complexes.
Reducing costs while maintaining a high level of quality in a building material requires a delicate balancing act. Cutting the quality of materials threatens the reliability and performance of the material and is never a good idea. Technological advances in production methods have resulted in copper pipes created with minimal material, yet still reliable and durable. The use of copper pipes in HVAC systems can reduce the diameter of condenser and evaporator pipes and coils, meaning less material, a potentially lower carbon footprint and more efficiency. The smaller internal space of an efficient copper pipe also requires less refrigerant.
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By nature, copper is not a highly reactive metal, something extremely beneficial for pipework that needs to carry refrigerant over long periods without eroding or damaging the HVAC system. Having a natural protection against corrosion is a great advantage and part of what makes copper a long-lasting standard for HVAC system systems. Most HVAC systems are placed in tightly-built spaces, creating moist environments that encourage the growth of mold and mildew. Copper has antimicrobial properties that discourage their presence from building up in hard to access areas.
Pressure independent control valves
Automated Control Solutions (ACS) supplies several brands of valves having begun life as a distributor of Honeywell before the latter terminated its distributor model and went direct to market. Today, ACS primarily distributes Danfoss valves, and particularly chilled water and air handling unit (AHU) valves. It services HVAC system integrators and mechanical contractors with high end quality international products.
Adrian Hofmann, Technical Sales and Support at ACS, says: “When it comes to the big tenders for large buildings and shopping malls, engineers like good quality valves and a Danfoss valve will last almost forever. There are two different sets of valves we do from Danfoss: conventional two- and three-way control valves with manual balancing. This is the traditional way that people still use valves – up to about 150mm in two-way, and in three-way up to 300mm for chiller plant managing. And we do Danfoss’ AB-QM 4.0 range, which is their pressure independent control valve (PICV) from 10mm up to 250mm, which are massive pressure independent Control valves combined with automatic balancing valves. In particular, data centres like those valves because they require less commissioning.
“We also do some iSMA Controlli valves and actuators as an alternative to Danfoss, they have some very specialised stainless-steel options with actuators suitable for outdoor installations with IP65 enclosures,” says Hofmann.
Adrian Hofmann, Technical Sales and Support at ACS at Frigair. Image credit: © Benjamin Brits | RACA Journal
Conventional valves have been around a long time, and Hofmann explains that one can either have on-off control or modulating control. “Modulating control has been around for ages on AHUs. You’d have a controller on an AHU unit giving a 0-to-10-volt signal to the actuator, which would be open or closed or anywhere in between the whole time, depending on the demand through the building.”
In the past, there were constant flow systems with three-way valves. There could be a set of pumps running full blast all day long regardless of the load, with the only thing changing being that the valve opens and closes and water either goes through the coil, or bypasses back to the chiller – a very energy inefficient system. “Now, with the design of the PICV, it’s a control valve and an automatic balancing valve all in one piece. There is no running up and down for weeks balancing the system, the valves are pre-set, and they will take care of the rest. There’s no bypass at the coils, which means variable speed drives (VSD) can now control the pumps to maximum efficiency, in the morning and evening, when the load is low, the VSDs run slowly, and entire plant runs more energy efficiently. As a result, those PICVs have grown in popularity – even though they’re expensive, they provide a good return on investment on energy saving alone, never mind the savings on installation and commissioning,” says Hofmann.
The PICV is pre-set according to the flow requirement during installation, and the manual balancing valve can only be set once the water is pumping through the whole system at full load. Only at that point can the commissioning engineers start adjusting each valve, whether it be for fan coil units, AHUs, the branches or the risers – on big systems there being typically hundreds of these valves. What happens is, as one starts throttling these valves to let the required amount of flow through, pressure starts increasing on the rest of the line with the result the engineers must return to the previous valves to throttle them and back to the first valve of all. This is because the pressure has increased in the system and they need to balance that valve again. This has to be repeated around three times to get a properly balanced system.
“PICVs always let just the required amount through the coil, regardless of changing system pressures, so the pump is running at the right speed, and the whole system is more efficient, for a power saving for the end user. They’ll pay more from the start but get their money back from power savings throughout the life of the system. Unfortunately, it is often about the CapEx rather than OpEx, and the mechanical engineer designs the system according to the client’s budget and it is the price of the system that ultimately determines which solution they go for.
“However, when a building is aiming for green star rating certification from the Green Building Council SA (GBCSA) they will certainly budget for PICVs in order to get the energy savings and the points. As green buildings are being pushed quite extensively, we are seeing an increasing adoption rate already for the past 10 years. However, there are still plenty developers who are not worried about their client’s energy usage because of the upfront cost,” adds Hofmann.
Gauges: analogue holds its own for now
SA Gauge quality manager Riaan Reinach, says : “There’s a trend to standardise on gauges, and at the moment everybody’s still trying to figure out what needs to be made on the pressure side of the systems. There are currently probably 20 or 30 different types of configurations and I expect this to standardise down to between four and six gauges. If new refrigerants enter the market or there is a push of the limits in terms of high-pressure to low-pressure then obviously that may alter things.”
Regarding the trend to digitise gauges, Reinach notes that such a gauge only gives the pressure reading, not the equivalent in temperature – whereas analogue gauges give the pressure and temperature equivalents already printed on the scale. This may mean that with digital there would be the inconvenience of having to switch between screens to see both readings. In addition, he says, “[A]t the moment digital is too expensive.”
“Pipes and valves generally are purchased as a set, with the choice of a gauge being determined by the consulting engineers based on what they want from the system and whether or not they even want a gauge on the system. You do not necessarily have to have a gauge – if the engineer is confident in the pump one can get away without having a gauge and can rather just have sensors on it. However, the majority of cases do have at least one gauge. One can also get away with using a gauge only in the commissioning phase and thereafter remove it and occasionally return it for a check-up every now and again.
“When it comes to choice of system, the technician or engineer would specify what they’re looking for, such as a certain amount of pressure or temperature: it is this criteria for pressure and temperature that dictates the choice of gauge. A refrigeration gauge is actually a pressure gauge with a temperature scale on, because the amount of pressure on a certain gas is equal to X-amount of temperature for the gas. If you pressurise gas to say 10 bar it could be equal to 10 degrees Celsius on R410A gas,” says Reinach.
End users don’t get involved in servicing gauges, he notes, they would have to send it for calibration to test it is still within its accuracy class. If they require a calibration certificate, which is becoming the norm these days, “[W]e would issue one to international standards”, he says.
“On the digital side there’s a lot of R&D happening – but for analogue there’s really no R&D taking place anymore because the product has been in the market for 100 plus years and it works on the same principles. Not much is changing other than perhaps trying out new materials other than copper beryllium, brass and stainless-steel tubes. A lot of the old school guys still prefer having analogue to digital because with analogue they can see it working, while with digital they’re less certain – it just gives a digital reading which could be frozen.
“The selection of raw material for the gauge depends on the media or liquids getting pumped through the system, determining whether to go to a stainless-steel gauge rather than brass or copper.”
Bringing it all together: pipes, valves, gauges and the IoT
IoT gives companies opportunities to intelligently monitor and control the performance and condition of HVAC systems 2. There are the five primary ways companies use IoT to improve operations:
- Preventative maintenance
- Energy efficiency
- Remote system monitoring and control
- Regulatory compliance
- Regular servicing plans
Whereas for a long time, ‘physical-based’ techniques were the driving force for the industry when optimising, modelling and maintaining HVAC systems, lately this is now veering towards data-driven approaches instead. Lloyd Townsend, product manager at WIKA, explains: “A data-driven approach is only as good as its data, of course, but as communication and information technology have continued to evolve, data has become more accessible, allowing HVAC companies to now collect and disseminate more data at once.”
WIKA Marketing Manager: Greg Rusznyak and Lloyd Townsend, product manager at WIKA. Image credit: © Eamonn Ryan | RACA Journal
It seems only a matter of time before Artificial Intelligence bleeds over to the HVAC industry, and WIKA marketing manager: Greg Rusznyak says we may be on the cusp of that time now. The CEO of WIKA in Germany has stated that by 2030 80% of its measurements will be digital, and Rusznyak for instance sees a role for ChatGPT in answering product and installation queries in real time within the near future.
“A lot of the time a customer wants information immediately and technology such as ChatGPT could remove the need for a human sitting idle waiting for a call, or another employee for whom the query is just a distraction,” says Townsend. That’s not taking jobs away but making workflow more efficient.
This future is what WIKA is at the moment working towards in collaboration with other players through organisations such as the Lora Alliance and the Mioty Alliance as part of Industrial Internet of Things (IIOT). “Our company is dedicating a great deal of research to this future trend.”
Townsend explains that while a significant portion of gauges sold in the South African market remain analogue, this reflects the persisting culture in the country whereby technicians still like to see a gauge’s reading, but elsewhere the trend is firmly towards digital.
He explains that digitisation of HVAC systems is typically run in BMS (Building management Systems) environments and not yet connected with ERP systems. BMS has the metrics to put the HVAC on and off, reduce power and adjust to external air environments and level of CO2. “We would typically be connected and feed data into that system. We have an HVAC application which feeds into a BMS, monitoring temperature, pressure and humidity and ensuring there is not too much CO2 in the air. We provide sensors, and many BMS developers will include such sensors in their design.
Bourdon tube pressure gauge with switch contacts. Image credit: WIKA website
High-quality pressure sensor with mounted diaphragm seal. Image credit: WIKA website
“The digital technology already exists. There remain only concerns as to how to include all the data and to verify its trustworthiness from a human interaction perspective – for at certain key points human interventions are required. It is this area customer scepticism arises which holds back adoption rates. The technology is ready – the question is, are South Africans ready?
“We have for many years made a regular analogue pressure gauge which remains a big chunk of our business. There’s still a lot of people who operate a plant in such a way that they can get up and walk to that gauge and see the pressure. However, we have seen a steady switch from analogue to digital over the last five to 10 years and that trend is definitely going to accelerate in the future,” says Townsend.
Rusznyak adds there’s nothing wrong with the analogue technology in existing plant and people will carry on using it, as it’s human nature for people to want to sweat their existing assets. But when gauges are due for replacement they will most likely opt for a digital alternative.
He says the education map will have to evolve with Industry 4.0 – with less requirement for mechanical engineers and more need of people with certain software knowledge to understand how applications work. There will be need for a quick decision matrix by digital instruments – so there will be a transition in functions.
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As an example, Townsend notes that one won’t need a technician to take a reading from a gauge, jot it on a clipboard and take it back to the control room. Instead, you might need a technician to service the instrument taking the reading. They do not anticipate digitisation replacing a high number of jobs, as people will always want to speak to another person rather than a chatbot.
The impact of digitisation will be lesser for simple on-off valves, but will impact proportional valves controlling airflow, for example, according to the demand for air so as to save energy or redirect it to a high-demand area.
Weathered rusty refrigeration rack in a factory. Image credit: wirestock | Freepik
System installation errors
There’s a lot that can go wrong, says Townsend. “We’ve had a few experiences from clients where equipment was selected to measure, say, the airflow in a duct: they want to use a pilot tube and a differential transmitter, and they ended up installing the equipment incorrectly. For example, a pilot tube creates a differential pressure as a negative and a positive, and by mistakenly swapping the measurement sensors connections around they get negative readings.
“Sometimes the decision on what equipment to use is a problem and causes accuracy issues. When dealing with HVAC systems, we’re dealing with huge ducts, pipes and valves. These decisions can end up skewing the ultimate operational efficiency. Sometimes contractors may install the element the wrong way around, and sometimes there’s a welding error,” says Townsend.
He adds: “Maintenance is performed according to set intervals, and these enable one to understand the potential degradation of the system over time.
WIKA’s air2guide flowmeter. Image credit: Wika website
“With an air-conditioning system, there would typically be an interval of every six months between each of the first two or three checks. The maintenance checks include: pressure value, air delivery, whether the filter is saturated with dust and more. They clean what needs to be cleaned, and document whatever action has been taken. From these initial checks they can decide whether to extend or shorten the maintenance interval. This can all be digitised,” explains Townsend. He notes that this can be affected by the external climate when local conditions prove to be much different from what was anticipated at the time of installation, for instance if the air is highly saturated.
Reunert lists common maintenance errors as, “Not using a spanner but rather using the hands with the result the technician may strip the thread on a gauge. Or the internal device can start twisting inside the case, creating a leak on the gauge itself which can also give an incorrect reading. Dropping the gauge or banging it as you walk past something like a toolbox can bring into question the validity of the gauge readings – there are springs and gears inside which can be dislodged,” he adds.
In conclusion, smart HVAC coupled with IoT can improve a building’s profitability. New and innovative methods of collecting and analysing data will constantly upgrade smart HVAC systems to meet comfort and maintenance benchmarks. Together, HVAC piping, valves and gauges contribute much to smart HVAC having a brighter, more efficient future.
References
- https://copper.org/applications/plumbing/benefits/
- https://www.particle.io/iot-guides-and-resources/hvac-iot/
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