Heat Pumps and Heat Waves: How overheating complicates ending gas in the UK

February 9, 2022 by Leave a comment

by Dr Aaron Gillich | Associate Professor and Director of the BSRIA LSBU Net Zero Building Centre

We have entered what many are calling the decisive decade on climate action. Among the most critical decisions that the UK faces this decade is how it will eliminate carbon emissions from heat. Heat accounts for over a third of our emissions, and over 80% of our buildings are linked to the gas grid. There is no pathway to Net Zero that doesn’t include ending the use of gas as we know it in the UK.

Given the size of the UK gas grid, no single technology or energy vector can replace it. We will need a combination of clean electricity and carbon‐free gas such hydrogen or biogas, delivered by a range of enabling technologies such as heat pumps and heat networks. And of course an extremely ambitious retrofit agenda that reduces the demand for heat in the first place.

The UK is investing widely in low carbon heating innovation. That innovation is essential, but is also unlikely to include any blue‐sky breakthroughs that aren’t currently on the table. In other words, the menu of low carbon heating technology options is set, and this decisive decade will be about deciding what goes best where, and how to ensure a just and equitable heat transition.

Low-carbon heating options

Of all the low‐carbon heating options available, low carbon heat pumps are the most efficient and scalable option that is market ready and can respond to the urgency of climate change this decade. The UK has set a laudable target of installing 600,000 heat pumps per year by 2028. Many have criticized this figure as unrealistic, but I believe that the target is highly achievable, and represents a pace that is in line with past transitions such as ‘the Big Switch’ that put us on the gas grid in the first place.

This race to replace gas in the UK has been widely discussed. As have the many barriers that face heat pump deployment in the UK. What I’ve heard discussed far less are the links between heating in the winter and overheating in the summer. Over the next decade, the end of gas will present both a threat and an opportunity to improve both the winter and summer performance of our building stock.

The threat of climate change is clear. The end of gas increases this threat because gas has allowed the UK to obscure poor building performance, and poor building knowledge for so long. Cheap gas has enabled a ‘set it and forget it’ approach to many building systems, and allowed us to maintain reasonable standards of comfort in most buildings despite very poor fabric performance. The irony is that this poor winter performance actually helps reduce the risk of overheating in the summer, as the leaky and poorly insulated buildings can more easily shed excess heat. It has been widely reported that many newer, better insulated buildings actually face an increased risk of summer overheating.

Replacing gas with heat pumps, or any other low carbon heat source, should be accompanied by ambitious retrofit to improve energy efficiency and reduce heat loss. There are many that argue heat pumps in fact require extensive fabric retrofit in order to function in most UK buildings. This is highly debatable and will be explored in detail in follow-up writings. Regardless, demand reduction and a fabric first approach is a good idea for its own sake.

Replacing gas with heat pumps, or any other low carbon heat source, should be accompanied by ambitious retrofit to improve energy efficiency and reduce heat loss.

But reducing the heat loss in winter will likely trap heat in the summer, presenting a conflict. The UK currently experiences over 20,000 excess winter cold deaths and around 2,000 heat related deaths in summer. It was previously thought that the increased temperatures from climate change would decrease winter cold deaths, but more recent work has shown that due to the increases in extreme weather events at both ends of the spectrum, it is far more likely that winter cold deaths will remain at similar levels, and summer heat deaths will increase dramatically under climate change.

We must use the transition from gas to low carbon heating as an opportunity to better understand our buildings. Many of 600,000 heat pumps we install by 2028 will be in new build, but up to half will need to be from existing homes.

Retrofitting a heat pump is also the time to think about not only how to improve energy efficiency for the winter but how to reduce summer overheating as well. Despite much effort towards a whole‐house approach to retrofit, most work remains quite siloed. Energy efficiency and heating installations are largely in separate supply chains, and the building physics knowledge to carry out an overheating risk assessment is even less likely to sit with the same project team. Overheating is also very poorly captured by the building regulations and planning process.

A holistic approach

The last few years has seen a growing awareness of overheating risk and an emergence of increasingly easy to use assessment tools. A very small fraction of UK homes have comfort cooling. Retrofitting a comfort cooling solution typically requires costly and complex changes to distribution systems. However, there are a range of low cost options, including using local extract fans to create interzonal air movement, or using night purges and thermal mass. Blinds are also incredibly useful, but often misused in summer, and can also help reduce heat loss in winter. There are also ways to use local microclimate features such as shaded areas or the North side of the building to bring in slightly cooler air from outside and reduce peak temperatures.

Improving the air tightness and fabric performance of our buildings to address heating in the winter will change how we implement these solutions for the summer. They require not only careful thought at the design stage, but also strong communication to help end users operate them properly. Simply opening a window is unlikely to help if the outside air is warmer than inside.

A significant problem is that there are insufficient drivers to force this type of holistic approach to design, performance, and communication. It is so often said that we need stronger policies in the area of heat and retrofit, and this is no doubt true. But while we await these policies it is incumbent upon each of us in this sector to share and collaborate as widely as possible, and use whatever influence we have over a given project to encourage a fair and forward looking solution.

In summary, the availability of cheap gas has allowed us to escape having to understand our buildings in much detail. Climate change is the catalyst for an untold level of change in our lives that we are going to start to truly experience in the coming decade. Heating and overheating are coupled issues that must be solved together. We must use the end of gas as an opportunity to understand our buildings better, and implement solutions to climate change that work across seasons, or we risk trading one problem for another.

In summary, the availability of cheap gas has allowed us to escape having to understand our buildings in much detail.

Filed under air conditioning, Airtightness, BACS, BEMS, best practice, BPE, building energy management systems, Building Performance Evaluation, Carbon, carbon dioxide, Climate Change, Construction, Cooling, emissions, Energy, energy consumption, energy management, energy perfomance, energy-efficiency, Engineering, Environment, environmental, global warming, Green Agenda, Heating, HVAC, low carbon, overheating, renewable energy, Sustainability, Thermal Performance, Zero Carbon Tagged with , , , , , , , , ,

What makes a good PICV?

September 22, 2020 by Leave a comment

by Andrew Pender, National Sales Manager at FloControl Ltd.

Over the last 5 years, PICVs have been widely accepted as the best method of terminal control in variable flow systems due to their energy saving potential.  The surge in popularity has led to an influx of products with varying designs, features and functionality.  This article reviews some of the mechanical PICV design elements and how they can impact on the PICV’s performance in an applicational context.

Where do we start?

To help specifiers and project engineers assess which PICV is best suited for an application, the BSRIA BTS1/2019 standard has been developed to provide a consistent test method for PICV manufacturer’s products to be benchmarked against.

Manufacturers should be able to provide test results in line with this technical standard which covers:

  • measured flow vs nominal flow
  • pressure independency or flow limitation
  • control characteristics, both linear and equal percentage
  • seat leakage test

Repeatability & Accuracy are central to the tests and they are key to good temperature control and realising the full energy saving potential of a PICV installation.

An accurate PICV means the measured results will be equal or very close to the manufacturer’s published nominal flow rate each time it is measured, known as low hysteresis.

Accuracy has a positive impact on a building’s energy consumption.  “Measured over time, a 1% increase in the accuracy of a PICV can result in a reduction of around 0.5% in the building’s overall hydronic energy consumption” (FlowCon International).

Valve accuracy is driven by the design, manufacturing process and material used for the internals of the valve.

  • The design of the PICV should allow for Full Stroke Modulating Control at all flow settings without any stroke limitation.  The flow setting and temperature control components should operate independently.  Some PICV designs use the stroke of the actuator stem to set the flow rate resulting in limited stroke and control.  This can cause issues at low flow rates whereby the PICV effectively becomes on/off irrespective of actuator selection.  
  • The manufacturing process and the component materials also contribute to accuracy. For example, injection-moulded, glass-reinforced composite materials cope better with water conditions that valves can be exposed to.  They also have less material shrinkage than other materials, delivering higher accuracy than valves that use alloy components.

What else should be considered?

The importance of accuracy and repeatability are paramount when selecting a PICV however there are other factors that should be considered:

  • Wide flow rate range – including low flow rates for heating applications, ideally covered by a small number of valves.
  • Setting the flow rate – setting the PICV can influence the accuracy. There are various scales used including set points related to flow rates and percentages. PICVs with very detailed scales with small increments between set points are more difficult to set accurately, leading to higher tolerances than the BSRIA standard recommended + 10%.
  • Wide ΔP Range – low start up pressure. To operate satisfactorily, the PICV requires a minimum pressure differential to overcome the initial spring resistance within the PICV, enabling the spring to move and take control. Care should be taken to ensure the minimum pressure differential is as low as possible to maximise the energy saving potential of the system.  The maximum DP should also be considered to ensure the PICV operates effectively under part load conditions.
  • Dirt tolerance – the Valve Control Opening Area [A] on all PICVs, irrespective of the manufacturer, is identical for each flow rate. The shape of the Control Area can be different depending on the valve design. A Rectangular flow aperture is more tolerant than an Annular flow aperture. Debris will pass through the rectangular aperture more easily.
  • Removable inserts – deliver the greatest flexibility and serviceability.  Products can be easily serviced in line without disruption. This is especially of value when water quality is poor or when flow requirements change due to changes in space usage.  Inserts can also be removed during flushing.  Valve bodies can be installed with blank caps eliminating the risk of damaging or contaminating the PICV element, whilst having a full-bore flushing capacity.
  • Installation – PICVs in general have no installation restrictions however in line with BSRIA BG29/20, it is recommended that PICVs should be installed in the return branch as small bore PICVs will have a high resistance which will hinder the flushing velocity during the forward flushing of terminal units.

Making the right choice

There are many aspects for specifiers and project engineers to consider when selecting the right PICV for an application.  The BTS1/2019 standard provides an excellent benchmark, but the individual designs also need to be carefully considered.  A correctly selected PICV will ultimately lead to a more comfortable indoor climate with better control of the space heating and cooling as well as potentially reducing the pump energy consumption in a building by up to 35%.

This post was authored by Andrew Pender, National Sales Manager at FloControl Ltd. All views expressed are those of the author. If you belong to a BSRIA Member company and wish to contribute to the BSRIA Blog, please contact marketing@bsria.co.uk

Filed under air conditioning, BEMS, best practice, BSRIA, BSRIA Member Post, Building services, buildings, Cooling, Design, Engineering, Heating, human comfort, HVAC, Technology Tagged with , , , , , , , , , , , , ,

District Heating and Cooling and Heat Interface Units are still closely tied markets

July 28, 2020 by Leave a comment

Socrates Christidis
BSRIA Research Manager – Heating and Renewables

District Heating and Cooling networks have witnessed significant growth in many European countries in the last five years and this is set to continue in the coming decade. Significant European policy initiatives, such as the Green Deal, country government promotions, alongside increased public and private investment are supporting new business models such as utilities selling heat as a service and not as a commodity, which will drive the market forward.

BSRIA research indicates that the share of heat pumps and Energy-from-Waste in district heating and cooling systems is increasing. This trend is in line with the development of the concept of 5th generation heat networks. These are demand driven and low-temperature networks, using locally available low-grade waste heat (A/C, datacentres, underground stations, etc.), low temperature renewable energy in bodies of water and solar energy instead of a central energy centre. In principle, such systems favour the use of substations at building level, but no heat interface units at the dwelling level, as these are likely to be replaced by heat pumps.

Currently industrial boilers and CHPs remain the main source of heating in District Heating networks. For instance, 85% of planned heat networks in the UK, will have a CHP as the primary source of heating and 50% will have a gas boiler as a backup. The remaining 15% will use geothermal, ground source or water source heat pumps.

Thus, in the short-term Heat Interface Units (HIUs) will remain the link between the apartment and the network.

Going forward, reducing demand for heating and increasing need for hot water and cooling imply that the market will see the uptake of:

  • All-in-one units (heating or cooling and hot water)
  • Cooling units
  • Hybrid units, with integrated electric water heating
Graph showing European HIUs market growth

The main threats for HIUs market progress are the currently lack of consistent quality of installation and COVID-19.

Heat interface units have a major impact on the overall performance of a heat network and successful operation and performance both depend on correct system design and specification, followed by competent installation and maintenance. This has been problematic, with systems inadequately designed and quite often oversized. We see some signs of improvements as the industry becomes more sensitised towards good quality district heating. Documentation is improving as well as codes of practice, testing of HIUs, and further testing on site; however, under tight budgets the emphasis is often for the lowest cost, specification compliant technology. Testing the unit in a lab and then onsite is optional but critical to ensure performance.

Closing of construction sites was the main impact of the Coronavirus pandemic, including lack of cash flow, as the invoicing is done when products are delivered onsite. The industry has also witnessed a lack of new orders from April to June, with some signs of recovery observed just after. Overall, the European sales in the first 6 months of 2020 were between 15% and 30% down, depending on country, when compared to the 6 first months of 2019.

Going forwards, new construction presents a slightly positive picture. During COVID-19 there has been delays but not cancellations in planning permissions; delays as sites operate under social distancing guidelines and some delays for new investment to come through. However, governments and authorities are still eager to go ahead with programs and incentives, with renewed emphasis on the environmental agenda.

Looking at estimations for completions of flats before and after the outbreak, the recovery is likely to accelerate in 2022, and the market is unlikely to recover before. The end of financial support schemes by governments (VAT deferral, loan schemes or furlough) is likely to have a negative impact on many businesses, including contractors. Indications are, that new build and residential sales will be hit harder than commercial ones. Southern Europe is also likely to struggle more, although recession is expected across most of European countries.

Taking all this into account, BSRIA sees the numbers of heat interface units growing steadily but at a single digit compound annual growth rate of just over 4% on a Pan-European basis. The market will become more diverse and will look for more flexible options to cater for high-end, electricity-only heating, mixed-used and communal areas.

To find out more about BSRIA’s District Energy and Heat Interface unit market studies contact us at:

Filed under BSRIA, Building services, CHP, Construction, Cooling, Energy, Heating, Market intelligence, market research Tagged with , , , , , , , ,

A BEMS is the key to unlocking a more sustainable and resilient data centre

March 24, 2016 by Leave a comment

Sam Fitzgerald, Key Account Manager at Trend Control Systems

Sam Fitzgerald, Key Account Manager at Trend Control Systems

Sam Fitzgerald, Key Account Manager at Trend Control Systems, explains the functions of a Building Energy Management System (BEMS) and the vital role this technology can play in today’s state-of-the-art data centres.

In order to minimise the potential for downtime, data centres must be resilient, compliant with all relevant standards and operating procedures, while at the same time minimising overall energy consumption. BEMS have the proven ability to maintain the high levels of uptime and energy efficiency that are demanded by users by proactively monitoring, analysing, understanding and improving a data centre’s building services infrastructure.

Under control

A BEMS monitors, manages and controls building services and plant by ensuring that it operates at maximum levels of efficiency and reliability. It does this by maintaining the optimum balance between conditions, energy use and operating requirements.

By controlling an entire estate’s building services from a centrally managed location, it enhances the ability to interact with, and improve the quality of, the data centre infrastructure. Intelligently understanding and responding to patterns of usage means that, for example, cooling can be fully optimised and lighting turned off in unoccupied areas.

Being aware of the way a data centre works makes it possible to determine which best practices to implement in order to protect IT assets, while minimising costs and the potential for downtime.

Energy levels

It is estimated that data centres account for around three per cent of the world’s total energy consumption and with growing use of the cloud and the rise of the Internet of Things, that figure is only going to go up. Furthermore, according to the Digital Power Group, the sector uses 50 per cent more energy than global aviation and is now considered one of the major sources of global CO2 emissions.

Efficient use of energy is clearly no longer an option and there is a growing raft of legislation and regulation that is specifically designed to ensure that energy consumption and carbon emissions are measured accurately, and that any applicable data is available for analysis.

Given that up to 84 per cent of a data centre’s energy consuming devices can be directly under its control, a BEMS is without doubt the most effective way to gain a true understanding of where savings can be made, monitored and sustained. A properly specified, installed and maintained BEMS will ensure that building services operate in strict accordance with demand, which will also help to deliver the lowest power usage effectiveness (PUE) rating.

Far from being ‘fit and forget’, a BEMS can evolve with the building over a period of time. It must be regularly maintained and, where necessary, adjusted to ensure that it provides the best possible quality of service.

The bigger picture

Sustainability isn’t just about energy usage though. A BEMS can also limit wear and tear on plant equipment by using it more efficiently and making sure that any maintenance issues are highlighted.

In addition, a properly configured BEMS will be scalable, future proof and full backwards compatible. A system that allows easy upgrading and reconfiguration is always preferable – not all systems are the same and the costs of installation can vary depending on the protocol used.

Trend is committed to ensuring the backwards compatibility of its technology. For example, its new IQ®4 controllers are able to communicate with the very first device that it manufactured way back in 1982. The IQ®4 modules are also interchangeable for additional future proofing, scalability and system longevity – all of which can protect the financial investment in a BEMS.

Always on

According to research carried out by Emerson Network Power and the Ponemon Institute, the cost of data centre downtime is just over $7,900 per minute. Total data centre outages in 2013 averaged a recovery time of 119 minutes, equating to about $901,500 in total cost.

As well as being incredibly inconvenient, it’s the damage to mission critical data, impact on organisational productivity, harm to equipment, legal and regulatory repercussions and lost confidence and trust among key stakeholders that can prove difficult to recover from. A data centre should therefore look to build resilience into its operation via a BEMS, minimising any risks associated with situations such as plant failure or environmental conditions falling outside acceptable parameters.

Alarms can be programmed into a BEMS, so that in the event of equipment malfunction the problem can be identified and rectified as quickly as possible. For instance, on an air-handling unit, if a flow sensor highlights that airflow is decreasing it is likely to mean that a filter is blocked. Addressing problems like this early on will ensure that temperature conditions in a data centre remain within those agreed in a service level agreement (SLA), minimising the possibility of penalties. A BEMS can also minimise the amount of time required to carry out such tasks by either automating them or undertaking comprehensive data acquisition.

Rules and regulations

Compliance with statutory legislation, key performance indicators (KPIs) and SLAs are fundamental to the success of any data centre.

A BEMS provides overall visibility of plant energy use and allows personnel to see in real time what’s happening within a facility, therefore helping to make sure that equipment stays within a manufacturer’s specified temperature and/or humidity range. In addition, details of data centre conditions on a 24/7 basis can be logged to provide a full audit trail.

A growing number of data centre operators are also choosing to put an energy management system (EnMS) in place to achieve compliance with ISO 50001 or the standards used to measure data centre efficiency developed by The Green Grid. Having a BEMS in place will help demonstrate a desire to continually improve a data centre’s energy efficiency.

Therefore, the requirement for this technology in data centres is only set to increase.

For further information please call Trend Marketing on 01403 211888 or email marketing@trendcontrols.com.

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Filed under building energy management systems, buildings, Cooling, data centres, Energy, energy management, energy perfomance, Performance Tagged with ,

Best & Worst Practices Please!

June 23, 2014 by Leave a comment

Julia Evans, BSRIA Chief Executive

Julia Evans, BSRIA Chief Executive

BSRIA recently held a workshop on behalf of DECC identifying priorities to promote low carbon heating and cooling in non-domestic buildings as part of the development of its low carbon heat strategy.  Attendees were drawn from both the Young Engineers and Energy and Sustainability BSRIA networks.  Personal thanks to AECOM’s Ant Wilson for chairing the event.

It was a busy day.  It recognised that both new and existing buildings have a pivotal role in reducing greenhouse gas emissions, and by 2050 one of the key requirements will continue to be how we provide heating and cooling.

BSRIA’s Peter Tse and Ian Orme both gave excellent presentations which drew on both good and poor practices identified from more than 50 independently assessed case studies.  These, I felt, answered the questions “what does good practice look like”, as well as “what are the consequences when its not followed”.

The workshop session resulted in many suggestions as to priorities for the future.  There were a couple which caught my eye.

In response to the suggestion that one of the priorities for DECC should be identifying independently assessed best practice and developing exemplars of new technologies, a number of delegates felt that instances of “bad practice” were even more helpful.  It seemed to me that a priority for at least a part of the audience was to know what to avoid doing.  Perhaps this reflects the industry’s receptiveness to messages about risk, and that we often learn most when we make mistakes.  The emphasis on “independent assessment” also resonated.  Many have become sceptical about instances of self-identified “best practice”, and BSRIA’s independent guidance on what works, and what does not, is there to assist the industry do things better.

Another of the workshop themes was on “skills shortages”.  After many years of recession, construction companies have euphemistically “right sized”, and this means that we have lost a lot of great talent from the industry.  Now that there are green shoots of recovery in construction, there is already talk of an exacerbated “skills gap”.  This gap makes it even more challenging for the industry to deliver buildings which meet the needs of their occupiers and where innovation is required to help tackle climate change, and meet the UK’s commitment to “zero carbon” and “very low energy” buildings. This reminded me of another of BSRIA’s strengths – training provision.

BSRIA's 2014/15 Training Brochure

BSRIA’s 2014/15 Training Brochure

Finally there was an astute observation that our recent quest for low carbon buildings has meant that we have worried less about the efficient use of energy, with the net outcome that we can end up with an EPC A rating for carbon design, but a DEC G rating for energy in use.  The move to policies that move us to buildings which are both zero carbon and nearly zero energy use will hopefully remedy this, although I suspect this particular journey may contain further unintended consequences before we reach that goal.

The workshop identified many requirements if we are to create environmentally conscious buildings that meet user needs, and importantly maintain these elements over the life of the building.

BSRIA’s mission remains to “make buildings better”.  As part of my role, I’m listening to our members and the industry what they expect from BSRIA.  I’d like to extend this offer to you, so if you have ideas about BSRIA’s future role, please send them to me: Julia.evans@bsria.co.uk.

To learn more about the BSRIA workshop you can download all the presentations from our website. 

Filed under best practice, BSRIA, Building services, buildings, Construction, Cooling, Customer Satisfaction, DECC, DECs, Heating, low carbon, non-domestic, Occupant Satisfaction, skills, training Tagged with , , , , , , , , , ,

The hidden menace of corrosion in heating and cooling systems

February 21, 2014 by 1 Comment

Written by Reginald Brown, Senior Consultant at BSRIA

Written by Reginald Brown, Senior Consultant at BSRIA

Most buildings services engineers will have come across a heating or cooling system that has not received water treatment and still appears to function perfectly and another that has apparently been treated but experienced serious corrosion related failures. Why should one be vulnerable and the other not? The answer is that most common metals are subject to corrosion but the rate of corrosion and risk of failure depends on a variety of factors including the chemical and microbiological environment, temperature, flow rate and not least the thickness of the metal.

In many respects water is the ideal heat transfer medium for building services. It has a reasonably high specific heat, is liquid over a convenient temperature range and is non-flammable, non-toxic and freely available. The downside is that water is an electrolyte that facilitates corrosion in metallic pipework and components. One might think that the obvious solution is to use plastic pipework but this can actually increase the risk of corrosion of the corrodible components that remain.In a steel pipework system, the dissolved oxygen in the system water will rapidly be used up as it reacts with the large area of corrodible surface but the loss of metal thickness should be insignificant. In a plastic pipework system there are few corrodible components so oxygen concentration will remain higher for longer and the corrodible materials will continue to corrode at a high rate. This means that almost all water based heating and cooling systems should have some form of water treatment to control corrosion, and it may be even more important in plastic pipework systems.

The usual construction programme for large building projects involves installation and pressure testing of pipework followed by pre-commission cleaning and commissioning several months later. During the gap between pressure testing and pre-commission cleaning the system may be both stagnant and still contaminated with manufacturing and construction residues. This is an ideal environment for the development of biofilm and corrosion.

In traditional steel pipe systems (using BS 1387:1985 or BS EN 10255:2004 medium or heavy grade pipe) this is not too much of a problem. The relatively thick pipe (at least 3.2 mm for 1 inch nominal bore and larger) can tolerate the initial corrosion due to the oxygen in the fill water and biofilm development during subsequent stagnation conditions. Provided the pre-commissioning cleaning is carried out effectively, ideally with a biocide wash prior to chemical cleaning, there should be minimal impact on the lifetime of the system.

Thin wall steel pipes and steel panel radiators may not be so fortunate. The thickness of 25 mm nominal bore thin wall carbon steel pipe is only 1.5 mm while a typical steel panel radiator is only 1.3 mm thick. If the initial corrosion was spread uniformly across the metal surface it would not be problem but what tends to happen is that small patches of the surface become anodic relative to their surroundings and are preferentially corroded leading to rapid localised pitting. If dissolved oxygen levels persist or are replenished due air ingress, continuing additions of fresh water or permeation through non-metallic materials then the pitting can progress to perforation. Components that should last 25 years can be perforated in a few months. This is one of the most frequent types of corrosion failure reported to BSRIA and can result in expensive remedial works even before the building is occupied.

Water treatment chemicals work by inhibiting the corrosion process, either by coating the surface of the metal (anodic inhibitors) or otherwise blocking the corrosion reactions (cathodic inhibitors). However, inhibitors are not the solution to poor closed system design or operational deficiencies and certainly won’t work to best effect in a dirty system i.e. one with a high level of suspended solids and/or biological contamination. Also, the system operation must allow the inhibitors and other water treatment chemical to be maintained at an effective concentration and circulated throughout the year.

In summary, the factors necessary to avoid pitting corrosion of steel components in closed systems are:

  1. Minimise the delay between first fill and pre-commission cleaning.
  2. Carry out effective pre-commission cleaning of the pipework system.
  3. Establish, monitor and maintain effective water treatment and water quality as soon as possible in the life of the system.
  4. Circulate water throughout the system on a daily basis to avoid stagnation.
  5. Avoid ingress of oxygen from inadequate pressurisation or excessive fresh water additions.

What happens in the first few weeks of the system can prevent pipe corrosion like this over the next 25 years

What happens in the first few weeks of the system can prevent pipe corrosion like this over the next 25 years

What happens in the first few weeks of the life of the system will influence its fate over the next 25 years. You can’t easily see what is going on inside a pipe but get it wrong and you could be looking at major remedial works in a tenth of that time.

A detailed discussion of corrosion and the use of inhibitors and other chemicals is contained in BSRIA BG50 Water Treatment for Closed Heating and Cooling Systems. Pre-commissioning cleaning is described in BSRIA BG29 Pre-commission cleaning of pipework systems. Guidance on the monitoring of water quality in closed systems is contained in these documents and BS 8552 Sampling and monitoring of water from building services closed systems – Code of practice.

BSRIA also runs a Pre-commission cleaning of pipework systems training course and provides independent failure investigations for all types of building plant and systems including pipweork corrosion.

This article was first published in Modern Building Services.

Filed under BSRIA, commissioning, Compliance, Construction, Cooling, Heating, Pipework, Pressure testing, Water treatment Tagged with , , , , , , , , , , , ,

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