Replacing a Boiler

Why & when you should replace a boiler? and factors to consider

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Why Replace A Boiler And What To Expect?

There are two main reasons to change a boiler system in a commercial building, the first is that it has come to the end of its economic life, and the second is when there has been a complete or partial failure and an emergency replacement will be required.

We cover both occurrences and can respond quickly to replace failed equipment, no matter the time or day to ensure that there is minimum disruption to the property.

For planned replacement, there is a significant amount of investigation required to ensure that you have the right equipment to last you for the next 20-25 years. A commercial heating system must be well designed to ensure that it gives trouble-free service over its lifetime. We look at what changes have been done to the building since the existing heating plant was installed e.g. double glazing, improved insulation, change of use, structural changes etc.

Important Questions

How have the building and product regulations affected the choice of equipment we can select now compared to when the last heating system was installed?
Are you in an Air Quality Management Area (AQMA)?
Do you want to switch from gas to electric?
Is the building listed or in a conservation area?
Does the site contain asbestos?
We can arrange  all types of inspections, reports and removal through our  specialists and partners.

General Considerations When Replacing A Boiler

There are many questions to ask before selecting the right solution for you, to ensure that your requirements are met within your budget,  installation is just as important as the operational costs over the life of the heating and hot water equipment, including both fuel and maintenance.

It is vital to assess the existing plant room and assess how it is being operated before any plans are made for replacement. The new equipment must comply with all current regulations and there must be an understanding of how future regulation changes may also have an effect on those choices. The changes in installation and emission regulations will have a significant bearing on what heating equipment is selected to meet your individual requirements.

Most new heating and hot water boilers will be fully condensing, but how does that impact your plant room? Can you reap the benefits? What changes must be done to ensure these boilers operate correctly?

When considering a new heating and hot water system don’t think like for like, either for sizing or heating mix. With new emphasis on low or zero heating sources, is there something that is available that would contribute significantly to reducing the emissions from the heating system? Are local regulations in place to stipulate minimum requirements such as the London Plan? Heat pumps are becoming ever more popular to supply heating, particularly in new builds but can be used for low temperature circuits and low system loads in existing buildings.

We also look at what your actual heating and hot water requirements are, if a total of say 500kW was installed 20 years ago but you can operate at 250kW without any issues why install more? This not just saves on capital costs but the smaller modulating boilers will match the real load much better, resulting in a considerably improved system efficiency, leading to substantial fuel savings over the years.

The major change when replacing standard boilers with condensing boilers is dealing with the condensate, the flues now must be sealed as the boiler flue gasses will be wet, cool and under positive pressure, while on older conventional boilers the flue gases will be hot and under negative pressure. As the condensing boiler flue gas discharge will plume, we will look at any potential impact on your building and how that will affect the surrounding area, particularly if we are looking to discharge the flue gases at a low level. Complying with the Clean Air Act is still paramount, but in central city areas can be a challenge.

As the cooler flue gasses in the condensing boilers are more condensed, smaller flues may be suitable. It is often possible to install new sealed flues inside the existing flue system to save capital and installation costs.

Both the boilers and flues will require condensate drains so attention will be required as to how this is to be accomplished, and will this solution be acceptable to the local water authority. Condensate is slightly acidic and may be required to be neutralised before it enters the drains. This can be quite complex as a 100kW boiler can produce ten litres of condensate per hour.

A Detailed Look At What To Consider

Condensing Boilers

Condensing boilers only condense, and give enhanced efficiencies if the water return temperature to the boiler is below 55°C. Older heating systems were often designed to operate at 71 – 82° C and hot water systems often requires 70-80°C primary water temperature, this is to ensure the secondary hot water temperature to the taps is the required 60° C to protect against legionella. It is important to assess if the plant room can operate at lower return temperatures to increase the boiler efficiency. Some boilers have twin returns so that any low temperature returns can be connected to the lower point in the boiler, which helps maintain the overall boiler efficiency. Check that the boiler can be fitted with variable speed pumps that also help maintain a lower boiler return temperature on lower loads.

Heating Systems

Heating systems will be increasingly subjected to emission reduction requirements and targets. It is important to minimise the heat requirement of the building and select the best combination of heating equipment, to meet both your needs and to minimise emissions; selecting Ultra-Low NOx boilers with very high efficiencies will be a must. Understanding not just the high load but minimum loads is also essential and selecting equipment that will meet the complete range of winter and summer loads as closely as possible. This load matching will significantly improve the overall system efficiency of the heating system.

When upgrading from a standard efficiency boiler system to modern boilers, it is possible to reduce the fuel used by 30 to 50% and NOx emissions by 80-95%.

There are many options for selecting a boiler, the type of materials it is made of, floor or wall/frame-mounted, and large or small water content all have advantages and disadvantages. As a result it’s very important to select the right boiler for the requirements of the site, get in touch and we will advise you of the options and take you through the whole procedure.

We carefully consider the whole design of the plant room to ensure that the auxiliary equipment such as pumps, valves, gas supply, ventilation, and flues are all selected whilst considering these factors to minimise installation and running costs.

Controls are a critical part of the system design and will be an intrinsic part to ensure reliable operation and help minimise energy use and emissions. We can design and install controls and control panels specifically for your site requirements

We work with you to understand your needs and try to make each stage as unobtrusive as possible, minimising downtime during the actual work period. All equipment is commissioned by the manufacturers to ensure that it is working to the optimum efficiency throughout the year, whatever the weather. Full training is also  given to ensure that you understand the operation and full maintenance documentation will be supplied.