Technical Questions and Answers

Answers

In what types of buildings have you successfully saved energy?

Schools, Leisure Centres, Swimming Pools, Libraries, Civic Buildings, Warehouses, Factories, Commercial Offices, High Rise Flats, Sheltered Homes, Residential Homes.

How much fuel will the Fuelstretcher save?

The scientists at the Building Research Establishment at Watford, where it was developed and validated, said that it would save between 5% and 30% of the fuel used in a heating installation, depending on the sophistication of other controls present. This estimate has been proved in the field, where savings of between 9% and 30% have been made in commercial installations. The average saving is in the region of 15% - even when used alongside a BMS.

How does the Fuelstretcher work?

By computing daily the heating system relationship between boiler output temperatures (Flow) and Building feedback (Return) temperatures in a continuous learning process (usually beginning early in the morning). The computer selects the optimum boiler temperatures for building comfort and boiler energy conservation for the rest of the day and evening. Under normal boiler operation the lower the boiler temperatures the less energy used or – more importantly - wasted by the heating system and building. All buildings and heating systems, whether new or old, waste heat energy to a lesser or greater degree.

What about reliability?

Manufacturing and quality control is of a high standard. As with most established electronic controllers functional reliability is high. In our case we have never had an operational failure. From a savings performance standpoint the controller has surpassed the expectations of the research.

Will it work with my heating system?

The Fuelstretcher will control and sequence multiple boiler installations of any size (as long as all the boilers feed into a common manifold or header). It will not work with steam systems but will save fuel on virtually every other boiler powered heating system using a variety of fuels. It is highly likely that it will work with your system and if it doesn’t we will know it!

If you reduce primary temperatures will our radiators be cooler with your controller installed?

Often yes. Radiators that are too hot to touch are invariably delivering wasteful heat in the form of “overshoot”. The key indicator of comfort is the temperature of the space being heated and its consistency and not the temperature of the radiator

I have Constant Temperature Circuits – they always need high primary temperatures?

Even though circuits have been designed for constant temperatures your local room sensors and comfort control will exercise control of mass hot water flow to the CT heat exchangers. If the Fuelstretcher logic, through its profiling, decides that lower primary temperatures can be used your local control system will simply call for a greater mass flow of hot water to the heat exchanger.

If you are reducing boiler temperatures for heating how do you maintain temperatures for Hot Water Services (wash basins showers etc) and ensure that no legionella bacteria develops in hot water cylinders?

We place an override sensor on the cylinder to protect cylinder storage temperatures but the Fuelstretcher has slightly more scope for energy saving if the Hot Water Services (HWS) system is independent from the comfort heating.

If the hot water storage cylinders are a long way from the boiler house and sensors are impractical how can you ensure storage temperatures are maintained?

We can replace the sensor with a boost timer switch to ensure that, following a brief demand analysis of HWS requirements from the remote cylinders, we can provide a lift in primary temperatures to meet the demand profiles of the normal day.

Does the building need to have a BMS installed for the Fuelstretcher to be effective?

No, in fact it is likely to save more if a BMS is not installed.

We have a Building Management System (BMS) in our building. Can the Fuelstretcher do what it does?

No, the BMS has the capability of providing many computerised building control and heating management functions. The Fuelstretcher is dedicated, as an energy savings measure, to saving fuel on boilers but within the BMS’s overall heating management and comfort strategy.

We have a Building Management System. We believe it can be programmed to do what the Fuelstretcher does so why should we buy the Fuelstretcher?

The Fuelstretcher is a patented technology and no other technology worldwide is legally permitted to “do what the Fuelstretcher does”. Even then computer modelling has shown an 11% saving by the Fuelstretcher over BMS demand compensation strategies. In practice the Fuelstretcher has consistently reduced heating consumption in buildings managed by a BMS by 12-15%.

How can I be sure it will not interfere with my BMS operation?

The Fuelstretcher will interface with any existing heating control system. It will operate within the supervision of Building Management Systems in terms of scheduling, frost setback and even its weather compensation control, as long as it has total temperature and sequencing control of the boiler. It is installed with full consideration given to the function of existing intelligent controls. In most cases existing Building Management System Integrators are invited to “partner” Fuelstretcher Ltd in the approach to building owners to provide a single voice to enhance the total intelligent control package. There are many Fuelstretcher controllers installed in this way and they all save fuel alongside the many valuable functions of the BMS.

Do any restrictions exist as to the type of boiler that the Fuelstretcher can control?

The Fuelstretcher will control most gas or oil boilers except:

• Steam boilers / generators
• Domestic boilers which serve individual dwellings

Condensing boilers are efficient - can the Fuelstretcher improve on their performance?

Not only can the Fuelstretcher save in the normal way but also its strategy is geared to helping the condensing boiler achieve maximum efficiency. If primary return temperatures are too high the condensing boiler will not condense and its efficiency is impaired.

What disturbance can I expect with installation?

Installation is quick and easy. It normally takes about 4 or 5 hours and does not disrupt the heating system. All the installation takes place in the boiler room and is electrical – no plumbing or breaking into your wet system is required. Apart from turning off the boilers for approximately 15 minutes to connect up to the burners, the ongoing operation of the heating system is not compromised. We actively encourage customers to use their normal BMS or heating maintenance companies or personnel to fit the unit. In this way, they become familiar with the controller and its behaviour within the total intelligent controls package.

Can the Fuelstretcher save fuel for CHP units?

Not directly, but most CHPs work with back-up boilers, which can be controlled in an energy-effective way by the Fuelstretcher. Most importantly the Fuelstretcher’s effect on the heating system is to reduce or eliminate the frequency at which the CHP dumps waste heat if return temperatures are too high for engine cooling.

How many boilers can be controlled and sequenced by the Fuelstretcher?

Any number by as long as they are connected to the same flow and return headers.

We are wary of so-called intelligent and programmable controls because, try as we may to stop them, people will fiddle with inputs and their value can be lost. How does the Fuelstretcher relate to this scenario?

We set up the programme immediately following installation. After this the operation is completely automatic and self-tuning. In fact no programming buttons are accessible to the end-user. Only an “Override“ key, for maintenance or troubleshooting purposes is available to switch the boilers to “ hand” mode.

How does one know if the Fuelstretcher is actually saving once it is installed?

We conduct controlled trials over a 6-week period to show reductions in fuel consumption when related to weather (degree-days). This is less accurate than longer term monitoring but has proved effective in indicating clear trends that the Fuelstretcher is saving. A more accurate assessment of savings performance is also carried out over at least a full heating season (if the client reports fuel consumption figures). We have options for linking Fuelstretcher sustainability to the measurement, monitoring and weather analysis of heating fuel consumption. In any case we offer the client contractually guaranteed savings over two years from the date of installation. A version of this involves the use of remote monitoring of meters and reporting against an historical benchmark.