Chris Goggin, Associate Director of continuous flow water heater manufacturer Rinnai, looks at the fast pace of change in the industry as the Government demands ever-greater efficiencies.

Change in the H&V industry over the past decade has been accelerated and the rate is going even faster as pressure builds to find better and more efficient ways of heating and conserving hot water.

As soon as anybody says the word ‘change’ panic sets in. However, it is not change itself that people should be wary of, but the manner in which change is managed. In the case of change in the H&V world the race to comply with Government goals to lower emissions and conserve energy can only be welcomed as we enter a period of fuel supply uncertainty.

The way to future proofing against rising energy bills and new legislation, both of which are inevitable, is to concentrate on the best available technologies for heating and hot water design and avoid the inertia that exists around simple direct replacement.  For instance you wouldn’t upgrade your iphone to a pager as technology has moved on.

Progressively, standards have decreed that building envelopes  must be insulated to create greater ‘air tightness’ so that thermal insulation is much improved.

Conversely, the demand for instant hot water has markedly increased and this means we need to adopt a new mindset that separates space heating from hot water provision. There is no need for a big hot water storage unit, for example, to satisfy the needs of large radiators as well as hot water. There is even guidance on the topic illustrating that considerations for separating heating from hot water should be a design consideration for energy conscious consultants.

Consideration has to be given to best available technologies and how they can augment hot water supply.  Consider an A-rated gas fired continuous flow hot water system, when used as a booster to renewables such as ASHP or solar thermal, an energy efficient gas powered continuous flow unit will be the modulate gas input maximising efficiencies lowering running costs and reducing emissions.

However, if we take the domestic setting as a marker, even though demand has changed significantly, eight out of 10 installers will still want to install the biggest combi unit they can find to ensure hot water needs are met with the payback being heat generated for heating. It is not the best and most efficient way forward.

For example, a well insulated house swapping from a hot water storage system such as this to a gas fired continuous flow hot water system can save 3kW a day, which equates to around £220 a year.

An A-rated gas fired continuous flow hot water system is a real consideration for large domestic properties when coined with a system boiler for domestic heat.  Greater gains can come from commercial usage office buildings, large and small commercial premises, hotels, hospitals and care homes and on to leisure centres and caravan sites.

A space-consuming and costly cylinder that has to be heated 24/7; 365 days a year to ensure hot water is always available is an anachronism in today’s energy and cost conscious world.

Even if no hot water is drawn off, a standard cylinder can lose anything up to 6kW of heat a day. All cylinders suffer from this to some extent and it can equate to over a year, to 2190kW of energy wasted. If you also look at the gas saving alone it equates to in excess of 200m³ of gas used.

So not only do we have to encourage a sea change in hot water provision we also have to open up minds to not always replacing like for like and turn to better and more effective systems.

A North Wales Council is currently in the process of replacing its stored hot water systems with continuous flow set-ups. The council has done its sums and is set to make considerable savings on running costs. When the water isn’t running the continuous flow system is not using gas which makes it an ideal solution for schools for example that shut for holidays. And, no worries about Legionella proliferating in the lay-off.

Even when a continuous flow system is chosen, more efficiencies can be built in by ditching the established mindset that always goes for overkill on hot water capacity just in case it is needed.

Litres of stored hot water just isn’t necessary when designing a gas fired storage system the mind set  more often than not is to design in a 15% overcapacity buffer.   It is high time we start sizing for actual demand and optimising efficiency for what’s been used, as opposed to sizing for what might happen at worse case and paying for what! – you wouldn’t leave your can running over night.

Here is an example: An installer is called on to install a hot water system to serve 14 showers at a gym and some WHBS. SMART  thinking will interpret that as needing three HDC1500i continuous flow units to ensure hot water at all times. The intelligence of the system means that the water heaters will only fire when demand increases i.e. only one heater fires when upto 5 showers are in use, ensuring optimum energy usage.

If you consider that an A-rated continuous flow water heater will probably not be in use all of the time it is always going to outperform any A-rated storage system as it would by necessity be switched on at all times slowly leaking heat through the cylinder.

The use of single or manifolded A-rated gas water heaters can really make a difference to running costs, but step up to a condensing system with a secondary steel heat exchanger within the unit and that is where the very high efficiency figures kick in. The other advantage of a condensing unit is that there is a greater modulation range 58 to 2.4 kW. The condensing process can deliver up to 95% thermal efficiency, which translates to significant energy savings when compared to standard continuous flow water heaters.

Controls are also a major step forward in achieving best efficiencies whether local or integrated into a building maintenance system.

Finally, the implementation of the Energy Labelling Directive (ErP)* last year means for the first time there is transparency for buyers looking for the best energy efficient range of water heaters.

In practice an A-rated continuous flow water heater has even more to offer in terms of efficiencies in operation as the A-rating applies only to when a unit is in use – ie when fuel is being burnt.

* All water-heating products sold in the UK need to meet minimum energy performance criteria in order to be legally placed on the market, and require an energy label.

For more information on the RINNAI product range visit www.rinnaiuk.com