Has the traditional boiler had its day?

Is the heating and plumbing industry about to wake up to the potential of solar energy in the UK? Eric Hawkins, Technical Director of Powertech Solar, has used his own property to provide a convincing case for a re-think of domestic heating arrangements.

Has the traditional boiler had its day?

Over the past five years my company has looked to educate both the homeowner and the plumbing, heating and building trades about the benefits and savings/profit potential of solar thermal energy (not solar PV electricity). I have to confess that success in this area has been very limited because I failed to appreciate just how much the plumbing, heating and building industries are resistant to change – you only have to look at the time they have taken to accept plastic pipe and push fit fittings.

We have spent years of advertising in various trade journals, communicating with Government ministers at the highest level and presenting at conferences and exhibitions to try to get the message across. The problems we face through climate change have yet to be recognised by the majority in this industry. For most companies it’s a case of business as usual until such time as the government starts to force every builder and heating engineer to produce buildings which focus on reductions in energy and water waste rather than how aesthetically pleasing they are to the house buyer.

I want now to bring an insight into the true benefits of solar energy having used my mid-terraced home, near Wimborne in Dorset, as a model of what is possible. This mid-terraced home within a 50 home development, built six years ago, is typical across the land except for one thing – it has been converted into a Sustainable Home.

As with 99% of most housing developments today, it was originally fitted out with a standard gas boiler/radiator/vented cylinder, un-insulated copper pipe plumbed in central heating system, commonly available from every plumbers/builders merchant up and down the country. On acquiring this new property I set about removing the miles of copper pipe from the loft area which adjoined the 60 gallon cold water and central heating header tank which was located near to the loft hatch so that nobody could gain space to the other 70% of the loft area.

The cold water storage size was doubled and relocated to a place in the loft out of the way and all pipework was replaced in plastic and fully insulated. The storage tanks were then connected with a rainwater harvesting system located between the shed and back of the house. To gain hot and cold water from filtered rainwater, a 3 bar pressure pump was purchased from Australia (still working today) which now switches between rainwater supplies into the loft water storage when available and to the mains.

Heating alternative

The small foamed lagged copper indirect vented cylinder next door to the bathroom was replaced by a 300 litre Powertech Combi Cylinder (Thermal Store) and located in the much larger loft space area. Unlike most other thermal stores that require store temperatures upwards of 74-86°C, the Powertech unit provides space heating (through its underfloor Ply-pipe heating system) and hot water at mains pressure (25-30 litres a minute) at 48-55°C.

As much as I was keen to have underfloor heating installed, the developer would not allow it, so we were stuck with the typical steel radiator located under windows and other well chosen places around the house, leaving our feet cold even with the gas fired central heating running at 20kW of gas burning an hour.

With most of the internal changes we wanted in place now completed, along with re-designing the bathroom and en-suite into something which worked, it was time to add the renewable energy and water appliances.

A bank of 44 x 1.8m long Apricus Vacuum Tube Heat Pipe Thermal Collectors were chosen to meet part of the home’s daytime space heating needs as well as 100% of hot water needs outside the heating season. In order to eliminate the need of the pre-installed gas boiler and its yearly servicing costs, a loft air-to-water heat pump was installed high in the loft space and central to gain any rising heat into the loft, as well as ambient air temperature through the tiles and vents.

Less is more

Unlike ground source heat pumps which extract low temperatures of heat (3-6°C) from under the ground through hundreds of metres of pipework and a lot of money, the loft heat pump uses just 700W of electricity, delivering 2.5kW of thermal heat output. The heat pump, unlike the gas/oil boiler, operates over a 12-16hr period raising the combi thermal store’s temperature degree by degree through the circulation of the stored water via the heat pumps heat exchanger and evaporator and back to the store.

When used in conjunction with solar energy collectors, a thermal store and underfloor heating, backed up by off peak/cheap rate night time electricity from a renewable energy resource, is perfect and has the very minimum in servicing costs over 20 years+ of its expected lifespan.

Even when installed with steel radiators and un-insulated copper pipes hidden under the floors, the home maintains its warmth from the initial boost in the morning from off peak electricity, starting at 5am until the heat pump switches off at 9pm.

Typical year-on-year running cost of electricity, off peak and day rates is running at £180 – allowing for four months of the year in summer when all the solar energy (100% tax free) provides all the hot water even into the next day from the 300 litre store.

Power back up

To cover all aspects of the home’s energy and water needs, this year we installed the latest 3 phase 400W Micro Turbine, along with 320W of Photovoltaic (PV) Solar panels, on the roof at the front of the house. These two generators of electricity, at 24V DC, are converted from a gel battery bank into 220 AC via a 2.5kW inverter.

The 700W peak power load, subject to daylight and wind direction, provides our home with 100% electricity for its CFL and LED lighting throughout the house, 100% power for the solar controller and pressure pump along with a socket for other power needs whenever a power cut may happen. (Householders with combi boilers don’t seem to understand that if there is no power for the 50W pump they have no hot water or heating.)

At the rear of the house, on the roof of the shed, a further 500W of PV panels provide power to operate the rainwater harvesting pumps, the garden lights and, in summer time, the deep freeze. A further step towards a more sustainable lifestyle, outside the home and for relaxation I have a poly tunnel and some land where 70% of our vegetables and some soft fruits are organically grown, again watered by collecting from nearby roof tops to reduce mains water use.

Growing market

Last year, over 7,000 solar hot water systems were sold and installed, compared to 2,000 in 1998. Sadly, the heating and plumbing industry has yet to understand why a growing number of homeowners are prepared to invest up to £8,000+ for a solar installation, in readiness for the explosive costs of present fossil fuel energies, rising servicing and replacement parts.

What has become clear over these years, is the Government’s failure to recognise the proven benefits of solar thermal energy and air-to-water heat pumps as they push towards a nuclear future, pointing out that small scale renewable energy technologies are not working – despite the fact it is only 2-3 years since the grant programmes, such as clear skies and the solar PV programme, were introduced.

What is clear is that at some time over the next two years the choice will be simple – moan about the rising cost of gas/oil and electricity and start to see a slow decline in standard central heating installations or grasp now the existing business opportunities that exist outside the established marketplace.

Looking ahead

Our goal is simple, it’s about reducing home carbon emissions which all of us produce and add to every time we drive the car or fly to our dream destination. My home in Wimborne has a year-on-year running cost of around £350, with the only servicing required to make sure the pumps are running and water filter is changed every four months. Reductions in carbon for this home amount to around 1.4 tons per year. The collectors pump solar heated water into a store (cylinder). In winter months there is enough air temperature to enable the heat pumps (which work in reverse of a fridge) to produce enough hot water to feed the hot water cylinder.

As far as we’re concerned the combi boiler is a thing of the past and no longer needed if any consideration is given to the homeowners ongoing rising costs. The combi boiler may be easy to sell and quick to install, but it leaves the homeowner with no back up water storage. Try living without hot water for just one day when you have kids. If there is a power cut they will have no heating or hot water – all for the sake of a 50W circulating pump. If the boiler goes down, the homeowner is held to ransom by a service engineer who has to be CORGI approved to even touch the boiler.

We need more plumbing/heating engineers educated to recognise that changes are on the way. Let’s move away from the past when it comes to boilers, copper pipe and radiators and start to train for the future (which has been going on for 10 years!).

30.01.2007. 14:57