The Boiler Story
St Thomas' Church installs central Newcastle's first
non-domestic biomass boiler
The new biomass boiler with ancillaries at St Thomas' Church
Introduction and background
St Thomas’ Church needed a new source of heating. The previous gas-powered boiler, believed to be as many as 80 years old, was finally condemned in March 2014 following repeated reports of the smell of escaping gas.
The Building Group at St Thomas’ commissioned a report into alternative sources of power for heating the church. The resulting document by consultant Jonathan Pope for C.P. Energy Ltd. investigated various options including harnessing ground- and air-sourced heat, solar panels, collaborating with Newcastle City Council on a district heating arrangement, retaining gas power and even tapping into heat from the underlying Metro subway system.
One option stood head and shoulders above the rest, and a vote was taken by the Building Group to pursue and secure the installation of a Biomass boiler.
Biomass fuel consists of pellets that are formed from virgin wood with a low moisture content. The timber comes from purpose-planted forests in the UK and as such the fuel can be said to be sustainable. Of course, other factors come into play when considering the question of sustainability. For example, one has to factor-in the distance that the fuel has to travel and how many deliveries may be needed annually, the carbon produced in the manufacture of the boiler and ancillaries and other such factors.
By using Biomass, St Thomas’ is not burning fossil fuels and thereby releasing carbon into the atmosphere irretrievably. Rather, trees are purpose-grown to provide the fuel. These trees absorb carbon dioxide from the atmosphere as they grow, carbon that is duly released again as the timber pellets burn. The process is therefore carbon neutral to a reasonable degree.
Another consideration is the price of fossil fuels and securing their supply. The cost of gas at the time of writing is fairly low - a situation that appears anomalous, historically speaking. North Sea gas fields are in decline, and it looks increasingly likely that Britain will have to depend on overseas supplies from countries such as Russia with whom political relations are parlous. While the cost of biomass pellets is currently slightly higher than that of the gas equivalent (and comfortably below that of oil and electricity per kW/hr), that cost will undoubtedly and logically prove a great deal more stable as will the security of supply.
One further argument in favour of burning biomass fuel is the Renewable Heat Incentive, or RHI. This tariff is a subsidy provided by the government to encourage sustainable heating installations. The rate degresses for new users as successful applications to the scheme are made, but is fixed for a given installation from the date of commissioning. It is paid monthly according to how much fuel is burned. The church is required to read the meter on a quarterly basis (a few days’ leeway is given), perform a simple calculation and upload the figures to the OFGEM website.
Having first fired-up the boiler and had its application accepted on 30th March 2015, St Thomas shall earn RHI income at a tariff of 6.8 pence per kW/hr for the next 20 years. The installation has been calculated to break-even well within its first decade of operation.
On inspection of the boiler room it was apparent that the red painted and flaking insulation on the pipework around the defunct gas boiler would necessitate an asbestos survey. Once the presence of asbestos was confirmed, this material along with pipework and the boiler itself had to be removed. The job was done by specialist contractors Nichol Associates Ltd.
The old boiler and pipework await removal
An airtight tent arrangement was erected around the boiler stairwell. All persons at work on the job had to be fully suited and booted and all waste correctly disposed of in accordance with HSE’s Control of Asbestos Regulations 2012.
The above images show the sealing of the boiler room area prior to asboestos removal
St Thomas' would like to thank The Rothley Trust for its generous grant towards the removal of asbestos in the boiler room. Finally, a full environmental clean of the boiler room was performed leaving a stark and empty shell. A clean slate!
Using the existing infrastructure
The boiler room at St Thomas’ was originally a coal store and furnace; coal was shovelled into the fire by hand, with the resulting heat dispersed around the church by water held in large diameter heating pipes and radiators.
An early stage decision was made to keep the biomass installation fully self-contained within the existing boiler room. This would negate the need for an unsightly, additional free-standing fuel store / boiler house as would normally be specified with this choice of heat production. An added advantage would be the removal of any need to gain planning permission for the work in this prominent, Grade II* - listed building. However, a Faculty, or permission for the work to proceed from the Diocese, would be in order.
The heating distribution system at St Thomas’ appears to date from around the 1930s. It consists of a huge circuit of large-diameter pipework feeding radiators on the ground floor and then up in a loop to the balconies. Serious consideration was made to the installation of a new pipe and radiator network and Dunphy Ecclesiastical were very helpful with this aspect of the project, which remains a future goal. However, and critically, retention of the existing pipework with its high volume of water has removed the need for a buffer tank in addition to the 1000 litre tank that is housed alongside the boiler. This additional unit would have needed to be positioned in place of - or on a purpose-built mezzanine above - the present WCs by the south Vestry, there being no more room in the boiler house.
The choice of installer
Several boiler installation companies were consulted before a contract was signed with The Wood Heating Company. TWHC, a company based locally in Cramlington, offered to supply a boiler with a high enough rating (enough power in kW) to heat the church’s large internal space adequately. Crucially, this boiler - an Austrian KWB Pelletfire Plus model - could be broken down into smaller modules in order that it be craned in through the basement-level boiler house doorway with no need to excavate a large hole as had previously been proposed. St Thomas’ sits on the site of the former St Mary Magdalene leper hospital and the archaeological survey that such work would necessitate would have been costly and potentially complicated. TWHC have gone out of their way to be helpful and attentive throughout the course of the project, and the installation solution they provided has proved to be extremely neat. It meets the needs of the church perfectly.
Funding the Installation
The cost of installing a biomass boiler at St Thomas’ came to around £65,000.The project was enabled by loans and donations from the church’s own congregation and from the general public.
Chimney Extension Question
With the project underway the question was raised of whether the chimney or flue outlet would need to be extended to a height of 600mm above the ridge (it sits some way below), as per document J of the Approved Building Regulations 2010. Following some investigation, it was discovered and subsequently confirmed by HETAS that this would thankfully not be necessary, since the installation would be doubly exempt from the regulation in that the boiler is rated at over 50kW and in that St Thomas’ is a historic building included in the schedule of monuments maintained under section 1 of the Ancient Monuments and Archaeological Areas Act 1979, which are exempt from compliance.
Lining the Flue
With the burning of any solid fuel, it is essential that the chimney or flue be insulated well enough that the exhaust gas remains hot enough throughout its journey from the boiler up to the chimney stack and beyond so that it may disperse safely into the atmosphere. Little was known about the layout and condition of the existing flue, other than that it was compromised. Consequently, initial drawings for this installation featured a new external flue, protruding from the upper east wall of the boiler room. Such an addition would have been unsightly, complicated to achieve on this Grade II* listed building, hazardous to the public and vulnerable to vandals. Further investigation revealed that the internal flue at St Thomas’ is lined by brick and climbs inside the wall of the South Vestry; it features two turns at acute angles before terminating centrally at the roof’s east end. It would need further lining. The choice would be between thermacrete and a stainless steel liner. Thermacrete is a heat-resistant concrete that is poured down the chimney around a balloon inflated to provide the correct (8”) diameter throughout. The balloon is then deflated and removed once the thermacrete has set. The stainless steel alternative is a simple, articulated, tubular metal shell. Thermacrete is more costly and is reputed to last longer. However the installer, Hancock Stoves and Flues, guaranteed the steel liner for a period of 25 years and ultimately we decided to leave the choice of liner in the hands of David Hancock. He chose steel.
The next step was to drop a coring ball down the flue from the roof in order to ensure that the required 8” diameter was available throughout the chimney’s length. Decades of soot deposits and the aforementioned tight turns resulted in what was hoped to be a formality turning into an all-day job. As the afternoon wore on, and after many hours of jiggling, the bottom of the coring ball was spotted from below. It was 3 metres above the boiler room, but it would drop no further. Anguish turned to elation when we realised that a knot in the rope above the ball had snagged on a protruding brick. It was freed, the ball dropped into the boiler room, and we were ready to fit the liner.
The big day came. Then it went. The week ended and Haymarket passers-by were continuing to marvel at the massive silver serpent lying in coils astride the roof of St Thomas’, its head disappearing into the chimney pot. It couldn’t make the turns in the flue. Hancock’s proposed to access the flue from inside the nave, an intervention we had wanted to avoid but which now it transpired was essential if further progress was to be made. Plaster was chipped-away at balcony level. Pilot holes were drilled. Stones were removed.
The final stages of the flue lining process
The unstinting efforts of the Hancock team resulted in the location of the flue from inside and a reworking of the turns in order that the flue liner could negotiate them. This was facilitated by bisecting the liner and dropping one half in from above and inserting the other section from below in the boiler room. The two sections were connected and the internal access holes made good with quite exceptional care and skill. The flue was lined.
Delivering the fuel
Access to the boiler room for fuel delivery was an issue at St Thomas’. The fuel would be delivered to the East end of the building, which is accessed by a network of narrow (as little as 1.5m wide in places) pathways lined with trees, bins and information boards.
Onsite sketch of the delivery route
It was good to know that the church owned the land itself so that no access permissions were required. Was this a Conservation Area? Were there any tree protection orders in place? What about a weight limit on the path?
All the above questions were investigated and satisfactory answers found in turn. A company providing high-quality fuel from a reasonably local source sounded positive about the project and had undertaken to conduct a drive-by in one of their wagons. Several weeks passed with no drive-by results forthcoming, despite repeated contact. Eventually an answer came in: No, the path was too narrow and the turns too tight for fuel delivery. Now the race was on to find another company to deliver. The trucks had to be of a specific type with a narrow track in order to make the turn and to minimise the impact of deliveries on the grass in the church grounds. One firm suggested parking on St Mary’s Place by the bus stop some 25 metres away. Quite apart from obstructing the traffic on that busy road, blowing pellets in from that distance and then performing a 90 degree turn into the fuel store would certainly have caused damage to this quite fragile fuel, in turn impairing the operation of the boiler itself.
With time running out, a firm - Pearsons - was found in the Border town of Duns with the right fuel from the right source delivered in just the right machinery and the right approach to be able to commit to delivery on the basis of the information provided.
Costs additional to the basic purchase and installation charges have been subscription to a service plan; the installation of a remote information sender (this attaches to the system and sends text messages to the church and to the installer in the event of a fault developing); pipe and radiator repairs; we have also required a series of powerflushes to remove decades of silt that had built up in the system – ably carried out by Enright Engineering. Finally, an additional sum was paid to TWHC for assistance with registering for the RHI programme.
Perhaps the most valuable lesson learned by the church over the lifetime of the project was to secure the commitment (the willingness and capability) of a given contractor to perform a particular job, and this at an early stage in proceedings. This must in practice involve an onsite survey and the development in person of a close working relationship in order that the nature and detailed aspects of the building and the task at hand be fully understood. On more than one occasion we had been quoted a price for a particular job and had an agreement in place, only to find at a later stage that the contractor was unable to fulfil their commitment.
The completed installation
Thanks and Acknowledgements
St Thomas’ Church is proud to have worked with the following expert consultants on this project:
Roger Styring, Engineer – Newcastle Diocese
Ian Ness, Architect
Ian Ayris and Newcastle City Council