The venerable Kidd Very High Efficiency (VHE) boiler is one of my favourites.  Designed for Archie Kidd’s personal use in 1959, and then productionised in 1982, it has been the forerunner in condensing high efficiency technology in the UK for 30 years.  Forget all the stories you hear about the Vaillant this, or the Worcester that, or the Baxi Bla Bla, the Kidd VHE was the first and last, the design is still current today, and 98% unchanged.

OK, so you’ve got a Potterton Kingfisher and it is still going after 25yrs?  Not a big deal.  The Kidd was available 5 yrs earlier and would have delivered 90% efficiency, instead of the 60% or so managed by the Potterton.  Think of all that fuel you’ve wasted!

That’s why Highgrove has a Kidd, along with other famous users, for example, music luminaires such as Sir Tim Rice, Peter Gabriel, Bjorn Ulvaeus.  And some less notable people, such as me.

Grade II listed farmhouse - beautiful!

Here we are in a Kent farmhouse, near Sittingbourne, and they have a 1983 Kidd oil boiler.  Now 28 years old, it is showing some signs of wear.  Mr Kidd has offered to refurbish it (yes, really) but the owners are remodelling the area once used as the boiler room, and there is insufficient space for the Kidd unit.

They will be sorry to see it go, but have been delighted with the economy and longevity it delivered.  And being solely mild steel, it is completely recyclable.

End of the road after 28 years of preventing energy wastage.

Connected to a very old (we reckon 1930s) one pipe heating system, we specified a new Worcester-Bosch oil Camray Greenstar utility.  This occupies only around a third of the space of the Kidd unit, but delivers a similar efficiency.

It is not going to last 28 years, but does come with a 6 year warranty due to a promotion Bosch are offering key installers at the moment (installation was Aug 2011).

Another neat job.

The one pipe system is perfectly compatible with a Worcester oil boiler, but it is difficult to remove debris in the pipework, due to the ‘Powerflushing’ systems not being effective.  Basically, with a one pipe system, the connection of one of our large Norstrom machines justs sends the high velocity water round a wide bore loop, with little effect*.  Instead, we fit a dirt separation device, in this case, a SpiroTECH Magnabooster2.  This can be emptied periodically by the homeowner.

*Some Powerflush machine manufacturers claim their machines can clean a one pipe system.  Simply not true.

The new boiler was tucked in the corner of the new utility area.  Some of the old 3″ pipework was rerouted and simplified to provide extra headroom in the new kitchen.

Finally, we fitted an additional cast iron school radiator in the lounge, and some modern programmable temperature controls by Honeywell.

New space efficient installation completed

OK. so we’ve covered a Worcester -Bosch gas boiler using an existing chimney, so here’s an oil boiler version.  Sticking with Worcester-Bosch, this one is a Camray Greenstar 18/25 Utility model.

We’re in a remote area south of Dorking, Surrey, accessed via a long farm track.

Farmhouse exterior

The property had a Trianco oiler, made around 16 years ago, with a leaking heat exchanger.  This is the end of the road for an oil boiler, because the heat exchanger is the whole metal frame of the boiler.

Facing the wrong way

Trianco have always been a budget boiler manufacturer, and have, as a company, seemingly lurched from one collapse to another, most recently last year, when their remnants were bought by an Essex metalworking company.  The other cheapy manufacturer, Perrymatics, failed many years ago.  But there are still lots of these products out there, because they sold so well.

The Trianco was connected to an old metal flue liner, incompatible with modern high efficiency condensing boilers.  For some perverse reason, the boiler had been mounted in an external boiler house sideways, rendering maintenance very difficult and compromising minimum manufacturer clearances.  This lack of access probably resulted in the boiler not being cleaned internally and the premature failure of the heat exchanger.

Original oil liner terminal on right, gravity is all that holds the tile cap on!

From measurements, we found that we could site the new Worcester -Bosch Camray unit facing forwards, enabling easy maintenance and compliance with manufacturer stipulations.

The Worcester-Bosch Flexiflue employed is near identical to the one used in the gas boilers, except that it is used for exhaust gas only – it does not provide an air inlet for the burner, this has to be arranged in the boiler room.

Instant access!

We used our preferred means of access to the chimney in the form of a 7.5ton elevating platform truck.  This is quicker than scaffolding and less likely to cause damage to the surrounding roof areas.

New liner on the way up

New flue termination completed

The new boiler was complemented by revised heating controls, including a Honeywell CM907 programmable room thermostat with Optimisation.

Finished installation

We’re in Purley, Surrey.

house in Purley

Our customer has an old atmospheric Potterton Kingfisher II 100,000 Btu in the basement, connected to the internal chimney system.

Old Potterton Kingisher

We could have resited the new boiler on the external wall but the flue outlet would have detracted from the external aesthetics of the house, so instead we discussed the option of connecting the new boiler to the old chimney system.  This is always the more expensive option, because the new liner system has to be installed from the rooftop and comprises a large number of parts.  However, in this instance, our customer wanted an ‘invisible’ installation so we specified the Worcester Bosch Flexiflue system.

Using a new, high efficiency condensing floor mounted boiler from Bosch, the FS30CDi (FS being floor standing), the Flexiflue system necessitating constructing a closure space under the old hearth termination.  This was built using blockwork.

New blockwork construction for Flexiflue termination

The chimney section above the roofline was found to be unstable, so the upper part had to be partially demolished and rebuilt.  This is not unusual as the heat and the tars tend to crack the mortar, allowing water ingress and subsequent frost damage over the years.

Old chimney needed some TLC.......

The new boiler extracts the exhaust fumes through a 60mm diameter flexible plastic tube all the way to the chimney top;  condensed water from the saturated vapours runs down the liner into the boiler and then to the drain.  The remaining ‘annulus’ of the chimney (in other words, the space remaining between the brickwork and the 60mm liner tube) is used to provide the air for combustion from the roof.  For this reason, the chimney has to be in reasonable condition, making the installation classed as ‘room sealed’, in other words, much safer than before.

new terminal almost completed

We are regularly asked whether the existing flue liner system in a chimney can be reused on a modern high efficiency boiler.  With a few possible exceptions for light commercial boiler applications, where a high efficiency boiler with a bespoke flue system may have been installed previously,, the answer is always negative.  This is because conventional boiler flues connected to a chimney liner require the liner to withstand high temperatures (up to 260C), and be made of a material not necessarily watertight or corrosion proof.  In contrast, a modern high efficiency boiler may only need a flue liner capable of withstanding typically 80C, but has to have resistance to water and acid.  The two solutions are mutually exclusive.

New Worcester FS30CDi boiler (before new blockwork and flue installed)

Unfortunately, my poor understanding of all matters iPhone has resulted in the loss of a large number of pictures for our installation gallery, but we still have a selection from this job.

NB: Other flue lining solutions we offer are available with Viessmann boilers, both domestic and light commercial.

Here we have a large private residence in an exclusive area of Hove, near Brighton.

Part of the property and one of our vans!

Our client had just purchased the property, and engaged us following finding this blog on our web site.

There were two main tasks;  firstly, one of the two boilers for the property had failed and was beyond economical repair.

The second problem was the water supply.  The road is on the top of a hill overlooking the coast and the water flow rate was very poor, in the region of just 8 litres per minute.  The static pressure was also poor, varying between 1.0-1.5 bar.  Our customer did not want to use the shower puumps, finding them too noisy, he wanted a modern unvented system.

We proposed fitting a new Worcester Bosch CDI conventional condensing boiler, to restore the heating to the house.

New Worcester Bosch 30CDi conventional condensing boiler

In order to transform the cold and hot water, we fitted a Trentclyde Charger and Mainsboost system, which was located in the garage.  The garage floor sloped, so we construucted a plywood base for the two 450 litre tandem accumulators.

New accumulators and Charger in garage

For the hot water provision, a Vaillant uniSTOR 310 litre unvented cylinder was installed in the loft space, having removed an old horizontal hot water cylinder and an assortment of cold water tanks.

The system can now deliver mains pressure wholesome water to all outlets, at a static pressure in excess of 3bar. Flow rates of 50 litres/min can easily be supplied, the accumulator banks being sited in the garage, have taken no additional space in the house.

Like all our systems, this was specified, designed and installed by ourselves.  The Worcester-Bosch boiler is warranted for 5 years.  The installation was completed in late February 2011.

For this posting were are in Lingfield, a small town in Surrey.  Our customers have bought an old house which has never seen the benefit of Central Heating.  Furthermore, it is January 2011 and there is snow everywhere.

Weather starting to turn

To leave the maximum room in the kitchen, we’ve suggested an external oil combination boiler.  A Worcester-Bosch external heatslave was our recommendation, it comes in an insulated and rather fetching dark green cabinet, noticeably better made than the product sold by their main competitor, with rubber seals round the doors etc.

Ricky connecting new pipework

We fitted all new copper pipework inside the house, together with our preferred Vogel & Noot radiators, which are Austrian built units with rounded corners, very child-friendly.

At one point the roads outside became impassable, so we had to halt work for three days.  As soon as the weather allowed, we were back on site, in this case this meant a Sunday.  It is pretty miserable installing an external boiler in the snow, it has to be said.

Fire valve, oil filter and oil isolation valve

We haven’t got any pictures of the finshed job, because it got dark very quickly.  But what a difference central heating makes to a house!

Like all our Worcester-Bosch installations, this boiler has a manufacturer on site warranty for 5 years, until 2016.

Here we are near Tunbridge Wells.

Near Tunbridge Wells UK

Our customer had an old wall mounted Boulter Camray oil boiler on the rear of his house.  The unit was beyond redemption, having had a small internal fire.

Old boiler bites the dust

He quite fancied moving the boiler further away from the house, so we looked into moving it down the garden.  Our customer was a builder, so he created a neat pipe trench and raised boiler plinth to our specifications.  The property has a river running nearby, which has been known to flood, so the raised platform will protect his investment!

Our pipe trench

We suggested a Worcester-Bosch Camray external condensing high efficiency oil boiler would do the trick.

Worcester-Bosch Camray external

The new boiler was connected to the house using barrier plastic pipe, which has low flow resistance and good resistance to frost.  It was insulated with Armaflex external grade insulation.  External armoured cable was laid in the duct and an RCD fitted to enable safer maintenance and accordance with BS 7671.

In common with all our Worcester-Bosch oil installations, the boiler is covered for 5 years on a full parts and labour basis by the manufacturer.

We’d like to extend our thanks to our customer, Ernie, who made a fantastic job of all the preparatory building work, in between replacing his lounge floor!  Our team was awarded with some rather nice wine at the end, too!

Our customer had an ageing Potterton wall hung boiler, which was affected by sludge, and wished to convert it to a mains pressure combination boiler solution.

The old boiler and cylinder had been squeezed into a new kitchen conversion, so it was very awkward to access the constituent parts.

Old boiler and cylinder hiding inside cupboard

We removed the old wall hung boiler and cylinder, and fitted a new Worcester-Bosch condensing combination boiler.  The hot water cylinder, tanks and associated controls were no longer required in the new configuration, and were scrapped.

New boiler in position

We cut a neat slot in the kitchen cabinet carcass, which allowed us to achieve the Worcester-Bosch clearances.  This was concealed when the access door is shut, making for a very neat installation.

Finished!

Like all Hot Water & Central Heating Worcester-Bosch installations, our customer benefits from a 5 year manufacturer warranty.

Architect designed house in reigate

This property had an old HarcoPak, which is an integrated hot water cylinder and cold water storage tank, mounted in a frame on the 1st floor.

It was heated by an old Potterton Kingfisher 100BF floorstanding boiler, which had been installed with a flue a couple of inches from the rear door and an undersized gas pipe;  both of which were contrary to the gas regs at the time the house was constructed, and still are.

We removed the Potty boiler, leaving a large hole for the on site building team of Mizon Builders to brick up.

Old boiler position

We relocated the new boiler into the garage at the other end of the building.  We suggested a Worcester-Bosch 30CDi conventional.  This is a 102,000BTu boiler based on a Junkers design (a German part of the Bosch Group), a rugged wall hung boiler compatible with UK open vented radiator systems. 

New Worcester 30CDi in the garage

Due to the proximity of the neighbouring property at this point in the building, we proposed a vertical flue solution, and our customer was happy to agree.  We used the services of our professional roofing subcontractor, to make the aperture and weatherseal the flue terminal.  We always use our skilled roofing specialists because the work has to last the lifetime of the roof.

New vertical chimney outlet

Next, the hot and cold water.  We converted the systems to an unvented cylinder, where water is at mains pressure to all outlets.  Wherever possible it is best to site the hot water storage where there is a relatively short pipe run to most points of use, so the original airing cupboard was retained and a new 300 litre cylinder shoehorned in.

In 2011 the UK Government are committed to provide ‘feed in tariffs’ for solar generated hot water.  This means the end of cash grants towards the installation of solar hot water, but heralds the beginning of an annual rebate for new, accredited solar installations (it isn’t retrospective).  In preparation for this, we installed an unvented cylinder that has a solar coil – making the addition of solar panels much simpler at a later date.

Range Tribune HE Solar unvented HW cylinder

The Range Tribune HE Solar is a well made unit from the Kingspan Group, which is very similar to the Worcester-Bosch branded Greenskies unvented unit.   It is reasonably common knowledge that they all come from Kingspan, the ones for Worcester get silver paint. 

On to the underfloor heating.  Our customer had a large conservatory area, and a kitchen and utility into which he rather liked the idea of installing underfloor heating.  The problem he had was the finished floor level; using conventional water underfloor heating the floor level is typically going to rise by around 75mm.  The alternative is an electric blanket – these are cheap to buy, cheap to fit, and around 300% more expensive to run than a gas fired UFH system.  Also, if the small element fails, digging the floor up is the only option.

As the floor already had insulation fitted when the building was constructed around 17 yrs ago, we specified the Velta MiniTEC system.  This unique underfloor system uses a 9.9mm pipe and a special polymer screed system, resulting in a floor uplift of only 15mm.

Velta miniTEC - and a 2p coin for scale

The floor is levelled and then a plastic castellated support sheet is glued to the floor.

MiniTEC being laid

Over a period of a few hours the rest of the support system was laid and the pipework grid overlaid.

Underfloor nearly finished

The existing radiators were prepared by Powerflushing, and separate heating zones set up to enable timed, programmable temperature areas.

Most of the new pipework was conveniently hidden and insulated within voids in the eaves.  A 28mm water supply pipe was installed for the new unvented cylinder supply, to obtain the best performance from the existing water main.

8 days later the works were completed, I look forward to seeing the finished kitchen area!

The old Potterton oil boiler had been installed around 1965, and would still be working were it not for a failed oil pump that was no longer available.

Old Pottterton 1960s unit

Sited in the utility room of this delightful property surrounded by fields,

 and with a large concrete asbestos flue running up the rear of the building, we suggested the replacement was sited in the detached garage.

Another boiler subject to the UK Government’s Scrappage Scheme ( which finished in March 2010), we recommended a Worcester-Bosch Camray Greenstar condensing oil boiler to replace it.

Old flue aperture bricked up, mortar drying!

Holes were core drilled in the utility room wall and the facing garage walls, sleeved pipework was then run between the two buildings at high level, insulated with Armaflex water resistant insulation.

Pipework link to garage

Electrical control cables were also run between the two buildings, using a neat matching conduit neext to the pipework.  Armoured cables were then run through the garage to the new boiler, where a 3 pole isolator was fitted to allow safe servicing.

The Honeywell frost protection kit was used, comprising a wall mounted frost thermostat, which turns the boiler on if the surrounding area drops below 5°C, together with a pipe thermostat set to 25°C, which turns the boiler off again once the system is warm enough to protect itself.

New Worcester-Bosch Camray 25-32 Oil Condensing boiler

The old flue was taken down and the aperture bricked up in matching bricks. 

We upgraded the system to separately selectable heating and hot water, and provided the latest Honeywell timing and temperature control, including their 7 day programmable radio room thermostat, CM927.

Finally, we tested the system and filled out our special Worcester 6 year parts and labour warranty card.

Rust, Rust and Rust

The Energysaver was one of Glowworm’s early efforts at a high efficiency boiler.  Like the ill fated Potterton Envoy and Baxi Barcelona, the Energysaver had the lifespan of a prawn sandwich.    Although manufacturers like Archie Kidd had perfected the art of condensing boilers decades earlier, the mass market British boiler industry left their designs to the last minute and used their loyal customer base as a test bed. 

Glowworm was snapped up by Vaillant (a leading German boiler manufacturer) over 5 years ago and the Energysaver model was quickly consigned to history and replaced by European designs.  Meanwhile, 5 or 6 years seems to be about the average lifespan before serious internal deterioration renders an Energysaver beyond economic repair.  A classic example of how ‘Green’ labelled products do not necessarily save the planet.

We now travel to Oxted Surrey, where we had been asked to provide a recommendation for a new boiler.

House in Oxted

Our customer had such a boiler and it was leaking.  Being in no mood to buy another boiler with a short lifespan, and due to the tight location within a kitchen unit, we suggested that a Worcester Ri series replacement would prove more reliable and long lived. 

New boiler in position

As usual, we provided a 5yr parts and labour warranty on the unit, and the primary component (heat exchanger) is covered by Bosch for 10 years.  Their only stipulation is that the boiler should be annually serviced.