Large loft extension underway, temporary roof being installed

The house pictured, located in Croydon, Surrey UK,  was being extended into the loft space.  The loft tanks for the hot water system and radiator header tanks had to be removed to make way for the new accommodation.

Our challenge was to provide a new heating and high pressure cold & hot water system in an 1900mm high cellar, which could replicate the shower performance of the existing powerful pumped tank fed system in the loft.  Furthermore, it should support the use of extra bathrooms in the loft area.

This project raised a number of challenging problems.  We could have fitted an unvented hot water cylinder in the basement but there were height constraints limiting the capacity, and no drainage. 

Unvented cylinders require an emergency discharge which must run downhill.  In the event of an over-pressure or over-temperature situation developing, a valve lifts discharging very hot water at mains pressure.  Clearly this was impossible in a cellar. 

The unvented regulations hint that in extreme circumstances, a metal catchment tank could be fitted in a cellar, together with a suitably rated submersible pump.   Problem is, the water could be discharged at 85C and there aren’t suitable submersible pumpsets available rated to keep working at this high temperature.  Furthermore, after many years of potential inactivity the pump could fail to operate at the critical day and then the cellar would flood.  So this was not a practical option.

DPS Pandora Heatstore

Instead, we looked at a heatstore solution.  This is a large vat of water contained in a shell, which in our case is indirectly heated by the boiler.  The water in the heatstore never changes, it is used purely as an energy storage media.  When hot water is required, a 100Kw rated plate heat exchanger is used via a simple pump to transfer heat into the cold main, instantaneously.

We specified a heatstore from Dedicated Pressure Systems, the recognised experts in this field, and based nearby to Hot Water & Central Heating in Epsom, Surrey.   The DPS Pandora was specified in a custom built configuration to just fit below the ceiling in the cellar and pass down the stairway.  DPS’s Pandora is unique becasue it does not require an overflow connection – which makes it ideal for our location.

Mainsboost accumulator upgrades mains water supply

To ensure the DPS Pandora could achieve the design hot water flowrate, we used a TCWS Mainsboost GC450 accumulator to boost the water supply within the property to a flow rate far superior to that provided by Thames Water.

The nett result is a fantastic shower performance which is somewhat akin to a pressure washer.  Indeed, our technical team inadvertently dropped the mobile shower head and got soaked trying to chase it around the bath.  It then slipped out of our hand and we got a second soaking;  a few choice words were exchanged.

We also had to remove an old balanced flue Potterton boiler from the utility room and fit a new high efficiency Vaillant ecoTEC 637 condensing boiler in the cellar.

New Vaillant 637 and zoning system pipework in cellar

As most boiler installers will tell you, fitting a boiler in a cellar leads to flue problems.  If we had fitted a flue to outside from within the cellar height, it would have appeared in the alley outside just 50mm from the ground level.  This is not permitted because the air inlet could be blocked by leaves in the autumn or snow in the winter (although we still see some fitted in this way) leading to a potentially dangerous situation.  We have seen dropped wells dug into the outside garden but these too do not meet regulations unless they are very large indeed.

Neat flue installation from downstairs cellar

We overcame this problem by extending the flue upwards  into the kitchen, by adapting the rear of an existing kitchen unit.  We removed the unit carefully from under the marble worktop and cut a suitable aperture in the rear, and then reassembled the unit around the flue.  This now discharged outside horizontally at an acceptable height of around 450mm from ground level.

Due to the proximity of the adjacent property, we fitted a neat Vaillant plume management kit (PMK) in black, which took the steam to a height of around 6 metres.

Plume management kit was employed to lift boiler steam to 6m high and direct it away from the neighbouring property

Finally, there was the problem of converting the existing central heating system over to a sealed type using expansion vessels instead of the old loft feed and expansion tank.

On the face of it, this is easy, but once again, the emergency pressure relief pipework is not allowed to pass through a vertical element (in case it gets blocked/ freezes).  And due to the absence of drainage in the cellar, dumping the expansion relief on the floor does not meet good practice or building regulations.

Emergency catchment tank

We approached this problem with two solutions.  Firstly, we fitted a galvanised 180 litre catch tank on the basement floor, so that if the 3 bar expansion relief valve did open inside the boiler, all the potential water in the heating system could be safely contained.

But this would be inconvenient to the homeowner if the tank filled, so we fitted an additional expansion relief valve downrated to 2.5 bar just above ground level to discharge conveniently outside.  In this way, the outside valve should lift before the boiler valve in a fault situation, preventing the catchment tank from ever being used. 

A spare plumbed zone valve bay was left in the cellar for a potential future conservatory extension with underfloor heating, and the existing heating system was divided into two zones with individual Honeywell CM927 radio linked programmable room thermostats.

So all in all, quite an involved job, but completed as per our detailed quotation, and delivered on time.   As usual, our Vaillant boiler installation is backed by a 5 yr parts and labour warranty.

View from the road

Our customer already has a ‘Hot Water & Central Heating’ installed oil fired cooker range (see our Heritage cooker page above), and was building an outside barn further down the garden.

The central heating boiler was an old oil fired unit, which was located in the hallway and could be heard throughout the property.

Our customer wanted a new boiler and also wished to convert the water system to a new unvented type.

Hot Water & Central Heating suggested that a Grant 3646 outdoor module was fitted, this is an outdoor boiler incorporating a weatherproof housing, designed to operate outside in all weathers. 

Grant Vortex condensing high efficiency outdoor boiler module

This freed up the cupboard in the hall, previously home to an oil boiler and a small vented hot water cylinder on braces above.  We removed these units and replaced them with a Range Tribune Slimline 210 litre unvented cylinder.  This upgraded the hot and cold water to mains pressure at all outlets, and removed the need for a loft mounted storage tank.

Range Tribune unvented installation in cupboard

In common with all unvented systems (and other forms of direct fed hot and cold water systems, like combination boilers and heatstores) the performance is greatly improved with a good water flow rate.  We ran a new 32mm water pipe to the road outside, for minimum hydraulic resistance.   The local water supply company were engaged to provide a new larger connection to the mains.

New water connection being excavated by Sutton & East Surrey Water

The new oak barn was home to a sun room, together with a utility room and shower room.  Hot Water & Central Heating installed underground pipe ducts to the main house to give hot and cold services, and also to feed the new underfloor heating.

New oak barn

Underfloor heating manifolds are quite large units, and it is prudent to site them where inspection and maintenance is easily carried out after the building works are complete.  This ruled out fitting the manifold under the sink or behind washing machines.  Instead, we installed a 7 zone L&K manifold in the ceiling void area above the utility room, hiding the pipework in a stud wall comprising part of the new shower enclosure.

Underfloor installation waiting for screed

The L&K system used nearly 500 metres of pipe, all laid on Building Regs compliant Quinn  insulation board.  The Underfloor Heating was laid in a day, and the concrete screeding completed the day after.  The flooring will be finished in tiling once the screed has properly dried out.

Another view of the underfloor pipework

Heating manifold hidden in ceiling area

Screed laid, all pipework buried. This area will be tiled soon.

Separate zone controls were fitted for the underfloor area, which were linked by armoured cable buried in a duct to the existing house.  Control of the separate heating zones is by Honeywell CM series programmable room thermostats.

Underfloor heating is an invisible but highly effective system*, and uses less energy to heat a space than conventional radiators.  This is because the human body feels warm at lower air temperatures when using underfloor heating. 

The new boiler works at around 92% efficiency, saving fuel but increasing comfort and reliability.  In common with all our Grant boiler installations, our customer received a 3 year on site warranty on the boiler.

*The only type of underfloor heating to be avoided is the electric type, because electricity costs around 12p per Kwh, compared to around 4.5p for gas fired heating and 6p for oil fired (this was written in June 2009). 

Don’t be fooled by sales literature claiming electric heating is 100% efficient and green, these are half truths.  Electrical heating uses energy generated by (usually) coal or gas in the UK.  From the power station to your house meter box, around 55% of the energy in the gas or coal burnt at the power station is lost in generating and transmission losses. 

So before even fitting underfloor heating, electricity is only 45% efficient.   And that generating efficiency partially accounts for the frightening price.  So a sales person could say electric heating is 100% efficient, but it would be a half truth.  If they said it was cheaper than gas or oil fired heating, it would be a lie.  The only electric heating that is efficient in comparison is using a heat pump, but that is addressed elsewhere on this web site.

Crystal Palace, our secret location

A TCWS Charger and mainsboost system was fitted, connected to an existing Gledhill Boilermate III heat store.

Charger & Mainsboost installed in garage

Now all the showers work on all floors. 

Charger/Mainsboost is a specialised water boosting product which utilises the ruling that water can be pumped from the mains at up to 12 litres per minute.  The water authorities are very particular at how this can be done, and in order to get approvals the manufacturer took around two years perfecting the design to prevent any possibility of backflow etc.  Once installed the Charger/Mainsboost can support flow rates of in excess of 40 litres per minute at pressures of up to 4bar…..irrespective of the quality of the supply.

Hot Water & Central Heating are your local and experienced specialists.

It was late when we finished

He had considered a solar hot water system in the loft, as he wanted to minimise his family impact on the environment;  with solar hot water it is important to maximise the hot water storage, or you quickly run out of solar heated water and have to use the boiler.

Unfortunately, the design of these properties leaves a low headroom in the loft, restricting the size of cylinder, and there is limited weight capacity for large volumes of water.

So, instead, he decided to fit the Vaillant ecoTEC+ 937 hybrid combination boiler.  The wall hung unit comprises an 837 combi with a set of hot water storage tanks built in a pod at the back.  This makes the boiler quite large and heavy (getting on for the size of a washing machine), but it delivers a superb performance of 20 litres per min for the first 200 litres of drawoff.

We fitted the new boiler on the brick gable wall and used a vertical flue system.  Five new radiators were also supplied and fitted, and we were fortunate to be able to use some existing ductwork from a warm air installation to hide most of the pipework.

New Vaillant 937 in the loft

The Vaillant 937 is a good alternative to an unvented cylinder and boiler in a medium sized house, because it takes up relatively little space.  Other similar solutions offered by Hot Water & Central Heating include the Worcester Highflow CDi range.

The secret to successful showering is in the garage

This has resulted in a pressure just above 1bar on the lower ground floor;  this house is on 4 stories and there are bathrooms on the 2nd and 3rd floors.  The result was that the bath took ages to fill, the shower on the 3rd floor could not be used, and the shower on the 2nd floor was poor.

Protests to Thames Water from most of the residents in the immediate area did not result in satisfaction, because they were supplying over the statutory minimum pressure to the bottom floor of the property.

Hot water in these properties is supplied through a Gledhill Systemate III heatstore.

Hot Water & Central Heating were asked to provide a solution for the problem, retaining the existing boiler and heatstore.

We fitted a TCWS Charger and Mainsboost system in the lower floor garage.  This innovative patented unit consists of a pumpset and an accumulator.  The pumpset uses less than 12 litres per minute and incorporates anti backflow protection, enabling it to be connected directly to the water main.

TCWS Charger and Mainsboost in garage

It is very quiet in operation, and charges a large accumulator on a ‘trickle’ basis to replicate the performance of an accumulator on a 3bar main.

The Pump incorporates programming to manage the duty cycle and the maximum/minimum pressure.  Once commissioned, the system needs no further adjustment and will continue to run in a power cut.  If the pumpset fails, an automated bypass allows the mains to still enter the property without user intervention.

If you have a water supply problem, and are in our area (see our main ‘areas covered’ button at the top of the page) we can advise you.

Following commissioning, our customer was very happy with the results, which now means that all bathrooms are fully back in operation.  We have already been asked to provide two other nearby households with quotations for similar systems.

Stop Press:  Following the success of this installation, Hot Water & Central Heating have received an order to install an identical system to the house next door in May 2009.

We spent 3 days in this loft

Our customer in Purley had a boiler fitted by Hot Water & Central Heating in 2005, and was in the process of having a bathroom refitted. 

Vaillant ecoTEC installed in 2005 - as good as new

Their old gravity water system cylinder was in the way of a new shower enclosure.

Old gravity cylinder - recycling beckons

We worked alongside their bathroom installers (Visions) to swap over from a vented bathroom setup to a new unvented cylinder in the loft. 

Tim holding up the uniSTOR 260

Our customer is a retired chemical engineer, and he specified one of the first Vaillant weather compensated heating systems when we originally installed his Vaillant ecoTEC 630 boiler in 2005.

Naturally, he decided to go for a Vaillant unvented cylinder, in this case the uniSTOR 260.  He now has what Vaillant describe a ‘total system solution’.  This is where the boiler controls know the precise hot water temperature in the cylinder, and modulate the boiler output according to the scale of the task. 

In a Vaillant total system solution there is no separate timer and programmer, all the heating and hot water is controlled from a single wall mounted controller.  We had fitted a Vaillant VRC400 back in 2005, but recently this has been superceded by the new VRC430, and as this was an inexpensive upgrade, our customer chose to have the newer model fitted at the same time.

Latest Vaillant controller was installed

The uniSTOR was sited in the loft space, involving a considerable amount of pipework and subsequent lagging.

There was a surprising amount of pipework in this job

We also upgraded the water supply from the garage, to give the best possible performance at the taps.

New water pipe (insulated) in garage on its way to the loft

Connected to a suitable water supply, unvented hot and cold water systems give a performance level similar to that obtained from a shower pump without the noise and unreliability associated with the latter.

Finished job

They have to be installed by a qualified installer and the safety devices suitably installed;  in our case, we ran the emergency discharge pipe in 28mm copper in a discrete corner of the property, rather than using the nearer back of the house, which would have been unsightly.

Discharge pipe was run at side of house

The subject of this post

Our customer wished to use the large cupboard currently occupied by the warm air system for storage.  They also wanted a mains pressure delivery of hot and cold water, and minimum wastful stored hot water.

Warm air cupboard after removal of old heater, new pipes shown

We suggested the new Worcester Bosch Highflow 440CDi.  This is a floor mounted unit, recently updated from the Highflow 440.  With identical dimensions to a washing machine, the new Highflow has a new control panel and has more flexible flue outlet arrangements.

Worcester Bosch Highflow 440CDi - nearly completed

The Highflow 440 incorporates a small internal unvented store of hot water, which enables it to deliver up to 20 litres of hot water a minute.  Being able to be sited under a worktop, it is a very neat space efficient solution.

Finished!

It is always difficult fitting radiators in a property formerly fitted with warm air, because there are pipes to run.  In this property there was a solid ground floor, but we found ways to minimise the visual impact of pipe runs.

Vogel & Noot Vienna Line radiator

Our customer agreed to specify our preferred Vogel and Noot radiators, which have a modern neat panelled appearance.  The single panel versions fit very close to the wall indeed, minimising visual impact in the room.  Honeywell radiator valves were used throughout, as usual.

Pipework can often be hidden on the other side of the wall

The new Highflow 440 CDi can be used with the Worcester outside plume management kit, which we fitted to take the flue output to a satisfactory high level discharge point, where it was unlikely to be a nuisance.

The new plume management kit now available on the 440CDi comes in useful here! That's a lot of steam.

The hot water cylinder and water tanks were removed, the Worcester Highflow now manages the supply of heating and hot water for the entire property singlehanded.

As a Worcester A+ installer, our customer enjoys a 5 year parts and labour warranty on his new boiler.  Our experience with previous Worcester Highflow models suggests he is unlikely to need it, but nevertheless it is covered until 2014!

In common with many houses in this area, an old gravity fed hot and cold water system using loft tanks was employed. 

Our customer wished to gradually update his house to new mains pressure fed bathrooms, using European high pressure taps, and wisely didn’t fancy the prospect of shower pumps.

He also wanted to make use of the loft space currently occupied by the large water tanks, and remove the old copper hot water storage cylinder on the 1st floor to make room for another shower.

Our brief was to design the plant to deliver his requirements, all within a cellar a little under 6 feet tall.

In the cellar we found a venerable Kidd Boiler, dating from 1990, so this was retained as it probably has a good few years of life left in it.   Launched in 1982, it was an early condensing high efficiency design that remarkably few ‘heating engineers’ have heard of to this day, even though it was probably the first commercial British condensing boiler.  Still made today, we still fit them!

Kidd Boiler Model 2 Gas (now available in white!)

I commonly hear ‘how reliable’ someone’s old Potterton has been……….  if they had fitted a Kidd instead 20 years ago it would have been just as reliable but burnt just over half the fuel in the intervening 20 years.  Notables including the Highgrove Estate and Peter Gabriel were savvy enough to understand the importance of not wasting fuel back then, but that’s another story….

We had to boost the water flow rate from the 20 litres a minute provided by Thames Water to in excess of 40 litres per minute.  We did this with a stored water pressure vessel.

We then needed a hot water storage system that could fit below the low ceiling, but have a fast recovery time in the event of concerted use.  We looked into a heatstore, but the costs of having a special unit fabricated to meet the space restrictions were very high.  Also the Kidd Boiler does not modulate, so ideally we would need a heatstore with a 46Kw plate heat exchanger to enable the boiler to discharge its power in a long burn, rather than a protracted series of short cycles, which wastes energy needlessly.

We ended up specifying the ACV Smartline tank in tank ‘unvented’ cylinder instead.  To those of you who think of a Megaflo when unvented cylinders are mentioned, this is a World apart.

ACV cylinder cutaway

The stainless steel water cylinder containing your hot water is suspended within another steel cylinder containing the boiler heated water.  When the water is heated it is surrounded 360° by the boiler water, resulting in a very fast warm up time indeed. 

So our Kidd Boiler can discharge it’s full output of 46Kw into the ACV cylinder, resulting in a quick heat recovery period.

The ACV cylinder has another trick;  although it is an unvented cylinder, it is designed to store water at 80ºC, rather than the 60ºC usually used.  The reason we normally store hot water at 60C is that at temperatures above this, limescale is precipitated from the water and deposits scale.  The ACV inner cylinder is ribbed, and every water draw off causes a movement, this prevents scale from building up.  The electrical immersion heater is fitted to the other jacket, so never scales up.

The result is that we can store more hot water energy in an ACV cylinder than an equivalent sized alternative, and most boilers will work more efficiently when driving them. 

Water Boosting Vessel and ACV Smartline hot water unvented cylinder

The equipment was all mounted well below drainage level, so a Drainmaster high temperature compatible pumpset was fitted.  The Kidd Boiler used to disharge its condense into a plastic 2 gallon drum (nobody manufactured condensate pumps in the 80s and 90s, so this was a common bodge), but now it can use the Drainmaster, along with a soon to be fitted sink, washing machine and of course the emergency discharge from the unvented system.  The Drainmaster is a pump in a vented sump, and is hot water rated for these types of application.

The outside Kidd flue had been damaged by builders, so we commissioned a new hand welded item from Kidd Boilers  (Mr Kidd, as usual, had the original installation drawings on file)

Finally, the latest Honeywell programmable room heating controller (CM927) was added to the installation to bring it up to date.

Honeywell Programmable room thermostst

We think the showers are now almost too painful to get under……..  but some of our customers like them like that!

Period house in Warlingham, Surrey

Our client has a woodworking business and was constructing an imaginative barn type conversion for their property, with lots of oak beams in an unusual semi circular design.

Firstly, we installed a Heritage Cooker in the existing kitchen.  Fitted with brass trim and a Jade Green enamelled finish, it was also specified with body colour hotplate covers.

Heritage Cooker

This particular Heritage Cooker was a gas fired unit, most of the Heritages we fit are oil fired in very rural locations.

In common with all 3 oven Heritage units, the control panel concealed behind the upper left hand door enables the unit to be timed according to the user requirements. 

Showing hidden control panel

From cold, the Heritage is ready for cooking in as little as 25 minutes.  Try telling this to an AGA owner and they start getting very defensive.  Especially in the summer when their cooker is making the kichen intolerably hot and using completely unnecessary amounts of fuel!

An old Potterton boiler and associated hot water cylinder was removed, and a new Vaillant ecoTEC+ 937 hybrid combination boiler was installed in the extension, together with a new water main.

Vaillant 937

We have fitted lots of this model over the past 18 months.  ecoTEC937 uses a buffer store of preheated hot water, to give a performance of around 200 litres of hot in the first 10 minutes, all from a (large) wall hung boiler.  This is a boiler that is a viable alternative for a small unvented cylinder installation for water delivery, if there is only 25 litres per minute coming in the property.

Separate circuits were installed for the underfloor heating system in the extension and the main radiators in the house.

Underfloor heating and radio controls

The underfloor heating manifold (and electrical consumer unit above) will be concealed inside a larder kitchen unit later in the project.

The underfloor heating is fitted with the OJ electronics radio thermostat system, so our customer has 4 zones of independently controllable underfloor heating, plus a separately timed and programmable radiator system, giving 5 addressable zones of heating in the house.

All ready for Christmas 2008, and the floor tiler!

When finished, the building will incorporate a modern kitchen, and comprehensively remodelled interiors.

We have assisted our customer in the selection of the heating system, but they have also contributed much to the specification, including the innovative Jaga Strada ‘low H20′ high efficiency radiators.

HWCH will be fitting a large underfloor heating grid on the ground floor, a 46Kw Viessmann 200 series light commercial boiler, accumulator boosted DualStream hot and cold water system, all controlled by the Honeywell Hometronic radiator and underfloor control system.

The industrial gas meter has been moved as part of the works, and our commercial gas engineer will be installing a new underground service to the house and swimming pool boilers.

Work is expected to finish in early 2009, but for now,here are some photographs;

Viessmann 46Kw boiler in utility room

Part of the underfloor heating grid just installed

Cylinder cupboard 35mm pipework under test