Our customer has a lovely period property near Gatwick, in Sussex.  It has a very cold kitchen and lounge, and was a conventional system with water tanks in the loft and a hot water cylinder on the 1st floor.

The boiler was an old Potterton unit on the ground floor at the rear of the property.

Now, these old properties are usually a bit tight on cupboard and bathroom space, so our customer wanted to lose the water tanks and hot water cylinder, add a utility room and ideally compress all the boiler and hot water functions into a small area.

Enter the Worcester-Bosch Highflow 550 CDi.  This unit is a hybrid combination boiler, and is identical in size to a washing machine.  It has a 42kW heat engine, and an unvented water store inside.  That is the ‘hybrid’ bit, because the hot water heatstore makes this boiler deliver flow rates of hot water that could normally only be obtained from an unvented cylinder.

For the first few hundred litres of water, the blending of the preheated store and the real time efforts of the combi boiler engine deliver close to 25 litres of hot water a minute.  In real use, the unit recharges its’ heat store very quickly so rarely drops below this output.  It is a powerhouse in a small box.

We removed the old water tanks, the old cylinder on the 1st floor, and the ld boiler, and replaced it all with the Bosch unit.  This used the same flue aperture outside so did not affect the listed building requirements.

New boiler does everything for a 4 bed house

Significant modifications were made inside to the heating system, with new Vogel & Noot Vienna Line radiators throughout.  A Smiths Kickspace fan convector was installed in the kitchen, and pipewor was renewed and upsized in key areas to improve circulation through the radiators.

All pipework in the boiler area was removed from wall ducting and relocated on the ceiling to allow for some new wall openings to be created into the adjacent kitchen.

Checking the combustion settings of the new boiler

As part of a Bosch promotion for Gold Accredited Installers, our customer has the benefit of a 7 year parts and labour warranty on the boiler.

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.

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.

Part of the front elevation

We were asked to specify a replacement for the existing Lennox warm air system, using a mixture of radiators and underfloor heating.

Numerous bathrooms in the house and a new annexe were to be converted to mains pressure hot and cold water systems.

We designed a four zone heating system, for maximum energy efficiency.  An unvented hot water system augmented by a TWS water boosting accumulator supplied the bathrooms.  A Worcester 30CDi boiler provided the engine room function.

Part of the garage plant

At the customer’s request, all the plant was to be located in the new garage.

Pipework detail

Worcester Bosch CDi boiler

Underfloor heating in new kitchen/dining areas

Lastly, we have a moody picture of the Vaillant 310 litre unvented and the accumulator.  I take some terrible photos with my iPhone and this is one of them.

Bit dark here

Our customer was very pleased with the installation, which they said performs just like we promised, it was fully completed in January 2011.

Old boiler location was to the right hand side of the cellar steps

The hot water cylinder was located above the cellar on a raised floor, which would have been the first landing of the stairs in the Victorian property’s original layout.

Old hot water cylinder location, floor to be lowered to make new bathroom

Sited in Caterham, Surrey, it would be fair to say that the heating system had been bodged up by the previous owner, along with the electrical work.  Various leaking parts had seen the attention of a silicon mastic gun, including radiator valves.

Our customer rather liked the idea of fitting a new bathroom in the area previously occupied by the hot water cylinder, and this meant lowering the floor, which from our perspective meant;

- a combination boiler

- relocation into the cellar for all the boiler plant

The problem with locating the boiler in the cellar is getting the flue out, and dealing with the boiler expansion relief and condensate water.  There is a boiler available in the UK which has some very flexible flue arrangements which would seem ideal for this application called a Keston, but for reasons we’d rather not go into in this public forum, they are never specified by ‘Hot Water & Central Heating’.

We fitted a Vaillant ecoTEC 837 in the cellar, and used a void area to run the flue to a suitable height for a horizontal discharge.  Gas Safe Register are quite rightly insisting that flues in voids must be able to be visually inspected and suitable arrangements are in place.

New boiler and high temperature lift pump below

The condensate and high temperature emergency discharge from the boiler were handled by a new condensate lifter product specially designed to accept high temperature water, this is unique we believe.  We no longer fit the Vaillant branded condensate lifter because Vaillant UK exclude it from their extended boiler warranty.

A Mainsboost GC450 accumulator was also fitted in the cellar to boost the water flow rate and separate the water supply, as the other 5 flats in the building cause water starvation issues as they are all fed from the same rusty water main around 200 metres long.  The water main here was delivering a very high static pressure, peaks of around 7bar were measured.  A pressure reducing valve was fitted to protect the appliances and provide a uniform performance via the acumulator.

The boiler exhaust was fitted with a Vaillant plume management kit, in white to match the building, as cars often part in the vicinity of the flue outlet, and the mildly acidic condensation could cause damage to paintwork.

New Vaillant boiler flue (in white)

Let the work commence

Now theres’s nothing wrong with warm air heating, and we fit the latest US Lennox condensing units for the more discerning customers.  But in common with many properties of this era, economies had been made with the ductwork, resulting in no direct heating of the third bedroom or bathroom.

Our customer had recently bought the property, and faced the choice of many similar households wondering whether to replace the warm air based boiler for a new one or pull it all out and put in a ‘wet’ radiator system.  It wasn’t practical to extend the warm air ductwork into the unheated area, so we suggested fitting a Vaillant ecoTEC+ 837 combination boiler in the front of the garage.

Nearly finished

We managed to utilise some of the old ducts in the property to conceal the new heating pipework, and lifting flooring elsewhere, resulting in a very neatly finished installation.

New radiator in the kitchen

Pipework detail

The relocation of the heating system meant that a very large cupboard was released in the kitchen, which is never a bad thing!

Insulated pipework inside garage

Our customer was very pleased with the results;

“I just wanted to say a big thank you to Simon and Hot Water Central Heating.  We are very

pleased with the work that’s been carried out – apart from the

radiators (we didn’t have them before) you’d never know the guys had

been here.

Sadly, we’re looking forward to it getting cold so we can test it out.

Happily recommed you to anyone.”

They wished to remove a couple of shower pumps and the water tanks and install a direct fed pressurized water system.  The problem was that the water flow rate into the property was around 9-10 litres per minute.  There was also a limited space to fit the entire boiler plant into.

It's easier to plumb the accumulator in this position

We had to boost the flow rate as well as provide the new boiler plant, all within a single cupboard.  We chose to fit a wall hung Vaillant ecoTEC 937, which is a ‘hybrid’ condensing combination boiler.  Most combination boilers heat water as you use it, but this restricts the available flow rate to around 15l/m for most units.  Hybrid combination boilers store some hotter water in preparation for usage, and then mix this with the water they ‘heat on the fly’ when a tap is opened……in the case of the Vaillant 937, this delivers the equivalent of 20 litres per minute of hot water for the first 10 minutes.

As we use hot water in bursts of activity, and then the system lies dormant, the hybrid combination boiler is a versatile solution.

But of course, we can’t get 20 litres a minute of hot water out of a water main only supplying 10 litres/min – so we also specified a Trent Clyde Mainsboost accumulator.   This stores water at pressure and enables a highly boosted flow rate when required.

Commissioning checks underway

With the accumulator, flow rates including cold and hot water of 30 litres per minute are easily achievable.

The finished hot and cold water/heating solution

We added a secondary heating expansion vessel, as the unit in the Vaillant boiler is only suitable for a modest volume of radiators.

The flue aperture was made good outside, and the decking lifted to provide a neat direct condense drain into the external drainage.

External discharge shown

As is usual with our installations, our customer has an extended Vaillant boiler warranty, from 2 years to 5 years.

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!

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.