The following pages covers all areas related to solar water heating for the next genaration of multi fuel solar central heating and hot water combined systems.
The choice of hot water cylinders offered in the UK today is explained in detail below
Option ONE, is a traditional open vented hot water cylinder made of copper sheet and spray foam insulated, which is typical in a British central heating/hot water system. The vented cylinder is supplied through a cold water storage tank located in the loft area of millions of homes. This type of installation delivers a safe hot and cold water supply without mains water pressure to 80% of a households hot/cold water outlets. These types of cylinder can be installed by any competent person as well as proffesional plumbers and requires no servicing over its life time. This type of cylinder being open vented through the cold water storage tank connected to the mains water supply allows the heated water cylinder to expand and vent automatically with no over heating concerns.
The 2nd Option is a hot water cylinder Imported from Europe of the unvented pressurized type, also now manufactured in the UK, which does not require a cold water storage tank in the loft space.
This provides the home owner with 100% mains water pressure direct throughout the hot/cold water outlets and toilets. These unvented steel/stainless steel pressure cylinders require a G3/4 certified installer to install these, (due to the dangers of splitting open, if they over heat) Is often sold with a service contract.
These cylinder types have now been retrofitted with a 2nd heat exchanger coil to except solar thermal collectors, heat pumps as well as the traditional gas/oil boiler coil. The maximum temperature must be kept below 70c for safety regions.
The 3rd option, designed and developed in the UK since 1990, was the introduction of what is now called a Thermal Store, initially made in copper and open vented, but providing hot water at mains city pressure indirect through an internal coils or external plate heat exchanger. What the Thermal store offers compared to option 1 and 2 is for the heated water in the store to also heat the house, as long as the multi fuel energy sources can maintain the temperature in the store at around 60-70c,
Like the first cylinder choice, the thermal store does not require a G3/4 certified installer, just a competent trained professional plumber. A Thermal Store is heated direct from all types of hot water heating devices, for greater heat transfer efficiency. If you understand how a Combi boiler works, this is how a thermal store works but with stored water.
The majority of UK houses prior to 1995 onwards were installed with open vented central heating and hot water systems, until the importation from Europe of the COMBI Boiler followed by unvented pressure cylinders.
The only part of the system that needed to be serviced was the gas/oil boiler, as the rest of the system was self servicing through expansion and venting through the open vented cold water tank or F&E tank as part of the system.
Open vented Thermal Stores are NONE pressure cylinders, which work in just the same way as a open vented hot water and heating system working perfectly well in millions of UK homes. But today, Thermal Stores offer much more, as a multi fuel heating and hot water system, where the hot water is now supplied at mains pressure indirectly like a Combi Boiler.
A vented open loop thermal store is the only hot water cylinder you should look to buy, if you want to use the TAX free solar benefit of sunlight. The same goes for wood burner back boilers. The heating of the thermal store by all hot water appliances is DIRECT, for maximum energy efficiency that can support day time home heating, subject to the age of the house and the insulation value.
I was one of 3 early developers of what today are called THERMAL STORES since 1990, which later led to the offering of a heat pipe tube collector from SUNDA (A German/China joint venture Company) in 1994, when I was offered the opportunity to test this new heat pipe collector in the hot sun of Cyprus.
In 2002/3 I started to import the APRICUS brand of heat pipe collectors into the UK as the co designer and developer. After UK testing was completed I started exporting into the USA from China and into Europe from the UK. In 2007 I began to promote my own heat pipe collector branded Suntech Solar adding to further energy efficiencies and the elimination of Glycol in the system and the high cost of installations.
A lot has happened since those days, which can all be found on my web site (www.solar-speedflex.com) that promotes the greater use of vented thermal stores, if you want to reduce your hot water and space heating bills, before our Nth Sea gas runs out, leaving the UK with 80% imported gas by 2020.
The UK is now a world leader in Thermal Stores, sadly the plumbing, heating and solar water heating industry are being sold unvented pressurised hot water only cylinders by the major volume manufactures for reasons I won’t go into right now.
In 2010, the introduction of the feed in tariff through a government department named DECC (Now shut down) was the beginning of the end of solar water heating sales, as everybody with spare money and a house jumped onto the band wagon by applying for the FIT subsidy, as a nice little earner of 10% while interest rates had fallen to 1/2% (a no brainer for many thousands of people).
On the introduction of the Green Deal and the Renewable Heat Incentive Scheme (RHI) with a 7 year subsidy to encourage people to invest in solar thermal and heat pumps. What was firmly not allowed by DECC and MCS, was the use of solar thermal collectors to support home heating.
In other words, the current installed cost of a unvented solar water heating cylinder with a electric or gas boiler back up is around £5,000 (Affordable cost say the STA) just to heat a tank of water which has to be shut down at 65c to avoid damage to the unvented pressure cylinder.This in turn destroys the glycol in the closed loop side of the cylinder, as the solar closed loop is under pressure and in summer months can heat the fluid to above 200c, but the glycol is destroyed at 130c. This provides another service cost for the home owner to pay out, as you do for the gas/oil boiler and unvented cylinder servicing contracts.
It’s now the time to re-introduce solar thermal hot water and heating to those home owners looking to update their current system. These will never find their way into today’s volume NEW house build market of 150,000 home a year, as seen as to expensive for the builders and are service free.
Unlike my very much smaller business today compared to 2009, I have 12 years of real day to day solar central heating home working living experience to share with anybody looking to invest in a multi fuel thermal store. British designed, British manufactured and now being marketed for the first time, delivered direct to the private home owners once I have educated those about the full cost savings and benefits from vented thermal stores. In most cases you need a loft space and a south to west facing roof for the solar heat pipe tube collectors to be installed onto.
In 2017, we are introducing a NEW heat pipe tube collector that allows the sizing of the collectors to be over sized without any worries about the overheating of the thermal store in the summer months, when the space heating is no longer required.
For maximum ££££ savings include a wood burner back boiler into the system package or a air to water heat pump if you have no mains gas, for a guaranteed mix of low energy producing heating devices that can protect you from the unknown cost of growing energy imports.
Feel free to contact me for a copy of the full range of my Thermal Stores, from 100 litre (solar ready pre heat only loft thermal stores) to the top of the range 300L with a square outer casing.
As with all UK manufactured Duplex stainless steel hot water cylinders, the manufacture warranty is 25 yrs, but the BIG £££ bonus saving for the home owner, is zero servicing for 5 years, while my own system of 12 yrs has never been serviced, with my wall hung gas boiler serviced just twice in 15 yrs, because its not under any closed loop pressure and has an extended life as is only working in the depth of winter, 50% in spring and 10% in summer as back up to solar thermal heat pipe collectors.
What is soon to follow on from the success of heat pipe tube collectors, since I started developing solar hot water and heating systems since 1990, is a NEW innovation within the heat pipe that stops the overheating of the hot water during hot summer months.
One of the major problems with heat pipe tube collectors as with all other closed loop pressure water systems, is once the cylinder is up to the temperature specified by the hot water cylinder manufacture of around 65-70c for UNVENTED cylinders, is that the solar pump stops working and this allows the expansion of heat and pressure to build up within the closed loop system through an expansion vessel and pressure release valves.
Having proven over the past 12 yrs that a vented Thermal Store on both the hot water side as well as the solar side, is the only way to maximise 100% of winter sunlight through the collectors to support home heating up to the end of May.
BUT what this NEW heat pipe innovation allows is for the Thermal store to remain in size at 250-300L, but for the solar collector array to be increased from my current 44 tubes to 60 tubes or higher if you have the roof space.
By increasing the collector area, you produce more heated water in the short winter months, with a greater increase from 1st March to end of May.
The heat pipe now has a restriction of 80c, which means when there is no more demand for heating, your solar system can provide up to 99% of your hot water in summer, without the overheating issue for vented systems