As with the rest of the web site, I am re writing a lot of what I wrote over the past 10 yrs as had become outdated and irelitive to whats more important today.

The NEW information I will be providing over this year is about the cost of heating a cylinder of hot water (now estimated at £500 for a family of 4) and how to reduce this over the year.

For much more than just reducing HW costs, go to my other pages covering my multi fuel thermal store (ThermoSolar) that provides both heating and hot water.

 This page is focused on just the hot water side of a homes and business needs, which has been ignored until now.

By now the majority of home owners as well as businesses have been alerted to the increase gas and electricity prices as from 1st April 2022 due to many reasons, but accelerated by the Russian invasion of Ukraine.

This is the first of many designs that uses both flat plate collectors like AES made in Scotland or an imported one from Austria through a UK importer/distributor.

Having spent 5 yrs in Cyprus where 99% of solar thermal HW only systems are of a Thermo Siphon nature, I see no reason why this simple, no pump concept cannot be applied across the UK.

Let’s take this photo above as one of many of my examples I have installed over my 30 yrs since I began to invest in solar thermal.

Imagine this building as shown on top of a roof of a Spanish villa, is the inside of your loft

This is the first step, to be able to have the space in the loft, with standing room if possible and a boarded over and insulated area of the loft, where walls below can support the Pre Heat buffer Cylinder full of a water/glycol mix.

For the collector to work as a Thermo Siphon system, the water as it heats up expands through the collector on the top left has to be as close to the position of the top of the pre heat cylinder to work.

As the weight of the cooler water in the store feeds the bottom of the collector (bottom right hand side), the heated water rises as its heated up in the 1.8m2 collector copper exchanger behind the glass. With less water pressure at the top compared to the bottom, also helps the process.

Below are just 2 examples of these 150-200L cold mains pre heat cylinders, only heated by a solar thermal collector or the excess electricity from a solar PV panel system. For a PV pre heat cold mains water thermal store, just need to add a 2 1/4 immersion heater boss. The majority of homes installed with a PV roof system today, only get paid £0.01p to £0.05p a Kwh (October 2022) which may changed over the next few months as pressure from home owners demand the Utility providers pay them a better rate. So for now best to dump the excess through an immersion heater to reduce your hot water costs.

If you use your existing HW cylinder, if unvented, the thermostat will be set at 65c.

If your HW cylinder already up to temperture, all that excess PV output will go to the grid.

The concept with a 2nd vented thermal store located in the loft, heated exclusivly by solar PV or Thermal, is that it can reach up to 85c safely

Verticle Model

From top to bottom

A. Is the open 22mm water feed pipe plumbed into an F&E tank

B. Is the hot water in from a flat plate collector as the water heats up, then expands into the buffer

C. is one of 2 cold water feeds to the bottom part of the flat plate collector

D. Is the pre heated cold water out via a TMV, set at 30c, for a constant temperature back to the cold feed of your existing unvented cylinder

E. Is cold mains water diverted from your existing unvented cylinder located in the airing cupboard

F. Is 2nd of 2 cold water feeds to the bottom of the collector as well as a drain TEE off.

G. Is a vent pipe that bends over the F&E tank

Buffer tank overall dimensions with 50MM sprayed foam is 1,100mm x 475Mm diameter

Horizontal pre heat buffer cylinder This model is only if you do not have the height for a vertical model.

This design is less efficient in HW transfer due to the fact the bottom half could be cooler than the top half. But is still of a huge benefit on very long sunny days.

A. Cold mains water in, via a 2L expansion vessel

B. 22mm open vent and feed pipe to a F&E tank to be installed above

C. hot water in from solar collector

D. Pre heated cold water out to existing unvented cylinder cold feed in

F. Cold feed to bottom of solar collector

G. Drain valve

Buffer tank overall dimensions with 50MM sprayed foam is 1,100mm x 475Mm diameter

The two new low running cost solar thermal pre heat options, is for the thermal store to be separate from the flat plate collector outside on the roof, working as a thermo siphon system protected by a water/glycol fluid mix via the F&E tank.

The 2nd option if the right positioning cannot be acheived is for the solar collector to work as a pumped system requiring a circulating pump and a solar controller with an added solar sensor pocket in the store.

Both options provide pre heated water at mains pressure to be supplied into your existing unvented cylinder or Combi Boiler through a temperature mixer valve (TMV). More details will be added, as I bring the components together along with installation info.

An estimated cost for the materials is around £1,000 + cost of labour