Easier, better or both?


Running on Sunshine

Solar thermal and solar PV panels

Our solar technology has worked amazingly well throughout the sunny UK summer this year.
– The solar thermal panels have provided us with hot water  on all but ~two days since April. And that’s heating  a 250 litre water tank to between 55 to 70 degrees Celcius each day.
– The solar PV panels have done their job too. The electricity meter runs backwards when the sun shines. The current meter reading is only 300kWh higher than it was at the end of March.  At 12.4p/kWh, that works out at a cost of £37.20  for all our electricity/hot water for the 4 months from April to July (or £9.30 per month) (excluding service charge). We don’t have gas or oil, so this will be our total spend on energy this summer.

Our usage will go up once the days get cooler and we start to heat the house. Generation will decrease once the clouds re-appear. But the performance of the system has surpassed our expectations. It’s wonderful to be running on sunshine!

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Our amazing solar thermal panels

We love our solar thermal panels and have been blown away by their performance. They were commissioned in late winter this year, so we have been able to monitor their output through the dull, cool spring and sunny, warm summer.

Solar thermal panelsWe use the solar thermal panels as the primary source of heat for our hot water.

(Technical details: Worcester Solar Lifestyle 2 Panel Retro-fit Solar System. Bosch Thermotechnology Ltd. Total capacity 2.2 kW. System filled with glycol.)

An air-to-water heat pump acts as the secondary heat source and also provides on-demand heating when necessary.

P1030309Our hot water is stored in a highly insulated Kingspan 250 litre unvented solar cylinder.

  • Cold water feeds into the bottom of the cylinder
  • During daylight hours heat is generated by the solar thermal panels and is used to warm the water via a coil in the lower part of the tank.
  • The heated water rises within the tank.
  • By the end of the day the thermal panels have heated the water throughout the tank.
    • On cold, grey winter days the water is generally heated to between 20-40°C (depending on the starting temperature and the number of hours of sunlight that day).
    • On clear sunny, summer days, the water is heated to 70°C, which is the maximum allowed by the system.
  • The heat pump is controlled by a timer, and comes on after sunset, if supplementary heating is required. The fluid in the heat pump circuit flows through a coil in the upper part of the cylinder, to raise the temperature to 55°C. This is a comfortable temperature for baths, showers, etc. Once a week a 65°C pasteurisation cycle is run to prevent legionella infection.

Since late winter we have barely needed the heat pump. The solar thermal panels have harvested energy from the sun to provide almost all of the heat for our hot water. Even on overcast days, the solar thermal panels have contributed some heat, so the pump has never had to heat the water from “cold”. Those two little panels have heated 250 litres of water to over 60°C almost every day for the last 3 months – amazing!!Energy from the sun


Our More Sustainable System for Heating our Home and Hot Water

Earlier this year we renovated our house and used the opportunity to revamp our heating and hot water systems.

We live in a rural village where there is no access to mains gas, so the house and the water were heated using an oil (kerosene)-fired boiler.

Our house is a modern (for the UK) detached property, with wall and roof insulation. Windows are double-glazed throughout. While undertaking the alterations, we discovered that there is no insulation under the floors – one explanation for the cold tootsies in winter.

As we both work from home, we needed a system that would keep the house warm during the day and in the evenings, but would cost less to run than the old oil-based system.

Solar PanelsOur new system was planned using the premise that we’d generate our own energy or use renewable energy sources where possible, and that we’d minimise our use of fossil fuels. It was also designed to make us independent of oil.

The wood-burning stove was the first item to be installed and significantly improved our quality of life during the recent long, chilly winter.

We have installed two solar thermal panels that heat our water during daylight hours. An air-to-water heat pump boosts the water temperature, when necessary, on cloudy days. Hot water is stored in a large (250 litre), highly insulated, dual coil cylinder. A bonus of the new system is that we now have mains pressure water for our showers and taps and have been able to remove the header tank in the loft.

Air-source heat pumpThe air-to-water heat pump also heats our home via radiators. As this system runs at a lower temperature than the traditional oil-based system, radiators with larger surface areas had to be installed. Photovoltaic  (PV) solar panels were fitted to generate some of the electricity required to run the heat pump. We import electricity from the grid to supplement what we generate from the PV panels.

We are now independent of oil and so will soon say goodbye to the ugly oil tank in the garden. We no longer have to juggle the timing of oil deliveries against the oil level in the tank and fluctuating (usually rising!) oil prices.

The installation is complete and I’ll keep you posted on our experience with the new system over the next few months.


Stove Top Fans

Stove Top FanOur cute little Sterling engine stove-top fan has arrived.

We decided to buy a stove top fan, to speed up the circulation of warm air around our living room, as it can take a while for the heat that radiates from the surface of our wood burning stove to reach other parts of the room.

We identified two types of stove top fans that are free to run, and don’t require batteries or mains power. Both use heat from the stove (or more precisely heat differentials) to drive the fan and are based on elegant, albeit different, scientific principles.

1. A Seebeck effect fan is driven by an electrical current, which is generated by a thermoelectric effect (i.e. a current is produced when the junctions between different metals are at different temperatures).

Sterling Engine Stove Top Fan2. A fan, which uses a Sterling engine to convert heat from the stove into mechanical energy. In this device, a column of air is heated, it expands, pushing a piston upward, the air is then rapidly cooled, it contracts, pulling the piston downward. The up and down movement of the piston, rotates an arm which turns the fan.

We chose a Sterling engine stove top fan, made by Kontax, a boutique engineering company based in Maidenhead, Berkshire. The fan is beautifully designed in stainless steel, glass and graphite.

This wonderful gadget works a treat. The living room now gets warm and cosy soon after we light the stove. Heat also circulates to the rest of the house. We have lots of fun and get an enormous amount of satisfaction watching the little engine bobbing elegantly up and down. It has been a great talking point with visitors too. We would highly recommend this ingenious device.


The Merits of Ash

We had a super lunch in the Crown and Trumpet in Broadway yesterday – a luscious lasagne for hubby and a cheerful chilli con carne for me (spiciness just right).

This old poem was hanging on the wall above our table. Quite a coincidence, after my last post about the performance of different species of trees as firewoods. I’ve transcribed the poem, as the attached photo is a bit wobbly.

Beechwood fires are bright and clear
If the logs are kept a year;
Chestnut only good they say
If for long it’s laid away;
Make a fire of Elder tree
Death within your house shall be;
But Ash new or Ash old
Is fit for Queen with crown of gold.

Birch and Fir logs burn too fast
Blaze up bright and do not last;
It is by the Irish said
Hawthorn bakes the sweetest bread;
Elmwood burns like churchyard mould –
E’en the very flames are cold;
But Ash green or Ash brown
Is fit for Queen with golden crown.

Poplar gives a bitter smoke
Fills your eyes and makes you choke;
Apple wood will scent your room
With an incense-like perfume.
Oaken logs, if dry and old
Keep away the winters cold;
But Ash wet or Ash dry
A King shall warm his slippers by.


Firewood

There is quite an art (and science) to making a good fire. Since having our new stove installed, our fire-making skills have improved daily. We can now get the fire going on the first lighting – most days. We have experimented with a variety of woods and have been fascinated to see how log size, tree species and degree of seasoning really do affect how well the wood burns (as all our “stove veteran” friends have been telling us).

After testing wood from a number of sources, we have decided to buy our logs from Tiddesley Wood, a nature reserve near Pershore. Their logs come from mixed woodland and are well seasoned, as they are stored for at least 2 years before being cut. As a result, their wood burns beautifully and the seasoning ensures that we can avoid the perils of a spluttering, popping and smoky fire. The woodland is sustainably managed and the profits from log sales go towards wildlife conservation.

As this is one of Tiddesley’s log-sale weekends, hubby popped over there today to load up his car with luverly firewood. We are so pleased to have our little Clearview stove and to have found such a super source of wood. This great combination is better than heating with oil in so many ways.


Tetsubin

We chose a wood burning stove with a flat top, as we thought this surface might come in useful sometime. When the fire’s going, the stove-top thermometer reads over 200 deg C. That’s a lot of energy, sitting (well, not quite sitting – but that’s a topic for another day!) right there. As boiling water in an electric kettle uses lots of electricity, we thought we’d rather use all the lovely heat being generated by the wood burning stove to boil the water for our evening cuppa’.

First we tried one of our stainless steel pots. The water got hot, tiny bubbles appeared on the bottom and we waited, and waited and waited. It never boiled – i.e. no big, enthusiastic bubbles. We repeated the experiment with a teflon-lined pot – same result. Interestingly, we gave up watching this one and about an hour later discovered that the water had all evaporated. This stimulated a debate between hubby and I as to the definition of “boiling”. He said that in order for the water to evaporate, it must have been boiling. I thought it wasn’t really boiling if it didn’t bubble properly. We don’t have a suitable thermometer, so couldn’t settle the debate by seeing if the water reached 100 deg C.

After repeating the experiment using different pots, varying the volume of the water, with and without lids, we decided that pots weren’t going to work and that we needed a proper stove-top kettle for the job.

I trawled all the local cookshops, hardware stores and other likely retailers looking for a suitable vessel. The kettles were all either ugly, badly designed or both. Scalding is pretty likely if you have a kettle with a handle that sits above the lid in a fixed position . This ruled out most options. Poor spout design and bold colours ruled out the rest.

Then I discovered the magical tetsubin –  beautiful, superbly designed Japanese cast iron kettles. I found the perfect one online. When it arrived, it was love at first sight. Petite and elegant, it holds 800 ml water, has a handle that folds down, out of the way, so that you can lift the lid, a spout that pours well and a little hole for the steam to escape. And best of all – when we placed it on the wood burning stove, it boiled!!!!!

Each evening we now gain enormous pleasure making tea using water boiled on top of our wood burning stove in our lovely little tetsubin. A much better way to make tea.