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Evaluation: a year from installation

by Unknown - 12:35 on 10 February 2015

Evaluation: a year from installation

The period covered

I began my blog in September of 2013 after we started using our Smart for central heating. However, it had been installed early in June. This evaluation covers the year from installation.

Why we installed a Smart

Please see the separate posting, Why we installed a Smart

Costs the previous year 2012-13, the last year of oil

 

  • Oil: 4500 litres of oil at a cost of £2975.85
  • Gas: One 46kg tank a year for our gas hob at a cost of £100
  • Logs: perhaps as much as 12 cubic metres of logs, which were bought locally unsawn and sawn by me at a cost of £300
  • Coal: 2 hundred weight of coal because we ran out of seasoned logs at a cost of £70
  • Total cost: £3445.85

During this period we had the house divided into two zones:

 

  1. Ground floor: Dining Room (22.25 sqm), Kitchen (21.94sqm), Hall/Stairwell (18.37sqm), Loo (1.3sqm), Porch (3.07sqm),Sitting Room (32.4sqm), Utility room (7.46sqm) Total: 105.79sqm Maximum Radiator capacity 22.3 kw
  2. Upper floors: First Floor: Study/Sitting Room (36.04sqm), Bedroom 1 (15.09sqm), Bedroom 2 (11.1sqm), Toilet/Shower Room (4.34sqm), Landing/Corridor/Stairwell (16.5sqm)
    Second Floor: Bedroom 3(18.52sqm, Bedroom 4(21.74sqm), Bathroom (10.57sqm), Landing/Stairwell (12.6sqm) Total: 146.30sqm Maximum Radiator capacity; 21.24kw Normally heated 14.64kw

 

The floor area is the internal area for each room. Our Green Deal EPC gives a total floor area of 268 square metres (slightly higher). In contrast, when I did a calculation of area including the thickness of the walls and some unheated space it came to 335 square metres. The radiators in three of the bedrooms were off except when we had visitors. The zones were never on at the same time. During the winter, they were programmed to come on as follows

  • 6.30-8.00 Upper floors zone
  • 8.00-9.30 Ground floor zone
  • 9.30-10.00 Water tank by itself
  • 10-12.30 No zones - wood stove in study or other room if needed.
  • 12.30-14.00 Ground Floor zone
  • 14.00-16.30 No zones - wood stove in study or other room if needed.
  • 16.30-17.30 Upper floors zone
  • 17.30-20.00 Ground floor zone
  • 20.00-21.00 No zones - wood stove in study or other room if needed.
  • 21.00-21.30 Water tank by itself
  • 21.30-22.30 Upper floors zone

In this schedule, the upper floor rooms were centrally heated for 3.5 hours a day and the ground floor rooms for 5.5 hours a day. The utility room was usually hot because it had the oil boiler in it!

Costs for 2013-14, the first year of pellets

Costs for the year after after the Smart was installed

  • Oil: 500(?) litres of oil at a cost of £306.76
  • Gas: half(?) of 46kg tank a year for our gas hob at a cost of £50
  • Logs: perhaps as much as 8 cubic metres, which were bought locally unsawn and sawn by me at a cost of £200
  • Coal: no coal so the cost was £0
  • Pellets: 8.49 tons at a cost of £1765.31
  • Total cost: £2322.07
  • Saving compared with previous year: £1123.78

The oil, gas and log costs are approximate. We bought 1000 litres just before the Smart was installed, because the oil tank was almost empty (I did not include this in the 2012-13 costs). We appeared to have at least half of it left in June 2014. It is used when we go away in the winter to keep the house heated, but the measure on the oil tank is very crude. It is even more difficult to measure the gas, but this is our best estimate at the moment. I cannot give exact figures for the logs and my estimate is based on the number of sections of my log store which were filled with sawn and split logs. I have not included electricity because there does not seem to be any significant difference in our electricity use. The cost of pellets varied: during the summer we used pellets in bags at a cost of £2.40 per 10kg bag, then our first filling when our bulk hopper was installed was £205 per tonne, but afterwards it was £210 per tonne.

The house was also much more comfortable. This was because the Smart enabled us to heat the core of the house for a much longer period during the day. The Kitchen had heat directly from the Smart's presence in it for 13.5 hours (the radiators in the kitchen were unnecessary and therefore were permanently switched off, the Dining Room and Hall had central heating for 10 hours, the Utility room for 2.5 hours, the Ground Floor Sitting Room for 2.5 hours and the Upper floors zone for 3.5 hours. We did not have to use the wood stoves as much as in the previous winter. In 2012-13, the average time for which rooms were centrally heated in the winter was 4.8 hours. In 2013-14 it was 5.8 hours - an increase of more than 20%. Year to year comparisons are always difficult. 2012-13 was a more severe and prolonged winter than 2013-14, but when you look at our costs you need to remember that we were centrally heating the house for a longer period of time each winter day in 2013-14.

When we had the Smart 120 installed, we had a separate programmer installed to control the ground floor sitting room. We also had a radiator installed in the utility room (which we use as a drying room) which comes on at the same time as the water tank. In the Autumn, I put secondary glazing on four of the single-glazed windows. There are another ten or more single glazed windows left to do (there are three bays which each have three windows in them, but I have counted each bay as just one window). During the winter, the zones were programmed to come on as follows:

  • 6.20-8.00 Upper floors zone Maximum Radiator capacity; 21.24kw Normally heated 14.64kw
  • 8.00-8.30 Core ground floor zone and Ground Floor Sitting Room Maximum Radiator capacity; 22.3 kw Normally heated radiators: 12.4kw (Klover renders some radiators redundant)
  • 8.30-10.00 Core ground floor zone and water zone Radiator Capacity + water 8.2kw (redundancy as above)
  • 10-12.30 No zones - wood stove in study or other room if needed.
  • 12.30-16.30 Core ground floor zone 4.6kw
  • 16.30-17.30 Upper floors zoneMaximum Radiator capacity; 21.24kw Normally heated 14.64kw
  • 17.30-19.30 Ground floor zone and Ground Floor Sitting Room Maximum Radiator capacity; 22.3 kw Normally heated radiators: 12.4kw (redundancy as above)
  • 19.30-21.30 Core round floor zone and water zone Radiator Capacity + water 8.2kw (redundancy as above)
  • 21.30-22.30 Upper floors zone Maximum Radiator capacity; 21.24kw Normally heated 14.64kw

 


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