I am trying to calculate the cost benefits of 'Combi' vs 'system boiler and tank'.
Looking at a System Boiler and Tank:
I am advised a 300 litre water tank (fed by an indirect system boiler) requires 2.4 kw of energy per 24 hours to keep hot.
Assuming 0.03p p/kwh cost for gas, the above equates to a cost of £0.072p per 24 hours, which again equates to £26.28 per annum to keep 300 litres of water hot.
Does that figure sound correct ? looks too good to be true.
I am also advised average hot water volumes for a 10 minute shower are 120 litres (12 litres per minute) x 0.70% (for the hot water portion) = 84 litres.
This assumes everyone takes a 10 minute shower, I take 5 minutes, but thats just me.
What over head of hot water should be kept in the tank, ie number of litres, 84 litres ... ie enough for one shower ?. working on 84 litres, the total capacity of the tank is 3.57 showers.
I am told a 24kw input recharges the 300L tank in 42 minutes, does that mean a single 10 minute shower of 84 litres could be replenished and be hot in 11 minutes (42 divided by 3.57).
Any thoughts appreciated.
Looking at a System Boiler and Tank:
I am advised a 300 litre water tank (fed by an indirect system boiler) requires 2.4 kw of energy per 24 hours to keep hot.
Assuming 0.03p p/kwh cost for gas, the above equates to a cost of £0.072p per 24 hours, which again equates to £26.28 per annum to keep 300 litres of water hot.
Does that figure sound correct ? looks too good to be true.
I am also advised average hot water volumes for a 10 minute shower are 120 litres (12 litres per minute) x 0.70% (for the hot water portion) = 84 litres.
This assumes everyone takes a 10 minute shower, I take 5 minutes, but thats just me.
What over head of hot water should be kept in the tank, ie number of litres, 84 litres ... ie enough for one shower ?. working on 84 litres, the total capacity of the tank is 3.57 showers.
I am told a 24kw input recharges the 300L tank in 42 minutes, does that mean a single 10 minute shower of 84 litres could be replenished and be hot in 11 minutes (42 divided by 3.57).
Any thoughts appreciated.
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