ROI: 1 Year
Energy Saving: Medium
CO2e Saving: Medium
ROI is the time it takes to return the investment in fuel savings for an average gas heated 3 bed semi-detached house and assumes no government incentive schemes are used: Years
How easy this is to do: DIY-Easy : DIY-Skilled : Specialist
How much energy will be saved with this measure: Low : Medium : High
How much Carbon Dioxide emission will be saved with this measure: Low : Medium : High
...but if your tank is older and un-insulated then according to the Energy Savings Trust by fitting a hot water jacket you will save about £50 per year. Your savings would be even more however if you regularly use an electrical immersion heater, since it costs a lot more to heat water with electricity.
Given that a new thick jacket (75mm) for a hot water tank costs about £15, it should pay for itself in less than six months. Even upgrading an old thinner jacket, is worth considering and will pay back the investment in about 2 years.
This energy/money saving measure is almost a must do. Even if you are renting off a landlord who is too tight fisted to put a jacket on the cylinder, you could buy one and take it with you when you leave!
Insulating hot water pipes will save you less, possibly £10 per year but DIY installation is very easy and materials will only cost about £10. So it will only take a year to payback this investment.