Hot Water - which is cheaper?

SuzySF

ummm this could be the wrong thread ...but .....i have an ongoing argument with my husband - we have oil fired boiler that heats rads n water,+ immersion if required (and electric and a bottle gas hob cause i dont like elec cookers but ...) the argument is ..I think it would be more economical to heat the water in the tank every day for 10 mins or so and keep topping it up, rather than heat a full tank from cold once a week for laundry ....he inists its cheaper to boil a kettle for dishes etc (there only 2 of us here and we have lec shower in bathroom - very rarely take bath prefer shwr)

I'm sure some one here can tell me which one of us right !!!! (please let it be MEEEEE)

Nile

Hello SuzySF


Welcome to the MSE site.

I've split your post from the original thread where you posted it and made it a separate thread for you. I've also given it a new title. I hope you get more views and responses now.

Kind Regards

Nile

moneysavingplumber

It's a complicated question because it depends on levels of insulation, amount of water used, temperature, and of course the price that you are paying for the fuel. Modern unvented cylinders are extremely well-insulated and Part L requires all pipe work up to a metre from the cylinder should also be lagged. Even foam lagged vented cylinders are pretty efficient, usually around a 20-25 minute reheat with a Part L coil. The efficiency of your oil boiler and buner will have an impact on cost as well. Energy efficiency guidlines dictate that all cylinder heating coils should be controlled by a timer, cylinder thermostat and motorised valve. If you are literally only using it for laundry and only washing laundry two days per week (for example) then I'm merely guessing with a modern cylinder it would be cheaper to heat it only on the days you use hot water.

BUT, beware of storing lukewarm water, it is a favourite breeding ground for legionella. If your use of hot stored water is so limited it may be worth changing your system, or actually changing your washing machine to a cold fill only. You can always substitute the hot inlet to the washing machine with another cold inlet supplied from a Y-piece off the cold valve, which would then mean the machine would heat as it uses.

Whatever happens, the storing of large volumes of water that sees such a little turnover needs to be addressed I would think.

SuzySF

thanks Moneysavingplumer !! i'll take your advice and just heat when required re: Leigonnaires disease - I already have a second hand pair of lungs !!! (transplanted ones in other words haha) so wont risk them as I'd be a creek without a paddle........just a get ticked off washing hands in cold water esp in cold weather ......

moneysavingplumber

Wow, I guess that would make you high risk indeed! Make sure you keep your shower head clean and don't run water that's been standing though any kind of atomising device, such as the mesh filters often found on the outlets of some modern taps. Even if you haven't used your electric shower for a number of days if you've been away, always take the head off first to wash the standing water through.

Ken68

Hi Suzy....this is what I do, heat the water for half an hour before doing the clothes...and use filtered rainwater in a dedicated kettle on other days to do the dishes. And one kettle (a seperate one) of tap water each morning makes a pot of tea plus personal washing together with electric shower. Gas and electric bills combined are £250 a year with Powergen Age Concern.
Thank you Plumber, nice to meet you.