Cheapest way to wash up

Likestowrite

I have a new gas combi boiler and live on my own. I save my washing up for the end of the day but I have to run off about a gallon of water each day before the water comes through hot enough to wash up. (The boiler is upstairs in a bedroom)

I also have a water meter.

I know gas is cheaper than electricity, so it should be cheaper to use water from the hot tap than boil a kettle. But in my case, taking into account all the extra water I'm using, would it be more economical all round to boil a kettle (probably a couple of times) to get the hot water for washing up?

macman

No, because it costs you approx 3 times as much to heat the hot water by electricity as by gas.
5 litres of water costs you a lot less than that differential of 300%. If you pay say the Thames Water rate of 128p per cu m (1,000l), then your 5 litres wasted is costing you about 0.6p. Or a total of £2.19pa.
It would be cheaper to use a dishwasher of course, if you discount the capital cost.

keystone

Take it in the shower with you. :cool:

Cheers

dibuzz

I've actually done that.
One Christmas our boiler broke so we carried all the washing up to the bathroom and washed it using the electric shower.
Never thought of getting in with it though

Ilona

I save my washing up (single person) for 4 or 5 days. Often make a meal in one pan, to cut down on the amount of dirty pots I generate. I boil a pan of water on the gas cooker and wash up in the sink with that.

I have a downstairs loo where I have a large bucket, I pour any slightly used water in that to be used for flushing. can you use your excess water for flushing? My bills are very low.
Ilona

Likestowrite

macman wrote: »

No, because it costs you approx 3 times as much to heat the hot water by electricity as by gas.
5 litres of water costs you a lot less than that differential of 300%. If you pay say the Thames Water rate of 128p per cu m (1,000l), then your 5 litres wasted is costing you about 0.6p. Or a total of £2.19pa.
It would be cheaper to use a dishwasher of course, if you discount the capital cost.

Thank you. that's very helpful. I didn't realise a dishwasher would be chaeper. I thought they used a lot of water.

deanos

Buy a cat and get them to lick the dishes clean

devondiver

Forgive me, Macman, but I think you may be slightly missing the point - which is that Likestowrite is wasting a gallon of HOT water. This therefore costs significantly more than you calculate. One could argue that this heat is not really wasted because it sits in the pipes and warms the house - but this probably does not apply in summertime.

Incidently - cold water washes dishes perfecly well - it just takes longer. Grease and waste food can be removed beforehand with kitchen roll, or old newspaper if you're really thrifty, and then dishes just left to soak in soapy water. Rinse with clean cold water and you're done.

macman

devondiver wrote: »

Forgive me, Macman, but I think you may be slightly missing the point - which is that Likestowrite is wasting a gallon of HOT water. This therefore costs significantly more than you calculate. One could argue that this heat is not really wasted because it sits in the pipes and warms the house - but this probably does not apply in summertime.

Incidently - cold water washes dishes perfecly well - it just takes longer. Grease and waste food can be removed beforehand with kitchen roll, or old newspaper if you're really thrifty, and then dishes just left to soak in soapy water. Rinse with clean cold water and you're done.

I suggest you read his post again then.
'I have to run off about a gallon of water each day before the water comes through hot'
The water is sitting in the pipes cold, and that has to be expelled before the hot water produced 'on demand' by the combi can flow. The hot flow from the combi is pretty much instantaneous once the hot tap is turned on. The delay is solely due to the length of pipe between boiler and sink.

devondiver

With respect Macman - yes, of course. But that gallon of cold water sitting in the pipe has to be replaced with hot water before the tap runs hot. When the tap is turned off the pipe is now full of hot water which slowly goes cold and is therefore wasted. There is a plumbing term for it - latent or dead areas - not sure without checking.

The term I was looking for is " a dead leg".

A quick search found this "The length of pipe between the hot water cylinder and a hot tap is known as a dead leg, because hot water left in the pipe after each use of the tap cools and is wasted. The longer the pipe, the more the waste.
Water at 60°C travelling through a 15mm copper pipe loses heat equivalent to more than 1 unit of electricity for roughly each 300mm of run a week - enough to heat about 45 litres of water.
Where a hot water supply pipe to a basin or shower would involve a dead leg of piping of more than 6m long, it is wiser to use an instantaneous heater instead." Source; http://www.readersdigest.co.uk/health-home/diy/central-heating/saving-heat

Sorry to have to drag it out but ....

mummyroysof3

Might be worth experimenting as when I run a sink for dishes I let the water run in cold first and by time sink is full its a decent temp to wash in still. If I wait for hot then put plug on its too hot for my hands so have to leave to cool or put cold water in lol. Mostly as there are 5 of us I use the dishwasher though and only wash up If there isn't enough to fill dishwasher fully