Improve combi hot water efficiency?

Spies

At the moment I use around 5kwh of gas for instant hot water here and there, my friend has a combi save which I think is some sort of thermostatic valve that only fully opens up when the water is fully up to temp? Do these actually work in terms of saving water/gas? 

Is there anything I can do without needing to get a plumber to install this extra doo-dah? 

theoretica

Be conscious of any times you turn on the hot tap (eg to wash hands) but then finish and turn off before you actually get the hot water.  That is waste of most of the heat into the pipes and I now sometimes decide to use the cold tap instead.

Alnat1

I'm using cold for hand washing, hubby claims he is but for some reason the tap is always pointing the hot way when I go in the loo. He also has to put up with the bar soap I've gone back to, cutting plastic use. Don't want to nag him, he already says I'm obsessed lol.

markin

Only way i can think of is to have very short pipes and fully insulated, keep it in eco if the boiler has it, And use cold for washing hands if you can.

QrizB

Spies said:

At the moment I use around 5kwh of gas for instant hot water here and there, my friend has a combi save which I think is some sort of thermostatic valve that only fully opens up when the water is fully up to temp? Do these actually work in terms of saving water/gas?

One of these?

https://www.britishgas.co.uk/home-services/home-improvements/combisave.html

BG seem to think they work, although I note they claim you can save "up to" 28000 litres of water and "up to" 600kWh of gas per year, which makes me think typical savings are a lot lower.

Is there anything I can do without needing to get a plumber to install this extra doo-dah?

From the look of it, it's a housing with a wax capsule thermostat (the same sort of thing you get in a car cooling system) that opens at 43C. It restricts the flow until the boiler is producing hot water.

I guess you could achieve most of the benefit by just letting the hot tap dribble for 10-20 seconds before turning it on properly?

I don't have a combi so can't say whether this works, but you could give it a go?

northernstar007

i always have my combi in eco mode to stop it warming the small internal tank
when i need a shower or hot water. take the sys out of eco mode. takes aprox 30secs to warm up then stick it back in eco mode and you have instant hot water and no water waste