Hot water usage - How to save.

bikes_and_dogs

I know that we all like to wash our hands in warmish water. So let's think about how much energy your comfort is costing you.
How far away is the tap from your boiler? The whole distance has to be filled with hot water before you receive your comfort. When you are done the pipe is left with unused hot water.
How many times do you turn on the hot tap because you want hot water? - But then turn it off before it even runs hot.
Do you have a mixer tap with a single lever? Every time you lift that lever and it's not fully turned to cold - your boiler is kicking in.

The only time I run hot water into a sink is for a shave.
If you have a beard you could save loads.

pblakeney

Use a flask.

bikes_and_dogs

pblakeney said:

Use a flask.

Eh?

N0bodyOfTheGoat

Put some money under the sofa cushions.

pblakeney

bikes_and_dogs said:

pblakeney said:

Use a flask.

Eh?

If that confuses you then you are going to suffer in life.

briantrumpet

All sorts of things. Shower for shorter times, put a restrictor in the pipe/head. Don't shower several times a day - I've had people stay who shower just before going out for a ride... nuts.

Don't wash up just a few things several times a day, do one bigger wash-up in the evening. Don't rinse in hot water - even if you are allergic to tea towels, the stuff will dry eventually.

Turn the thermostat on the hot water down, so there's less heat loss from the tank. If you're having to add cold water for everything, it's set too high.

I'm sure there's more.

masjer

^ Sensible advice, but hot water cylinders should be set at over 60 degrees to kill legionnaires bacteria.

briantrumpet

masjer said:

^ Sensible advice, but hot water cylinders should be set at over 60 degrees to kill legionnaires bacteria.

Would it be less energy intensive then to deal with bacteria by UV treatment? Also, is the risk increased anyway by having header tanks, rather than closed mains-water-pressurised systems?

masjer

briantrumpet said:

masjer said:

^ Sensible advice, but hot water cylinders should be set at over 60 degrees to kill legionnaires bacteria.

Would it be less energy intensive then to deal with bacteria by UV treatment? Also, is the risk increased anyway by having header tanks, rather than closed mains-water-pressurised systems?

The 60 degree thing is only applicable if you have a hot water storage tank.

rjsterry

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

surrey_commuter

The factory settings on my HW were 2 hours three times a day. I have got that down to 30 mins twice a day.

masjer

Kind of tied in with hot water, although washing machines are cold fill. Using bio washing liquids/powers on a cool rapid cycle will save some cash.
I only ever use my machine on daily or rapid settings. Some of the wash cycles last 3 hours!
Bio can still be effective at as little as 20 degrees.

rick_chasey

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

mully79

I know from last winter that boiler on full power costs loads but efficiency is a bit of a minefield.

I’ve turned the combi boiler hot water and central heating temp down from 75deg C to 55 deg C (octopus suggestion) and no one else in the house has noticed. With no smart meter it’s going to take a while to work out if that’s better or not.

surrey_commuter

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

rick_chasey

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Probably. I pay £12 a month insurance which includes a free service once a year.

If it breaks they fix it for free or the replace it for a flat fee of £200.

So far I’ve only had one year where something hasn’t broken and they come within a day.

pangolin

rick_chasey said:

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Probably. I pay £12 a month insurance which includes a free service once a year.

If it breaks they fix it for free or the replace it for a flat fee of £200.

So far I’ve only had one year where something hasn’t broken and they come within a day.

Servicing working well then.

rick_chasey

Ha I guess so. It’s a pretty poor boiler tbh. When it works it’s great, efficient etc but it is well known for breaking all the time.

briantrumpet

It strikes me that it's topsy turvy if the temperature that water is heated to is dictated by things other than the temperature you need it at for general use.

I wonder if a small electric water heater might be a useful investment for most uses of hot water, if energy is going to stay at such elevated prices for the foreseeable future...

orraloon

briantrumpet said:

..
I wonder if a small electric water heater might be a useful investment for most uses of hot water....

Like a kettle?

tomato.pazzo

briantrumpet said:

I wonder if a small electric water heater might be a useful investment for most uses of hot water

Probably not.
Energy from electricity costs ca x3 as much as energy from gas.

tomato.pazzo

briantrumpet said:

I wonder if a small electric water heater might be a useful investment for most uses of hot water

Probably not.
Energy from electricity costs ca x3 as much as energy from gas.

rjsterry

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

It's a school for stupid people. If a boiler is going to break down it is more likely to do it when being more heavily used - in the winter. Also, not all boilers are equal.

rjsterry

mully79 said:

I know from last winter that boiler on full power costs loads but efficiency is a bit of a minefield.

I’ve turned the combi boiler hot water and central heating temp down from 75deg C to 55 deg C (octopus suggestion) and no one else in the house has noticed. With no smart meter it’s going to take a while to work out if that’s better or not.

It's worth getting a smart meter or a smart thermostat like Nest. You can see the effect of turning things on or off instantly. And a better thermostat will heat more intelligently.

webboo

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Most boilers come with an 8 or 10 year guarantee however you have to a yearly service for it be honoured.

lesfirth

webboo said:

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Most boilers come with an 8 or 10 year guarantee however you have to a yearly service for it be honoured.

Read the small print in your guarantee or service contract very carefully.
Most are not worth what you are paying.

diplodicus

mully79 said:

I know from last winter that boiler on full power costs loads but efficiency is a bit of a minefield.

I’ve turned the combi boiler hot water and central heating temp down from 75deg C to 55 deg C (octopus suggestion) and no one else in the house has noticed. With no smart meter it’s going to take a while to work out if that’s better or not.

It will definitely be better. A condensing boiler ceases to condense at temperatures over 55°C, therefore it will be 6% to 10% (according to people who teach these things) more efficient if it is permanently in condensing mode (below 55°C)

Hot water is apparently only 15% of gas usage when compared with space heating.

The most efficient way to use a gas boiler at the moment is a "domestic hot water priority" system. This is where the system can detect whether it is doing hot water or heating. If doing hot water then it runs at 70°C to avoid legionella and 55°C for heating to remain in condensing mode. Retrofit can be awkward though

pblakeney

lesfirth said:

webboo said:

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Most boilers come with an 8 or 10 year guarantee however you have to a yearly service for it be honoured.

Read the small print in your guarantee or service contract very carefully.
Most are not worth what you are paying.

This.
My wife paid “insurance” for 13 years before I told her it was worthless. All they did was a check and declare it okay, until it wasn’t. Then the “insurance” didn’t cover it. That’s what it took for her to concede that I was right.

webboo

lesfirth said:

webboo said:

surrey_commuter said:

rick_chasey said:

rjsterry said:

I think you are also advised not to turn combi boilers down too low as this starts to affect the efficiency. Makes sense as rate of heat transfer is proportional to temperature temperature difference.

A simpler piece of advice is get your boiler serviced before winter comes in as it’ll save you the cost of the service over the course of the winter, and make sure they set it up for maximum cost effectiveness.

There is a school of thought that you are paying somebody £80 to hoover the insides

Most boilers come with an 8 or 10 year guarantee however you have to a yearly service for it be honoured.

Read the small print in your guarantee or service contract very carefully.
Most are not worth what you are paying.

At previous house boiler started playing just after first service. Just rang the manufacturer’s and they came out and fixed it. This currently boiler was due it’s first service but the engineer cancelled cause of covid. Boiler stopped working again rang the manufacturer’s and they came out and fixed it( replaced the fuel pump)
We don’t pay for the guarantee it came with boiler.

mully79

…

diplodicus said:

mully79 said:

I know from last winter that boiler on full power costs loads but efficiency is a bit of a minefield.

I’ve turned the combi boiler hot water and central heating temp down from 75deg C to 55 deg C (octopus suggestion) and no one else in the house has noticed. With no smart meter it’s going to take a while to work out if that’s better or not.

It will definitely be better. A condensing boiler ceases to condense at temperatures over 55°C, therefore it will be 6% to 10% (according to people who teach these things) more efficient if it is permanently in condensing mode (below 55°C)

Hot water is apparently only 15% of gas usage when compared with space heating.

The most efficient way to use a gas boiler at the moment is a "domestic hot water priority" system. This is where the system can detect whether it is doing hot water or heating. If doing hot water then it runs at 70°C to avoid legionella and 55°C for heating to remain in condensing mode. Retrofit can be awkward though

Thanks for this, inspired me to do some more research.
The gas flue condensation temp* is 55 Deg C and can be used to preheat returning CH water as long as its below 55 Deg C.

if return water is higher than 55 then I guess that more energy is wasted as the return water would be heating the flue gas being exhausted.

im assuming that the 55 deg C dew point varies slighty with ambient temperature hence more advanced controls have an outside temperature probe so that this balance can be optimised.

davidof

Top tip: take a large thermos into work and fill up from their hot water