Hot water settings

BUFF

Alive_Kicking said:

So I posted originally to find out the most economical way time-wise to heat my water up. Its more so I can wash my hands in warm water and have a bath occasionally. What should I set it as?  Is half an hour morning and night sufficient?  Thanks.

For washing hands only I would go with kettle (making sure that you either heat only enough not t scald or add sufficiet cold to achieve the same effect). For a bath via heating a hot water cylinder I would start off by heating the cylinder only just in advance of when required - maybe start off with 1 hr in advance & progressively reduce that time until you find out what it actually requires to heat the volume of water that you require to the temp that you want.

Ensure that your cylinder is well insulated/lagged & that you regularly heat the water in the cylinder to a temp that will prevent the potential risk of Legionella.

Alnat1

BUFF said:

For washing hands only I would go with kettle (making sure that you either heat only enough not t scald or add sufficiet cold to achieve the same effect). 

You don't start messing with a kettle when your hands need washing, you wash your hands in whatever temperature water is in the tap. Otherwise you'd need to wash the kettle afterwards.

I've found my hands are less dry/chapped if I wash in cooler water so I only use the tap on cold anyway for a "bathroom" wash. It can be a bit chilly when the incoming water is colder in winter though. If it's a "been in the garden and my hands are filthy" type wash I go tepid.

Green_hopeful

We have a gas boiler and cylinder. We have worked out that 40 minutes a day is sufficient for all our needs. It gives us 3 short showers a day and incidental hot water although we don’t use much. The hot water comes on for 30 minutes in the morning and 10 minutes in the afternoon. We use more in the morning. We measured it used 6 kWh a day which at about 10p a kWh is about 60p. Before we were heating it for longer and it was 11 kWh per day but I tweaked it to get just enough hot water for our needs. It’s a bit tricky to work out what your meter is reading but our meter is in m3 and it works out appropriately 11 kWh per m3. So if we use 0.5 m3 it’s about 5.5 kWh. 

You could put the hot water on for 30 minutes and see how much gas that uses. From absolutely cold that might make it use more gas to start with. You can work out how much that costs and decide if you want to do it. You might be able to reduce it to 20 minutes. At least then you know what it’s costing you. 

Qyburn

Do you have a cylinder thermostat? To some extent that will reduce the impact from programming water heating for longer than necessary, because irrespective of the programmed time it will only run until that thermostat switches it off.

Scot_39

You can probably heat a whole small cylinder of water every day by gas for less than the price of a 10 min electric shower and a couple of kettles.

Just the physics of heating just the water
A typical uk 3pt 1.7l 3kw kettle full of water takes around 0.17kWh of energy.  At ave 30p SR c 5p
A small 110l HW cylinder to 60degC 5.8kW from 15C incoming - so would have to use 100% of hot from previous day - 5.8kW, to 65C 6.4kW.  That 5.8kWh at gas 7.5p - allowing c85% efficiency - 58p.
Your tank may be larger.
So 34x energy, 12x the cost.

But realistically wouldn't need the full tank most days - some only heat every 2-3 days.

I heat mine daily - cylinder immersion on for 30-40 mins summer only slightly longer winter - so rough average for light use 2.5kWh  - main wash via electric shower.  

If take the every 2nd day need - 2.9kWh / so daily ave 29p - still higher than my ave - maybe 6x the cost of a kettle.  And that ignores possible savings on cost of running your shower.

A deep bath would probably reset that using pretty much the whole of a small water cylinder.But if it replaced the shower that day  that saves - at 5min  at 9kWh at c30p = 22p.  10min c45p. Its not the disaster you might think.

I'd suggest heating the cylinder water to 60-65, which would typically need say a min 5-10c higher flow temp in the boiler for short to medium boiler runs. Maybe set timer for a few hours -  the boiler should cut out on thermostats anyway.

And perhaps being overly cautious -  keep cylinder hot for a day or 2 - then flush out any unused hw pipes with that hot water - before use for - if been a while.

Then slowly set times / temperatures down to suit.  

My immersion heater runs c30 mins in summer  - about 1.7kWh in bill units - on a light use day.

Gas boilers are typically a lot more powerful (so could need less time) - but then heat indirect via coils in tank - so just find your own systems balance.

If you find its too expensive you can go back to curent system.

But hot water like heating is a balance of how much you want  and the costs of providing it - and gas is currently far cheaper for raw costs. Raw ave cap bill rates c30p SR electric, c7.5p gas - 4x raw, mean you can use more energy for same price.

But also bit less efficient - so maybe less e.g. 3x or 2x for a gas hob etc.

And it seems silly to pay the 30p SC and not take advantage of the option.
I would love mains gas - to cut my bills.  My ave multirate electric rate is c25p / kWh - over 3x the price of gas.

Yes let gas run too long etc it will cost more, or use more water because it's available e.g. take daily baths rather than quick showers -- it will probably easily cost more. 

But thanks to the price differential, you might find more convenient comfortable living level at similar costs. 

Just as some, but not all, find with running tightly controlled gch vs room by room heating by plug in electric heaters suits them better at an affordable level.

Try for a couple of weeks - see where your balance ends up.

Do it now before winters high bills kick in - and you should be able to cope with any small cost swings.

Take meter readings say weekly and work out costs of gas vs savings on electric.  Or use your ihd if smart metered as a guide.

jvjack

Alnat1 said:

BUFF said:

For washing hands only I would go with kettle (making sure that you either heat only enough not t scald or add sufficiet cold to achieve the same effect). 

You don't start messing with a kettle when your hands need washing, you wash your hands in whatever temperature water is in the tap. Otherwise you'd need to wash the kettle afterwards.

I've found my hands are less dry/chapped if I wash in cooler water so I only use the tap on cold anyway for a "bathroom" wash. It can be a bit chilly when the incoming water is colder in winter though. If it's a "been in the garden and my hands are filthy" type wash I go tepid.

And never pour boiled kettle water into empty bathroom porcelain sink. It cracks it. Mine now sealed with gorilla tape till replacement..

lohr500

We still need the OP to advise if they have a hot water cylinder or a combi boiler.
Suspect based on the original question of what settings to use, there is a hot water cylinder.
But if there isn't a cylinder then the advice needs to be focussed on best operation of the combi boiler. 

Scot_39

lohr500 said:

We still need the OP to advise if they have a hot water cylinder or a combi boiler.
Suspect based on the original question of what settings to use, there is a hot water cylinder.
But if there isn't a cylinder then the advice needs to be focussed on best operation of the combi boiler. 

The op specifically asked about heating a tank - so I answered on the basis of an old indirect hot water cyclinder.

From the OPs opening post

"what would be the minimum amount of time I could heat the tank?"

Alive_Kicking

lohr500 said:

Firstly you need to establish if your gas boiler is a combi boiler (which provides hot water on demand) or a traditional type boiler which heats up water in a storage cylinder (immersion tank). Do you know which type you have?

This will help forum members to suggest what settings to go for.

Boiler-wise, Its a traditional boiler, not a combi. With this in mind, I am mainly looking for opinions on how long to have the water heating up for,morning & evening.

Alive_Kicking

Strummer22 said:

Alive_Kicking said:

So I posted originally to find out the most economical way time-wise to heat my water up. Its more so I can wash my hands in warm water and have a bath occasionally. What should I set it as?  Is half an hour morning and night sufficient?  Thanks.

If you've got a hot water tank, and you just want warm water for washing hands, then half an hour in the morning might do it. The tank should stay warm enough all day and you wouldn't be using enough for it to top up with cold water again. You'd probably need half an hour in the evening only if you were going to have a bath, so perhaps generally leave it off in the evening and turn it on only if you're going to have a bath. 

Thanks very much, I'll give half an hour in the morning a go!