Energy Saving

[Adam W.]

@Cabinetman
I have a system boiler with a 30L tank and the pump runs all the time. The tap is at least 20M from the boiler, so there was a huge amount of water lost and also loads of heat energy lost too with hot water in the pipe cooling off before the tap was run again. So it was a win for the small amount of energy to run the pump and the pipe is very well insulated along the whole length of the loop.

The loop runs under the sink and I just took off a short spur at the kitchen tap and for the bathroom. In the bathroom the pipe runs along the edge of the heated slab too, so there's minimal water waste.

Denmark has very high water costs and our water use is minimal compared to other Danish households. I really wanted to use grey water for flushing the loo too, but it was epic setting it up, so I didn't bother in the end. If I convert the loft with a bathroom upstairs, I'll put that in for the downstairs toilet.

@Just4Fun

It's a Grundfos Alpha1 N stainless steel pump which has been going for about 7 years.

https://product-selection.grundfos.com/uk/products/alpha/alpha1-n?tab=models
A regular heating pump will corrode when used for DHW circulation and it's probably why yours failed.

 

[Krome10]

Opening the window fixes that

I presume the smiley face at the end means you're comment's tongue in cheek? Just checking....

 

[John Brown]

New dishwashers (last ten years' worth at least) do a better job if you don't rinse first.

That's interesting. I'll look it up.

 

[Sporky McGuffin]

That's interesting. I'll look it up.

There's a thingy called a turbidity sensor (apologies if I've spelled that wrong). If it doesn't detect enough "stuff" coming off the plates and so on it'll reduce the wash strength. All you need to do is maybe scrape off any big lumps, but pre-rinsing is actually counterproductive.

 

[Trainee neophyte]

There's a thingy called a turbidity sensor (apologies if I've spelled that wrong). If it doesn't detect enough "stuff" coming off the plates and so on it'll reduce the wash strength. All you need to do is maybe scrape off any big lumps, but pre-rinsing is actually counterproductive.

Does this mean that instead of washing up, you need to regularly go pearl diving into the dishwasher filter? I hardly ever have to look at my dishwasher (which is 15 years old) - except when the tourists abuse it...

 

[Sporky McGuffin]

I have not needed to in all the time I've had a dishwasher.

 

[Sandyn]

Just like I've always questioned the reasoning of replacing old style incandescent bulbs with low energy types. The CH just has to work harder.

I am of the same opinion. It just seemed like common sense to me that incandescent lamps are just heaters which give off some light, 10% light and 90% heat, so if you change to LED, 60% light 40% heat (that's overall efficiency) you are reducing the amount of heat produced. If the house temperature is controlled and remains the same, the CH will have to supply the difference, so savings will be minimal.
In a hotter climate, it's a different story, there would be a bigger saving because the air conditioning would run less to remove the extra heat from the incandescent bulbs.
I did some calculations on my usage and the total power consumption has gone up slightly, converting everything to LED. The reason is, I have much higher lighting levels in and around the house with incandescent, 21500 total lumens for Incandescent and 64700 total lumens for LED.

I'm not suggesting we go back to incandescent. I love LED lighting, but they didn't give the whole picture. I would like to see how much energy it takes to make an LED bulb compared to incandescent, the whole life cost of both, including disposal and recycling.

 

[John Brown]

I am of the same opinion. It just seemed like common sense to me that incandescent lamps are just heaters which give off some light, 10% light and 90% heat, so if you change to LED, 60% light 40% heat (that's overall efficiency) you are reducing the amount of heat produced. If the house temperature is controlled and remains the same, the CH will have to supply the difference, so savings will be minimal.
In a hotter climate, it's a different story, there would be a bigger saving because the air conditioning would run less to remove the extra heat from the incandescent bulbs.
I did some calculations on my usage and the total power consumption has gone up slightly, converting everything to LED. The reason is, I have much higher lighting levels in and around the house with incandescent, 21500 total lumens for Incandescent and 64700 total lumens for LED.

I'm not suggesting we go back to incandescent. I love LED lighting, but they didn't give the whole picture. I would like to see how much energy it takes to make an LED bulb compared to incandescent, the whole life cost of both, including disposal and recycling.

All of which might be relevant if you heat your house with electricity, and live in a climate where you need to heat your house all year round. Otherwise, apart from the energy involved in manufacturing and recycling/disposal, it makes no sense in a place where electricity is so much dearer than gas.

 

[Terry - Somerset]

Even in the UK it can be both dark (so you need lighting) and warm (so you don't need to waste energy on excess heat). Same argument could also apply to hot water cylinders.

This thread has rightly explored expensive ways to save energy and cost - eg: ASHP, GSHP, but there may be some cheaper interventions with quicker payback.

I have been having a look at wi-fi controlled thermostatic radiator valve. Wi-fi because I assume thay can be individually set (time and temp) without having to continually visit each radiator.

Easy if app or central controller based to override standard daily settings - with a little thought could turn on/off having regard for external temperatures.

Cost looks like it may be below £1k for controllers + approx 12 radiators. With gas costs of ~£1200pa, payback insde 1 or 2 yers may be feasible.

Does anyone have any experience of these - reliability, frequency of battery replacement, recommendations (or to avoid) etc.

 

[Oakay]

That’s interesting, do you have it running all the time or every other five minutes or something? Wouldn’t work with my Combi boiler I shouldn’t think. Seriously thinking of changing next time to a hot water tank again, really fed up with running the tap and wasting all that water whilst the boiler fires up and delivers -eventually – also the future Swmibo hasn’t got into the habit of not running the hot tap for a few seconds, it doesn’t give you any hot water and it eventually beggers up the boiler (According to my Plumber). Ian

Our gas combi is in the upstairs bathroom, we have quick hot water there but long run-off for the kitchen but as we have hard water, to minimise scale we use a jug filter to fill the kettle. We fill that jug from another jug which we use to collect the run off previously collected while waiting for hot water to come through to the kitchen tap. Saves wasting the run-off water.

 

[Oakay]

I have been trying to get my better half to fill the kettle just after it has boiled, so the water gets to room temp ready for the next brew and thus save electricity; or so I thought !

Last night I measured 2 pints of water into the kettle and left overnight. The next morning I timed it to boil and auto shutoff - 2 minutes 41 seconds.

Later I remeasured same amount of water straight from the tap and timed it to auto shut off - 2 minutes 43 seconds !!!

Amazed at how little difference, I was expecting it to be much longer.

ANY THOUGHTS / COMMENTS ON MY FINDINGS

There will be a bigger differential when we get frosty weather.

 

[Oakay]

1 We have a plastic kettle because it's light. I bought a similar kettle for my Nan years back and was amazed at the difference in kettle weights available. She could then make tea much more easily. More weight means more material needs heating as well as the water.

2 I bought a new thermos earlier this year, a Thermos Ultimate series. It's the best flask I've ever had. If I leave it in the shed overnight I can still make tea on day two, I'm fussy with tea too. But more to the point, it's supposed to be more energy efficient to fill the kettle totally up then use it from a flask whenever you want a brew. I started doing this a wee bit, and also discovered that you are obviously no longer waiting for the kettle to boil, you just pour the flask and there's your tea. Weirdly satisfying to not be waiting.

3 Also, kind of almost related, I had always thought it was a thing that an upright fridge or freezer was wasteful because the air you had paid to chill falls out every time you open the door. I read someones experiment to see if that was the case and it was so tiny as to not be bothering with. They calculated, for comparison, after a warm or hot bath do you pull the plug? You would save many times more money than the fridge loses by leaving the water in the bath when you have finished until it had given up it's excess heat to the house then drain it, or you are paying to heat your drains! You do get more condensation though.

A 0.9L Thermos Ultimate costs £30 How many months of using it to save boiled water will it take to see £30 knocked off my electricity bill at today's prices? (I appreciate that will vary depending according to contract and the proportion of the daily standing charge within each contract, but a rough figure would be useful for anyone with the time to work it out).

 

[Oakay]

Just like I've always questioned the reasoning of replacing old style incandescent bulbs with low energy types. The CH just has to work harder.

If you have electric heating maybe, but gas is much cheaper....also bear in mind most lighting is near the ceiling and heat rises.

 

[croft36]

your a teeny weeny wood elf aren't you! My mug holds 900ml on its own and I have around 8 mugs a day of tea not coming round yours bob for a cuppa, I'd die of thirst

I know of someone who drank a lot, he didn’t know he had diabetes until it was too late. Just saying (lol).

 

[John Brown]

I have been having a look at wi-fi controlled thermostatic radiator valve. Wi-fi because I assume thay can be individually set (time and temp) without having to continually visit each radiator.

Easy if app or central controller based to override standard daily settings - with a little thought could turn on/off having regard for external temperatures.

Cost looks like it may be below £1k for controllers + approx 12 radiators. With gas costs of ~£1200pa, payback insde 1 or 2 yers may be feasible.

Does anyone have any experience of these - reliability, frequency of battery replacement, recommendations (or to avoid) etc.

No, but I am also interested in this, as we have a sprawling house with some rooms that are unoccupied all day. So any real world experience would be welcome.

 

[Sideways]

Does it require the same amount of energy to heat water throughout the range of temperatures? So does 20 to 30c take the same energy as 90 to 100c?

Sorry if that's an obvious or stupid question but I really don't know!

I'm curious because I've got one of those kettles where you can select the desired temp...

Interestingly no.
As explained on a popular R4 science prog a couple of days ago, the amount of energy needed to raise the temperature of water by 1 degree DOES vary with temperature but by less than 1%. An interesting question of cause or coincidence that the body temperature of most mammals is close to the point where water requires the least energy to raise it's temperature. So when we get cold, it's very slightly easier to warm us up than if we all ran at much higher or lower temperatures.
Thx to Quora for the chart below

 

[John Brown]

Interestingly no.
As explained on a popular R4 science prog a couple of days ago, the amount of energy needed to raise the temperature of water by 1 degree DOES vary with temperature but by less than 1%. An interesting question of cause or coincide that the body temperature of most mammals is close to the point where water requires the least energy to raise it's temperature. So when we get cold, it's very slightly easier to warm us up than if we all ran at much higher or lower temperatures.
Thx to Quora for the chart below
View attachment 120827

I didn't know that. Is this behaviour observed in other materials, or is it an anomaly of water, like its non-linear temperature/volume characteristics?

 

[Jacob]

I didn't know that. Is this behaviour observed in other materials, or is it an anomaly of water, like its non-linear temperature/volume characteristics?

It's called "specific heat" Specific heat capacity - Wikipedia

 

[Stevekane]

If it's tea you're making, this might be useful (from The perfect water temperature for brewing tea | Tealovers.com )

General Guidelines
Manufacturers will usually provide temperature guidelines for you to follow but if these are not available the following general guidelines can be used:
Pu’er teas: 200° to 212°F (93°to 100°C)
Black teas: 190° to 200° Fahrenheit (88° to 93°Celsuis)
Oolong teas: 180° to 200°F (82°to 93°C)
Yellow teas: 175°F (79°C)
White teas: 160° to 185°F (71° to 85°C)
Green teas: 140° to 190° F (60° to 88° C)

What's more:
"When the water starts bubbling furiously and great volumes of steam are rising, the water is no longer suitable for making tea. Using boiling water can make the tea bitter. You may not notice this if you are using cheap industrial tea where the subtle leaf flavors are not noticed but it will be evident with a better tea."

Plus, if it's boiling away like that (if memory of o-level physics serves me) you're wasting energy converting water at 100C to vapour (latent heat of vaporization). This has stuck in my head for decades, and I've always tried to manually switch off the kettle just before it starts to vaporize - I'm quite sure I've saved a fortune and already done my bit to prevent glbal warming.

So if you're boiling the water in your kettle to make tea (or coffee) you're already wasting energy and, worst of all, spoiling your tea.

Interesting, I knew about the coffee but not the tea water temps, and weve just bought an Aldi elect kettle that allows you to preset the temp, there is a digital readout on the top and it switches off automatically,,,,however our impression of well brewed supermarket teabag tea is that using water thats been allowed to go off the boil gives it a horrible taste! Maybe we need to experiment with it.
Steve.

 

[John Brown]

It's called "specific heat" Specific heat capacity - Wikipedia

Thanks, Jacob, I knew that, but always believed it to be a constant. I guess it's close enough to a constant for most practical purposes.