Trivial Pursuit, Electrical Edition :D

cormie

Hey folks,
I'm just curious about the below trivial questions and was wondering if anyone may have the knowledge to know the answers :pac:

First off, from what I've read online, isolator switches on cookers and electric showers, are meant to be kept permanently on and only switched off if the cooker/shower is getting maintenance done. Even though there may be a little red light illuminated while they are on (on the switch itself and then a light illuminated on the shower unit or oven too), the amount of electricity used is so little that it's better off just keeping them on, as they aren't really designed for constant switching on and off and can often get damaged by being switched on/off several times a day and the cost to get an electrician out to replace them every few years, would be more than the cost to just keep them on for the same time period?

Is there any safety concern to keeping them on? Is it better just to switch them on and off as they are needed? One electrician said that they should be switched on/off as needed, but this contradicts what I read online about it?


Secondly, what would be the most efficient way to have hot water supplied to the kitchen sink (and possibly outside tap fed from the same pipe) and the shower? Are electric units far more efficient than immersion and an E7 timer to heat the tank on the night meter and have hot water through the day? So one you never have hot water stored and the electric units heat them on demand, and the other you have a full tank of hot water to last you the day.

Then to compare to either of the above, how would the cost of heating 10l of water with a kettle, compare to heating 10l of water from the immersion, or with an electric unit?

I've never really seen electric units anywhere but in the shower. Why is this?


Thirdly, is there much drain on having things like a 4 way surge protector plugged in and live, even if nothing is being used from it? Then what if you have wifi router and speakers plugged in and turned on, or a tv on standby?


Also, is it true the more full a freezer is, the less energy it uses to keep the contents cold after they have all been frozen to a certain temp?


Any feedback on the above would be greatly appreciated

cormie

cormie wrote: »

Hey folks,
First off, from what I've read online, isolator switches on cookers and electric showers, are meant to be kept permanently on and only switched off if the cooker/shower is getting maintenance done. Even though there may be a little red light illuminated while they are on (on the switch itself and then a light illuminated on the shower unit or oven too), the amount of electricity used is so little that it's better off just keeping them on, as they aren't really designed for constant switching on and off and can often get damaged by being switched on/off several times a day and the cost to get an electrician out to replace them every few years, would be more than the cost to just keep them on for the same time period?

You don't need two off switches I'm a believer that isolators are just for servicing..I'm sure someone will disagree.
Neons use naff all current; maybe 1.8mA or 0.4W

cormie wrote: »

Is there any safety concern to keeping them on? Is it better just to switch them on and off as they are needed? One electrician said that they should be switched on/off as needed, but this contradicts what I read online about it?

The appliance has a local switch that is designed for load breaking duty. I'd use that instead.

cormie wrote: »

Secondly, what would be the most efficient way to have hot water supplied to the kitchen sink (and possibly outside tap fed from the same pipe) and the shower? Are electric units far more efficient than immersion and an E7 timer to heat the tank on the night meter and have hot water through the day? So one you never have hot water stored and the electric units heat them on demand, and the other you have a full tank of hot water to last you the day.

Heat exchangers on waste plumbing to recover discarded heat. Solar Thermal and or passive PV diversion.
An immersion is electric. Heat on demand will always be more efficient than heating more than you need. Stored heat will always have losses. Irish stores are generally too small and lossy to make sense. At the end of the day X amount of kWh will heat Y amount of water with 100% efficiency whether that heat is retained in the water is an installation specific question. I get the sense you mean economic instead of efficient though.

cormie wrote: »

Then to compare to either of the above, how would the cost of heating 10l of water with a kettle, compare to heating 10l of water from the immersion, or with an electric unit?

Same for all.

cormie wrote: »

I've never really seen electric units anywhere but in the shower. Why is this?

Welcome to Ireland...how often do you see non-mixing taps and no plug stopper?

cormie wrote: »

Thirdly, is there much drain on having things like a 4 way surge protector plugged in and live, even if nothing is being used from it? Then what if you have wifi router and speakers plugged in and turned on, or a tv on standby?

Surge protectors are usually just a neon and a few over-priced MOVs which are open circuit no-load so not consuming significant power.
Wifi routers use about 10W speakers; depends on the design, tvs same. A lot of modern electonics are transistor switched so you can't turn them off even if you wanted to. Yes they use power, no it's not a lot, it's still an ecological issue to which you can offset the usage with some solar PV, take it on the chin and pay for it as an entitlement of the modern era or turn them off if you are not using them.
If you were running from a battery not a grid you'd turn them off or put them on timers guaranteed.

cormie wrote: »

Also, is it true the more full a freezer is, the less energy it uses to keep the contents cold after they have all been frozen to a certain temp?

Absolutely, same goes for a fridge. Matter resists changes in temperature more than air. If the freezer is full of air opening the door creates a massive temperature change the compressor then has to compensate for, if it's full of matter then the contents will quickly cool the fresh air. I fill the air in my coolers with water as space allows, works great.
The most efficient fridges are hacked freezers with aftermarket thermostatic switches.

Stoner

Good stuff sir liam

2011

Sir Liamalot wrote: »

You don't need two off switches I'm a believer that isolators are just for servicing..I'm sure someone will disagree.

I agree with you 100% on this, but I think it is worth mentioning that many disagree with this.


One of the reasons for my position on this is that I have seen many isolator fail prematurely as a direct result of frequent operation (once or more per day over a protracted period). Some of these failures can result in the isolator itself becoming a fire hazard. This has come up many times on this forum.

cormie

Wow!! Thanks a lot for all the info, I think you may have won the game :pac:

Sir Liamalot wrote: »

You don't need two off switches I'm a believer that isolators are just for servicing..I'm sure someone will disagree.
Neons use naff all current; maybe 1.8mA or 0.4W



The appliance has a local switch that is designed for load breaking duty. I'd use that instead.


Cool, so the only real reason anyone should use the isolator switch is if they have young kids who might go turning ovens on, but other than this, keep everything on, even if the isolators themselves and the appliances have "on" lights, as the cost of these to be illuminated is trivial, especially if the isolator breaks after time and needs replacing with a €50 call out minimum?

The electrician I mentioned who said they should be switched off said it to a friend who called them after there was a faint burning smell coming from the shower isolator switch when it would be on :eek:



Heat exchangers on waste plumbing to recover discarded heat. Solar Thermal and or passive PV diversion.
An immersion is electric. Heat on demand will always be more efficient than heating more than you need. Stored heat will always have losses. Irish stores are generally too small and lossy to make sense. At the end of the day X amount of kWh will heat Y amount of water with 100% efficiency whether that heat is retained in the water is an installation specific question. I get the sense you mean economic instead of efficient though.

Both economic and efficient, the more efficient the system, the more economic I'd hope Would heat on demand not end up being more expensive than stored hotwater, if you use the same amount in the day, but the stored hot water was heated over night with cheaper rates?


Same for all.

Sorry, I should have said using 10l of stored hot water from immersion that was heated on night rate, versus the cost of heating 10l of water with the kettle on demand during the day?


Welcome to Ireland...how often do you see non-mixing taps and no plug stopper?

I see what you mean So you'd recommend an electric unit by the kitchen sink for instant hot water, it's just not a common feature in Ireland?


Surge protectors are usually just a neon and a few over-priced MOVs which are open circuit no-load so not consuming significant power.
Wifi routers use about 10W speakers; depends on the design, tvs same. A lot of modern electonics are transistor switched so you can't turn them off even if you wanted to. Yes they use power, no it's not a lot, it's still an ecological issue to which you can offset the usage with some solar PV, take it on the chin and pay for it as an entitlement of the modern era or turn them off if you are not using them.
If you were running from a battery not a grid you'd turn them off or put them on timers guaranteed.

Thanks for advice


Absolutely, same goes for a fridge. Matter resists changes in temperature more than air. If the freezer is full of air opening the door creates a massive temperature change the compressor then has to compensate for, if it's full of matter then the contents will quickly cool the fresh air. I fill the air in my coolers with water as space allows, works great.
The most efficient fridges are hacked freezers with aftermarket thermostatic switches.

Thanks for the advice, what do you mean about hacked freezers? Do you mean because the walls of it are thicker and there's generally more solid matter with trays, shelves, insulation etc, it all keeps it cooler, so it's more efficient as there's less air that will escape? I'm guessing the hack just allows you to put the freezer at fridge temperatures in a freezer body?

You mention solar and PV a few times above, but for someone without the money up front to invest in these installations, it'll probably be best to hold off and save up, especially with the tech advancing all the time? I read just recently about these two advancements:

http://educateinspirechange.org/nature/environment/cost-iphone-can-now-buy-wind-turbine-can-power-entire-house-lifetime/


and

http://www.iflscience.com/technology/highly-efficient-and-ultracheap-perovskite-solar-cells-announced/


So maybe worth holding out for?

I appreciate isolators are a contentious topic. The clue for me is in the name. Each to his own.

Careful with the micro-wind unless you have one of these in your garden it's usually snake oil.



Turbulence in urban environs is a major viability factor.

Solar's brilliant, works great, low impact works all day.

Gallium arsenide is the most efficient PV type we've had that since the 70s...not allowed use that on terra firma though (but Cadmium gets a pass :rolleyes:)
Fine for satellites along with radioisotope thermoelectric

I prefer the idea of an underground 1000L+ thermal store fed by geothermal, heat recovery, solar thermal, Solar PV, a WBS and a combi boiler (redundancy). Setup right you'd never have to actively heat a drop.

ted1

A kWh of gas is 1/3 of the price of electricity. So provided you have a gas boiler then gas is the cheapest way, however there will be some losses in the pipe work and you may heat to much water. Electric showers only heat the water you need so are a very good option.

Certain systems don't pay, waste water heat recovery is one, very low return on investment, but undeniably more efficient.

If you had a system that was insulated well enough then using night rate electricity would be economic because you afford ~50% thermal loss before you make a financial loss.
EDIT: [ comparing electric to electric, gas is another matter....in terms of embodied energy...hrmm more maths...]

The cost of heating water is the same in energy any time of day. The economics entirely depends on the system losses. Which you can measure with a timer and some thermometers and factor the point of use differential as well as the atmospheric losses.

I'd recommend RE water heating over conventional...that's just how I roll, I'm happy to pay more for clean energy, but tempered by being a skinflint frugal.

cormie

Replies in bold again

Sir Liamalot wrote: »

I appreciate isolators are a contentious topic. The clue for me is in the name. Each to his own.

I've an isolator in my kitchen for the cooker with no light. Makes it easier to leave on, although my mam would always turn the one off in the family home after using the cooker, and it's actually survived the 30+ years since the house was built and still going. But for convenience sake, I'd probably be keeping them on.

Careful with the micro-wind unless you have one of these in your garden it's usually snake oil.

Turbulence in urban environs is a major viability factor.

So without super strong wind hitting it direct, it's a waste, thanks for the warning

Solar's brilliant, works great, low impact works all day.

Gallium arsenide is the most efficient PV type we've had that since the 70s...not allowed use that on terra firma though (but Cadmium gets a pass :rolleyes:)
Fine for satellites along with radioisotope thermoelectric

You completely lost me there


I prefer the idea of an underground 1000L+ thermal store fed by geothermal, heat recovery, solar thermal, Solar PV, a WBS and a combi boiler (redundancy). Setup right you'd never have to actively heat a drop.

That sounds like it would have huge set up costs though and probably not economic for a small domestic house?

ted1 wrote: »

A kWh of gas is 1/3 of the price of electricity. So provided you have a gas boiler then gas is the cheapest way, however there will be some losses in the pipe work and you may heat to much water. Electric showers only heat the water you need so are a very good option.

Never thought of gas for heating water actually!

Sir Liamalot wrote: »

Certain systems don't pay, waste water heat recovery is one, very low return on investment, but undeniably more efficient.

If you had a system that was insulated well enough then using night rate electricity would be economic because you afford ~50% thermal loss before you make a financial loss.
EDIT: [ comparing electric to electric, gas is another matter....in terms of embodied energy...hrmm more maths...]

Thanks again, but you reckon solar would be advisable for a domestic set up (or motorhome set up - I see your info under your username )

The cost of heating water is the same in energy any time of day. The economics entirely depends on the system losses. Which you can measure with a timer and some thermometers and factor the point of use differential as well as the atmospheric losses.

I'd recommend RE water heating over conventional...that's just how I roll, I'm happy to pay more for clean energy, but tempered by being a skinflint frugal.

I'd be similar in that I'd be more supportive of clean energy, but when you say you're happy to pay more, does it not end up paying for itself after the initial investment, although it may be 15/20 years? Also, what's RE water heating?

Here's a good one some mistakes to be learned from.

I'm a fan of micro-wind

If you have at least a half acre site, no neighbours downwind and an average windspeed of 5 m/s then wind will work. Most people don't so they're just wasting their time and money. Siting is very important for wind energy.
Unfortunately most people buy a turbine before an anemometer.

Gallium arsenside and radioisotope are space technology, marvellous generators and detrimentally toxic.

I have PV everywhere...started with 150W on a motorhome 3½ years ago...mad addictive stuff them silicon wafers. I'd consider a 10 year payback quite long. You could install a ELV system quite inexpensively just to heat water. You can get all the equipment second hand gear at discount from the UK because it's not eligible for feed in tariffs and most people don't want it. After that a tiny 48V battery, a wind turbine diversion controller, a 48V immersion element, a redundancy air heater anna discriminating single pole double throw contactor; job's a good 'un and no sparks required.

Solar thermal is a more efficient, more expensive mechanical thermodynamic based system I know not a lot about. Works better in the Winter but requires more maintenance.

RE = renewable energy

I'm not entirely sure if the PWM wave will cause relay chatter. If it does you'll need to cascade relays with a voltage sensing driver.

Actually the penny dropped, keep it simple stupid.

Here's an easier more reliable system that won't cost any more than the last one.

Just set the solar controller regulation 500mV higher than the diversion controller.

Stoner

Sir Liamalot wrote:

Actually the penny dropped, keep it simple stupid.

Sir Liamalot wrote:

Here's an easier more reliable system that won't cost any more than the last one.

How much would that cost liam

I get the TriStars for about £90 but they RRP about £120. (sorry about all the £s but the UK is a much better market for this gear) Battery is only a token to signal the load controller; 4 x house alarm 12v jobs will suffice, they don't even have to be new because they never do any work. Their job is to be fully charged all the time.
The shunt is about €30.

You can get PV professionally installed new for about €1 per watt but I usually pick it up used for much less. I've another 1kW in the spare bedroom waiting for me to rig somewhere.
I have a tendency to find cheap PV, batteries and controllers where-ever I go. I even buy stuff listed as broken because I have a pretty good success rate for fixes...usually there's nothing wrong with it though. :pac:

Cable and gubbins, sure you know yourself. Those MorningStar controllers are something else...ridiculously reliable and head and shoulders above the rest. Spent the day in the workshop today watching a Victron mains charger trying to tell me it was finished charging when my Ah counter read 95% SOC because it was last synced to a MorningStar.

A good battery SOC meter is between €100 and €200, a crap one is €30 but I'd just buy an energy-volt-ammeter instead of a crap one. The meter shown above is counting the diversion load not the battery state of charge though...depends where you put the shunt.

Cheaper than a grid tied inverter, sparks, export meter, LV solar immersion diverter regulated equipment and the rest...
and it's far more efficient too
No inverter self-consumption or inversion losses.

cormie

There comes a stage in a lot of threads I start, where the information supplied gets so overwhelming, I don't know what to reply to it anymore, it's gotten to that stage already

So I've one question, do you do this for a living and do you offer a service where you come and assess a house and suggest/plan and even install the best solution and explain the cost savings and reasoning to someone who would be clueless about all this?

When I get information like this, I usually wish the person giving it could manage the whole thing for me because I see their passion and knowledge on the subject

cormie

cormie wrote: »

There comes a stage in a lot of threads I start, where the information supplied gets so overwhelming, I don't know what to reply to it anymore, it's gotten to that stage already

You're not alone Cormie, I have that effect on a lot of posters.
Many's the poster has iterated those sentiments to me....I forget most people can't see moving electrons the way I do.

cormie wrote: »

So I've one question, do you do this for a living and do you offer a service where you come and assess a house and suggest/plan and even install the best solution and explain the cost savings and reasoning to someone who would be clueless about all this?

I'm afraid not, I'm what's proverbially referred to as a cowboy. I have an entirely less than ecological career. I'm just a proponent of DIY and alternative thinking.

Happy to help in any advisory capacity I can though.

cormie

Haha, I can see where they are coming from

I'll try digest a few things first anyway and if I decide on something I'll follow on! Thanks again for all the help!

Stoner

Stoner wrote: »

How much would that cost liam

Forgot to mention the "Temperature Sensor" MorningStar use is ~£30.

...but it's just a glorified thermistor, here's one I reverse engineered earlier..works exactly the same.

cormie

I've just posted a follow on thread from this. A few of the initial Q's in this thread were for a friend moving into a new place, minor queries back the compared the the thread I've just posted now that they have gotten the keys

If anyone dares, the link is here: http://www.boards.ie/vbulletin/showthread.php?p=101544771#post101544771

seems a combi boiler, solar and stove set up is on the cards!