Minimising Electricity Consumption

[Alan]

“ He has doshed out around 20,000 low energy lightbulbs “

Hows the Land Fill site dealing with the high Mercury content when the bulbs get put to rest. As a country we are well behind Germany in the safe recycling syndrome.

Regards

Alan

[NickW]

The content of mercury in CFL's is offset by the reduction in airborne emissions from coal and oil burningthat occurs because of their use (compared to using incandescent bulbs). Additionally mercury in a licensed, properly managed landfill is of far less concern than vapourising the substance and emitting it to the atmosphere.

Nick

[Ork-NAK]

Mercury? Being Orkney I think we have that covered too. There are good recycling facilities here for flourescent bulbs, batteries and all the waste electrical stuff.

So taking the good recycling, longer life of the product, lower energy consumption per unit of light and the lower initial purchase cost (free), I think we are on a winner here. 

Neil

[tony.]

you will probably find modern a rated appliances such as a dishwasher will have a cold feed only, and heat the water it needs, rather than take water from a hot water cylinder that will be toped up with cold water/combi which will be using another appliance using electricity/gas/oill.

modern a rated washing machines are the same

tony

[dhaslam]

There is an odd reason why washing machines have cold feed only.     With dual feeds it was assumed that  domestiic hot water would be over 60 degrees C and therefore would be too hot for all except 90 degree washes so it was only used for the highest temperature wash which is rarely used.     I am consiidering using a mixing valve to the cold feed which can be set to 40 degrees. .   

[tony.]

There is no odd reason why it has a cold feed only.

it is more energy efficent to heat the water that the appliance uses.

why wast more money on a mixing valve.

just accept that cold feed is the way to go

[Mike N.]

I was under the impression that the reason modern machines are cold fill only is that they use relatively little water and end up just taking cooled water out of the dead leg of the hot pipe, and still have to heat it anyway.

Mike

[kristen]

"it is more energy efficent to heat the water that the appliance uses"

For most households I suppose ... <sigh> but that would not be the case for solar-heated water, surely?

[lightfoot]

On the subject of dead legs, for reference 10m of 15mm pipe holds just under 1.5 litres of water.  Obviously the better the pipe is insulated, the longer it will take to cool.

Also for a given mass flow rate and pipe length, the smaller the pipe the higher the heat loss, or smaller pipes lose heat faster and need proportionally more insulation than larger pipes.  The same is true for cylinders/stores.  However you could also say, the greater the standing volume of water as in dead legs etc, the greater the potential heat loss.


Lightfoot.

[kristen]

I'm fed up with our Bosh dish washer.  Its not very old, but frequently fails to empty and I have to get the Vax out to clear it, and then it works fine.  The filter is useless - in the sense that it is very hard to extract for cleaning, but even when I do I can't see anything there that would stop the pump working.  It also won't work with a timer (electronic start that gets reset/forgotten when its turned off)

Anyway, that's just rant, I need to replace it.  I would happily replace the washing machine for A* too.

But I would like them to use hot water, on the basis that I am aiming to make that as cheaply as I can, and the amount of electricity I use for washing during the day is a concern.   (I'd prefer to run these devices at night on Economy-7, but realistically the washing machine does need some daytime use because of the way we live our life).

Anyway, question:

If I have a circulation pump on the DHW (there's probably a more technical name, the sort of thing that comes on when it detects some demand from a tap being turned on), how quickly would that get hot water to the device - compared to how little water these things use nowadays, and would that be ale to prevent it using electricity in its heating cycle?

Failing that, or maybe even just as a more suitable alternative, I quite like the idea of giving it a 40C mixed feed, although I don't know how much cold-rinse these things would otherwise do.

Thanks,

Kristen

[jason]

Hi Kristen

What about the Chilie pepper hot water recycler seems to put all the waste cold water from the hot tap back into the cold water system.
Has anybody tried any thing like this?
must be woth a try on long dhw pipe runs.
just a thought
jason

[lightfoot]

Hi Kristen,

Going by the info you supplied on other threads, it sounds like you have a bronze pump on a DHW secondary return circuit.  It's purpose is to keep the DHW water circulating around a circuit to avoid the delay in having to draw lots of cooled water out of the circuit and minimise dead legs, and in your case it is also heating some towel rails along the way.

Obviously the water doesn't stay hot by itself and by turning the pump off, you are saving energy and you are also limiting the heat loss to the volume of water left standing in the pipes.  However due to the low quantiles of hot water required by dishwashers etc, if the pump was only activated when a tap was opened or the moment the appliance called for water, then by the time the pump had cleared the circuit of cooled water (note, no pump can circulate water in a dead leg), the demand would probably be over, leaving the hot water to cool once again in the circuit / dead leg.  Even if you had mains pressure DHW or a booster pump, you would still have to run off the the same quantity of cooled water in the dead leg before you get hot water.

So the only real solution would be to run the pump at some point prior to the expected peak DHW demand and maybe use the appliances after your morning/evening showers etc to minimise the amount of cooled water to be drawn from the circuit / dead leg by the appliance.

Hope that helps.


Lightfoot.

[stephen]

Grundfos do a recirculating pump (the comfort) which cycles the hot water back to the tank. Its designed for long runs so the pipes are always filled with hot water.  this pump has a timer and temp sensor built in so when the return temp reaches a set temp it swithches off.

you could time it to turn on mins before the washers come on etc saving electricity, assuming the hot water is cheap to make i.e solar etc.
If you have a free circulating pump you could set it up through a timer and pipe stat (set on return flow) to do the same thing.

http://www.grundfos.com/web/homeUK.nsf/Webopslag/DMAR-6EGDHG

regards

Stephen

[kristen]

Thanks all.

Lightfoot: You've remembered it pretty much spot on, but I don't currently have a pump; there is  currently a gravity circuit using towel-rails to "drive" the water round, but once I get around to a revised system  I won't want the gravity circuit using up all the heat 24/7, and plan to put an on-demand pump instead, with possibly some sort of timer for "ten minutes before the morning rush"  and so on.   If the dishwasher and washing machine are on Economy-7 timers then I guess something could be rigged up to give a similar X-minutes boost to the recirculating pump before then turning the dish/washing machine on.

Or without dead-legs will the on-demand pump drive the hot water round the circuit fast enough that the dishwasher will actually get some hot in time?

(Assumption: the pump  can drive water round the existing towel-rail circuit, and thus there are no "dead legs", and such water would then be mixed in with main-pressure hot coming via a coil in the thermal store.  Just typing that I'm wondering how I ever get the water "hot", if its mixed with the reticulated water, but I assume that there would normally be some blending with the Cold feed to get a safe temperature, so maybe the recirculating water can blend before the mains-cold blend valve.  All sounds complicated, now that I type it  )

Mind you, if the Dish Washer can use an external time clock I presume I can get a switch that signals the circulation pump for, say, 30 seconds and then turns on the Dishwasher for an hour or so?

Kristen

[tony.]

surely the cost of all this extra equipment, controls, pumos and cabling isnt worth the bother, just buy a a rated machine.

Theres no point in doing stuff just for the sake of it.

Your trying to reduce energy, but buying all this extra equipment doesnt help.