Last nights DIY SOS

[stef]

afternoon chaps,

has anyone seen last night's DIY SOS, the episode with the eco house? They used a mains step down unit
to lower the power consumption (by lowering the supply voltage) to 220 V. This unit seemed to me very light
weight so it can't be a step down transformer so I assume it must be a MOS FET stack which is triggered
by a sine signal. A switch mode PSU would be inappropriate for a mains supply.
Has anyone any experience with such a unit? (efficiency, price, noise, heat)

TA

 

[danzor]

I saw this unit the other day, think edf/supply companies sell them, they're used to reduce our supply so we use less and save more trees etc, anyway I'm rambling just hungover

 

[Guest123]

Sounds like a V-Phase unit.


Welcome to VPhase

 

[danzor]

That's the one!

 

[davelerave]

is it just a voltage regulator?

they'd be incorporated into ups's and some genny's

you wouldn't want to have any excessive installation voltage drops if that 'thing' is bringing the supply voltage down to 220v

 

[Phil]

was a v phase, spoke to the guys at the elex show in harrogate seems ok. they are holding events all over the uk have a look at thier website maybe worth while popping into one for some free coffee and bickies if your quiet. they retail out at around 299

 

[rocker]

Correct me if I'm being a berk but I'm not sure that decreasing voltage and then plugging normal appliances into it is going to save any trees/emissions/ethiopians. What am I missing, here?

(I didn't watch the show BTW)

 

[davelerave]

your v2/r will be reduced-hence lower emissions

think i'd prefer the voltage up around 230

 

[rocker]

Oh okay. So 12v downlights are much more economical than 230v, are they?

 

[davelerave]

Oh okay. So 12v downlights are much more economical than 230v, are they?

drop the voltage - lumens/lux drops so does input power

 

[davelerave]

you've raised a good point though

the output on lights and heaters will drop when the supply voltage is reduced

i'm dubious about the benefit

take a 230v 3kw heater ,resistance 17.6 ohms

-drop the voltage to 220 and your input power is 2750w

-lamp life may be extended etc.

that's the green part


the downside is reduced light output from bulbs etc,kettles take longer to boil etc.

and stats will call for heat more anyway as output is reduced

 

[stef]

That is a good point: the kettle will take longer to boil so there won't be a saving at all. With the lights,
I don't know whether I would notice any difference. I also wondered whether there would be high frequency
noise being fed into the mains which could cause some disturbance within audio/visual high tech kit.

 

[davelerave]

ya some positives but

reduced light output -negative

heating takes longer uses same input power anyway - negative

you could be down to 210v with max installation VD of about 9v-negative

thumbs down imo

 

[Voltimax]

Trouble is with V-phase units (if you look at the installation instructions) They won't accept all circuits and you will have to reconfigure the consumer unit if there is one existing.

 

[Knobhead]

The water in your kettle take X watts per litre so as you say longer to boil, so still the X number of watts have to be used.
Lighting from what I can remember from my apprenticeship (lighting was measured in “Foot Candles” then), the output doesn’t fall linear with the voltage so say for a 5% drop you would loose say 7.5% of light output.

Keep the voltage high