Electricity price for tumble dryer versus dehumidifier

Ben84

grahamc2003 wrote: »

Yeah, plug in energy monitors aren't totally accurate. But then again no other measuring device - whether for home use or professional - is totally accurate. I said it was very accurate, which it is in the context of home energy monitors, and certainly far more accurate than owl meters for example.

I keep hearing from various sources that the plug in monitors are fairly inaccurate, but I've looked for a reason and still I'm not sure why?

As for measuring, the best device which is already present in most houses is I'd assume the electricity meter installed before the fuse box? You'd have to unplug and switch off everything else to use it for measuring a single appliance, but it can be done.

Bella56

Ben84 wrote: »

As for measuring, the best device which is already present in most houses is I'd assume the electricity meter installed before the fuse box? You'd have to unplug and switch off everything else to use it for measuring a single appliance, but it can be done.

Now that would be MSE dedication, sitting in the dark hallway waiting for the tumble drier to finish I'm almost tempted but the littl'uns would not be impressed. Also the fridge doesn't like being unplugged, even for the name of science.

With regards to fabrics and tumble driers, I'm sure the dehumidifier is better for them, even if they are a bit crunchier when dry. Our clothes develop holes really quickly, so I've tried turning down the spin on the washing machine from 1200 to 900 as I've heard that can be the problem, but I've also heard that tumble driers are hard on clothes for fading, shrinking, and general wear and tear so to speak.

In the real world, we'll use the dehumidifier at night when we can, and tumble dry when there's less time or I can't be bothered. At least now we'll know how much we're saving when we're hanging miles after miles of wet laundry in the bathroom. :cool:

Bella56

Any results from the tumble drier monitoring, Graham? I'd be interested to see what the difference is between your reading, and our less scientific method!

grahamc2003 wrote: »

Yeah, plug in energy monitors aren't totally accurate. But then again no other measuring device - whether for home use or professional - is totally accurate. I said it was very accurate, which it is in the context of home energy monitors, and certainly far more accurate than owl meters for example.

Also true that some items of clothing may not be suitable for tumble drying, but the majority of everyday clothes are (according to my wife). But my implied question was, of those clothes that can be dried both a tumble drier and by a dehumidifier, aren't the results better from a tumble drier (my wife assures me they would be)?

grizzly1911

Keeping the spin higher would be better for drying times.

We have variable spin and tend to use 1200 rather than 1400 on the basis it may not stress the machine so much. It can go as low as 800, which we often use on a cold wash, by default, for the dogs' towels etc.

There is a massive difference between 800 and 1200. 1200 -1400 not really noticeable. Wonder how much energy the faster spin takes;)

Interestingly my mum still has an ancient stand alone vertical spin drier which has an 1100 spin. She is adamant it still gets more water out (runs into a bowl) after a 1200 and 1400 horizontal spin in the automatic washer:( Perhaps she just spins it to death.

Thank goodness we have a good sized airing cupboard with room for an airer.

chris1973

I keep hearing from various sources that the plug in monitors are fairly inaccurate, but I've looked for a reason and still I'm not sure why?

By way of the quality and to what level of precision they are built and how (or if) they are calibrated at the factory. Most people would not expect a surgeon to carry out surgery on them using a 50p magnifying glass when there was a £20,000 scanner available to him which would allow for more accurate results!.

Most of these energy monitors are made extremely cheaply in the Far East (one of the reasons why energy companies can buy them in bulk and just give them away en masse) open them up and you'll find the same bog standard resistors and IC's as are used in Childrens Toys, clock radios etc, some of the measuring circuit components have a +/- 5% swing and as much as a +/- 20% swing in some cases.

An item is only as good as the weakest component in its chain, so if you have components designed to vary by 5% - 20% then it stands that so, do the calculations it is called upon to calculate and display.

I work in the Electronics Manufacturing Industry, and believe me if it was possible to replace £10,000's worth of calibrated test equipment with £5 stocking fillers then trust me, our M.D would be first in the queue.

In addition, we send away our test equipment to an independent lab every year for calibration and its amazing just how much accuracy they do lose over the course of just 12 months, i'd hate to think by how much these domestic devices varied as the temperature and humidity changed and the battery voltage varied, and the device 'aged', not to mention other factors such as RF interference and dropped signals etc

I've also compared the real time household usage results between a couple of domestic energy monitors and a loaned calibrated clamp meter, and believe me, the differences in the real time displayed results are chalk and cheese. Even two models of domestic energy monitors can display differing readings when fed off the same meter tails, and compared side by side

IMO these meters should not be relied upon other than for 'novelty purposes only' as some of them are quite capable of producing more fiction than J.K Rowling

One of the biggest drawbacks of these monitors is their inability to track rapidly changing loads, such as your washing machine motor changing its rpm, or just running for a few seconds at a time on a wash cycle. I've also seen lots of lag where an appliance has switched off several minutes ago, but for some reason the signal between the sender and monitor has been lost (or its refresh rates are too slow) so the meter goes on recording a higher than actual consumption for minutes longer than was factual.

I also found that one monitor struggled to measure the load accurately of a modern appliance which controlled the temperature of the element by pulsing it, a design now getting quite common in appliances for heating and motor control.

Yes, they have a place, if only to remind you of what appliances cost more to run and to warn you when a high current device is left running, but don't live your lives around them, or their accuracy.

grahamc2003

Bella56 wrote: »

Any results from the tumble drier monitoring, Graham? I'd be interested to see what the difference is between your reading, and our less scientific method!

Ah, erm well, I pulled the plug out to put my new energy monitor in, then plugged the already time-delayed-and-set timble drier back in and looked forward to seeing how much energy the thing uses. Next morning, I read the meter - 0.1kwh, and a drier full of damp clothes. Looks like I didn't press the 'go' button - not very popular for that!

So I'l, try again tonight.

As the the accuracy/inaccuracy of energy monitors, I think the confusion arises because the whole house Owl types are quite inaccurate (and at low consumption extremely inaccurate), while the different technology 'plug-in' types are very accurate (+-0.5% mine claims). (In addition to the different technology of both, the owl types can't measure at all the power factor, whereas the plug in types can accurately measure it, telling you how much power is paid for but wasted by the equipment - the owl types just inaccurately measure how much is paid for, not how much is usefully used).

grahamc2003

Measured the energy usage last night - the tunble drier used only 1.6kWh, at a cost of 9p. It took out about 0.5l of water out of the clothes. They had been slightly dired on the line for a couple of hours in the fog (told her not to bother, but would she listen?). Mine is a Hoover condenser type, which senses the dryness of the clothes and turns off when they reach the correct level of dryness (after doing some 'airing' and reverse tumbles). So it looks like the heating element isn't on for much of the time the machine is working (as I would have expected).

My dehumidifier on low (about 420w) measured 2.9kwh for the full 7 hour cheap rate session, costing me 18p. That means the low powered heater in the (dessicant) dehumidifier was on all the time (the room is nowhere near 45% humidity where the dehumidifier decides it's dry enough and turns itself off).

So on that basis, it looks somehwer around twice as expensive to dry clothes aitrh a dehumidifier than with a tumble drier (I'm assuming it takes 7 hours for the clothes to dry using a dehumidifier - is that about right?).

Bella56

Hmm, line drying for a few hours first is def. cheating Shame that they weren't a usual wetness. Mine takes at least 2 hours to dry a full load but also we seem to pay more for electricity. Then again, we are on Economy 7

macman

Bella56 wrote: »

Hmm, line drying for a few hours first is def. cheating Shame that they weren't a usual wetness. Mine takes at least 2 hours to dry a full load but also we seem to pay more for electricity. Then again, we are on Economy 7

So the sensible time to use your drier is overnight on a timer. If the neighbours don't object to the noise.
Using a 3kw drier on peak rate will indeed be expensive.