Energy ratings for tumble dryers

Martyn1981

Sterlingtimes wrote: »

I know that currently I use 26,000 kWh (£1,000) in electricity per year, and 83,000 kWh (£1,000) in gas per year.

The best I can do is to get energy efficient technology, appeal to the family and hope that somehow solar PV makes a dent in these numbers.

Hiya Sterling. Are you sure about those numbers, they are 10X our pre PV figures. Also the kWh's v's £'s don't seem to add up, wouldn't both gas and leccy be about £3,000 each?

We've got a condenser drier, and do use it all year round (our guilty secret), but the stated consumption levels seem rather high. For 2 months before PV was installed I recorded daily leccy import and noted that laundry day, usually Sunday was approx 5kWh more than the other days, but that was for 2 washing loads (spin dried), and 1 drier load, so presumably the figures are for the max load, max wet, and max time(?)

Mart.

zeupater

Sterlingtimes wrote: »

The crux of the problem here is that I can work on getting the technology right but I cannot finely control the behaviour of the house occupants, e.g. impose showering windows and durations, dictating washing and drying times.

I know that currently I use 26,000 kWh (£1,000) in electricity per year, and 83,000 kWh (£1,000) in gas per year.

The best I can do is to get energy efficient technology, appeal to the family and hope that somehow solar PV makes a dent in these numbers.

Hi

I'd seriously look at the cheaper options before going out and spending £loads on anything in particular .... joking aside, washing line and a flow restrictor on the shower head would be examples of the low hanging fruit which is ripe for picking with both solutions potentially being in place by next weekend ... it's fun measuring, but measuring alone saves absolutely nothing ... we used to consume high 30's bordering on 40000kWh of gas/year, that much would probably now last us to the middle of this century ... surprised what you can achieve with a little application ...

Apart from that, the above figures look really odd .... £1000/26000 & £1000/83000 means that you're paying 3.8p/kWh for electricity and 1.2p/kWh for gas .... that's about a quarter of the average cost on both .... are you sure that there's not a fundamental error somewhere ?? .... :doh:

HTH
Z

zeupater

Martyn1981 wrote: »

Hiya Sterling. Are you sure about those numbers, they are 10X our pre PV figures. Also the kWh's v's £'s don't seem to add up, wouldn't both gas and leccy be about £3,000 each?

We've got a condenser drier, and do use it all year round (our guilty secret), but the stated consumption levels seem rather high. For 2 months before PV was installed I recorded daily leccy import and noted that laundry day, usually Sunday was approx 5kWh more than the other days, but that was for 2 washing loads (spin dried), and 1 drier load, so presumably the figures are for the max load, max wet, and max time(?)

Mart.

Same wavelength this side of the border .....

They'll be using cotton to standardise the test material on something which absorbs & retains water well as opposed to lightweight fabrics which don't ... I doubt that any load apart from towels or bedding would equate to the one used for the test ...

Z

Sterlingtimes

Sorry, my mistake. The electric is 8,273 kWh and the gas is 26,077 kWh in a year. The price for each is £1,000 per year.

Martyn1981

Sterlingtimes wrote: »

Sorry, my mistake. The electric is 8,273 kWh and the gas is 26,077 kWh in a year. The price for each is £1,000 per year.

Not fair you beat me to it - I didn't look on here last night, and when I woke up this morning my brain immediately said - "He's transposed those numbers, it was 83,00[STRIKE]0[/STRIKE] for leccy and 25,000 for gas." I wish I had a wipe memory function when it comes to numbers and bed time!


@ all - Ok, silly question time, but I was pondering the heat pump drier. I get the basic idea of the technology, and I understand that heat pump water heaters are getting very popular in the US, but .....

during the heating months, assuming the tumbly is within the heated envelope of the property (ours is in the un-heated pantry) is it fair to 'think' that it's gas powered, in the sense that the tumbly uses some leccy power to steal heat from the house that has been supplied by GCH?

Also, if it's a condensing heat pump tumbly is there any net loss of heat, assuming the hot water is left to cool before disposal? Probably over-thinking this!

Mart.

Sterlingtimes

Martyn1981 wrote: »

... during the heating months, assuming the tumbly is within the heated envelope of the property (ours is in the un-heated pantry) is it fair to 'think' that it's gas powered, in the sense that the tumbly uses some leccy power to steal heat from the house that has been supplied by GCH? Mart.

Mart, I had the same question (and still do). The vented dryer produces a lot of hot air that is wasted. We could probably grow vines in the part of the garden where the air exits the house. The condenser dyer appears to convert the hot air to water but not to re-use the hot air. So the condenser dyer is most less efficient than the vented dryer. It seems that that heat pump dryer is re-using the heat that would otherwise be lost (like a condensing boiler). But, does it steal heat from the house?

zeupater

Hi

Effectively ....

The vented option draws in air, heats it with electric elements and tumbles the fabric in the warmed air stream. Some of the energy in the warm air is 'grabbed' to enable evaporation and humid air is expelled (/vented) through the wall .... The energy efficiency of this depends on the equipment and positioning ... Some vented machines are really pretty efficient if they have low temperature & eco modes, however the cycle time increases if these are used .... ours has both and is controlled by a humidity sensor - it has no cycle timer. On the positioning side, you're effectively extracting air from the house & I'd be amazed if the energy consumed in space heating is added to and included in any comparative figures ... ours is in an unheated utility room with controllable/sealable ventilation, so there's no excess waste of house space heating. The only problem with having the eco functionality is getting MrsZ to use it - it seems that the tumble dryer is a last minute/last resort appliance for when the other 9999 items of clothing aren't suitable, but the one which has just been washed is ....

Condenser dryers effectively contain the same air inside the machine, again heating with electric elements. Warm humid air is passed over a plate heat exchanger which is cooled by a separate external source airflow (effectively heating the room) ... cooled moist air inside the machine quickly passes it's dew-point and water condenses .... It takes a similar amount of energy to dry the load, but there's no 'additional' heated&vented air waste, it's retained within the house and there's no extraction of domestic warm air ...

Heat pumps don't 'steal' heat from the house, but they do 'borrow' it. Again, the unit is effectively sealed, but this time we have a refrigeration circuit transferring (pumping) some heat from the surrounding air into the appliance, but importantly, the highly cooled evaporator surface is used to lower the dew-point of air flowing over it so that condensing, and therefore drying, happens at a lower temperature ... It's almost certainly the lower heat requirement rather than the system COP on heat provision which results in the increased cycle efficiency ...

HTH
Z

Cardew

Have you seen these figures - and at a stupidly high electricity rate of 15.2p/kWh(you can enter your own figure)


http://www.sust-it.net/energy-saving.php?id=41


I have a Miele heat pump condensing model and the costs are far lower than those stated

zeupater

Cardew wrote: »

Have you seen these figures - and at a stupidly high electricity rate of 15.2p/kWh(you can enter your own figure)

http://www.sust-it.net/energy-saving.php?id=41

I have a Miele heat pump condensing model and the costs are far lower than those stated

... odd that a simple division shows the costed figures are based on 111 cycles/year - how does that work, 9.25 per month -or- 2.14/week ? ... be nice to know where they've got that from considering that by their own criteria the comparison should use 148 6kg dry cotton cycles/year ....

... don't they teach basic arithmetic anymore .... :wall:

Z

Sterlingtimes

I mentioned to Mrs Sterling this evening that it is not every husband who would set up a couple of test rigs to measure her laundry energy usage. She did not seem very impressed.