Tapo P110

BooJewels

I did say - in response to @badger09 specifically when mentioning using the P110 for monitoring her lamp - that the P100 would do for static constant load items like a lamp, where the wattage is known.  It clearly wouldn't help with something like a washing machine.

markin

An electric kettle was a good test to show it reduced the washer power use but it wont save any money, It has to be Gas heated water, Fire top kettle, or even an E7 heated hot water tank.

BooJewels

markin said:

An electric kettle was a good test to show it reduced the washer power use but it wont save any money, It has to be Gas heated water, Fire top kettle, or even an E7 heated hot water tank.

That would have been my assumption before I tried it - and fully understood that was what had been intended when people were suggesting it to save on the machines electricity consumption.  I also only rarely do a 90°C wash - only to freshen the machine periodically.

But the reality is that it did use tangibly less juice (see caveats below).  I had slightly miscalculated (net difference was minimal), in that I thought that my kettle was 2kW and took 5-6 minutes to boil 1.7 litres (twice).  I actually just plugged it into the Tapo P110 (kettle label says 3kWh) and it used 0.201kWh to boil, taking 4 minutes.  So the 2 x kettle fulls were 0.402kWh, 2 litres from an already running hot tap - what would that be, say 0.050kWh @ 10.3p, plus the wash cycle itself was recorded as 0.245kWh. Total cost @ 34p per kWh/10.3p for gas - around 23p for 0.647kWh + 50Wh gas.

The recent 90°C load done was recorded as 1.844kWh @ 34p would have cost 63p - so it appears to have saved 40p.  That worked out significantly greater than I was expecting.  I suspect that some of the difference can be explained by this test wash being empty of laundry and the previous load was towels - and whilst this is an old machine, I understand there is some adjustment in the amount of water used, depending on the weight of the load - but I don't know how that works.  My empty test load didn't take in any additional cold water - the power used would have increased had it done so to get up to the required water volume, then temperature.  So maybe it's not a fair comparison.

k_man

BooJewels said:

markin said:

An electric kettle was a good test to show it reduced the washer power use but it wont save any money, It has to be Gas heated water, Fire top kettle, or even an E7 heated hot water tank.

That would have been my assumption before I tried it - and fully understood that was what had been intended when people were suggesting it to save on the machines electricity consumption.  I also only rarely do a 90°C wash - only to freshen the machine periodically.

But the reality is that it did use tangibly less juice (see caveats below).  I had slightly miscalculated (net difference was minimal), in that I thought that my kettle was 2kW and took 5-6 minutes to boil 1.7 litres (twice).  I actually just plugged it into the Tapo P110 (kettle label says 3kWh) and it used 0.201kWh to boil, taking 4 minutes.  So the 2 x kettle fulls were 0.402kWh, 2 litres from an already running hot tap - what would that be, say 0.050kWh @ 10.3p, plus the wash cycle itself was recorded as 0.245kWh. Total cost @ 34p per kWh/10.3p for gas - around 23p for 0.647kWh + 50Wh gas.

The recent 90°C load done was recorded as 1.844kWh @ 34p would have cost 63p - so it appears to have saved 40p.  That worked out significantly greater than I was expecting.  I suspect that some of the difference can be explained by this test wash being empty of laundry and the previous load was towels - and whilst this is an old machine, I understand there is some adjustment in the amount of water used, depending on the weight of the load - but I don't know how that works.  My empty test load didn't take in any additional cold water - the power used would have increased had it done so to get up to the required water volume, then temperature.  So maybe it's not a fair comparison.

I think this will be the difference.
The load with towels would have used much more water. As towels absorb a lot, more water would needed to fill to the right level.

There will also be a bit of extra heat to heat the towels too, although I suspect that is minimal compared to heating the water itself

BooJewels

I think you're right @k_man - it certainly makes sense to me, but I don't know what the mechanism is for measuring the water fill.   But I can also imagine that fabric in the machine would immediately absorb heat from the water and require further heating too.

My takeaway from this is that at least when I periodically do my machine freshening hot wash, I can pre-fill it with my own hot water and save myself some pennies.  

k_man

I think any saving is from using gas heated water, rather than kettle Vs washing machine heating (the latter both are direct electrical).

BooJewels

Indeed @k-man - I did get that point.  I did a normal load of lightly soiled washing today and tried the hot water fill technique, just using combi boiler heated tap water - I put 6 litres in.  Unfortunately, I missed that I still had the 'quick wash' selected from the machine cleaning cycle until too late - so don't have a direct comparison - my regular washing is done as a longer 30°C wash.

But my 30°C quick wash today using tap hot water used 0.116kWh of electricity (cost 4p) where a full length wash at 30°C averages around 0.420kWh/14p.  A quick wash at 40°C uses 0.544kWh/18p and I bet my wash ended up nearer to 40°C than 30°C as the glass felt quite warm, where it doesn't really with a regular 30°C wash.

I'll do a full length 30°C wash with hot water fill in a few days for a more accurate comparison.  

ETA, rather than bump the thread:  I've since done a full length 30°C wash, filling it with 6 litres of combi boiler heated hot water at about 50°C.  The machine ran for a couple of minutes, then took in a smidge more water - as it was a small batch of towels, it maybe sucked up loads of the water and it decided it needed a bit more.

It used 0.220kWh of electricity (7.5p), compared to the usual 0.420kWh-ish (14.5p), so saved 0.2kWh - about 7p.  My takeaway from this is that I often hand wash and only use the machine to spin, but it might be worth putting my hot water into the machine instead and save myself some sink time so that I can do something more interesting.

vic_sf49

I've just joined the Tapo 110 experimenting brigade. (Pack of 2 = £16.99.)

One is collecting data about my fridge freezer, to see how power hungry that is. Shall leave that in situ for a few months.

The second is for my washer, to see which cycle uses what kWh, and whether shorter is better etc. As it's in my garage, I can now turn it on while sitting in my bed, after checking whether the sun is shining on my solar panels.

As I also have a smart water meter, I can compare water consumption to.

I feel a huuuuuge spreadsheet is about to happen.

Once the fridge freezer has been analysed, that Tapo will just be used as a smart plug.

Slinky

I've been filling my washing machine with gas heated hot water for several months now, via a watering can, we have plenty of water in the cylinder spare. This morning's 1 hr wash at a nominal 30C (it will be hotter from the temperature of the15 litres of water I've put in), was 0.118kwh, I then needed to do a quick wash of a valence sheet on a bed we were moving and only have one sheet. 15 minutes at 30C was 0.03kwh! It's not a wash I normally use, I put 10 litres of water in the machine, it drew in quite a lot more and there was a lot of vigorous sloshing rather than the gentle turning of the hour wash.

Alnat1

@Slinky Why do you use gas to heat water that you don't use? Wouldn't it save more to only heat what you need each day?