Inverters appearing in domestic appliances

[9fingers]

Inverters in the sense of Variable Frequency Drives have been in use for many years to give machines variable speeds when used with 3 phase motors as some of you know. However they are being introduced to various domestic items now.
*Air conditioner/heat pumps to give variable rates of heating and cooling as well as variable fan speeds
*Washing machines to avoid the the relatively rapid brush wear of universal motors running hell for leather at ever increasing spin speeds and simple electronic control of tub speed between washing and spinning.

I needed to replace our chest freezer as it was running the compressor for ever longer periods to keep down to temperature - quite noticeably during this summer. Being a large model 450 litres if and when It died we would have no way to preserve the contents so I decided to get a new one before it died.

There is not much choice around that size so my choices we largely based on availability and price. I found one sold by Buy it Direct for a sensible price and just checked on their Ebay shop and whilst it was a little dearer Ebay had £75 off voucher. Result! Looking at the features I saw it was "Inverter drive".

It duly arrived the next day complete with a Ding on the case at one end where it will not be seen up against the wall but pointed it out to the driver who immediately rang back to base, and laying it on medium thick before passing his phone to me and the operator offered £50 refund - be rude not to accept I thought!
Plugged it in via a power meter and it drew about 100 watts to start with and then it cut back to 30 watts for a bit and started the usual on/off cycling and not seen it get about 30 watts. Daily consumption is just over 0.5 kWh per day which is 12pence on my current tariff.

Opening up the side panel reveals a small module about 120 x120 x50 mm which must be the inverter and a little compressor that runs between 60Hz and 225Hz it is also whisper quiet.
So it must have some sort of proportional speed control running fast under heavy demand and on tick over to maintain temperature. Very clever and amazingly economical compare to its predecessor which in its knackered state is using between 4 and 5 kWh per day.

So if you need to buy new refrigeration equipment, I'd say its well worth seeking out a model that uses an inverter provided the price is right.

 

[AJB Temple]

I'm a bit puzzled why a chest freezer would struggle to keep temperature. It's a big block of frozen food & cold air in what should be a leakproof cabinet as long as the lid seal is OK. I presume you checked the lid seals and thermostat. What do you think was causing the excessive running?

 

[Malc2098]

Just checked, my recent investment in a heat pump tumble drier also has an inverter.

Economical, powerful and maintenance-free​

The ProfiEco motor from Miele is a particularly powerful inverter drive, engineered to deliver its performance as economical and quiet as possible. The motor is electronically controlled, which means it doesn’t use carbon brushes and isn’t subject to the usual wear. An innovative design that ensures many years of efficient, carefree, and convenient laundry care.

 

[Cabinetman]

A half down from 4 or 5 kWh per day is a massive saving over a few years. Definitely worth trying to get one, are inverters prone to having problems?

 

[9fingers]

Yes the seals are good and thermostat holding within a couple of degrees. Almost certainly a worn out compressor. Quite likely 20 on more years old.
Another failure mechanism although not in my case is the insulation failing. Condensation forms in the insulation and it slowly turns into a block of ice. Firstly you get poor performance then the cooling circuit rusts through and lets the gas out and the compressor runs continuously but there is no cooling

 

[9fingers]

A half down from 4 or 5 kWh per day is a massive saving over a few years. Definitely worth trying to get one, are inverters prone to having problems?

Yes it is a big saving but the old one almost certainly has a worn compressor causing it to run over 50% of the time. It would not have used that much power when new.

The inverters i use on my machines have been faultless. Obviously modern ones in white goods have had their electronics “value engineered” but manufacturers know they need to maintain reliability so its a careful balance. Im not concerned about electronic reliability.

 

[Woodbloke]

When our old fridge freezer let the milk curdle, I reckoned it was time for a new one. SWIMBO insisted that we had an A rated appliance (no point in discussing it) so we opted for this one which apparently has an inverter compressor. Nice bit of kit - Rob

 

[AJB Temple]

We put wireless thermometers on even our domestic grade freezers and fridges. I try to keep the freezers at minus 25C and the fridges at about 3C. FSA requirements for catering businesses are Freezers must be below -18C all the time, and Fridges not to go above 5C. The wireless thermometers are cheap nowadays and will record max and min and send alerts etc if a range is exceeded. It is surprising how much appliances vary.

 

[Woodbloke]

We put wireless thermometers on even our domestic grade freezers and fridges. I try to keep the freezers at minus 25C and the fridges at about 3C. FSA requirements for catering businesses are Freezers must be below -18C all the time, and Fridges not to go above 5C. The wireless thermometers are cheap nowadays and will record max and min and send alerts etc if a range is exceeded. It is surprising how much appliances vary.

Interestingly, when our old fridge freezer went TU I checked at our local ginormous Tesco supermarcardo to see what their fridges were kept at and I spoke to a couple of nice ladies who pointed me to the thermometers attached to each fridge. They read 2C, which is what our new one at home is now set at, with the freezer at -20degC (the new ff has a digital readout on the front, so it's dead easy to set the temps) - Rob

 

[Cabinetman]

You rmentioning the insulation freezing up reminded me of a thing in Grimsby which had at one time the Worlds largest volume of freezer capacity in cold stores, some of the oldest suffered from permafrost which buckled the floors making them unusable for forklift trucks etc. (When I was about 21 they were stripping one of the cold stones out and I got some of the Pitch? Pine and made a fence out of it that lasted decades.)
Thing was there was nothing they could do with the building for about 15 years till the ground thawed out.
Cold stores now are built with an air gap underneath them.
Ian

 

[AJB Temple]

Rob - if your freezer will go a bit colder I would. And use the fast freezer when you can as that helps to stop ice crystals forming in the food.

With fridges they very a lot. One of ours is a Samsung american thing and if I set it at 2C then the bottom drawer will be below freezing, which is why I set at 4. In the other fridge, it is a two drawer unit in my prep area and it is dead stable at whatever I set it. But that one I take stuff out ready for immediate use so I don't want it too cold.

 

[Lons]

Rob - if your freezer will go a bit colder I would. And use the fast freezer when you can as that helps to stop ice crystals forming in the food.

With fridges they very a lot. One of ours is a Samsung american thing and if I set it at 2C then the bottom drawer will be below freezing, which is why I set at 4. In the other fridge, it is a two drawer unit in my prep area and it is dead stable at whatever I set it. But that one I take stuff out ready for immediate use so I don't want it too cold.

Our 12 month old Beko upright freezer is set at -18 which is what the manual says is recommended and is the default setting. Are yo saying that isn't cold enough?

 

[9fingers]

We put wireless thermometers on even our domestic grade freezers and fridges. I try to keep the freezers at minus 25C and the fridges at about 3C. FSA requirements for catering businesses are Freezers must be below -18C all the time, and Fridges not to go above 5C. The wireless thermometers are cheap nowadays and will record max and min and send alerts etc if a range is exceeded. It is surprising how much appliances vary.

Adrian, do you have any info on preferred makes please. Ideally I'd want something that can sit on the wall with a probe going into the freezer and wifi alert to my phone as you mention. Thanks Bob

 

[Woodbloke]

With fridges they very a lot. One of ours is a Samsung american thing and if I set it at 2C then the bottom drawer will be below freezing, which is why I set at 4. it too cold.

Ours is also Samsung but the fridge has got a recirculating air feature so the temp is the same all the way through it from top to bottom - Rob