heat pump dryer question

[gizmo]

I have recently picked up an LG heat pump dryer that had been discarded. It is only 3 years old.
Model DVH5-08W.

I have only had a basic look at it so far, it appears to be more or less working, but...

1. it doesn't appear to be drying very well?? So far I have only tried a couple of tiny loads, basically a large hand towel to test it on the quick 30 / 1kg cycle. The towel at finish was warm and steamy but not dry.

2. There is a fan behind a louvre at the back, it doesn't appear to turn at all. I think it is the evaporator fan, but it might only be used for the condenser clean cycle???

 

This model doesn't have an access panel to look at the condenser, like other heat pump dryers I've seen. But it does claim to automatically clean its own condenser.

I have marked one blade of the fan with a dot, after doing the quick 30 cycle the fan blade had not rotated, so I suspect this little fan may be faulty. It looks like a little generic fan, probably easily replaced. After running a while, the fan louvre gets cold so I think it is an evaporator fan, if faulty that would explain poor performance.

 

Does anyone who knows these LG heat pump dryers have any advice?

 

I'm very busy at present, so I may not be able to follow up for a bit, I apologize in advance. (getting ready for a trip...)

 

Thanks.

 

[henene4]

That fan at the back is a cooling fan and has no connection to the self clean functionality.

The self cleaning uses the water in the bottom of the heat exchanger and a diverter valve.
Once the self clean cycle starts, the diverter changes to divert the water to the self clean nozzles over the condenser and activates the pump.

If you are curious, that model should have a condenser clean option on the panel.
Download the manual, read the chapter and run it.

If the towel got warm everything should be fine.
It's a heat pump - it can't really properly heat with also properly cooling.

Heat pump dryers have a kind of weird cycle time curve.
A single item might take 45min, 5 items might take 1h, a full load 90min.
Smaller loads don't drop cycle times as much as with other cycle time.

Main reason is that getting heat into the dryer takes longer, and the hotter it gets the more moisture it removes per air cycle.
The more moisture it removed, the quicker it can heat up.
Exponential growth it evaporation speed, basically.

Here's a video illustrating the self clean functionality:


This video is of the older style machines with a single speed compressor and additional heater for the EcoHybrid system.
The new style uses an inverter compressor instead of a resistive heater.
The base design is pretty much the same though:

 

[gizmo]

Thanks Henrik, very helpful.

 

What you say about small loads vs large loads agrees with what I saw today, I dried a small load of maybe 5 to 10 items, socks and t shirts.  I did a regular cottons cycle, it worked fine enough and everything was dry. (cupboard dry setting.) The fan on the back still didn't move... I assume that's a fault? It took a long time to heat up, several minutes, but it did heat up OK eventually. If that rear fan isn't working, it would not work as effectively, is that right?

 

This dryer is inverter-driven compressor.

 

 

[henene4]

The rear fan is just for cooling down if either the process temperature gets to a specific level and/or certain components get above specific temperatures.

If you dry small loads, it might not even activate at all.

 

[eronie]

The fan on the back is for the cooldown part of the cycle.

 

[gizmo]

I just watched the second video, that is fascinating.

I will do a few more loads, some larger ones, and maybe it is OK? Or maybe it needs cleaning out. It certainly seems to have lint dust after the filters, as far as I can see without dismantling.

 

I had misunderstood how the heat pump dryer worked, I thought it was like a split-system air conditioner and took ambient room air, gathered heat from it ( through an evaporator) and transferred the heat to the dryer's internal airflow. The second video explained that all the added heat is from waste heat in the compressor, which it why it takes up to 15 minutes to get up to full heat. Explains why the rear fan may only work intermittently or not at all on small loads/short cycles - I thought it was moving room air through an evaporator. So the rear fan is just to cool the compressor if it gets too hot?

 

The fan did NOT operate at the end of the cottons cycle, so it doesn't seem to be part of a cool-down phase. There didn't really seem to be a cool-down, or it wasn't very effective - the clothes finished still quite hot.

 

[henene4]

Heat pump dryers rarely cool down much.

Most have a temperature guided cool down and only run any meaningful cooldown above 55C.

Yes, that fan basically just cools the compressor and other components.

 

[ozzie908]

I have a BOSCH

Heatpump dryer its really rather good but its major issue was it took a long time after finding the 1st and 2nd filter was almost closed up due to limescale I used lime away on them and its amazing how much quicker it works when the air can get through it...

 

[gizmo]

I did a reasonable size load yesterday, it worked perfectly and... the rear fan came on after a while. So all is good.

The only thing I can fault is a slight squeak / squeal sound inside when running with a load (didn't hear it before with a tiny load), it sounds like maybe a slightly slipping drum belt?

I will open it up when I get back and give it a clean out and check over.

I can't believe it was thrown away, it's an AUD$1500 dryer here, barely 3 years old.

 

[thatwasherguy]

Congrats on your find!!

I’ve never understood why people throw away perfectly working appliances either. It seems to me that it is no different than throwing a bunch of cash straight into the trash can. At least this one didn’t go to waste.
Thatwasherguy.

 

[launderess]

"I’ve never understood why people throw away perfectly working appliances either."

Careful now! One person's rubbish is another's found treasure.

Speaking for myself... and I am unanimous; leave people throw things away that are perfectly good. They often will find new homes before getting anywhere near local tip.

Miele vacuum cleaner

Hoover vintage vacuum cleaner

Three Keurig coffee makers

A Nespresso coffee maker

Regina "electric broom"

Haier portable washing machine

Instant Pot

Nini "Foodie" dual air fryer

Two NIB sets of dishware

and more..

Rather like Edwina Monsoon pushing that full trolley in supermarket one often just passes things by out of exhaustion.

If one had one's skates on could have had a new Miele heat pump dryer and vintage but NIB Maytag "Porta-washer" twin tub.