Any chance you might post the Model number of your dryer? You may get a little help with that info.

Walt I just wanted to say...hello. hope all is well with you.

Hi Mama. And likewise, I hope that things are going well for you and the family. It's always a pleasure to pop into this forum to see you here (I'll confess to still missing Larsi though :) ).

As for the dryer, Jarvis, it's a Blomberg heat pump condensing dryer, WM98400SX. I've again had the door open and the filter cartridge out and door open for a few days to dry out and it smells fine. I'll run another load tomorrow and anticipate the musty, mildew smell returning. I hate to make (and pay for) a service call for this, but something isn't right.

Wet lint residue, low drying temps and pretty much continuous humidity create perfect conditions for musty odors. Bosch/Siemens even went so far to make a cleaning solution that flushes the inside of the heat pump dryer during a dedicated cleaning/soaking cycle.

Cleaning the heat pump is possible but a lot of work. Maybe you can flush some Lysol solution through the dryer.

Where in the world are you?

Thanks whirlpool. We're in Seattle. How does one run a liquid through a dryer to flush it out?

I agree that the temps, moisture and lint are perfect for a musty stew and I'd have thought that this would be a more common problem than what I'm finding through online searching.

A few thoughts come to mind t eliminate problems. Maybe check if the drain line is kinked or not positioned right (check the install manual) and also see if the unit is level.

If nothing has changed and the smells started recently, one must suspect a lint build up and/or moisture accumulation somewhere.

I see that your dryer does not have a removable water tank but rather drains the condensate out immediately. Hm...

The problem is that there is a basically a drip tray underneath the entire visible "metal unit" of the heat pump. There's always water in there, mixed with lint.

Thoroughly cleaning it most likely means disassembling the dryer to get to the bottom of the machine. :(

I suppose you could use one of these pressurized spray bottles and spraya cup or two of non-corrosive, non-foaming disinfectant solution in there via the accessible front, let it sit for a minute, briefly run the dryer to pump it out and repeat.

That is just a guess, though. Have you tried automaticwasher.org? A lot more heat pump dryer users in there (I actually only have a regular condenser dryer).

Alex

Thanks for the ideas zneret and Alex. Automaticwasher.org is a great thought too. We've been using the dryer for a couple of years now without issue, so I don't think it's a problem with the drain line, and I'd wondered about the pressurized aerosol spray as a first step, though I'm leaving town for a few weeks and that's the easiest step of all. :) Seems that the designers could have been a better job of making these parts accessible to clean. Grrr.

Here's a German language video on YouTube where someone cleans the the front of the condenser in a Siemens/Bosch heat pump dryer. Interesting to see how he has to literally cut out an access window to reach the target area, and then somehow already has on hand a replacement cover that screws in perfectly over the cut out area after he finishes cleaning it.

http://www.youtube.com/watch?v=nJ-2l_gC9RE

I was not able to positively identify the liquid that he pours near the top of the machine, that then flows down and rinses the condenser. All I can figure out with the help of Google translate is that the label on the bottle may have the words "natural", "refreshment", and possibly "tastes good".

Hmm, I have an email notification about a message on this thread liking to a German language YouTube video with someone cleaning a Siemens/Bosch condenser. Did Houzz axe the message???

Thanks zenhar24, your message magically reappeared. Interesting video, and I had to smile at the "selfCleaning condenser" label on the outside of a filthy condenser that had to be cut open. Ridiculous that these aren't easier to clean. I can reach the fins on our Blomberg fine so don't need to slice it open, but it'll be interesting to try and figure out what he poured on.

Might just be a defective or poorly designed unit. I have a Frigidaire dryer that does the same thing once a year or so. Try using the highest option and try to wipe it down after use. The smell may be mold.

Yes, M translated that video pretty much 100%. Bosch/Siemens hrat pump dryers flush the condenser with the condensate that is stored in the water tank. It's an ingenious system... that works better on paper than in real life. The newest Bosch/Siemens dryers have eliminated that sealed service door and just made the condenser accessible to the user just like on all other heat pump dryers.

Anyway, your dryer is a different brand and plain water does not kill mold.

I think spraying down the inside of the heat pump area could be an option. Heck, I've seen people taking their Electrolux dryer outside, removing the back panel and flushing the think with a pressure washer!

For what it's worth, this is the stuff Siemens sell in Europe:

https://www.siemens-home.bsh-group.com/uk/shop-productlist/cleaning-and-care/laundry-care/cleaners/00311829?search=00311829#/Togglebox=-1188775611/

This document is in German and for an older AEG dryer - but it shows the dryer being pressure washed. ;D

https://forum.teamhack.de/filebase/download/50/

Hi there, wondering if you ever managed to solve this problem. We’re experiencing the same issue with our Blomberg heat pump dryer.

Hi Emma-- I'd honestly forgotten that I had this problem, as it hasn't been evident in a long time. I don't remember what I did (if anything) at this point unfortunately, but the suggestion above to spray high pressure aerosol air through the fins pokes a brain cell. I know I didn't make a service call and I don't think I took anything apart further, but there may be suggestions in the video that I tried. I do leave the door open for a day or so after I use it so, like the washer, it can dry out decently. Sorry I'm not more helpful, but please let us know if you find a solution as it'd be great as a reference.

Hello! I have been scouring the internet because I have had a similar problem with my "self-cleaning" whirlpool W6 D94WRUK heat pump dryer that is not even a year old. I'm so happy to find this thread as it helps me know I'm not crazy!! LOL I have been in contact with whirlpool, had 3 technicians out and they have been 'stumped' as to the problem and origin of smell, more or less just telling me to deal with it. The heat exchanger appears clean but the smell seems to be coming out right underneath it as Whirlpool_Trainee suggests. Has anyone had any experience with this on the Whirlpool models to indicate that its a similar issue with a drip pan underneath? It is so hard to get in there and requires a full disassemble, so I want to have some confidence in telling the next techniction that comes out to take apart where he needs to look! Thanks for your input.

Ive also found this interesting review/assessment from someone in the States re the hybrid heat pump dryer US model that I think could be a more depressing and deeper issue possibility of whats going on with my machine. basically a design flaw or two...

https://www.whirlpool.com/laundry/dryers/electric/p.7.4-cu.-ft.-front-load-hybrid-heat-pump-dryer.whd862chc.html?

under "Unhappy Wife, Unhappy Llife"

Judging by pics I found of your dryer model, there seems to be a small cover at the left side of the dryer towards the bottom of the unit. The self-cleaning filter should be behind it - judging by this video.

https://youtu.be/vexNc1d7NAU

Thanks for your reply! yes, actually I have taken this off and cleaned that filter before. The area there, as well as the front of the condenser are clean. The smell seems to be coming from further down/in the machine. It seems that it might be sitting water somewhere. The deeper I search online, the more i realise how many problems there are with heat pumps and how the designers' different versions are essentially troubleshooting new problems from model to model. My old vented semi-pro, huge whirlpool dryer worked for 17 years but of course cost a bomb to run and was far from energy effecient. Was why I trusted whirlpool with this purchase, but am very disappointed so far in this one.

Have had a Miele T1 heat pump now for years. It is approaching 6000 operating hours. No problems, no smells. Just routine maintennace.

I think Miele has this technology figured out. It is at the top of the price spectrum, but maybe that is the cost to have a well functioning appliance?

In all the heat pump dryer cleaning vidoes I have seen on YouTube, the solution is always to take the whole dryer apart and rinse the heat exchanger.
There's just no easy fix, unfortunately.

We Have a Miele T1 TCE520 WP in the UK and I can tell you Miele are just as guilty as other manufacturers of creating a poorly designed cleaning door to access the heat pump condenser. We have tried the cleaning of the fins with a tooth brush/ paint brush & soap solution, but there is very limited access. The musty smell is everytime now and it looks like the only option is to take the machine apart to clean it!

I doubt that this is approved by manufacturers, but in addition to vacuuming, brushing, and compressed air in an aerosol can, I've tried a careful blast from the (electric) leaf blower through the fins when I detect a hint of smell. It's pretty powerful and, at least anectodally, seems to help. My thought is that whatever lint is dislodged will blow back into the drum area and get caught in the filters in the next dryer load.

Hey, thanks for posting back . Used steam cleaner and the smell is gone. Essential maintenance from now !