Hotpoint/Hoover dryers' airflow designs

[Marky_Mark]

Hi guys

 

What are the pros and cons of the different airflow designs of vented dryers?

 

I've noticed that older Hotpoint and Hoover dryers had their lint filter at the rear of the drum.  I think some used a negative pressure design where the air was sucked outside by a fan at the rear of the drum behind the lint filter.  Others used a pressurized design where air was blown into the drum.  Presumably all with halo of heat.

 

In later machines, the lint filter was relocated from the rear to the front of the drum probably in the 1980s.  Obviously a more convenient place for it to be and I guess users are more likely to clean it more often.  But did this bring other disadvantages?  Do these different designs affect noise, drum capacity, drying time, efficiency, lint build up in the cabinet, plus other factors?

 

Mark

 

P.S. would love to see these machines in person some day.  I just love these vintage machines and wish I could own one.  Would be fab to go to one of the wash-ins at the candy store over at Alistair's place!

 

[realvanman]

Lint Screen Location

Until I picked up a 1971 Maytag DE806, I did not realize that some dryers had the lint screen in the back. The light bulb is behind it too

My daily driver '84 Whirlpool has the top one, and I'm running a '90's Kenmore at my facility that has it inside in the front.

Until I worked on one I thought all dryers pressurized the drum, but negative pressure makes sense to control lint build up inside the machine.

Would love to hear about the merits of each design.

Keith

 

[Marky_Mark]

Keith, I just googled a photo of your Maytag DE806.  I absolutely love the look of it -- very mid-century modern!  And I love the "ding" of the real bell for end of cycle signal.  How fabulous!

 

I think all Euro dryers are now like your Kenmore with the lint screen at the front, either in the door itself or below the door.

 

I agree with you about negative pressure reducing lint build-up.  I guess the drum is never going to be airtight and so a pressurized design will increase lint build-up.  I have also heard that reducing pressure inside the drum will improve the evaporation rate, but I can't imagine the pressure is reduced significantly to have any appreciable effect in that regard.

 

I know that many members have used both Hoover and Hotpoint dryers, along with other brands, that changed the position of the lint screen.  So I'd be really interested to know what other differences this change brought about.

 

Mark

 

[iej]

Miele vented dryers have the fan mounted at the front right, under the drum. Air is sucked in, via the filter in the door, the heater pack is behind the drum. So, they are also negative pressure, just configured more practically than the old Hoover machines.

 

[iej]

This video explains a lot an Aussi service technician figures a Miele vented dryer out.

 

[electron1100]

Hoover Dryers

The ealier Hoover dryers were non pressurised, a fan at the back of the drum draws air through the rear mounted filter which is then drawn over the heating coils, simple but effective.

Then Hoover moved onto the pressurised cabinet, the cabinet is basically sealed so that air is drawn in by a large fan at the bottom back of the machine, the air can only escape through the heater coils then the filter then the outlet.

Both designs have the filter at the back of the machine which is not the most convenient place unless you have the dryer stacked on top of the washer etc

These are the two designs I am very familiar with from Hoover both work very well at drying as you have whats known as a "Halo of heat" in the drum and high air flow rates giving even drying throughout.

Gary

 

[Marky_Mark]

Hi James, that's an interesting video and in fact I did watch it a few months ago.  I liked seeing the inside of that machine.

 

Hi Gary.   Ah right, so you have found that both of those two Hoover designs (pressure & non-pressure) with the filter at the rear are just as effective.  Yes I see what you mean about the filter at the back being easy to reach if the machine is stacked, otherwise it's a bit tricky.  I would love a dryer like yours that reverses every 37 seconds!  Matched with your Electron washer too -- how cool!

 

So, for example, if you had the choice between a vintage Hotpoint dryer with the filter at the rear and one with the filter at the front, there isn't really any difference other than the convenience of where the filter is?  I think Hotpoint changed the location to the front before Hoover.

 

Mark

 

[electron1100]

Creaky back

The filters are easy to extract and put in providing your back isn't like mine (stiff) it is because of this that I made the comment, other wise they are easy to get to.

I too think Hotpoint moved the filter before Hoover did, unfortunately Hotpoint also changed to plastic drums on there dryers aswell which is some thing I don't like.

Gary

 

[iej]

I wouldn't buy a dryer that didn't have a stainless steel drum as they just create huge amounts of static.

 

[maytag85]

Old thread

But here’s some literature from about 1967 or 1968 on various dryer designs from different manufacturers from around that time. Not sure if this is from Consumer Reports, but highlights the design of the Maytag Halo Of Heat dryers. Definitely a straight forward design with the air cooled cabinet, heat source, drum, lint screen, fan, and ductwork.

 

[combo52]

All US dryer small and large have an air cooled cabinet

Except the positive airflow Norge dryers and the 1957 through 63 Westinghouse 25 inch wide space mate dryers.

Sean there was nothing particularly great about HOH dryers in fact it was found to be rather bad idea to have a heat source of the front of the drum because a fire hazard Hot front cabinet surfaces which posed a burn hazard, etc.

Again Maytag gave up on this lousy design and redesigned their dryer much closer to whirlpool and other modern dryers, this was not caused by the government or energy regulation but just a desire to build a good product and succeed in the market

John L

 

[maytag85]

Reply #10

From what I remember when I used my Maytag DE306 before I ended up taking the wiring off of it for the DG606 to DG306 conversion, the cabinet never got that hot to the touch and was relatively cool to the touch when in operation. Usually whenever I checked to see how dry things were or had to add something in, the high limit thermostat would trip not too long after I opened the door and yes the lint screen and venting was clean. The high limit thermostat in the Maytag DE306 (at least the one that came with it) was a L140-10 thermostat. I doubt that thermostat was original but certainly did it’s job in being sure the front of the cabinet and drum didn’t get too hot to the touch. I am sure that HOH dryers that got hot to the touch at the front of the cabinet probably had the high limit thermostat replaced by repair techs that just stuck one on from another dryer rated at a much higher temperature or were replaced by someone who didn’t know any better.