Tumble dryer exhaust thermostat

[jayseeblue]

Hi,

I have a problem with my Mother In Law's Creda T601CW Tumble dryer (electric). It blows hot then a few minutes later blows cold five minutes later back to hot. I've taken the front (exhaust?) thermostat out this is located inside the door hole. There is continuity across it. I then taped the two wires together and started the dryer up and it stays hot all the time. My question is does anyone know if these front stats reset themselves, if so then this would be the answer to the problem as by the time I remove the stat it may have reset itself and so showing continuity on the multimeter.

Also i notice the heater element coils are red hot at the top and hot but not red on the bottom of the element. Is this normal and is it due to the top one being sheltered from the main blast from the blower?

I hope this makes sense.

Thanks to any replies

Jon

[NT]

Yes, if it didnt reset it woudlnt be any use as a thermostat

NT

[Peter Parry]

The thermostat is doing its job. Almost certainly the inlet or exhaust is partially blocked with accumulated dust which is reducing the airflow and allowing the heater to get the air too hot. It is possible the thermostat is faulty but I'd clean out the inlet air vent and the full outlet path before doing anything else. If the dryer vents to outside is there a permanent flap on the outside wall and is this stuck closed?

[Chris J Dixon]

A very valid point. I was not too happy when my brand new all-singing all dancing Bosch tumble dryer kept telling me the outlet was blocked, the old crude one never complained. When I eventually went outside and checked, it was quite right, the exterior grille was well clogged with fluff.

You won't want to hear of a friend of mine whose garage was quite seriously damaged when his tumble dryer caught fire in the night.

Chris

[Jules]

Agreed. I took our old one apart last year and pulled a staggering amount of crud out of it. I'm tempted to get the tin snips to it actually and rig it so it'll be a bit easier to dismantle the next time (I had to flip it over before to get to some screws on the underside).

re. heating element colour, ISTR ours glows red on part of it but not the rest - I expect the behaviour the OP's seeing there is normal.

I bunged our dryer down in our basement, which means the vent's only a few inches above ground level outside now. As it's winter and we get a lot of snow around here, the dryer's got a note taped to it to remind people to check the vent's clear before use...

cheers

Jules

[Doctor Drivel]

Yes, if it didnt reset it woudlnt be any use as a thermostat

[Doctor Drivel]

Buy a consdensing dryer, then no vent.

[Chris J Dixon]

If the thermostat is not resetting, how do you explain the OP's description?

[Jules]

Yeah, might be an option once I've dug a sump down in the basement and hooked a pump up (which I need to do sometime so I can throw the washing machine down there, too)

In the spirit of DIY, maybe I can turn the existing dryer into a condensing one... :-)

[Doctor Drivel]

I responded to this: "if it didnt reset it woudlnt be any use as a thermostat". Which is incorrect.

[Doctor Drivel]

The water is emptied into a tray. You empty the tray.

[Jules]

Not necessarily:

"the difference in temperature causes the moisture in the warm air to condense into drops of water, which are pumped to the same drain as the wash water."

and:

"The condensed water can be either pumped away to a drain line (e.g. into a standpipe shared with the clothes washer) or stored in a container within the dryer to be emptied later (not all models offer both options)."

and:

"The condensate is collected in the bottom of the chamber and is pumped down the same drain as was the wash water"

etc.

[Calvin Sambrook]

The terms are a bit overloaded which causes confusion.

A thermostat is an operational device which opens and closes as the temperature changes and is used to maintain a constant (static) temperature, within a tolerance band. A high limit switch is a safety device which opens if the temperature ever reaches an abnormal level. It latches and requires a manual reset. The problem is that the high limit switch is often incorrectly termed a high limit "stat".

On most conventional tumble drier designs the thermostat is in the air path, often at the front. The high limit switch is usually around the back with a small button accessible from the outside, often coloured red.

I really wouldn't expect to be able to tell that the operational thermostat was switching on and off by feeling the output air changing temperature as dramatically as described, it should really have less hysteresis than that however it does sound like it is working. I'm with the others who've already commented that most drier problems like this turn out to be lack of adequate venting. Sort that then see where you go from there.