I bought a new GE 7 cu ft electric dryer to replace an 16 year old Kenmore dryer (with top lint filter) because the old dryer occasionally causes brownish marks on the collar tips of shirts.

Apparently the tips of the shirts were caught in the gap between the rotating drum and the stationary back plate. The gap of the old dryer will get wider due to the wearing-out of the felts/supports at the rear and at the front of the drum. So I decided to replace the old dryer.

The construction of the rear end of the GE drum is completely different from that of the old Kenmore. There will be no gap at the rear to catch the tips of the shirts.

The new GE 7 cu ft dryer seems to hold a bit more clothing than (say about 5% to 10% more than) the old Kenmore. It takes about 48 min to dry a load of cotton clothing using the normal cotton sensor cycle.

I think that the design of the drum of GE is better but the overall construction of the Kenmore/Whirlpool is better.

I think that the equivalent model in USA is GTDP400EMWS.

A) From 0 to 10 min, the temp was increasing slowly from 68F to 113F (47F increase)

B) From 10 to 20 min, the temp was increasing very slowly from 113F to 118F (only 5F increase).

C) From 20 to 32 min, the temp was increasing slowly from 118F to 149F (31F increase).
During the periods of A, B and C, the inlet thermostat was cutting IN/OUT one of the heating element to maintain the set-temperature of the inlet.

D) From 32 min to 50 min, the outlet thermostat took over to the set-temperature of the outlet. The outlet temp as measured varied from 136F to 154F. When the temp exceeded 154F, both heating elements were cut OUT (OFF). When the temp fell below 136F, both heating elements were cut IN (ON).

E)From 50 min to 56 min (cooling down period) the outlet temp fell slowly to 104F and at 56 min the buzzer sounded to end the drying cycle.

If so, the INLET thermostat is likely an overheat safety thermostat and should not be cutting the element out during normal operation. It only comes into play if there's insufficient airflow across the element.

Could be what happened during your test is that at start of the cycle (from 0 to 32 mins), the overheat safety thermostat was cutting the element out rather than letting it run continuously as it should to reach the target outlet temp (~155F). When the clothes are cold/wet, evaporating moisture holds the exhaust air temp down and the heat has to run longer to reach the target temperature. After 32 mins the clothes were sufficiently moving toward dryness and holding heat, the exhaust air temperature reached the target temperature and the element cycled off via the exhaust outlet thermostat (which is the only thermostat that should control the element during normal operation). The element then ran for shorter periods to maintain the ~155 air temp and didn't overheat the safety thermostat.

There are two heating elements (say about 2700 watts each at 240V) in the GE dryer.

A) When the Temperature Selector is NORMAL, both Control Inlet and Drum Outlet are HIGH.
B) When the Temperature Selector is PPress, Control Inlet is LOW and Drum Outlet is HIGH.
C)When the Temperature Selector is Delicate, both Control Inlet and Drum Outlet are LOW.

The weaker part is the old exhaust hood which has 2.5" opening. This 2.5" hood is not recommended by the manual of GE dryer.

I bought an new hood which has 4" opening. The new 4" hood was installed to replace the old hood yesterday.

There is less restriction of air-flow using the new hood.

I will try to find out if there is any improvement in drying time.

A) From 0 to 10 min, the temp was increasing slowly from 66F to 117F (51F increase)

B) From 10 to 20 min, the temp was increasing very slowly from 117F to 122 (only 5F increase).

C) From 20 to 30 min, the temp was increasing slowly from 122F to 151F (29F increase).
During the periods of A, B and C, the inlet thermostat was switched ON/OFF one of the heating element to maintain the set-temperature of the inlet.

D) From 30 min to 45 min, the outlet thermostat took over to the set-temperature of the outlet. The outlet temp as measured varied from 133F to 154F. When the temp exceeded 154F, both heating elements were switched OFF. When the temp fell below 133F, both heating elements were switched ON.

E)From 45 min to 51 min (cooling down period) the outlet temp fell slowly to 102F and at 51 min the buzzer sounded to end the drying cycle

Note:
1) There is about 10% reduction in the drying cycle with the new hood.
2) But I think that there could be about 2 to 5% reduction in heating cost because the inlet temperature is maintained by the Control Inlet Thermostat.
3) The temperature variation at the outlet is about 3 deg F with the Control Inlet Thermostat in active mode.
4)The temperature variation at the outlet is about 20F (say 133F to 154F) with the Drum Outlet Thermostat in active mode.

The GE uses two thermostats at the inlet - Safety Thermostat and Control Inlet Thermostat.
I would think that
a) the Safety Thermostat would work at a temperature close to the "High-limit Thermostat of 250 deg F" and
b) the Control Inlet Thermostat would work at a temperature lower than that of the Safety Thermostat (say 20 to 50 deg lower). It is designed to maintain a regulated inlet air temperature. It has two inlet set-temperatures for this model with Normal/PP/Delicate. With a lower inlet temperature, it would take a longer time to reach the target temperature at the outlet.

I think that there are also two inlet set-temperatures in some new 29" WP dryer model with Normal/PP/Delicate(Gentle Breeze model?).

a) The inlet temperature of the GE is maintained from 180F to 210F by the Control Inlet Thermostat and the Safety Left Thermostat
b) The Thermo Hi-Limit Right Thermostat will shut down the whole dryer if the inlet temperature exceeds 250F when all the other thermostats fail to work.

Thus it seems that the GE dryer is working at a lower inlet temperature than the 29" WP dryer. This could be the reason why the WP does not cycle the heater until the target temperature at the drum outlet is reached.

a) NORMAL Temperature:
The temperature at the drum outlet varies from 133F to 154F when the target temperature is reached.
The Control Inlet temperature would be maintained within a limit (say 180F to 210F)

b) PPress Temperature:
The temperature at the drum outlet is same as that of the NORMAL.
However the Control Inlet temperature limit will be lower than that of the NORMAL (say could be 10 to 20F lower).

c) Delicate Temperature:
The temperature at the drum outlet varies from 122F to 147F when the target temperature is reached.
The Control Inlet temperature limit is same as that of the PPress.

I will use the PPress Temperature most of time because the clothing seems to be softer with a lower inlet temperature .

I think that there is practically no difference in energy usage. Perhaps it is better for the clothing (especially for Cotton/PP mixed load) using lower inlet heating temperature.