Heat Tape Temp Consistency

Does anyone else have issues with heat tape being different temps in different levels of a snake rack? I have two racks. One has a single piece of 4" weaved through each level. The rack is built into the wall and only 3 levels. Bottom level read at 90, middle and 85 and top at 99. What could be causing this? I have another 6 level rack where the heat tape is cut into 6 equal sections and run in parallel with eachother. I get the same discrepancies, just not quite as bad. It seems odd that I have a 14 degree swing on a 3 level rack. Whats the deal? I'm reading with a temp gun btw.

It is not unusual to see a temp fluctuation over a longer length of heat tape. For that reason, I am not a fan of the weaving installation, I would rather use a separate piece on each level.

In addition, you can see a different temperature result because of ambient temp differences related to height, or access to airflow (directly under a ceiling vent for example). Your tubs closer to the floor may be cooler, and high tubs may be warmer, so you have to keep that in mind as well.

I think in this case, you are seeing a larger issue using the longer run.