How to Choose Between Over-the-Side and Bottom-Mounted PTFE Heaters

Tank heating can be accomplished by hanging a heater over the rim, or fastening it through the bottom wall. Each method has different effects on the installation cost, maintenance and thermal performance. Understanding the difference between over the side vs bottom mounted PTFE heater provides an advantage in picking the best option for certain operational demands.

PTFE Heating Element, Over-the-Side
A PTFE heater is usually suspended over the tank rim on an over-the-side bracket or mounting frame. Installation of this unit is simple, as it does not require any penetration of the tank wall and can be easily installed and removed for maintenance. Eliminates need for tank penetration , also makes cleaning easier and lowers chance of leakage .

But the over-the-side heater has its limitations. The heated section could not extend all the way down to the bottom of the tank which might lead to less consistent heat distribution, especially in bigger tanks. Practically, having the heater could block access to the tank, making maintenance activities more difficult or leaving less space for other equipment.

Bottom Mounted PTFE Heater
The PTFE heater is fixed on the bottom by inserting it via a flange welded on the tank bottom. This technique also provides for full immersion depth, meaning that the heating element is at the lowest point in the tank, allowing for uniform heating from the bottom up. Furthermore, this setup leaves the tank rim area free of obstructions because the heater is mounted directly to the bottom of the tank.

The bottom-mounted heater distributes heat more evenly, but is more difficult to install and remove. Often removal involves draining the tank or disconnecting the flange which can be time consuming and add to the maintenance complexity. One thing to remember with bottom-mounted heaters is to make sure that the flange is sealed properly to avoid any leakage. Usually this worry is addressed with PTFE - lined flanges or gasketed designs .

Criteria for Selecting Over-the-Side vs Bottom-Mounted PTFE Heaters
When picking between an over the side vs bottom mounted PTFE heater there are various things to consider:

Heater Removal Frequency: If the heater must be removed frequently, an over-the-side layout is preferred. This is especially true for smaller tanks, or for applications where frequent examination and maintenance of the heater is required. It can be easily removed for quick access without draining the tank.

Space Constraints: The over-the-side heater does not require any modifications to the tank and is perfect for smaller tanks with limited space, or where there is a need for flexibility in heater placement.

Even Heat dispersion If you have a larger tank or a system where you need even heat dispersion the bottom mounted heater is usually better. It provides even heat distribution from the bottom up, which is important in procedures that require uniform temperature conditions.

Bottom-Mounted vs Top-Mounted: As the name suggests, a bottom-mounted design is perfect for permanent and large size installations where space usage and even heating is a necessity. However, for temporary setups or systems that change often, the over-the-side heater may be more convenient.

Heater Configuration Comparison 
Feature Over-the-Side PTFE Heater Bottom-Mounted PTFE Heater 
Installation Complexity Easy, no tank penetrationTank upgrade and flange weld required
Maintenance Access Easy to remove and maintain More complicated, tank must be drained to remove
Uniformity Heating may be less uniformProvides even heating from bottom to top
Best Use Small tanks, frequent heater removal, temporary setupslarge tanks, permanent installations, Uniform heating requirements
Summary
The choice between over the side and bottom mounted PTFE heaters is not just a mechanical one, it has major ramifications for day to day operations, maintenance and long term efficiency. The over-the-side arrangement is lightweight and easy to remove and use, while the bottom-mounted configuration provides better heat dispersion and space savings. The initial installation is an element in heater selection but so is the whole lifecycle. The chosen configuration needs to satisfy the operational demands and maintenance needs.