1. Turn gas to off and turn off power to heater and ensure the entire unit is completely off.

2. Decouple the manifold from pool plumbing system to allow excess water to drain from the sytem.

3. Remove drain plug from the manifold to ensure all water has drained from the system fully.

4. Photograph all wire and sensor locations to ensure exact replacement is achieved, and unplug the 8 wires (each color set of 2 are interchangeable to either prong of that sensor).

5. Carefully remove all sensors (and pipe or plug) from the manifold.

6. Remove the 10 1/2 inch hex head cap screws with ratchet or socket wrench (the bottom 2 bolts may be slightly shorter - replace in same holes!) Carefully unseat manifold assembly from the header.

7. Remove backplate by carefully levering off with a prey tool, open, photograph, remove all parts.

8. Create your new manifold assembly by adding o-ring to thermal regulator cap. Screw cap to manifold shell. Tool tighten couplers. (Depending on the flexibility of your system, you may decide to do this step AFTER mounting to the header!)

9. Seat both coupler o-rings into the connector tube holes on the shell (do NOT place on connector tubes first!) Hand tighten couplers. (Depending on the flexibility of your system, you may decide to do this step AFTER mounting to the header!)

10. Install all sensors into new shell (using new PTFE tape as needed), hand tighten. If using the square bolt pipe plug optional o-ring is included (seat in hole first!) Install and tool tighten.

11. Using reference photo, reinstall interior parts into manifold (take care to correctly position the spring - loaded regulator assembly).

12. Carefully align backplate with shell (remember alignment with header if some holes covered) and making sure the rectangular 0-ring is correctly seated, use the floor or flat surgace press backplate in place (backplate assembly will be under pressure from the thermal regulator assembly, so you only need to seat so it doesn't spring back out).

13. Seat manifold assembly onto header, and hand tighten the bolts (see 6 above). Tool tighten all bolts working out from the middle, until all are torqued on sungly. (Bottom bolts are harder to finish, don't neglect or these become more difficult!) Couple manifold to pool plumbing, making sure any 0-rings are properly seated in pool plumbing. Turn system back on and test.

Here's a video that includes these instructions: