chapter-first page-fancyhdr: hide title, but keep page number

Question

In my diss (book document), I have headers (chapter title and page) appearing on chapters' first page as well. For each first page, I would like to remove the chapter name, and just keep the page number. This will prevent repetitions. From the second page onwards, classical heading should apply (chapter/session name + page number). I would like to have the same for TOC and LOF as well, but TOC shows no headers at all on the first page.

Any help would be greatly appreciated.

Sincerely,

Udiubu.

Below the relevant coding:

\documentclass[openright,a4paper,12pt,twoside]{book}
\titleformat{\chapter}[display]{\normalfont\huge\bfseries}{\chaptertitlename\\thechapter}{16pt}{\Large}
\usepackage{fancyhdr}
\setlength{\headheight}{15.2pt}
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{
\markboth{\thechapter.\ #1}{}}
\renewcommand{\sectionmark}[1]{
\markright{\thesection.\ #1}}
\lhead[\thepage]{\leftmark}
\rhead[\rightmark]{\thepage}
\fancyfoot[C]{} %remove page number from footer
\makeatletter %insert header on title pages
\let\ps@plain\ps@fancy
\makeatother

\begin{document} 

... %other pages here

\newpage
\begin{onehalfspacing}
\section*{Acknowledgments}
These are the aknowledgments
\end{onehalfspacing}

\cleardoublepage
\begin{doublespace}
\pagenumbering{roman}
\setcounter{page}{11}
\tableofcontents
\thispagestyle{fancy}
\end{doublespace}

\newpage
\thispagestyle{plain}
\addtocontents{lof}{\protect\addcontentsline{toc}{chapter}{Figures}}
\listoffigures

\mainmatter
\pagenumbering{arabic}
\pagestyle{fancy}
\chapter{Lorem Ipsum}

Lorem Ipsum 

\end{document}

Answer 1

The line

\let\ps@plain\ps@fancy

is responsible for the behavior you obtain. Whoever advised you to use it didn't do you a favor: it makes the plain page style, used by default on chapter starting pages, equivalent to the fancy page style.

Just remove the line.