# Equal Spacing in Title Headings - Parskip

I have formatted the titles of chapters, sections etc but I can't get the spacing between their elements equal to each other because as I have seen the command \setlength{\parskip}{10pt} adds to those spaces. Why parskip plays a role in the spacing of the titles? How can I prevent that?

MWE

\documentclass{book}

\usepackage{titlesec}

\titleformat{\chapter}[display]%
{%
\Huge \centering \bfseries%
}%
{%
Chapter\\
\vspace{10pt}
\thechapter%
}%
{10pt}{}%
[%
\vspace{20pt}\rule{\textwidth}{1pt}%
]

\setlength{\parskip}{10pt}

\usepackage{fontspec}

\usepackage[english]{babel}

\begin{document}

\chapter{Title}

Text here

\end{document}


Under the scope of \centering, \\ issues \par, so the \parskip enters in the way. Just say \setlength{\parskip}{0pt}\centering\bfseries. Since the chapter titles are typeset inside a group, the value of \parskip will be restored for normal text.
Or, better, don't change the standard value of \parskip.