svmono: how center figure vertically?

Question

How can I center a figure vertically within a full page, when using the svmono class? The traditional solutions I found in the forum doensn't seem to work with this class. Please note this is NOT for actual submission to the publisher, but for private use.

Thanks and regards, Jorge.

P.S. The svmono class can be downloaded here.

Example (UPDATED):

\documentclass[graybox,envcountchap,vecarrow,twoside]{svmono}
\usepackage[paperheight=240mm,paperwidth=170mm,top=2.5cm,inner=2.5cm]{geometry}

\usepackage[caption=false,font=footnotesize]{subfig}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{floatrow}

\begin{document}

% Some text
\lipsum[1-5]

% A figure in an new page
\clearpage
\begin{figure}[p]   %doesn't work
%\begin{figure}[H]  %doesn't work
\centering
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-a}}

\vspace{1cm}
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-b}}
\caption{This figure should be centered vertically}
\end{figure}

% Some text in an new page
\clearpage
\lipsum[6-10]

\end{document}

Actual output:

Desired output:

Answer 1

Here is a way that doesn't use the figure environment but caption package instead:

\documentclass[graybox,envcountchap,vecarrow,twoside]{article}
\usepackage[paperheight=240mm,paperwidth=170mm,top=2.5cm,inner=2.5cm]{geometry}

\usepackage[caption=false,font=footnotesize]{subfig}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{caption}

%This code makes thhe whole job of vertical centering the image
% #1 includegraphics options
% #2 image name
% #3 image caption
\newsavebox{\mysavebox}
\newlength{\myvspace}
\newcommand\addCenteredImage[3][]{%
\clearpage
\savebox\mysavebox{\vbox{\phantom{.}\par\includegraphics[#1]{#2}}}%
\setlength\myvspace{\dimexpr(\paperheight-\dimexpr(\ht\mysavebox+\dp\mysavebox))/4\relax}%
\phantom{.}\vspace{\myvspace}\par\usebox\mysavebox\captionof{figure}{#3}\clearpage%
}


\begin{document}

% Some text
\lipsum[1-5]

% A figure in an new page
\addCenteredImage[height=10cm,width=10cm]{example-image-a}{This figure should be centered vertically}

\lipsum[6-10]

\end{document}

It is a way with simple commands as far as I can understand them.

The output is the desired of your image.

Edit for subfigures: (After OP's edit)

\documentclass[graybox,envcountchap,vecarrow,twoside]{article}
\usepackage[paperheight=240mm,paperwidth=170mm,top=2.5cm,inner=2.5cm]{geometry}

\usepackage[caption=false,font=footnotesize]{subfig}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{caption}

%This code makes thhe whole job of vertical centering the image
% #1 includegraphics options
% #2 image name
% #3 image caption
\newsavebox{\mysavebox}
\newlength{\myvspace}
\newcommand\addCenteredImage[1]{%
\clearpage
\savebox\mysavebox{\vbox{\phantom{.}\par #1}}%
\setlength\myvspace{\dimexpr(\paperheight-\dimexpr(\ht\mysavebox+\dp\mysavebox))/4\relax}%
\phantom{.}\vspace{\myvspace}\par\usebox\mysavebox\clearpage%
}


\begin{document}

% Some text
\lipsum[1-5]

% A figure in an new page
\addCenteredImage{%
\centering
\includegraphics[height=3cm,width=8cm]{example-image-a}
\captionof{subfigure}{Test 1}
\vspace{1cm}
\includegraphics[height=3cm,width=8cm]{example-image-b}
\captionof{subfigure}{Test 2}
\captionof{figure}{This figure should be centered vertically}
}

\lipsum[6-10]

\end{document}

Output:

Answer 2

A page float is typeset using

\vspace*{\@fptop}

<material of the float>

\vspace*{\@fpbot}

The svmono class sets \@fptop to zero, leaving \@fpbot to the default value of 0pt plus 1fil.

Just add the proper setting.

\documentclass[graybox,envcountchap,vecarrow,twoside]{svmono}
\usepackage[paperheight=240mm,paperwidth=170mm,top=2.5cm,inner=2.5cm]{geometry}

\usepackage[caption=false,font=footnotesize]{subfig}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{floatrow}

\makeatletter
\setlength\@fptop{0pt plus 1fil} % <--- restore the values
\makeatother

\begin{document}

% Some text
\lipsum[1-5]

% A figure in an new page
\clearpage
\begin{figure}[p]   %doesn't work
%\begin{figure}[H]  %doesn't work
\centering
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-a}}

\vspace{1cm}
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-b}}
\caption{This figure should be centered vertically}
\end{figure}

% Some text in an new page
\clearpage
\lipsum[6-10]

\end{document}

Answer 3

Thanks everyone for your kind suggestions. The solution proposed by Sigur does the trick (see below). Regards, Jorge.

\documentclass[graybox,envcountchap,vecarrow,twoside]{svmono}
\usepackage[paperheight=240mm,paperwidth=170mm,top=2.5cm,inner=2.5cm]{geometry}

\usepackage[caption=false,font=footnotesize]{subfig}
\usepackage{graphicx}
\usepackage{lipsum}
\usepackage{floatrow}


\begin{document}

% Some text
\lipsum[1-5]

% A figure in an new page
\clearpage\null\vfil
\begin{figure}[h]
\centering
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-a}}

\vspace{1cm}
\sidesubfloat[]{\includegraphics[height=6cm,width=8cm]{example-image-b}}
\caption{This figure should be centered vertically}
\end{figure}

% Some text in an new page
\clearpage
\lipsum[6-10]

\end{document} 

Output: