LPG Water Heating Calculations

Can someone please verify the following calculations for my hydronic heating.

The heating load is approx 45kw per hour

Using LPG as natural gas is not available:

I litre of LPG costs approx 74 cents.

Each litre of LPG equates to 25 Mj ?

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Physical Properties of LPG (Propane)

<table align="center" border="1" bordercolor="#ffffff" cellpadding="4" cellspacing="0"> <tbody> <tr> <td class="style13">Mj/litre of liquid</td> <td class="style13">=</td> <td class="style13">25.5 Mj/litre of vapour</td> </tr> <tr> <td class="style13">Mj/kg of liquid</td> <td class="style13">=</td> <td class="style13">50.4 Mj/kg of vapour</td> </tr> <tr> <td class="style13">Mj/m of vapour</td> <td class="style13">=</td> <td class="style13">96 Mj</td> </tr> <tr> <td class="style13">litres/tonne</td> <td class="style13">=</td> <td class="style13">1975 litres of liquid</td></tr></tbody></table>

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The boiler I am looking at is as follows:
http://www.simonsboiler.com.au/produ...80_350_430.pdf

This states:

Hourly Gas Input (MJ/hr):
LPG (Propane) 185

Hourly Energy Output (kW):
LPG (Propane) 41

So the cost of 45kw per hour would be:
($0.74/25) * 185 = $5.47


Anyone care to verify this... please

Thanks