Select Size

Select Size

The best Heat Pump is the right size


Selecting the best heat pump for your home is about size. Too small, and the unit will overwork, and your room won't be warm enough. Too big, and you will spend more of your money on the unit and your electricity bill.

Heat pumps come in different output temperature ratings. The heat rating is the KW (kilowatts) of heat. Note that this is not the power consumption but the production of heat.


The key to selecting the best Heat Pump is to match the KW of heat to the room you want to heat.



This article can be broken down into two heat pump sizing methods:


1. Most accurate is the Secret Formula

2. Using a quick guide


Before you begin you will need to know what part of your home you want to heat?



Secret Formula


The calculation method is extremely accurate as it makes allowance for insulation and the climate of you home.

To use this method, you will need to know how to calculate m3 and what insulation you have in the room you want to heat. All the info you will need is broken down into 3 easy steps.


  1. M3, how to work out your m3
  2. Watts, how to calculate how many watts of heat you require to heat your home
  3. Secrete formula


If you would like one of our friendly representatives to talk you through use the ASK A Question button at the bottom of this page.



The secret formula is M3 X Watts

  • M3 is the volume of air in the room
  • W is the watts of heat required
  • Our secrete formula


Step 1, M3

To work out the M3 measure and multiply the rooms Length X Width X Height.

L X W X H = m3


Step 1, example,

The Bedroom is 5 (l) X 4 (w) X 2.4 (h)

or 5x4x2.4= 48m3


Step2, Watts

*Starting from 40watts add 5 watts for every piece of insulation you do not have and add 5 watts for heating issues such as cold climate, drafts. Ie the less insulation you have, the more watts (heat) you require.

Double Glazing, Wall Insulation, Ceiling Insulation, Under Floor Insulation, 

Ad watts for each heat loss issues your home has.

Drafts, Cold Climate, Skylights, Large windows, Cold Climate


Step 2 example,


*Start from 40yes/no40
Double Glazing
No5
Wall Insulation
No5
Ceiling Insulation
Yes0
Under Floor Insulation
Yes0
Drafts
Yes5
Large windowsNo0
Skylights
No
0
Cold Climate
No
0
Total
55W

In this example, W = 55 or the home requires 55 watts of heat per m3 to heat the room.



Step 3, M3 X Watts (secret formula)

Multiply your results together

M3 X W = requirement



Step 3 example

Using the results from our step examples 1 and 2 

  1. The room was 48m3
  1. Requires 55 watts
48m3X 55Watts = 2640 watts or 2.6kw


To put this into practice


A Heat Pumps heat output is measured in KW which is simply 1000 watts of heat. Once you have worked out step 1,2 and 3 all you need to do is match the heat pump to your requirements.



Note: Due to being the best value and most reliable we are promoting Hitachi Heat pumps If you are not already aware of their benefits click here for product overview.


The performance of your Hitachi.




If you have completed the instructions you don't need to use the Quick guide, The next stage is to select the location you want your heat pump installed, This article will teach you what you need to know to choose the best place for your Heat Pump. Click Here


Hitachi Quick Guide


Match your room size to the red on the New Zealand map (climate zone).

Note: 

Model number RAF-=floor mount

Room M2

    M2 Average NZ Room

      

      

      

    10m2

    Single Bedroom

    Ras-25

    Ras-25

    Ras-25

    15

    Double Bedroom

    Ras-25

    Ras-25

    Ras-25

    20

    Large Bedroom

    Ras-25

    Ras-25

    Ras/Raf-35

    25

    Small Lounge

    Ras/Raf-35

    Ras/Raf-35

    Ras/Raf-35

    30

    Average Lounge

    Ras/Raf-35

    Ras/Raf-35

    Ras/Raf-50

    35

    Average Lounge

    Ras/Raf-50

    Ras/Raf-50

    Ras-60

    40

    Large Lounge

    Ras/Raf-50

    Ras-60

    Ras-60

    45

    Large Lounge

    Ras-60

    Ras-60

    Ras-70

    50

    Open Plan

    Ras-60

    Ras-70

    Ras-80

    55

    Open Plan

    Ras-70

    Ras-80

    Ras-80

    60

    Large Open Plan

    Ras-70

    Ras-80


    65

    Large Open Plan

    Ras-80



    70

    Large Open Plan

    Ras-80




    Disclaimer

    Sizes are a guide only and based on a moderate to a well-insulated house with an average percentage of window area for the room type and a ceiling height of 2.7m max. 


    A list of our Hitachi heat pumps can be found on our product page.


    Room size case study


    A typical New Zealand Home Divided into 3 Zones

      Lounge and study (45m2) = RAS-60


      Ideal for rooms 35-50m2, a clever control feature automatically provides optimal comfort via a combination of indoor/outdoor sensors.


      Kitchen and dining (30m2) = RAS-35


      Ideal for rooms 20-30m2. Ras-35 is our biggest seller. It's perfect for the smaller living areas and rumpus rooms. You'll enjoy a comfortable environment all year round.



      Bedroom (20-30m2) = 3X Ras-25


      Ideal for rooms 10-20m2. It's perfect for bedrooms, studies, and offices and rooms up to 20 square metres. The intelligent, compact design operates in near silence due to a diagonal heat exchanger.




      The next step


      Select the perfect location for your Heat Pump click here to go to our location page which will teach you


        1. What direction will the air flow around your home
        2. What are the mechanical requirements for your Heat pump (how a Heat Pump works)








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