Heat Pump Sizing Calculator for New Plymouth Homes
Punch in your room and we'll give you a real kW range, not a guess. Sizing here has to handle damp Taranaki air and draughty old weatherboard, not just the odd frost.
What are you heating?
How big is the space?
How old is the home?
Sun and exposure in winter?
Our suggestion for your home
This is a guide based on your answers, not a fixed quote. The real answer is a free site visit, where we measure the rooms, check the insulation and confirm the size and price for your home.
Get your sized quote
Send us your details with your calculator result attached and we'll come back with honest options and a fixed price for your home.
As a rough start, allow about 0.10 to 0.15 kW per square metre of floor for a well-insulated room, and more for older New Plymouth homes with single glazing or poor insulation. A 40m² lounge often needs 5 to 7kW. Get the numbers checked before you buy.
What actually goes into sizing a heat pump
Floor area is only the start. The real number depends on ceiling height, how many walls face outside, how much glass you've got and whether it's single or double glazed, which way the room faces, and how well the place is insulated.
A square-metre rule gets you in the ballpark, but two rooms the same size can need very different heat pumps. A sunny north-facing lounge in a modern build is easy. A south-facing room with big single-glazed windows and no underfloor insulation needs a lot more grunt.
Use the calculator to get a starting kW range, then let us confirm it on site. We'd rather measure the room than guess from a floor plan.
Why New Plymouth homes usually need more than the chart says
A lot of the housing here is older weatherboard that heats slowly and loses warmth through gaps, single glazing and thin or missing insulation. The generic online charts assume a tidy modern build, so they under-size for these places.
Then there's the damp. Taranaki winters aren't bitterly cold, but they're wet and the mornings are slow to clear. A heat pump here has to work against moisture and cool damp air, not just a dry frost. Undersize it and it runs flat out all winter, never quite getting on top of the room.
Wind exposure matters too. Coastal and valley suburbs like Waitara, Glen Avon and Frankleigh Park cop more wind chill on the walls and windows, which pushes the heat load up. If you're weighing up brands and models, our rundown of the types of heat pump will help you match the unit to the room.
One room, or heating the whole house
If you just want the lounge sorted, a single high-wall unit sized to that room is usually the cheapest way in. Size it to the space it actually heats, not the whole floor plan, or you'll waste money and comfort.
Want warmth in bedrooms and living areas too? One outdoor unit can run several indoor heads with multi split heat pumps, which suits older homes where running new ductwork is a pain. If you're building or renovating and want it hidden, ducted heat pumps in New Plymouth heat the whole house from one system, though they cost more up front and need the ceiling space.
Each of those approaches sizes differently, so tell us what you're trying to heat and we'll work out the total load properly.
From the number to a working system
Getting the kW right is half the job. The other half is where the indoor and outdoor units go, cable and pipe runs, and drainage so condensate clears away from the damp side of the house. Good heat pump installation in New Plymouth is what makes a correctly sized unit actually perform.
Sizing also drives the price. A bigger unit and longer runs cost more, so it pays to know what you need before you shop. Our breakdown of heat pump installation cost shows what drives the figure.
Send us your room details or give us a call on 06 242 5842 and we'll sort the sizing, then the quote.
Common questions about heat pump sizing
What size heat pump do I need for my room?
For a rough guide, a 20 to 25m² bedroom often suits a 2.5 to 3.5kW unit, and a 40m² open-plan lounge usually wants 5 to 7kW. Older New Plymouth homes with single glazing or poor insulation sit at the higher end of those ranges. Measure the room and check the glazing before you settle on a size.
How many kW of heat pump per square metre?
A common rule of thumb is around 0.10 to 0.15 kW per square metre of floor for a reasonably insulated room. That climbs for high ceilings, lots of glass, exposed walls or an older weatherboard place. It's a starting point, not a final answer, so get the room assessed.
Is it bad to install a heat pump that's too big?
Yes, oversizing causes real problems. A too-big unit heats the room fast then keeps cycling on and off, which wears it out sooner, uses more power and does a poor job of pulling moisture out of the air. In damp Taranaki that last part matters, so right-sized beats oversized every time.
Does insulation change what size heat pump I need?
Absolutely. Insulation, glazing and draughts change the heat load more than floor area does. A well-insulated, double-glazed room needs a smaller unit than the same-sized older weatherboard room with single glazing and gaps. Tell us the insulation you've got and we'll size to it.
Get the size and the quote sorted
Tell us your rooms and how they feel in winter, and we'll size the right heat pump and price the install. Call 06 242 5842 or send your details through.