Free Heat Pump Tools and Calculators
Over the years I have created a number of calculators and tools aimed at heat pump owners.
These time saving pages allow you to ditch the pen, paper and calculator to get quick answers to commonly asked heat pump questions.
Descriptions and links below will direct you to specific pages on the site.
These tools and calculators form part of both my Heat Pumps Explained and Vaillant Arotherm Heat Pump Guide series, which cover how heat pumps work, how they’re sized, and how to interpret performance and running costs.
Hot Water Calculator
The biggest mindset shift for me moving from a combi boiler to a heat pump was hot water. The most eye opening aspect is how slowly it can take to heat the water. Especially compared to the instantaneous nature of hot water from a combi.
So here’s a little Hot Water Calculator that tells you long water will take to heat.
Input parameters:
- Starting temperature (°C)
- Target temperature (°C)
- Amount of water (L)
- Power output during DHW (kW)
- COP of hot water run (optional to show electricity usage)
Hot Water Calculator (reheat times for heat pumps)
Watch this short video where I talk you through the hot water calculator
Mass Flow Rate Calculator
Mass Flow Rate is the calculation to determine heat output.
Input parameters
- Flow rate (L/h)
- DT (K)
- Heat output (kW)
- SHC (kJ/kg·K)
Use the Mass Flow Calculator to enter any two of flow rate, DT and heat output to solve the missing one.
Heat Loss Survey Tool (What size heat pump?)
Getting the right size heat pump installed is crucial to ensure good performance and low running costs.
With this Free Heat Loss Survey Tool you can use gas usage data from very cold days along with the outside and inside temperature to get a ball park estimate for the heat loss of your house.
Note: this does not replace a full room by room and total heat loss survey from a qualified and experienced installer, but it can help give you an idea about heat loss numbers.
Free Heat Loss Survey Tool – What Size Heat Pump?
Heat Pump Cycling Calculator
If you’ve noticed your heat pump clicking on and off a lot in spring or autumn, don’t panic. That’s cycling and in most cases it’s completely normal.
Because your house doesn’t need much heat when it’s mild outside. At some point the demand drops below your heat pump’s minimum heat output (its “can’t go any lower” point). When that happens, the unit has to cycle, turning off for a while, then back on again, to avoid overheating the house.
If it didn’t do this, the heat pump would just run constantly and you’d end up far too warm indoors.
We have a dedicated heat pump cycling calculator and in this cycling and minimum modulation article we go into why it happens and whether the amount you’re seeing is normal.
Heat Pump Cycling Calculator (Minimum Modulation)
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