Comparison
If the manufacturer's calculator is free, why pay for a calculation?
It is the fairest question anyone can ask us, so here is the answer without hedging. Briefly: a manufacturer's free tool is built to select their equipment, not to calculate a building.
What each one is for
Two different tools for two different jobs
We are not claiming a manufacturer's calculator is bad. We are claiming it does something else - and that this follows from what it was built to do.
| Manufacturer's calculator | HeatAlgo | |
|---|---|---|
| Why it exists | To help select equipment from the manufacturer that published it. | To calculate the building, and select equipment from that result. |
| Which catalogue it selects from | One manufacturer's - by definition, the one that owns the tool. | Generalized power classes, averaged from several manufacturers' catalogue data on a shared EN 14825/14511 basis. A reference point for output, not a list of models to pick from. |
| What the sizing rests on | As much building data as it takes to point at a unit - because that is the job it was built for. | A design heat load computed room by room to EN 12831-1. |
| How many modules see the same house | As many as that one tool covers. | Four - heat load, heat pump, underfloor heating and ventilation - from one set of inputs. |
| What you are left with | An equipment selection. | A PDF report carrying the whole calculation, to hand to a client or attach to a quote. |
| Whose interest it serves | The manufacturer that published it. There is nothing wrong with that - it is the tool's job. | Ours, and you pay us for the calculation rather than for the sale of a particular unit. |
About the price
Theirs are free and ours is not
There is no way around that and we will not try to find one. If you need an approximate output rating and you trust a per-square-metre rule of thumb, a free calculator is enough and you do not need to pay us.
You pay us when you need a calculation you can defend in front of a client - broken down by room, with its assumptions stated, and a document at the end of it.
We charge per house, not per unit. One unlock covers every module for that building.
Do not take our word for it
We calculated one house and published all of it
The complete input set, every step, and the result from four modules, in a form you can recompute by hand. It is the only way we know to back the table above with something other than our own opinion.
Questions
Before you ask
Does a manufacturer's calculator get it wrong?
We do not claim that and we have no grounds to. We claim it answers a different question - 'which of my units fits here' rather than 'how much heat does this building lose'. If the second question matters to you, the first tool will not answer it however faultlessly it calculates.
Can I use both?
Yes, and many installers do. Calculate the building with us, then use the manufacturer's tool to see which specific unit from their range covers the figure. The order is the whole difference.
Why do you not name any programs?
Because we have not audited anyone else's software, and without that every sentence about a specific product would be guesswork. What a manufacturer's tool is built to do we can write about, because it follows from its role. How a particular program calculates, we would be asserting without evidence.
How do you differ from energy-certificate software?
We compute the design heat load - the output needed in the coldest hour, which is the basis for sizing a heat source and the system around it. An energy performance certificate is a different calculation and is issued by a certified assessor. Our report does not replace one.
Check us on a building of your own
You do not have to take our word for it, and you do not have to pay to start. Create a free account, enter your house and see what the engine returns.