Algo AI is the assistant built into every HeatAlgo module: the heat loss calculation, heat pump sizing, heat recovery ventilation and underfloor heating. It answers questions about the app and about your project, reviews calculations, corrects values in forms, reads building documents and manages projects - always in a conversation, with a receipt for every change. One thing it never does: it does not calculate the heat loss - that is always the algorithm, to EN 12831-1. This article describes where Algo is, what it can do in each place, how its modes and limits work and what happens to what you send it. What is new in the app this October: the October 2026 update.
Where to find Algo
Algo is one assistant in three places - only what sits beside it differs.
- Beside a project. The "Algo AI" button in the top bar opens Algo next to the module you are working in: as a column beside the form on a wide screen, over the whole screen on a narrow one. Algo reads that module's document, can review it and change values in it. Opening another project moves the conversation to that project.
- On its own page. You reach it from the "Algo AI" item in the side menu, from the "Algo" link next to a project in the menu, or with the full-screen button in the column. The conversation history is on the left. Under the question field you pick the project the conversation is about ("Choose a project"); without a project Algo answers general questions only. On this page Algo reads every module of the chosen project, changes values in them on your instruction, and creates, renames and deletes projects.
- From the field on the Start page. The field "Tell Algo what to do in your project..." opens Algo's page with the question already sent. Next to it are ready-made questions, such as "Find what is missing in a project" or "What can you do in heatalgo?".
In the underfloor heating module you open Algo with the icon in the drawing toolbar. You can ask questions and start the automatic drawing from a floor plan. Review the proposal before replacing existing work.
What Algo can do
- Answers questions about the app: where a field is, on which step, why something is not visible. It attaches "Go to: ..." buttons that take you to the right screen and step.
- Answers questions about the project: what is in the heat loss calculation, what the loss in a room is, what to change to lower the result. It reads the module documents, so you do not have to retype anything. It also sees each module's result and findings as the screen shows them for your plan - on a free account, what the free preview shows. A figure that only the report shows, it says so plainly and does not try to work it out.
- Reviews the project. The "Review this project" button (or a question like "what is wrong in this project?") starts a review. The result is a list of things to check with two levels: "Probably wrong" and "Worth a look". You go through each item in the "What was found" panel with "Put into the form" and "Skip" (or "Apply all" / "Skip all"). On a free account Algo reviews the inputs; it reviews the calculation results once the project is unlocked. If the form changed since the review, Algo says the result is stale and asks you to run it again.
- Changes values. On your instruction ("set n50 to 1.5", "change the bathroom temperature to 24") it writes values into the module. Every save has a receipt in the conversation, "I saved N values", with the list of changes ("What changed") and an "Undo" button.
- Reads documents. You upload a building design, a window schedule, an energy performance certificate or a photo of a nameplate, and Algo proposes values for the form. In the heat loss calculation it reads the whole building design and enters the rooms, building elements, windows and doors.
- Brings data in from a ready source. At the start of heat pump sizing and heat recovery ventilation, when the heat loss calculation is ready, "Import the heat loss calculation with Algo" brings the data in and Algo asks for what is still missing; "Import without Algo" brings it in without the conversation. At the start of the heat loss calculation, "Import the client form with Algo" does the same once the client has sent the form back.
- Manages projects: creates a new project, renames one, deletes one (with restore) and puts the project list in the conversation, from which you open the right one.
- Answers questions about regulations and about help for the app, citing sources.
- Answers in the language of your message: a question in German gets a German answer, even in the English app, and a room name does not change the language of the conversation.
What Algo does not do: it does not calculate heat loss or hydraulics - every calculation is done by HeatAlgo's algorithm (the heat loss to EN 12831-1, ISO 6946 and ISO 13370), and the report carries its figures. It also does not export reports, does not send anything to the client and does not work on several projects at once. A dedicated capability draws underfloor heating from a floor plan: in it Algo reads only the rooms, doors and windows from the plan, and the algorithm draws the loops, supply runs, edge zones and the manifold. You draw the ventilation ducts yourself.
Modes: Propose and Automatic
In the conversation beside a module you pick the working mode:
- "Propose" - Algo marks the proposed values on the form's fields, and you approve each one before it is saved.
- "Automatic" - Algo saves changes right away, without asking. Every save has a receipt with an "Undo" button, which works for 30 days. If the document changed further in the meantime, undoing may be impossible - Algo says so plainly.
Algo's own page runs in automatic mode only. If you had unsaved changes on the form and Algo saved its own, the form refreshes to Algo's version - so save your changes before asking for corrections. Before Algo changes a value, we save a copy of the project's previous version.
Reading documents
You attach PDF files and JPG, PNG and WEBP photos to the conversation - by dragging them onto Algo's window ("Drop the document here") or from the "Add" menu and "Load a document". You can send up to 5 files and 20 MB in total at once; other file types Algo skips and says so. You can also paste plain text, for instance a row from the window schedule.
Documents attached in a conversation about a project start a reading in the background. It starts at once and uses the same monthly Algo limit as the conversation. In "Propose" mode Algo shows the data it read and you save it with "Put into the form"; in "Automatic" mode it saves itself. "Undo" takes the save back. If the document contains nothing that fits the form, Algo says so plainly instead of guessing.
In the heat loss calculation Algo reads the whole building design: the floor plans, the sections, the technical description and the joinery schedule, and the energy performance certificate too. You start with "Start with Algo" on the step 1 start screen and attach the documents in the conversation about the project. Algo enters the rooms with their names and areas from the plan, the building elements from the sections, the description and the certificate, and the windows and doors placed in the walls of the right rooms - from the marks on the plan and the joinery schedule. Then it lists what is left to complete, and each item leads to its field. Fields with nothing in the documents stay empty, and Algo never overwrites your value with one the documents do not state. A reading uses the same monthly Algo limit as the chat and does not use a report. The limit grows once you buy a report and is largest with a subscription; when it is used up, Algo says so before the start. One reading also fills heat pump sizing and heat recovery ventilation at no extra cost. One account can run up to 10 readings per 24 hours. Administrative pages (decisions, applications, pages about a person) are deleted as soon as they are recognised and never go on to the reading. The heat loss calculation guide describes it step by step.
On the underfloor and ventilation drawings Algo can offer to use an uploaded file as the storey's floor plan ("Use this file as the plan?"); if the storey already has one, it refuses and points you to the drawing settings.
The files and their page images are stored only for the reading and deleted automatically 24 hours after it starts, and the reading's result after 30 days at the latest. Only what you approve stays: the values, the floor plans of the confirmed storeys, and a floor plan you set with a button as the drawing's backdrop in underfloor heating or heat recovery ventilation. The documents are read by an AI model on OpenAI's platform in the United States, reached through OpenRouter under a data processing agreement. The privacy policy, section 4, has the details.
Sources under an answer
When a question concerns regulations (e.g. a subsidy programme or the F-gas regulation), help for the app or what changed in HeatAlgo, Algo looks for the answer in our knowledge base: guides and help articles, announcements about news, the changelog, product pages and selected regulations. Under the answer a "Sources" section then appears with cards: "Guide", "Update", "Regulation", "Page" or "Changelog", with the publication date or the legal state date. A card opens the source in a new browser tab.
Algo can be wrong - under the question field you see the reminder "check the source". An answer without source cards is an answer from knowledge of the app or from your project, not from the knowledge base.
Conversations and history
Conversations are kept. On Algo's page the "Conversations" list lets you return to any of them, rename one ("Rename") or delete it; "New conversation" starts an empty one. The same conversation is available in the column beside a project and on the page. If you close the tab before Algo finishes answering, the conversation is paused with a "Continue" button.
The monthly limit
Every account has a monthly allowance for conversations with Algo and project reviews. You see usage in Algo's window as a percentage ("You have used X% of this month's Algo budget"); the counter resets on the first day of the month. Free accounts have the smallest allowance, accounts with a purchased report a larger one, and a subscription the largest. A project review draws on the same allowance as questions - one review uses more than one question, because Algo then reads the whole module document. The larger allowance for a purchased report applies in the month of purchase; from the next month an account without a subscription returns to the free allowance. The allowance alone cannot be topped up - a report or a subscription is what raises it, both described in the pricing. We do not publish the figure; the allowance is counted in model usage, and you see its state as a percentage.
When the allowance is used up, the conversation stops with "This month's Algo budget has been used up" and cannot be resumed until the start of the month; the "See plan" button leads to a purchase. The form and the calculations work normally - the limit concerns the assistant only.
Wrong answers and other problems
Under every answer there is a "Report a wrong answer" button - the report reaches us together with the conversation and helps improve the assistant. You withdraw a report with "Withdraw the report".
Messages you may see:
- "Algo is temporarily unavailable" or "The AI service is temporarily overloaded" - try again in a moment,
- "The answer took too long and was interrupted" - ask a shorter question or send fewer files,
- "The answer stopped before the end" - everything that arrived is in the conversation; ask about the rest,
- "Algo is currently switched off" - the assistant is temporarily switched off on our side.
What Algo sees and what we keep
Algo sees the content of the modules of the project you are talking about, and what you write. It also reads My library - the constructions, windows, doors, units, fittings and radiators saved on your account - but adds, changes or deletes an entry only when you ask it to, and you can undo each such change with "Undo" beside the entry in the conversation. It has no access to other accounts or to billing. We do not send the model the data that identifies your client, stored in the project. What you send to the AI model is described in the Privacy Policy; in Settings you have the switch "Keep technical logs of the assistant", which decides whether we keep the content of requests and the model's reasoning summary for investigating errors - details in the article on settings.
AI sections on your floor plan
In the underfloor heating module Algo does one more thing: from an uploaded plan it reads the rooms, doors and windows, and the algorithm draws the whole draft from them - no AI model takes part in the drawing itself. Rooms get loops, the supply runs take the shortest way through the doors to the manifold, and the algorithm splits a room that is too large so that no loop goes past its maximum length or 350 mbar. It also adds an edge zone along window walls where the floor alone cannot carry the load, looks for the lowest supply temperature and places movement joints. It takes the scale from the plan's dimensions or from its printed room areas, and asks for it only when the plan gives neither. On a storey with no manifold it places one itself - one per 14 loops - and you can move it. You review the draft on the drawing and apply it with one button. One generation per account is free - the first read of a plan spends it, not Apply - the details are in underfloor heating from a floor plan.
Algo names the draft's rooms from the text on the plan, and names unlabelled spaces in the app's language. You can also upload the plan as a HEIC photo from an iPhone - that applies to the underfloor heating plan only, because in the conversation Algo reads PDF, JPG, PNG and WEBP. While a draft is open, the drawing is locked until "Apply" or "Discard"; panning and zooming the view still work.