This article collects the questions that come up when working with the underfloor heating module after the first drawing: why something is not visible, what a warning means, how to fix something. If you are just starting, go through the step-by-step guide first: how to use the underfloor heating module. The EN 1264 calculation model is explained in the guides on pipe spacing and loop length and on flow temperature.
Rooms and sections
The room is not calculated. A section drawn on the plan must be assigned to a room. Click it, and in the "SECTION" drawer pick the room in the "Assign to room" field. The side panel has an "Unassigned sections" list with an "Assign to room" button and arrows to move between them. Rooms come from the heat load calculation (the import button in the panel, with the demand and temperature) or you add them by hand with "Add", giving a name, floor, demand in watts, type (standard up to 29°C floor surface or bathroom up to 33°C) and temperature.
The room balance. The side panel shows for each room the underfloor output at the current parameters (e.g. 35/30°C) against the demand: "Meets heat load", "Surplus N W" or "Deficit N W". In brackets is the loss through the floor that the floor gives off downwards.
The free room. On a free account the first room in which you draw a loop is fully calculated - the message "Fully calculated on your free account: ..." names it. The condition is assigning the section to a room. On the free plan we calculate a few projects at a time, so the first room in a new project may be calculated with a delay, with a date on screen; an unlocked project is calculated in full right away.
A room on the wrong storey. In the room's edit view pick "Move to storey". Rooms with drawn loops are tied to their storey's plan and cannot be moved while the loops exist. The update from the heat load calculation ("Update data from the heat load calculation?") moves only rooms without loops.
Loops, lengths and splitting
A loop too long. The length is computed from the real geometry together with the run to the manifold. The limits depend on the pipe: 16x2 - a warning from 80 m, hard limit 90 m; 17x2 - 90 and 100 m. The warnings "Splitting the section improves reliability" and "Split this section" appear in the section drawer. You split there in the "Split line" field (horizontal - parts one above the other, vertical - side by side); if the shape does not allow one direction, the app suggests the other, and when the automatic split finds no cut, you split the section by hand. The balance panel has a "Split N long loops" button, which finds cuts for the whole storey at once and shows how many sections can be split. Each part after the split has its own run - the split divides the pipe in the room, not the way to the manifold.
Pipe layout. By default "Auto" chooses between a spiral, a classic meander and a bifilar meander and says why ("High confidence spiral for a simple rectangular room", "Bifilar meander covers a narrow room better"). You change the layout in the section drawer in the "Pipe layout" field, and the pipe direction horizontal or vertical. When a shape has no ready drawing, the app says "This section shape is best split into smaller areas" instead of drawing a faulty layout.
Editing node by node. "Edit nodes" in the drawer copies the generated layout as a manual drawing with editable nodes; from then on parameter changes do not redraw it. "Restore auto" discards the manual changes and generates the layout anew. The "Draw pipes manually" tool (O) draws a pipe from scratch inside a section; the list of such sections is in the tool panel under "Hand-drawn pipes".
Holes in a section. Right-click the section and pick "Cut an opening" (e.g. a column, stairs) - the loop avoids the cut-out area. The same menu has "Duplicate section".
Flow, spacing and parameters
Flow below 0.5 l/min. The supply is clearly higher than the loop needs. Lower the supply temperature to the required one (the project parameters show "Required supply" - the temperature the drawn floors ask for, set by the leading loop outside bathrooms), widen the spacing, or merge a very small section with its neighbour. Flow above 1.5 l/min - split the section.
Spacing larger than recommended. The spacing warning means that at the project parameters the room's demand needs denser pipe. The section drawer has a "Set the recommended spacing (N mm)" button, and the balance panel "Apply the recommended spacing" for many sections at once - with a preview of whether any loop would exceed the recommended length because of it. When the demand exceeds the floor's output even at 100 mm, the app says so plainly: check the supply temperature and the covering, or add a radiator.
Edge zone. The "Edge zone" field in the section drawer tightens the spacing in a 0.5 m band along the walls. It works only for generated layouts - a manual drawing stays without the tighter band.
Project parameters. The "Project parameters" dialog (from the "..." menu on the toolbar) sets the supply and return temperature (a new project: 35/30°C), the pipe, the default floor covering, the screed over the pipe (typically 45 mm), the run pair spacing, and shows the design spread and the required supply. The parameters belong to the whole project, not to one storey. The floor output is computed to the EN 1264-2 thermal characteristic from the pipe actually laid in the section, and the flow to EN 1264-3.
Return temperature not above the room temperature. The floor then gives off no heat - raise the return in the project parameters. The supply must be higher than the return, otherwise the flow is not computed.
Manifolds and runs
You place the manifold with the "Manifold" tool (M) with two clicks at the ends of the cabinet. In its panel you set the number of ports; the warning "More circuits connected than ports" means you need to increase the number of ports or add a second manifold. The "FLOW METERS" list in the side panel assigns sections to ports and shows the total flow and the flow per m².
You draw the run (route) with the "Draw supply route" tool (R) from a section or a manifold; Enter finishes the route at the last point, Backspace removes the last point, Esc cancels. You set the run pair spacing by default in the parameters and for a single route in its panel; select several routes and right-click to change the spacing of many at once.
Storeys
Storeys are tabs above the drawing. "Add storey" offers "Storey above" or "Basement (below)"; you rename by clicking, and "Delete storey" removes its backdrop, rooms, loops and manifolds with no undo. Storeys imported from the heat load calculation are created by themselves. On a free account you draw on one storey - instead of the add menu you see "One floor on a free account", which leads to unlocking the project; storeys from the heat load calculation do not count towards that limit.
Backdrop and calibration
Formats and limit. PDF, PNG or JPG; with a multi-page PDF you pick the page in the "Select page" dialog. The plan file can be up to 25 MB.
Changing and rotating the backdrop. "Background settings" (an icon on the toolbar) let you change the scan, rotate it by any angle or reset the project. Rotate before drawing - drawn sections, manifolds and routes do not rotate together with the backdrop.
Calibration. The "Calibration" tool (C): two points a known distance apart and the distance in centimetres; the range message reminds you not to type metres. Recalibration is in the project parameters dialog ("Calibration set - Re-calibrate"). Calibration is per storey - every new one needs its own.
Snapping. When drawing geometry was detected in the file, drawing snaps to walls. You toggle the grid with G and set its origin with Alt and a click; Shift forces a 90° angle, Shift with Alt 45°, and Ctrl (Cmd on a Mac) draws without snapping.
Export and other
The printable plan and the full PDF are described in the article on reports; the messages about the plan preview before export are there too. "Report notes" (the notes icon) go at the end of the PDF.
Keyboard shortcuts and gestures are in the "?" dialog on the module bar; the full list is in the "Useful keyboard shortcuts" section of the guide. The most important: V select, H move a section or manifold, P section, M manifold, R route, O manual pipe, Space with dragging pans the view, Ctrl with scrolling zooms, Ctrl+Z undoes.
"Project was changed on another device" - someone (or you in another tab) saved a newer version; click "Load newer version". "Failed to save the floor plan for storey" - the rest of the project is saved; upload the backdrop again with "Upload again".
"A new generation of drawings" - older projects get an offer to update their layouts and lengths to the new generator. Before updating, download the existing PDF with the button in that dialog, because the layouts and metres will be recomputed; "Later" postpones the decision.
The mobile view is not supported - the module needs a computer or a tablet.