VDI 4645 2023-04 PDF

Full title and description

VDI 4645:2023-04 — Heating systems with heat pumps in single- and multi-family houses — Planning, construction, operation. Guidance covering the design process from preliminary investigation and concept development through detailed planning, recommended hydraulic schematics, component sizing, documentation, commissioning and operator instruction; includes extensive annexes with examples, checklists and calculation aids to support practical planning and execution.

Abstract

This VDI guideline provides a comprehensive, practice-oriented framework for planning and operating hot-water heating systems driven by heat pumps in single- and multi-family residential buildings. It aims to reduce malfunctions and optimise system performance by describing recommended procedures for site assessment, system concept selection, hydraulic and component sizing, commissioning, documentation and user handover. A dedicated training sheet (VDI‑MT 4645 Blatt 1) defines qualification, examination and certification requirements for personnel.

General information

• Status: Current.
• Publication date: April 2023 (01 April 2023).
• Publisher: Verlag des Vereins Deutscher Ingenieure (VDI).
• ICS / categories: 91.140.10 (central heating systems); 91.140.65 (water heating equipment).
• Edition / version: 2023-04 (current edition; corrigendum published July 2023).
• Number of pages: 208 pages (bilingual German/English). *

*A separate training sheet VDI‑MT 4645 Blatt 1 (Schulungen, Prüfungen, Qualifizierungsnachweise) is published as a complementary document (approx. 21 pages).

Scope

Specifies recommended procedures and technical considerations for the planning, selection, installation and commissioning of hot-water heating systems using heat pumps in single- and multi-family dwellings. The guideline addresses site and load assessment, choice of system concept and operating mode, hydraulic layouts, sizing of heat generators and auxiliary components, interaction with heat distribution and storage, measurement and verification of performance, operator training and documentation. It also supplies checklists, worked examples and annex material to support planning and handover.

Key topics and requirements

• Preliminary site investigation and heating-load assessment.
• Selection of system concept and operating mode (e.g., source type, parallel/series arrangements).
• Recommended hydraulic schematics and piping arrangements for reliable operation.
• Dimensioning rules for heat pumps, heat emitters, storage and distribution components.
• Commissioning procedures, performance verification (e.g., seasonal performance metrics) and measurement protocols.
• Documentation, handover to the operator and operator training/qualification requirements.
• Checklists, sample calculations, annexed examples for surface heating and radiator systems, cost considerations and an example plant log (Anlagenbuch).
• References and interfaces to related VDI standards and legal/regulatory items (e.g., F‑Gas regulations where applicable).

These topics are treated with practical examples, annex tables and flowcharts to support consistent planning and quality assurance.

Typical use and users

Primary users are building services engineers, HVAC/plumbing planners, installers and system integrators, energy consultants, manufacturers and product developers, commissioning engineers and building owners/operators seeking prescriptive guidance for residential heat-pump heating systems. The document is used for detailed planning, preparing tender/contract documents, commissioning checklists and for training curricula for qualified personnel.

Related standards

Commonly referenced standards and documents include the VDI series and related work (e.g., VDI 4640 geothermal/ground-source guidance, VDI 4650 and other building-service/heat‑pump technical rules), applicable EN standards for components and installation, and national regulations (such as the F‑Gas regulation and local building codes). Annexes of VDI 4645 provide cross‑references to the most relevant companion rules and calculation standards.

Keywords

heat pump, residential heating, hydronic heating, planning, commissioning, VDI 4645, Wärmepumpe, Einfamilienhaus, Mehrfamilienhaus, hydraulic schematics, commissioning, operator training, checklists, Annex, Anlagenbuch.

FAQ

Q: What is this standard?

A: VDI 4645:2023‑04 is a VDI guideline for the planning, construction and operation of hot-water heating systems using heat pumps in single- and multi-family houses; it provides procedural and technical recommendations plus extensive annex material to support practical implementation.

Q: What does it cover?

A: It covers the full planning chain from preliminary investigation and concept selection to detailed hydraulic design, component sizing, commissioning, documentation and operator instruction — and supplies checklists, worked examples and calculation annexes.

Q: Who typically uses it?

A: HVAC planners, installers, system manufacturers, energy consultants, commissioning engineers and building owners/operators involved with residential heat-pump systems. Training providers and certifying bodies also use the document as the basis for qualification schemes (see VDI‑MT 4645 Blatt 1).

Q: Is it current or superseded?

A: The 2023‑04 edition is the current version; it replaces earlier editions (including the 2018 edition) and was followed by a corrigendum published in July 2023 that corrects limited editorial/technical items. Users should consult the corrigendum when applying the guideline.

Q: Is it part of a series?

A: Yes — VDI 4645 is part of a broader set of VDI/VDI‑MT guidance on heat pumps and building services. A related VDI‑MT sheet (VDI‑MT 4645 Blatt 1, April 2023) specifically addresses training, examinations and qualification evidence for personnel.

Q: What are the key keywords?

A: Heat pump, residential heating, hydronic system planning, commissioning, hydraulic schematics, operator training, VDI 4645.