Identify what each system is intended to do
Heating and cooling concern temperature. Ventilation concerns air exchange. Equipment may combine functions, but its documented arrangement needs to establish what it actually provides.
Start by listing the systems already installed and the rooms they serve. If a function is unknown, mark it as unknown rather than inferring it from a visible grille or control.
For an existing ventilation system, service records are a useful starting point. Our maintenance page explains the equipment details to gather.
Compare arrangements in the context of the home
Natural ventilation uses openings and outdoor conditions. Mechanical extract ventilation removes air using fans, while a balanced arrangement includes both supply and extraction. These approaches need to be considered with the layout and use of the property.
Mechanical ventilation with heat recovery, or MVHR, adds heat exchange between outgoing and incoming air. Heat recovery is a feature of that ventilation arrangement, rather than proof that the home’s heating or cooling requirements have been resolved.
Positive input ventilation, or PIV, uses a supply approach. If proposed, ask how the arrangement fits the whole property and how air is intended to leave. Comparing system names alone leaves those design questions unanswered.
Define the building work around the equipment
A coordinated project needs clarity about:
- The rooms included and any planned layout changes.
- Existing heating, cooling and ventilation equipment.
- Equipment locations and known access restrictions.
- Possible duct routes requiring assessment.
- Building work already arranged.
- Maintenance access and records expected after installation.
Our installation page helps turn those details into a project outline. State whether equipment has already been selected or whether system choice remains part of the discussion.
Keep unresolved concerns in view
If condensation, odours or discomfort prompted the project, describe them separately. The presence of a concern doesn’t establish that one system change will address its cause.
Ask how the proposed ventilation relates to existing equipment and what assumptions need checking. A clear scope should distinguish confirmed requirements from decisions still awaiting assessment.
For a London home, the first useful step is a description of the property, the intended work and the information you already hold.