What an MCS installation should leave behind

When an MCS installation is finished, a set of documents should arrive. They are easy to file and forget, and they are the only evidence that exists of what was designed, what was installed and what it was tested to do.

They matter three times: when a grant or an export tariff is claimed, when something goes wrong and a warranty is called on, and when the house is sold and a buyer's solicitor asks what that thing on the roof is.

The MCS certificate

Registered by the installer on the MCS database after the work is complete, and issued to the customer. It carries a unique certificate number, the address, the technology, the capacity and the commissioning date.

This is the document grant schemes want. It is also the one an energy supplier wants before paying an export tariff on a solar installation, and the one a conveyancer will ask for. If it has not arrived within a few weeks of commissioning, chase it: registration is the installer's job and there is a time limit on doing it.

The design

For a heat pump, this means the room-by-room heat loss calculation: every room with its area, its elements, their U-values, the design temperatures used, and a total. Alongside it, the emitter schedule showing what is in each room and what it delivers at the design flow temperature, and the design flow temperature itself.

For solar PV, the output estimate with its five inputs visible: capacity, postcode zone, pitch, orientation and shade factor. A shading assessment where one was needed. A string layout showing which modules are on which input.

These are the documents that let anybody check the work later. If a heat pump is not keeping a house warm, the heat loss calculation is where the diagnosis starts, and without it the next engineer is guessing.

Commissioning records

Evidence that the system was tested and set up, not merely connected.

For a heat pump: the flow temperature and weather compensation curve as set, the system flow rate and temperature difference, the hot water setting and the arrangement for the pasteurisation cycle, and the refrigerant charge if the circuit was worked on.

For solar PV: the inspection and test records required by BS EN 62446-1, covering string open circuit voltages, short circuit currents, insulation resistance and earth continuity, and the electrical installation certificate for the AC side.

The commissioning figures are a baseline. Three years on, when output looks low, comparing against the string test results taken on day one is how a fault gets found.

Operating instructions

Written for the householder, not extracted from a manufacturer's service manual. How to run the system, what the controls do, what to expect it to do, and what is normal.

The last of these matters more than it sounds. A heat pump owner who does not know that steam rising from the unit on a cold morning is a defrost cycle will call it a fault. A solar owner who does not know that output falls by four fifths in December will think something has broken.

Maintenance requirements

What needs doing, how often, and by whom. Heat pumps need the outdoor coil kept clear, the system pressure checked, the strainer cleaned and the antifreeze concentration checked where there is one. Unvented cylinders need annual attention by someone qualified for them. Solar systems need very little, which should be said plainly and not padded out with invented servicing.

Where a manufacturer's warranty is conditional on servicing, that condition should be stated here, not discovered when a claim is refused.

Warranties and guarantees

Three distinct things, and they should be distinguished.

The manufacturer's product warranty, on the equipment, from the manufacturer. Its length and what it covers, including whether labour is included, since a compressor covered for parts only is a modest protection.

The installer's workmanship warranty, on the installation, from the installer.

The insurance-backed guarantee, which is what stands behind the workmanship warranty if the installer ceases trading. MCS contractors are required to hold this, and it is the one people most often assume they have without checking. It is a separate policy document with its own number.

Notifications made on your behalf

Building control notification, usually through a competent person scheme, with a compliance certificate. This applies to a heat pump and to the electrical work in a solar installation.

The network operator notification: a G98 confirmation for a small solar installation, connected first and notified within 28 days, or a G99 approval for a larger one, which has to be obtained before connection.

Copies of both should come with the rest of the pack.

If it does not arrive

Ask, in writing, and be specific about which document is missing. Most gaps are an oversight in the office and get filled once they are pointed out.

If asking does not work, the installer's certification body is the next step. They audit the company and can require it to put things right, and a complaint about missing documentation is a straightforward one for them to act on. The certification body is named on the MCS certificate and on the company's entry in the MCS directory.