1. Ideally an installer should be registered with MCS (Microgeneration Certification Scheme) so it is important to ask for their registration number, and double check online (www.microgernationcertificationscheme.org.uk ).
2. You should also check which certification body has certified them competent, and check with that body if there are any outstanding issues.
3. Look for membership of a recognised consumer code such as RECC assurance scheme, Glass & Glazing Federation (GFF) or Home Insulation & Energy Scheme (HEIS).
4. Are they members of any other recognised bodies such as Trade Association (HPA, HHIC, B&ES etc), Trustmark, CheckerTrade . If so what does that mean in practice? How robust is the policing of the body? Do they check up on the work and if so how? A quick call to the Trade Association will confirm membership requirements.
If ‘Ground Source’ is beingconsidered, are they members of the Ground Source Heat Pump Association? This is not a requirement, but a good indicator.
5. Obtain credible testimonials for previous projects and check the validity of the testimonials. If in doubt ask for a list of installs and select for yourself one or more you would like to visit/follow up.
If the business is new or start-up (or they are unable to give you any example sites) ask where their experience was gained and perhaps ask for more stringent performance guidance (e.g. typical maximum running cost anticipated) and consider an agreement to retain small percentage of monies for a period of time (not exceeding 1 year).
6. Above all- do not assume anything. Legitimate installers will give you straightforward honest answers and back up any definite statements with relevant evidence. Do not be over suspicious but if any claim doesn’t make sense or has not been supported with hard evidence then be cautious. Remember good installers rarely make outlandish or brash statements but are measured and realistic in their responses and promises.