Bathroom Design & Installation Thames Ditton

The answer is no, if your boiler is not working at all, in fault mode or has an issue present that is constant. It should be booked in for a breakdown or diagnostic visit this is because of the following reasons.

1. Diagnosing faults takes time and this is not allowed for within a service.
2. The boiler must be working and functional in order to carry out a service.
3. If parts or works are required on the boiler, the service should be conducted when its operating correctly.
4. There are specialist breakdown engineers, so ensure you are getting the correct Gas Safe Registered Engineer rather than someone that can do Boiler Services but may not be as experienced in faults.

The are a couple of exceptions to this rule.

1. The fault is very intermittent and so is not happening all the time. In which case we can take a quick look to see if anything is obvious whilst servicing the boiler, but may need to advise more diagnostic time or that the issue should be happening when the engineer is on site.
2. You are having an issue with your thermostat, we can take a quick look at this whilst servicing your boiler.
3. You are having an issue with a radiator we can have a quick look at this whilst carrying out the service.

Not necessarily.. no. This is because of a few reasons.

1. When carrying out a service they go through certain checks. If a part is behind many other parts, or is an electronic component  for example. You cant possibly see or check this, if the issue has not been raised specifically or a fault is not occurring at the time. However if there was an issue with a part that could be obviously & visually determined or if one of the analyser readings came back incorrect determining an issue. They of course would advise you.
2. At some point many things in life become un-operational or a defect arises. What suddenly makes that happen after its been fine for years can be down to many things, or simply just wear and tear. Therefore a service doesn't provide you a warranty on your boiler. It's advised to keep you safe,  to keep up with new regulations and up keep general condition for a maximum life span potential.
3. Think of it like your cars M.O.T they will have a list of vital checks that must pass, but they wont be taking apart your engine innards just to check it.