Scalding hot water after oil burner service?

MayoForSam

We got our oil burner serviced about a month ago, the guy came and serviced it no problem, all running grand.

We use it to heat the rads and also to heat our hot water. However, since the service, the water temperature has increased substantially, almost to scalding-hot levels. This is potentially dangerous if we're not careful turning on the hot tap and is also probably a waste of energy and oil.

How would any oil burner getting serviced have caused the water to get so hot? I have turned down the thermostat on the oil burner almost to minimum but that had no effect. Would a faulty thermostat be the primary culprit?

Billy Bunting

Its possible that the guy needed to turn the boiler thermostat up high while doing the FGA, he may have forgotten to turn it down, simple procedure, go to boiler and turn down the thermostat.

Wearb

If you turn down the thermostat while burner is running, does it stop. If you turn it up while stopped does it start up. Could still be faulty even if these tests do as expected, but will be an almost certain proof of thermostat failure if nothing happens. Make sure when trying this out that the controls are calling for heat, i.e. room stat turned up and timer on, or whatever controls you have.

TPM

The thermostat is the only thing that controls the water temperature, if you have turned it down and the water temp is still extremely hot it would point to it being faulty.
Is it a combi boiler?
If so you should have a seperate thermostat for the domestic hot water temperature.
If its not a combi check that your immersion isnt over heating the water, it could just be a coincidence with the boiler service.