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Our complex winter-summer boiler control unit for an oil-fired forced water heating system frequently calls for a temperature that the boiler never achieves on a cold day. The burner will turn off even though the temperature in the boiler is 20 degrees colder than the target that the controller shows on its display.

Is something broken?

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Is something broken?

Almost certainly.

I used to have an oil-fired forced-water heating system and the water exiting the boiler would be at 60C regardless of the room thermostat setting (e.g. 20C). The sort of system I used had a fixed boiler temperature. The room temperature is achieved by cycling the boiler on and off, not by continuous adjustment of the boiler output temperature.

This had a relatively simple control system, nevertheless, there's no reason for a boiler to be producing tepid water.

Some boilers have diagnostic lights and the manuals sometimes contain troubleshooting sections.

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