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Strange short cycling Vitoden 222

asimion Member Posts: 2
edited November 2021 in Gas Heating
Hi there,

Lately, quite often, my boiler is acting weirdly. 
- boiler: Vitoden 222
- no call for heat
- all taps closed( no hot water request)
- boiler is short cycling( 30s).Secondary circulating pump on(like there is hot water request). Temperature can reach 99C. 
- radiators without thermostatic valves are very hot (suggesting a 3way valve malfunction as heating is not requested).

Any ideeas?

btw, anybody knows how the need for hot water is detected( there is no flowmeter or presostate on the boiler).

Thank you.


  • Alan (California Radiant) Forbes
    If this is a new installation, the installer could have set up the boiler for outdoor reset, i.e. the boiler will start heating as soon as the temperature drops below WWSD (warm weather shut down). If you've had the boiler for awhile and this is something new, then you might need an new outdoor sensor.

    Also, some of these boilers have had a factory recall. Fine your serial number here and find out if it's part of the recall here.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab