Very high LPG consumption

wilts0

We've just discovered our new home (small converted former school, 5 bedrooms, no high consumption habits) has managed to use 2,000L of LPG in 8 weeks.

Calor confirm it won't be a leak as it's tested on delivery, that leaves either the boilers (2x Viessemann Vitodens 100, one for hot water and one for heating) or the stove top (modern LPG conversion 5 ring).

There was nothing on the PIF when we purchased (completed Dec 2020) to suggest this level of consumption, and Calor are stumped.

We have a heating engineer booked, but my only suspicion at the moment is the temperature of the hot water is incredibly high, near 80-90c. This also runs 24/7..
Any other suggestions to get this nailed?

J_B

20,000L

Assuming that the 'standard' domestic tank is 2100L (?) that's a refill every week - really?

wilts0

J_B said:

20,000L

Assuming that the 'standard' domestic tank is 2100L (?) that's a refill every week - really?

Typo there! too many 0's that's 2,000

Rodders53

2000 litre = 14,000 kWh of energy in 8 weeks.  What does the EPC estimate for annual heating/hot water use?

Two boilers is pretty unusual in one dwelling.  What exact ratings are the two - they come with 5 outputs 13, 16, 19, 26 & 35 kW from a quick looks see of the makers website.  They are also 'heat only' aka 'system boilers' so not combi for the water, I think?

Therefore turn the HW boiler's stat down. 60C max is needed if hot water stored in a tank for Legionella reasons.  The tank thermostat may have stuck in 'on demand' position?   Stored water heat loss is proportional to the temperature difference so that is a concern.  It's also a scalding risk, even if thermostatic mixer  valves are on the bath and showers, other taps probably don't have them?
The HW will only need to be on once or twice a day for a few hours to reheat water used, depending on your water use. That'll save a bit immediately
Heating boiler. What does it supply?  Radiators, underfloor heating manifolds?  What temp is the CH boiler circulating water set to?