When the hot water went off in a shared London house over the weekend, the tenants were shocked to discover the thermostat had been locked "in a cage".
BBC employee Alex Milsom, 21, told his housemates he would turn the water back on - but couldn't get past a new lockbox covering the Google Nest thermostat, which controls the heating and hot water.
The landlady had visited the property and installed a clear thermostat cover.
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"We have no idea what the temperature is," Milsom told the BBC.
"The Nest screen only lights up when you stand close to it, but the box has stopped that from working and we can't see the number."
Milsom, who lives with six or seven other tenants in a semi-detached house in Ealing, west London, pays £700 (NZ$1415) a month to a private landlady, who covers the cost of utility bills.
According to experts interviewed by the BBC, landlords are permitted to control the heating in multi-occupancy homes. The same applies to a standard rental property with fewer than three tenants if the landlord covers the bills.
There are also no clear-cut rules against boxing off the thermostat.
Milsom says he and his housemates had control over the temperature and the hot water via the thermostat in the communal kitchen - until now.
"On Sunday night, I woke up in a sweat because the heating was on, but the next morning I had to shower at work because there was no hot water," says Milsom.
Milsom shared the "funny" story on Twitter on Saturday (local time).
"Welcome to renting in London! My landlord has just put our thermostat in a cage," he wrote.
The post subsequently went viral, with more than 35,000 likes.
A handful of landlords pointed out in the comments that the caged thermostat could be in response to the tenants being careless with utilities.
Policy director for the Residential Landlords Association, David Smith, told the BBC: "It is a matter of good tenancy management and we encourage landlords to speak first with tenants before taking such action."
Although tenants have a right to heating and hot water, whether a landlord can box off a thermostat depends on the conditions of the tenancy agreement.
It could pose a breach of health and safety if the tenants' inability to access the heating and hot water leads to hazards such as extreme cold or heat.