It looks like this is what they currently do. I believe the goal is to retire some of these older district heating systems and just use renewables for electric generation. https://www.helen.fi/tietoa-meista/energia/energiantuotanto/voimalaitokset In the short term they can shut down some of the gas/coal/pellet thermal centers without needing to build a new generator.
And Helen is also pulling heat from waste water. The latest heat pump was just the next logical step.
Hanasaari shut down last year and Salmisaari is going to be closed by april next year, after that Helsinki will have no coal or pellet power plants left.
Electricity generation isn’t the main problem, but that those plants were responsible for a huge majority of central heating in Helsinki (iirc they were designed on purpose to be so inefficient they generated 2/3rds of their output as heat for that use). That’s why they are building wacky solutions like huge underground lakes and stuff
