We bought a house with floor heating, and replaced the old boiler. We installed a Saunier Duval Isofast condens 21 gas burning boiler and an external Zilmet zb190 heat exchanger between the boiler and the pipes in the floors (and an external pump to drive the secondary circuit).
After a few weeks everything was switched on I noticed that the secondary circuit is connected in reverse to the heat exchanger.
As far as I know, on this exchanger, the primary in (hot) should be near the secondary out (the secondary out which is going into the pipes in the floor) in order to catch as much heat energy as possible from the primary circuit.
I checked the manual of the zb 190 and it says too that the primary in should be near the secondary out. This is the manual: https://www.manualslib.com/manual/1947132/Zilmet-Z2.html?page=5#manual
However in my installation the secondary out is near the primary out.
As a consequence (I guess) the temperature of the water going into the floor is quite low, similar to the temperature returning to the boiler from the exchanger.
I think that it would be better (less fuel consumption) if the exchanger would be connected correctly, but I don't know how much would it be better?
Is it worth to make the installer to correct the piping, or is it nitpicking (I think it is a few hours of work for him to re-route a few pipes) ?