This thread is getting more and more 'interesting'. A bit like speculations about the composition of distant stars and planets.
russ_watters said:
Boilers are closed-loop and are only there for heating. They can have an additional feature that runs a separate loop to heat potable water, but that is an optional extra.
You have fallen into the trap that I fell into on an earlier thread. "Boilers" are different, all over the world, apparently. (At least in the most important places. lol)
In the UK, "boilers" (for domestic use) were initially there for heating domestic water only. We had running hot water, decades before Central Heating. Over the, systems were :
With hot water tank (sometimes with an electrical immersion heater included):
Hot water, gravity operated,
HW and CH, both gravity operated
HW, gravity and CH pumped
HW and CH, both pumped.
Then:
NoTank - Combi System
I still can't be sure if the OP's system is one of the above.
The earlier thread about domestic
Steam systems in the US was an eye opener for me. They seem to be a lot of trouble for domestic use but, with a full time janitor to keep them going, in a large apartment block, the higher heating capacity would make them attractive in cold winters. I Googled Acroliner boilers and there's a whole other world out there! I must say, theUK systems are a lot less threatening and seem more user friendly.
Althepump said:
The heater with coils bring electricity to make water hot through the coils.
I hesitate to suggest anything about such an alien engineering culture but the electric input to the boiler could be just for ignition and oil pump. It would be a surprise to me if there were a heating coil inside the boiler itself; an electrical element would be unlikely to have the power (10kW+) to supply the needs of instant domestic hot water.