Load-side Controls

I've been asked to share some system documentation, so here goes.

All I have so far is the load-side stuff to control the oil boiler, storage transfer pump, load circs, and whatnot.

Some probably non-obvious abbreviations: Stfy=satisfy, AqStat=aquastat, CFH=call for heat.

Bus at top is 24VAC.

Returns to 24VAC common for relay coils K1-K4 are not shown.

No detail for power relays K8-K12 is shown.

I see now that AqStatBuf1Top is missing from the plumbing schematic.

A lot of the complication is due to the house having been converted to hot water from steam years ago and the radiators are large and the piping is fat. So when a radiator zone activates it dumps a bunch of cold water into the return side. I put in a Wilo variable speed radiator load circ in and that helped a lot, but finally I added an aquastat on the oil boiler return with bang-bang control to keep the oil boiler up to temp, for as much as I'll ever use it again if this project ever gets done.

Cheers --ewd