When we brought the new high velocity air handler online, we had made a temporary connection to the radiant manifold with 3/8″ pex tube. While this would help us get through the cold weather, it did not provide for the second air handler, and the control for the slab in Harley Haven was wonky. This also did not position us for a chiller to provide air conditioning.
We went with the classic primary water loop, with secondary loops connected with a pair of closely spaced tee fittings. We were able to get a tee/valve assembly – the valve allows to fill/ purge the secondary circuit easily.
The upstairs air handler was not in use, so we were able to connect it all the way. We also included a drain valve at the bottom of the unit. We also have a pair of shut off valves at the top so we can isolate the mixing valve and circulator for service. This unit also had a 14″ return vent above the equipment, so we had to hang it from the blower module.
With the secondary loops in place, we could start in the primary loop. The first part was the connection to the boiler. This was basically a secondary loop, so it has much of the same valves and pump.
From here, we have a purge/drain valve, followed by a loop shutoff valve, followed by air purge unit, pressure regulator and expansion tank (all valved for easy service) another valve and the primary circulator. All of these valves make it easy to purge air from the system after service.
Next up, we had to power and control the circulators. We installed a 6 zone Taco zone controller. This included a circuit for the primary loop, as well as for each secondary loop. The boiler pump connects to the aquastat. The zone controller also tells the aquastat when a zone needs heat.
Since most of the circulators were not below the controller, we came out of the bottom of the controller with EMT, and looped it up to some junction boxes for distribution to the pumps.