Thanks in advance folks. I need to target the best thermostat brand / model to solve a problem and suggestions for supplemental heating for a wall of windows.
The Problem: New house 2017, slab on grade concrete floor with poured in PEX tubes for hydronic heating. Great rm has a wall of windows facing SW, cathedral ceiling 20 ft hi, great heat gain in winter, large overhanging eave so not a problem in summer. Lochinvar WH 55 boiler, short boiler loop into a short spaced double T, passing heat to distribution loop. Boiler uses reset curve, set plenty high. Distribution loop with WILO Stratus ECO adaptive head pump into all zones with solenoid valves controlled by ambient sensing stats, 6, SIP home, foam ceiling, blower door rated at 1.0 ACH/50
The problem is the boiler / radiant heating contractor failed to provide, what I think at least, is the correct Thermostat type-- dual sensor slab stat that use the SLAB SENSOR to modulate the heat, not the ambient thermistor on the wall. These ProOne T 755S stats do the opposite-- ambient room sensor sends feedback for control and the floor sensor is relegated to only use as over / under temp limiter. The problem this causes is there is severe time delay from the carpet in the room preventing the ambient sensor from getting timely feedback that the slab has lost significant heat and then, too late, it needs a big slug and has a big delay getting the room back up again in the morning. Secondly, the pump system is oversized and even with throttling down I cannot seem to reduce flow enough to allow boiler to reach set point (of the system feed piping, not boiler loop) unless only 3 or less zones are in demand. After a 4th zone opens up it cannot make it to set point.
So, for the first problem I would like to retrofit the stat to one which will remove the delay back to the boiler by controlling the slab temp directly. Looking for suggestions for slab sensor modulated hydronic stat, please.
For 2nd problem, looking for suggestions to allow the Great room, alone, to be on one circuit that runs at the flow and higher temp not required by the rest.
3rd problem: The great room cannot under any cold weather conditions below 25°F outside be heated by this system past 70°F. I would like it to be a BIT more comfortable. Other zones, no prob reaching set point. I am considering removing the carpet in a strip about 2 ft wide near the windows and replacing with a less insulative surface to allow what heat I AM pushing out to GET to the area of need. Then on each side of the 6x8 ft patio door place a 500 watt baseboard heater under those 30" windows to provide a heat barrier from the cold be radiated into the room at least in those areas. I can't put more KW in because I am planning on keeping the solution simple so I can just plug these two units into receptacles nearby, no new circuit. What do you think of this idea?
THANKS folks! Brian