Thermostats + controls for 2 temp system

Baldrick_2

Since I am getting no response from other thread, let's put things differently.

What would be the best way to control a 2 temp system?

Trinity Ti100 has it's own Sentry 2100 unit, but alone it will do no good for more than 1 zone.

Primary loop with a 009 pump and then secondary header with 008 pump and manifold for high temp and branch with I-series 3 way setpoint mixing valve, 008 pump and manifold.

I would appreciate advice on what control panel and what thermostats to use, to make this system most efficient. Too late for slab sensor though.

First floor has a thermostat that does central air. Worth replacing it with 2 stage H, 1 stage C thermostat that would do both warm air and radiant? For me it makes sense only if warm air is activated only as emergency, at ~50F. Don't need it for faster temp gain since I don't plan for setbacks.

Or go with dedicated radiant thermostat there?
Second floor need dedicated radiant T-stat.
It would be great if first floor T-stat could program and control both zones.

Taco or Tekmar controls? NT series Tekmar thermostat or something simple?

Michael_32

A couple of questions

How many zones on each loop (Hi-temp/lo-temp)? How are we handling individual zone control, with valves or circulators? Hi-temp loop is for air handlers/hot water coils?

I'd run it with Taco Zone relay panels, ZR for Zone Valves, SR for Zone Circs. I'd use one panel for each system and tie in the 008's so they start on a call for heat from any zone on the loop. The end switch on each panel can be used to fire the boiler, and it can control the system circulator.

I'd use multi-stage heat thermostats just to avoid the forced air coming on based on not enough setpoint differential between different stats, and cumulative sensor error over time. (Just had to fight this one with non-integrated controls on gas-packs and radiant floor heat). The single stat will always read the same room temp for both stages of heat and any error over time will be the same for both.

Cheers,
Michael

Baldrick_2

Michael,

Each secondary 008 pump does one temperature. There are 2 of them, one does 5 slab (low temp) loops, second does 12 underfloor loops (high temp).

I don't want warm air furnace to turn on at all, unless temperature is below 50F, in case of boiler failure. No sure if there is a two stage thermostat that would do that.

The only 2 stage heat / 1 stage cool thermostat I found so far is TekmarNet 545. As far as I know, SR502 wouldn't take the full advantage of it plus I am not sure what would be a good choice for a second thermostat.

With 1 stage heat, I know that SR502 would do the job perfectly, I just need an advice for pair of thermostats, where one would be also able to control the second zone.

To sum up:

With 2H/1C main thermostat (Tekmar 545 or ???) - what controls - what 2nd thermostat?

With 1H main thermostat (???) - SR502 controls - what 2nd thermostat?