Need Expert feedback/opinion on 3 zone radiant heat setup

djphish

Hello,

I'm in the planning stages of my 3-zone radiant heating project and I'm looking for any input / critique of the set up I'm about to build. I have attached a schematic to this post detailing the layout.

This heat supply is supplementary to forced air heat in the house. (It is not the main source of heating the house)

In summary:

The main loop will be serviced by an IBC combi boiler which is already installed. The boiler has a separate pass-through circuit for instant hot water. This is already hooked up to service the house needs and is not included in the attached diagram. The second 'heat circuit' in the boiler allows for a closed loop radiant heat. There is a safety heat purge valve on the boiler built into this circuit along with an internal pump that is activated by the boiler whenever there is a call for heat on this circuit. This will be the main water circuit as per attached diagram and will be 1 inch in diameter. On this circuit, there will be a fill connection and an expansion tank. A microbubble air eliminator will also be installed.

Off the main circuit there will be 3 heating zones. Each zone supply and return will be connected by closely spaced tees, which will connect the 1 inch pipe into 3/4 inch pipes in each zone. (The manifolds will distribute into 1/2 inch pipe heating loops). As per IBC documentation, these will be "closely spaced tees are maximum
four primary circuit piping diameters apart, with a minimum of eight pipe diameters of
straight tubing upstream of first tee and a minimum four pipe diameters straight
tubing downstream of second tee.

Each zone will also have a thermostatic mixing valve and a 120 v pump with a built-in check valve. The pumps will be switched on/off by a 3 zone Taco switching relay. If an zone thermostat will call for heat, that zone pump will be activated along with the boiler main heating circuit as per diagram.

Zone 1: Garage radiant floor
-thermostat for this zone will be mounted on the wall in the garage, since room temperature will be the 'deciding factor'

Zone 2: Bathroom towel racks
-thermostat will be activated by a temperature probe directly behind the return manifold, since towel rack temperature will be the 'deciding factor'
Question 1: Any suggestions of a specific 'temperature probe' that can be used here to 'close the loop' on this zone's thermostat?
Question 2: Any suggestions of a specific thermostat (brand / model) to use with a temperature probe?

Zone 3: Basement radiant floor
-thermostat will likely be wall mounted in the basement, since the basement is colder than the upstairs of the house. The other option is to also use a 'temperature probe' here to 'close the thermostat loop'
Question 3: Looking on feedback on whether the thermostat should be activated by ambient air temperature in the basement or via temperature probe of the water in the basement loops (like in zone 2)?


Any feedback and suggestions are greatly appreciated. (Once the design is finalized and I embark on building this setup, I will update this post with photos.)

Thank you for your help in advance.

hot_rod

Why the 3 mix valves? Can you just run the boiler on ODR, same temperature to all zones?

A hydraulic separator, delta P circulator and 3 zone valves.
The Sep gives you 4 functions and really cleans up the piping.

If you pipe as shown you need to run the boiler 20 degrees hotter then the SWT you need to allow the mix valves to work, and you have the series temperature drop on the primary loop.

Tomizai

I agree with Hot Rod. Also, I would suggest making a small boiler loop and running your zones off an "antler" method. Each of your zones would get the same supply water temp. See the pic included (if I can get it to post)

Ironman

hot_rod said:

Why the 3 mix valves? Can you just run the boiler on ODR, same temperature to all zones?

A hydraulic separator, delta P circulator and 3 zone valves.
The Sep gives you 4 functions and really cleans up the piping.

If you pipe as shown you need to run the boiler 20 degrees hotter then the SWT you need to allow the mix valves to work, and you have the series temperature drop on the primary loop.

^^  ^^  ^^

What he said.

MikeL_2

     I agree with hot rod, and perhaps no tstats needed. Consider ODR with an adjustable heating curve including constant circulation below warm weather shut down. There are several manufacturers that have radiant mixing stations, or, the ibc boiler may have on board or accessory programming available.....