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Radiant Heat Expansion- Pumps, Zone Valves, Zone Controller

BenGBenG Posts: 4Member
I have a 200K BTU Noritz hot water boiler (max 140F) that supplies DHW directly, and through a heat exchanger heats water for a 1500 sq. ft first floor only radiant heat system. There is a circulator pump just outside the boiler that moves the DHW and a 2nd pump for the radiant water loop. Controlling this is a two zone i-Link controller with the radiant heat system on Zone 1 (Zone 2 is empty). Physically next to the Zone 1 pump is the start where a Zone 2 pump could be added. For reference, I did not install this system it came with the house.




I am looking to add heat to 2 unheated rooms (each less than 200 sq. ft) . To do this I am considering adding a Tomotoyi HC-20 to each room, but I am stuck how I should do the pumping, zoning, and plumbing.

- Should the heat convectors be in series with each other? If so should I use mono-flow tees or zone valves to isolate? I want to maximize the available hot water to each system, so I am leaning towards mono-flow tees and zone valves so that if both demand heat the 2nd unit will get hotter water than it would without the tee. Thoughts?

- The heat convectors have their own thermostats. If I use zone valves, and connect the HCs to the valves, can I wire both valves to the future 2nd zone pump? My thought process is... If one HC demands heat then pump turns on. If one HC was running and then the other HC wanted heat the 2nd valve would open but since the pump is already running nothing bad happens?

- With my current controller, can I have two zone valves wired to a single pump? Or, do I need a three zone controller, but 2 pumps (and I would jump Pump 2 and 3 together?).

thanks!

Comments

  • BenGBenG Posts: 4Member
    diagram of my existing set up and Pump 3 plan
  • John RuhnkeJohn Ruhnke Posts: 797Member
    I think you could simplify things a bit here. Instead of the three way zone valves, I would use two way zone valves. No need to mix the temperature down for convectors. With the 140 hot water setting that heat exchanger wont put out more than 130 degrees. Then you could eliminate the check valves and mono flow tees.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • BenGBenG Posts: 4Member
    Yes I agree. After further research I am planning on using a zone valve manifold from Cross and piping each HC directly to and from the manifold. This system connects to a single circ pump so I think that should be all set now.

    Question on the piping...

    - Both circ pumps are connected through a common return to the heat exchanger...is that okay? Pump 2 does not have a built in check valve. Should I add one?

    - Do I need check valves to separate the return flows as I diagrammed?
  • John RuhnkeJohn Ruhnke Posts: 797Member
    The pump leading to the HC's does not need a check valve because the zone valves will shut off the flow when the zones are off. The radiant zone needs a flow check. A check valve isn't good enough. A check valve just stops the flow from going backwards. A flow check stops both forward and backwards flow. When the radiant pump comes on it produces enough force to push through the flow check. Flow checks are very common and a standard in our industry.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
  • BenGBenG Posts: 4Member
    My zone 1 radiant pump is a grundfos up26-99 without a check valve built in. I purchased a replacement valve for the UP26 series and was planning to install it on this pump. Is what you mean or do you mean a standalone valve?
  • John RuhnkeJohn Ruhnke Posts: 797Member
    edited September 10
    @BenG
    The check valves that come built into the pumps are all flow checks. If the pump didn't come with one you can buy them separately. Just make sure you ask for a flow check when you buy it.
    John Ruhnke
    Hydronics Designer
    Hydronics is the most comfortable and energy efficient HVAC system.
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