Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Non-Electric Control of Radiant Floor

Kestrel
Kestrel Member Posts: 102
Mark,

I was intrigued by a couple of things you said on my other water-temp post from the last couple of days.

That thread was a wealth of information, but I think my specific queries got a bit tangled in the various lines of discussion.  I'm posting them again below - I'd love to hear your thoughts when you have a moment, and of course anyone else who want to chime in!



Also, I've reposted a revised schematic - I'm curious, basically, what you would suggest I use for 'Valve A' and 'Pump B', and how to control how to send water/heat to the radiant floor subsystem.



Thanks!!





MARK: "If you use a fixed temperature non electric thermostatic mixing valve,



it will essentially only kick in if the supply water temps from the



source is greater than its set point, which works fine. It avoids



overdriving the radiant floor zones. When the boiler is supplying water



temperatures below the mixing valves set point, then there is no mixing



occurring. "



Do those sorts of valve mix down to a specific temperature?  Mix down to that point and no further?



Are there non-electric valves that maintain a constant

proportion?  Such that if I have the ODR and the higher supply

temperature on a curve, that the valve will generate a similar curve,

though with lower max temp, and shallower slope?



As I think about this - is there a difference in comfort between

heat from the floor and heat from radiators?  If so, then once my

heating needs fall with the shoulder seasons, I'll need the supplemental

radiators less, and can employ the floor for a greater portion of the

heat delivery - yes?  During those periods I can turn down the TRVs and

let the mixing valve be open more to the primary supply temp.











MARK: "If this is not a major consideration, I would suggest you consider the



use of non electric thermostatic controls, even on the radiant floor



circuit (Oventrop, Danfoss, Honeywell etc). That control is



proportional, and works fantastically with the DCECM pumps you will be



using."



By that sort of control, do you mean some sort of proportioning

valve?  In the schematic below, would you make pump 'B' also an ECM?  If

so, what would control its flow rate - analogous to the TRVs on the

radiators?  What sort of non electric thermostatic control do you mean? 

In the location of valve 'A' on the schematic?  Or on the individual

loops of the manifold?  I am certainly planning on using that sort of

system on the radiators - TRVs on each rad, with a Grudfos Alpha (or

Wilo Stratos - any opinion?).  Again, how would you implement a

non-electric control on the floor radiant circuit?

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I answered this last night...

    I wrote 1/2 a book, and clicked on the picture you drew to verify design before submitting, and my book disappeared... Bummer. Learn from my mistake. Look at the picture BEFORE you type a response, or lose your work to the cyberspace...





    Also, I've reposted a revised schematic - I'm curious, basically, what you would suggest I use for 'Valve A' and 'Pump B', and how to control how to send water/heat to the radiant floor subsystem.





    Take 2 RESPONSE: Valve A would be a non electric 3 way mixing valve. Pump B would be a DCECM pump like the other pump, and you would want to add a 2 way non electric TRV to the outlet of the pump B. Eliminate the electronic thermostat and allow both pumps to run off of the boilers control logic, based on OSA temperatures. If they are not needed, their power consumption will be minimal. They will ramp up as needed. This is called constant circulation with ODR. It is the ultimate in comfort and efficiency compared to a bang bang system.



    MARK: "If you use a fixed temperature non electric thermostatic mixing valve,



    it will essentially only kick in if the supply water temps from the



    source is greater than its set point, which works fine. It avoids



    overdriving the radiant floor zones. When the boiler is supplying water



    temperatures below the mixing valves set point, then there is no mixing



    occurring. "



    Do those sorts of valve mix down to a specific temperature? Mix down to that point and no further?



    Are there non-electric valves that maintain a constant

    proportion? Such that if I have the ODR and the higher supply

    temperature on a curve, that the valve will generate a similar curve,

    though with lower max temp, and shallower slope?



    As I think about this - is there a difference in comfort between

    heat from the floor and heat from radiators? If so, then once my

    heating needs fall with the shoulder seasons, I'll need the supplemental

    radiators less, and can employ the floor for a greater portion of the

    heat delivery - yes? During those periods I can turn down the TRVs and

    let the mixing valve be open more to the primary supply temp.



    RESPONSE: Yes, the 3 way NETRV can only mix down to a fixed point. Ranges run from 80 to 140 degrees F. I prefer to use Sparco (now Honeywell). If you want a lower curve than what the boiler provides, then you will have to provide a motorized 3 way, along with the necessary logic to make it work, but I personally don't think its necessary. Just allow the floor to follow the boilers curve until the curve exceeds the 3 ways setting. Don't confuse the NETRV 3 way with a NETRV 2 way. One (2 way) limits flow through a circuit. The 3 way does NOT limit flow through a circuit, but limits TEMPERATURE.



    The NETRV will parallel the boiler reset curve exactly, until it reaches its plateau, and stays there. It opens and closes its hot and cold ports to maintain a constant output temperature. No real flow control restrictions associated with a 2 way valve.



    As it pertain to comfort, other than being able to set foot on the warm floor, there is no difference in comfort. Radiant heat affects the Mean Radiant Temperature (MRT) which drive the bus of human comfort. Set up properly, the panel radiators will automatically blend in as needed. You need to limit the floors temperature of operation to 85 degrees, or you will discover what the MEAN in MRT stands for... I know Oventrop makes a dual bulb floor control that senses air and floor temps, and if one exceeds the other (overly warm floor for example) is closed flow down to almost nothing.



    My definition of COMFORT is not being aware of your surroundings. You are neither hot, nor cold and you don't hear anything running in the back ground. Simply stated, you are comfortable. If you are making manual adjustments to your system, you are not comfortable. Its your system, but I think you will find your comfort point and cease having to make adjustments on a regular basis.





    MARK: "If this is not a major consideration, I would suggest you consider the



    use of non electric thermostatic controls, even on the radiant floor



    circuit (Oventrop, Danfoss, Honeywell etc). That control is



    proportional, and works fantastically with the DCECM pumps you will be



    using."



    By that sort of control, do you mean some sort of proportioning

    valve? In the schematic below, would you make pump 'B' also an ECM? If

    so, what would control its flow rate - analogous to the TRVs on the

    radiators? What sort of non electric thermostatic control do you mean?

    In the location of valve 'A' on the schematic? Or on the individual

    loops of the manifold? I am certainly planning on using that sort of

    system on the radiators - TRVs on each rad, with a Grudfos Alpha (or

    Wilo Stratos - any opinion?). Again, how would you implement a

    non-electric control on the floor radiant circuit?





    RESPONSE: Don't confuse the operation of the 2 way NETRV (proportional FLOW control) to the function of a 3 way (proportional MIX control). THey do different things. The 2 way will at times be barely open. If someone floods the room with cold air, then it opens and flows enough water to satisfy the call, and as it approaches set point, closes down proportionally.



    Yes, B should be a DCECM pump.



    As it pertains to pumps, both brands are good. I think WILO has more experience in this area than Grundfos, but both are great pumps, and I recommend their use even if the flow is bang bang. THe wire to water efficiency is just so much better. Eventually ALL motors will be DCECM. It is THAT much more efficient than the current technology.



    As for the manifold, if each circuit served a separate room, you could attach 2 way NETRVs to each circuit (33 foot max cap tube length) but if it is all serving one zone, then I'd pipe it on either the supply or return and stop/control all flow to the manifold.



    Hope I covered all your questions.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Kestrel
    Kestrel Member Posts: 102
    Thanks for Re-Posting

    Oh, man, how frustrating to lose all that writing - thanks for taking the time to educate m, I really appreciate it.



    I've attached another schematic of what I believe you are discussing.



    DCECM pump - gotcha.



    Valve 'B' - referred to as '2-way TRV'.  This sounds essentially the same as the TRV you'd attach to a radiator (as I'm planning to do).  I'm thinking that the sensor, and adjustable dial, would be on the main floor wall somewhere, a la a thermostat, and connected to the valve body in the basement via a capillary tube - yes?

    I've done a little looking around the innertubes for something like this, and am coming up empty.  Would you use precisely the same piece of hardward you'd put on a radiator, or is there a specific product for this application (I assume the latter)?



    Valve 'A' - the '3-way NETRV' - is this the same as a manual thermostatic mixing valve, ie Taco 5000 series, or Honeywell MX?  This valve would allow untempered supply water through, following the boiler ODR curve, up to a point - say 140 or 150'F - and then limit the water going to the floor to that set point if the supply is hotter - during the colder parts of the winter, protecting the wood floor and my feet - yes?



    Thanks again for the time and patience!
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Wicked evil thread....

    Believe it or not, I posted the other half of my book in response to your last set of questions, and the internet monster ate that one too!!!



    Sheesh..



    You asked, Valve 'B' - referred to as '2-way TRV'. This sounds essentially the same as the TRV you'd attach to a radiator (as I'm planning to do). I'm thinking that the sensor, and adjustable dial, would be on the main floor wall somewhere, a la a thermostat, and connected to the valve body in the basement via a capillary tube - yes?



    ANSWER: Yes, the end function is the same, but appearance is completely different. See http://www.oventrop-na.com/us/index.asp?sprache=US for information on all of the valves available in the North America market.



    Yes, maximum length of cap tube varies with product chosen, but worst case single use control is 33' (10 meters).



    You asked; I've done a little looking around the innertubes for something like this, and am coming up empty. Would you use precisely the same piece of hardward you'd put on a radiator, or is there a specific product for this application (I assume the latter)?





    RESPONSE: Go to the link I posted above for a good selection of these beauties.



    You asked, Valve 'A' - the '3-way NETRV' - is this the same as a manual thermostatic mixing valve, ie Taco 5000 series, or Honeywell MX? This valve would allow untempered supply water through, following the boiler ODR curve, up to a point - say 140 or 150'F - and then limit the water going to the floor to that set point if the supply is hotter - during the colder parts of the winter, protecting the wood floor and my feet - yes?



    ANSWER: Yes, correct on all assumptions. I've not used the Taco 5000, so can't comment on it.



    Let's see if it works this time...



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Kestrel
    Kestrel Member Posts: 102
    Thank you...

    for your diligence!

    How frustrating - I really appreciate you sticking with it - I was beginning to think I had been too obtuse and you'd had enough.

    So...onto installation!  I'll post back when I'm making some progress (or, more likely, run into the next unforeseen issue!)
This discussion has been closed.