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Add on Radiant, need help hooking up

Hi everyone, first time on here but it looks like I got to the right spot for some expert help. We just put an addition on our house and used Warmboard for the in floor heating. Warmboard designed the tubing layout. The addition is a little over a 1000 sq ft and there are 6 loops. I used a Caleffi manifold with 3/8 pex in the floor. I ran back to the boiler with 3/4 pex. The existing house is baseboard heat, 3 existing zones.
My question is how and where I can tie into the existing system? My idea was to go into one of the areas I outlined in the attcahed picture. Is one better that the other? Also my plan was to use a mixing valve for supplying the heat to the manifold. Would that be acceptable?
I know you guys may say that I should hire a pro to do this and I totally agree but I'm getting to the end of this project and my money is getting very tight. I can handle the mechanical part of it but I am unsure of the design part.
Any help you guys can give is greatly appreciated.


  • Harvey RamerHarvey Ramer Member Posts: 2,214
    Either one of those spots will work. You'll want to come off that loop with 2 closely spaced tees. You'll want to use either an injection mixing or 3-way motorized mixing strategy. That will allow you to run ODR on that zone. Important for radiant.
    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • chriscookchriscook Member Posts: 3
    Thanks for the input Harvey. I do have an ODR on my boiler. I have an oil fired Buderus. Would I still add another to my radiant zone or is that overkill?

    Thanks again for the help.
  • Harvey RamerHarvey Ramer Member Posts: 2,214
    Well, what are the low and high temps of the ODR curve you running to the baseboard? Unless you are using a high efficiency baseboard, they will undoubtedly be higher than what is required for the radiant. You will find with the warm-board, you don't need a very high temp even in the coldest weather. Probably the highest temp for the warm-board will be lower than the lowest temp for the baseboard.

    So you can see, another ODR device may be in order.
    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • overpopoverpop Member Posts: 52
    As far as if you should do it yourself, I had a similar situation where I had 3 baseboard zones and I ran radiant. Come time to have a professional come in hook it up and replace my boiler. Well, they were either too busy, job was too small, or they figured I would be a pain since I at least knew something about plumbing. Buddy of mine said to read Pumping Away and that led me to the journey of installing it myself and in the process finding plenty of mistakes that for years the professionals made. You can do it, just be as neat at the nice looking install you already have.
  • Rich_49Rich_49 Member Posts: 2,540
    Did I read correctly that you used 3/8" pex in Warmboard ?
    "Conduction is King" Terry Alsberg , Owner, Warmboard
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • chriscookchriscook Member Posts: 3
    Great looking install overpop and thanks for the reading suggestion.

    Rich, you read correctly but that was a blunder on my part. I have 1/2 rifeng for the pex.

    Thanks again guys.
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