Mechanical room layout- radiant with solar tie in

Discussion in 'HVAC Heating & Cooling' started by minniehill, Feb 19, 2012.

  1. minniehill

    minniehill New Member

    Messages:
    4
    Location:
    Ontario
    A short story for you!
    I built my house 5 years ago and payed a hvac contractor good money to design/layout and install my radiant heat system.
    I have many issue with it in this short time. No air vent installed resulting in cold zones. Undersized pumps. Undersized piping (my opion). Ghost flow overheating due to no check valves. Cheap mixing valve to trying to control 1200sqft of 6" slab and 1200sqft of thin slab.

    I have now installed solar panels and would like to integrate it with my current system. I am looking at completly redesigning the mechanical room plumbing to achieve this. I would like to try and use as many of the existing componets as possible.

    I have 1 baseboard loop, 1 thin slab with 5 loops 280' 1/2 pex, 1 6" slab with 5 loops 280' 1/2 pex

    I have:
    1 propane DHWT with internal HE
    2 dual coil solar storage tanks
    3 taco 005 pumps
    1 taco 008
    1 taco 010
    2 motorised ccv mixing valves (7.4cv)

    I have on order a spirovent mirco bubble air eliminator and etx-30 expansion tank.


    I have lots of control equipment and can manage that as long as I understand the theory behind the design.
    I do not want to inject hot water with a circ pump
    Solar is closed loop
    Radiant is closed loop

    I have 2 ways I have drawn it but not sure if they are the "best" way.
    What would you charge for mechanical room layout?

    Ben
  2. minniehill

    minniehill New Member

    Messages:
    4
    Location:
    Ontario
    Will.it.work. (800x566).jpg
    CV1 will be outdoor reset valve
    CV2 will be a divert valve that will divert solar injected heat around heat tank if the temp is higher then requested by the floors.
    Solar pump will only run if (1) store temp is greater then floor return (2) one of the 2 slab pumps must be running.
    Will this work or can someone please sketch out how it should be done?
  3. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    You have a mess on your hand because your radiant guy was a dopey - make it more complicated guy. I am a keep it simple, sort, and have 6 or 7 300' loops on ONE pump with simple ball hand valve temp and zone control. Its an OPEN system, so the only control is a check valve and its tied to the potable hot water, so you get endless hot water in the winter and free floor cooling in the summer.

    I have done this for several++ houses and have NEVER had a call back in 25 years.

    http://www.radiantec.com/systems-sources/open-system.php

    Here is a good starting link. The only question is what temp are you running the water at? For open systems, you want to keep it 120 to 150F.

    To use solar you would simply have a heat exchanger tank that feeds into the water heating device.
  4. minniehill

    minniehill New Member

    Messages:
    4
    Location:
    Ontario
    Ballvalve, would you even consider running potable water though the lines now? They are greyish/black and smell a little now. Would you not be worried about about that at the tap?
    Also I am on a well with hard water.

    Ben
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    If you are in Ontario, meaning Canada, ( not Ontario, CA) you should not even consider direct solar thermal. That is 1970's technology, and has numerous drawbacks, not the least of which is potential freeze. Most solar thermal today is done with glycol loops and a heat exchanger. You should not try to size and design it yourself.....for starters, if you are bucking for any rebates, the design must pass serious scrutiny in terms of sizing etc. A solar manufacturer/contractor will provide design guidance for you.
  6. minniehill

    minniehill New Member

    Messages:
    4
    Location:
    Ontario
    Jimbo,
    You are right, Canada. Solar is a closed glycol loop for freeze protection. Floors are closed loop water due to water quality, very high mineral content.

    In my dual coil storage tanks lower coil is solar feed and the upper coil will have the radiant floor water circulated. The tank medium is potable curb water that is preheated and then fed to th DHWT.
  7. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    So you are probably stuck with all the mechanicals, but I have very hard water and have never seen any evidence of it precipitating onto the walls of pex. 1/2" with all the pumps should be perfectly fine for flow.

    If you were able to flush the pex and go open, it only feeds the water heater and does not cross connect with the cold outlets, also you would gain another exchanger for the solar, but have the burden of freezing of components, as pex does not typically break in a freeze.
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