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Need plumbing help

Ben_17 Member Posts: 18
I would be imbarrassed to show you the mess that is at my combi DHW tank now.

I would like to redo it all and would like your feedback. All pipe is 3/4" copper including the heat exchanger coil in the tank.

My big question is do I break the loop out of the tank or leave it as it is drawn? The mix valve will be outdoor reset.




  • STEVEusaPA
    STEVEusaPA Member Posts: 6,378
    Doesn't look right

    You're missing a number of components, namely 2 more circs, or zone valves. It needs to be more of a primary/secondary piping. Can you explain a little better what's going on, and why, it appears you only want the return water from the radiant loops going to the solar tank?
  • Ben_17
    Ben_17 Member Posts: 18

    If I am thinking about this correctly my floor return water is the coolest water and should have the greatest delta T to my solar store. I did neglect to show the 3-way valve in the solar store circut that prevents/bypasses the store tank when it is below floor return temp

    Thinking about it now.. I guess I would have to break the pipe just above the solar return line to prevent short circuting back to the floor supply line.

    I shouldn't need any more circ's...... each one would send water around a complete circut...... I think....

    But is this pipe layout the most efficent way to get my solar energy to the floor?
  • Zman
    Zman Member Posts: 7,496
    Stop and regroup


    Please don't take this the wrong way, you need help with this.

    I checked out your posts on the solar side.

    I think you have a couple of choices.

    You could hire a professional designer to do the necessary calculations and design this correctly.

    You could take a break from working on this a read a good book on hydronic design. I like Modern Hydronic Heating by Seigenthaler, there are plenty of good ones out there.

    The first thing you need to do is calculate the output of those solar collectors. Then you need to size the pipe (in copper)  to the array. The correct size for 120 evac tubes is not 3/4". Next you need to figure out how to store the energy. Dumping it into a concrete slab all summer seems like a waste of collector. The efficiency curve of the collector is also an important factor in your storage calculation.

    On the heating side you need to calculate the load of the heat zones (based on the heat loss of the building and the size and temp rating of the emitters) The pipe and pipe size is then calculated. You cannot service 2500 square with 3/4" pipe. Then comes the heat transfer. The heat exchangers in the solar tanks need to be sized for the heating load, as does the back up heat.

    Your drawings lack many critical components including expansion tanks, air vents, check valves ect. It is so important to remember that water will never go were you want it to. I will only go were you make it go.

    I absolutely love your passion for DIY and solar. I can tell you from experience. It is time to regroup.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Ben_17
    Ben_17 Member Posts: 18
    Heat side/solar side

    Each circ feeds 1200 sq/ft of in slab floor. Zone 1 is 5 (1/2') loops at 280' in a 2 inch slab. Zone 2 (basement) is the same but a 5" slab. The feed to the baseboards is 3 (1/2) loops for 2 upstairs bedrooms (200sq each with 6' baseboard) and a bathroom (120sq with 3' baseboard).

    The contractor that installed this for me when I built my house didn't install any air vents or check valves. He was the one that sized and installed the combi DHWT with the internal 3/4' exchanger.

    The system is 5 years old now and it is a nightmare with temp swing and cold upper bedrooms. I have installed a few check valves and a mix valve and a small PLC to cycle the floors if the pumps are off (time vary with outdoor temp).

    I am ready to tear it all out and start from the beginning...... Need help!

    As for the solar side..... I am cash poor due to saving for my wedding this Sept. What I am working with has to stay for this year but I have to build in some overheat protection! I have 2 spare pumps, spare rtd's and a controller that will do it..... again just need advise. Will the 2 closely spaced "T"s in the supply line from the collector with a mix valve work as a dump to my garage floor?

    All and any help is appericiated,

  • Zman
    Zman Member Posts: 7,496
    Detailed drawing


    If you post a detailed drawing or picture including pipe sizes,heat exchanger specs,pump sizes ect. You can probably get some help here. Pipe sizes are very important. For example each of your 1/2" loops should have a flow rate of at least .75 to 1 gpm. It sounds like you have 8 of them (6-8 gpm) fed by a single 3/4" pipe (4 gpm max.). I think if you really want to get this thing figured out you need to learn some fundamentals. Another (free) option would be to go to some of the manufactures web sites and take video tutorials. Taco has some good stuff in the "flow pro university", Many of the solar companies have sample layouts that provide a good starting point.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Ben_17
    Ben_17 Member Posts: 18
    edited February 2012

    I got a start with the taco software. mind if I email it to you Z?
  • Ben_17
    Ben_17 Member Posts: 18
    will it work?

    radiant/solar integration done right?Starting fresh again--- story from the top.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.

    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?

    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?

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