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Input requested on system design and proper control

I'm doing a full reno on my 1000 square foot house and have decided to install in floor heat in the basement and also on the main floor. I'd appreciate some input from the pros before I (potentially) commit to a costly mistake.
I did room by room heat loss calculations and came up with ~16000 btu/hr for the whole house. I've made some running changes to the design that should lower that number a bit but I haven't recalculated. My highest heat loss is the kitchen and it works out to 21.4 btu/hr/ft^2. The lowest is the basement bedrooms at 8.9 btu/hr/ft^2. I'm planning on having 7 loops of 1/2" oxygen barrier PEX, each one 300' long.
The basement has an existing slab poured over 80% of it. The remaining 20% is crushed rock. The slab is very sloped and has cracks. My plan is to install a dimple board product over the entire floor to act as a moisture/radon barrier and also a thermal break. On top of that will be R10 EPS followed by my PEX loops which will be covered by 2 inches of cement (2" total, only 1.25 inch above the PEX). The plan is to have the cement as the finished floor but I might put carpet/cork etc over the cement in the rec room to avoid trips to the ER with the kids. There will be 3 loops in the basement, 1 for both bedrooms, 1 for the rec room and 1 for the utility room and bathroom.
Main Floor
The main floor will have 4 loops, 1 for the Master bedroom, 1 for the 2 bathrooms and walk-in closet, 1 for the living room and 1 for the kitchen. With the exception of the bathrooms, all the flooring will be 3/4" Red Pine. The bathrooms will be tile. I currently have 1" pine for a sub floor run on a 45. My plan is to install sleepers (1x2.5" pine) on the opposite 45 with a 4" gap between them. In that gap I will run the PEX tubing which will then be covered in cement. It will be 1" thick. This is being done for a few reasons, first to provide a method for fastening the finished flooring and second to reduce the overall weight. I considered the aluminum plates in the joist bays but frankly it sounds like a pain and is a fair bit more expensive. I'm also concerned about contraction noises which I'm expecting to be eliminated by having all the PEX in concrete. I will run a layer of sill gasket below the cement/PEX to create a thermal break between the cement and sub floor. The joist cavity will also be insulated with R12 from below.
Heat supply
My plan for the remainder of the first year is to run this system off a 50 gallon electric water heater. I plan to install at least 6 50 gallon tanks by next winter. Only 2 of them will be wired up, the remaining are holding tanks. I plan to heat the water during off peak hours and then use the stored heat during peak times. Eventually I want to build a solar water array that will heat the storage water instead of electricity. I may also tie in a wood boiler when the garage gets built which will also be heated by this system.
This is the area that I have the most questions.
My plan was to vary the water temperature in the loops to control my air temperature. Since there is wood over the cement on the main floor I know I need to be mindful of the temperature swings and extremes. Is this as simple as getting a thermostat that has an air and slab sensor and setting my min/max values for the slab?
I was planning on installing my 7 loops on 1 manifold and using manual valves to balance the flow to adjust the temperatures throughout the house. The more I think about this, the more I think it's a bad idea. At the least, I think I need to separate the upstairs from the basement.
Regarding the 6 50 gallon tanks, my plan was to install them in series with each tank supplying the next from the top to the bottom. I plan to feed the injection pump from the top of the last tank and return the water to the bottom of the first tank. I'm hoping that this approach will maximize the thermal stratification. I plan on having a separate pump for the tanks that only activates when the tanks are heating the water. I'm thinking something that will cycle the water at least twice through the tanks during the heating cycle will be sufficient. As for controlling the tank temperature, I was going to use the factory thermostat at the highest setting and then use a timer to ensure that the heating elements don't come on during peak hours. I'm thinking something with outdoor reset might be worthwhile here or I could just manually adjust it each week/month depending on the expected conditions.
I haven't given any significant thought to tying in the solar part since that is likely a year or 2 out. If there is something I should do now to significantly make that easier in the future, I'm all ears.
General Questions
- As for air removal, should I install an air bleeder on the top of each tank or is there a better idea?
- I'm planning on filling the system with distilled water. Is this necessary? I have (at present) untested well water or I could haul out some city water (lake fed).
- Should I install any sort of filter on the system?
- Where and what sort of gauges should I install to monitor my system?
- What system pressure should I aim for?
- Would it be sufficient to replace one of the water tank temp/pressure relief valves with one matched for the system pressure? What sort of differential is preferred between system pressure and relief?

I've attached a picture of how I'm currently planning to plumb this up. There are additional valves that I will be installing but I figured I'd redo the picture with more detail once I get some input.

Thank you.


  • hot_rod
    hot_rod Member Posts: 16,312

    Any way to use one large tank, A lot of heat loss with multiple tanks like that

    Better piping options also for multiple tanks, if you must
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTechdelta T
  • Jamie Hall
    Jamie Hall Member Posts: 18,947
    The solar is a bit problematic. You will either need backup heat -- or a big (3,000 gallon very well insulated, since it will be well above ambient) storage tank to carry you through the night -- or a cloudy day.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SuperTech
    SuperTech Member Posts: 1,792
    I know it's a far fetched idea, but how about using something like a boiler to do the job. Use your electric water heater as a buffer tank and run the system using outdoor reset to maintain supply water temperature. You could still use solar or a wood burning boiler in conjunction with it. I don't like using water heaters for space heating, even for low temperature applications. Perhaps I have seen too many poorly done jobs like that

    No offense but your questions lead me to believe that this is the first time you ever thought about Hydronics. You made a great choice but you need to educate yourself further before attempting this. Reading the books Pumping Away and Primary Secondary Pumping Made Easy will teach you a lot more, a lot faster than asking questions here.

    I would probably do radiant flooring in the basement and use panel radiators with TRVs in the rest of the house.
  • burn_your_money
    burn_your_money Member Posts: 5
    Thank you all for the input so far.

    hot_rod - Thank you for the link. I'm working my way through the article now and will definitely be rethinking the plumbing. The heat loss factor is less of a concern for me using multiple tanks as they would be located directly below the kitchen (highest load loop). I haven't been able to source any large buffer tanks locally which was my primary motivator for considering using the hot water tanks. I will continue to look though.

    Jamie Hall - My intention was to primarily use the solar during the shoulder seasons to minimize my electric bills/wood usage. It would most likely not be used at all during the actual cold parts of the year. If I tie my DHW into the system (using a plate exchanger) then the solar would be used for the better part of the year but again, not in the winter.

    SuperTech - One of the most frustrating aspects of the HVAC/plumbing industry is all the secrecy. Since I'm not licensed finding any solid information is extremely difficult. I suppose part of the issue may just be my lack of knowledge of the technical terms rendering my searches fruitless. I've tried looking for info on electric boilers and the few options I was able to find came preconfigured with pumps and other hardware that didn't match my goals. Also, since pricing is virtually impossible to find I really can't make an informed decision if the increased costs of a boiler are justified over a water heater for my application. I'm not against a boiler, I just can't find the information I need.

    That's a big part of reason I am so happy to have found this forum. As I see it, anyone who spends 40+ a week doing something and then takes from their free time to freely help others online is in the top percentile of their trade or at the very least aspires to be.

    Your assumption that this is my first time thinking about Hydronics is close enough. I've thought about it many times but this is my first opportunity to actually make something of those thoughts. I'm not surprised it shows. I will check to see if the local library has those books.

    My parents have radiators at their house and I find them frustrating to work around. Open wall space is a big priority for my house but at the same time, if the in floor doesn't work, that's most likely what I'll be switching to.
  • ratio
    ratio Member Posts: 3,178
    Well, there are a number of good books here, but take a look here too.
  • SV9_9
    SV9_9 Member Posts: 37
    edited March 2019

  • burn_your_money
    burn_your_money Member Posts: 5
    As much as I'd love to read all these books, realistically I don't have time. I will read as many of them as time permits though.

    Since the reno is currently underway, does anyone see any glaring issues in my plan that need to be addressed during the construction phase? Controls and tanks are easy enough to change after the fact but if you guys see issues with my in floor idea on the main floor or anything else, I'd like to know sooner rather than later please.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,689
    Not finding proper information is less because of 'secrecy' and more about people just don’t know, but will take the job anyway.
    My recommendation is to hire some here or from here:
    to properly design your system, explain all the options.
    It can even be done remotely. Here's a guy from this site, if available and interested, would be a great choice (as well as many others):

    Ramer Mechanical LLC
    303 Shed Road, Newville, PA 17241
    (For some reason, 'Find a Contractor' isn’t working)
  • SuperTech
    SuperTech Member Posts: 1,792
    Yes no secrecy in in the books I recommended. You will learn all the knowledge you need to get started on this project in those books, and they are a pleasure to read.

    It seems like you are reluctant to look at other options besides electric. They make some very nice gas boilers that work extremely efficiently with a radiant hydronics heating system, wether it's in floor or cast iron emitters. Panel radiators don't take up the space of the old cast iron radiatiors. TRVs give you wireless temperature control of each room, giving the occupants optimum comfort. PEX makes running tubing simple and but it seems like most people can't do a neat job with it.
    Whatever you do, make sure that the manufacturers instructions are followed. If you don't have the skills, tools or trainings to complete the job properly. Stuff like combustion testing and commissioning the equipment it is usually more cost effective to have an experienced professional equipped with all the necessary tools perform the job.
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 1,864

    (For some reason, 'Find a Contractor' isn’t working)

    Our developers are working on this issue. Thanks!
  • burn_your_money
    burn_your_money Member Posts: 5
    I hadn't considered that someone would be willing or able to work remotely with me on this project. I am in Ontario which may or may not complicate things.

    The only reason I am leaning towards electric is because natural gas is not available in my area. Propane, oil and electric all work out to about the same cost per BTU (without a buffer tank) but the equipment cost is lower for electric, plus I don't need to hire anyone for annual inspections or maintenance and my home insurance is cheaper. If I can fill my buffer tank off peak, that actually makes electric my cheapest option. My total estimated electrical consumption for space heating is $550 for the year.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,689

    (For some reason, 'Find a Contractor' isn’t working)

    Our developers are working on this issue. Thanks!
    What are you doing up so late? 😁 (the internet never sleeps?)

  • Rich_49
    Rich_49 Member Posts: 2,692
    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
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 1,864
    edited March 2019

    (For some reason, 'Find a Contractor' isn’t working)

    Our developers are working on this issue. Thanks!
    What are you doing up so late? 😁 (the internet never sleeps?)

    Exactly! All fixed now.