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Radiant heat cost

As an owner's representative, I am trying to promote the use of hydronic radiant heat in the floor of a daycare center (new construction, Kansas City, KS). The advantages are obvious, but the design engineer and the contractor are throwing back construction costs that are absolutely astronomical. This is an 11,800 square-foot building with 9 zones heated by an electric boiler. Can anyone give me a "ballpark" reference cost (per sqft? etc.) so that I can counter the quote or believe the quote from the contractor. The current quote from the contractor is prohibitive and will eliminate the radiant heat from the design as a so-called "value-engineered" change. I am worried that they just are not used to doing this type of work and want to value-engineer it out.


  • Mike Reavis_2
    Mike Reavis_2 Member Posts: 307
    has the current contractor successfully installed a

    radiant floor heat system? I would want to know.

  • It is a very large, national, construction management firm who claims to have the best subcontractors that are the most experienced in their field.


  • GMcD
    GMcD Member Posts: 477

    The ignorance levels out there. The company I work for is currently designing a radiant floor heating system into a 10,000SF two storey Natal Care Center in the Pacific NW and the value engineering we went through indicates that the radiant floor with HRV system is the best value-engineering approach. Low maintenance, high comfort, low energy costs, long operating life, and capital costs essentially the same as throwing in some gas fired furnaces and split system DX cooling. I think your Contractor and Engineer are doing a disservice to the project by not doing a proper life cycle cost comparison and providing an open minded approach. When I hear stories like this I think the Contractor and possibly the Engineer may have other motives to design and install their "favorite system" - it's low design effort for them, low risk, and profitable from a business point of view at their end, but ends up costing the Client a whole lot in the end in operating costs and comfort.
  • Mike Reavis_2
    Mike Reavis_2 Member Posts: 307
    you should be able to get want you want,

    even if that means seeking legal representation.

  • Geoff,
    Thanks for your positive support. I am very frustrated, but need some ammunition. Can you give me an idea of the mechanical costs for the system that you referenced in your comments? It's very close to the same size and scope.

  • questions

    did they supply a room-by-room as well as total heatloss calc? Are there factors that restrict the tubing on centers?

    why an electric boiler?

    Concrete is the cheapest radiant install possible. I don't know what you are considering "astronomical" but I would be surprised if the cost were truly prohibitive.

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  • Tube spacing is approximately 16" - 18". I have not seen any load calcs. Electric boiler was selected because electricity costs $0.035 per kWh and gas is $0.85 per Therm.

    Astronomical is $100,000 higher than a standard packaged RTU system. (about 67% more).

  • packaged RTU system?

    What do you mean by that. I know what an RTU system means to me, but I doubt you're talking about the same thing here :D

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  • Geno_15
    Geno_15 Member Posts: 158
    I yiyi

    I have a hard time believing $100,000 with an electric boiler. It is a lot of labor to install 9 zones, I would find a contractor to look at the prints and give you an estimate. It may be they don't want to do it, that makes the price go up!

    Hands down radiant is the most efficient, expensive, and comfortable. You are building a day care so comfort should play into it.
  • Constantin
    Constantin Member Posts: 3,796
    I'm pretty dense but...

    ... if the construction calls for concrete slabs everywhere, the added cost is almost noise. The PEX costs next to nothing to install, and the concrete protects it well. You simply have to be a bit more dilligent about control joints (install sleeves), areas where stuff will be anchored to the floor, etc.

    Installing 1,400 sq ft of radiant tubing in the basement slab took 3 guys one day in my house. So let's do some quick math:
    • IIRC, ½" tubing costs something like $0.5 per foot (O2-barrier variety).
    • If you assume 1' of tubing per square foot of floor space is required you're probably looking at about 13,000' of tubing (with waste and whatnot). Thus, tube materials will come out to about $6,500 plus sleeves, manifolds, and all that other BOP (which may be substantial).
    • If you extrapolate from my basement (probably conservative considering the twists and turns here), the manhours will come out to something like 200. You can do the rest of the math depending on the burdened labor wages in your area.
    • Thus, the total cost for such a system can be less than $15,000 before markups. I doubt this will be far more than the furnace system that will be required if the air-route is chosen instead.
    • Radiantec (the bane of many installers here) has published estimates of $1.5 to $1.75 per square foot of radiant-heated floor area in homes, before the addition of the heating plant (they expect you to install it). However, Radiantec has also published pricing by floor type, manifolds, etc. for commercial projects. Considering how well liked they are by some folks, you may want to apply a grain of salt.
    Nonetheless, I think the above excercise + info should be ammo enough to ask the folks to be a bit more reasonable with their estimates. In fact, I highly recommend you check out the "Find a Professional" service as a first stop to get a real quote. After all, my conjecturing won't get your client warm when it's cold out.

    Lastly, anyone who recommends a electric boiler for that large a structure should have their head examined (that is unless you happen to have nearly free electricity nearby). In fact, your space may be able to benefit from a geothermal heat pump with some supplemental fossil heating. Again, only a real professional can help you there, I'm just an engineer homeowner.
  • electric cost

    The way I figured it, if you burn gas at 85% efficiency, you're paying $.85 for 85,000 BTUH

    Your electric cost for the same amount of energy is $.87

    I'm not sure the payback for all of the extra installation and building penetrations and equipment costs is there.

    I'd go electric, myself.


  • A packaged RTU is a rooftop unit with gas heat and electric cooling (D/X).


  • The thermal equivalent cost of electricity at $0.035 per kWh is $10.25 per million Btu. Natural gas at 80% combustion efficiency and $0.85 per Therm costs $10.63 per million Btu. The energy costs are essentially equal.
  • Constantin raised a good point

    if electricity is cheap especially, geothermal would be a good thing to consider. It's a little pricey up front but can really chop down that energy cost.

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  • Constantin
    Constantin Member Posts: 3,796

    Electricity around here costs 5x more than where you are (at least for us peons called home-owners on a residential plan). Anyway, on your basis justifying a geothermal heatpump or anything else than an electric boiler appears to be more than a little difficult.

    If you are certain about the trend of electricity costs, you may even consider bypassing boilers, manifolds, and all the other stuff... and go to resisitive heating mats that can be cast right into the concrete just like PEX tubing... in fact, they ought to be even simpler to install than PEX tubing. However, they do lock you into using electricity, so future fuel-source changes would be impossible.

    Whether you use a water or resistive-matt-based system, I still see no reason why the price adder would be $100,000 over what is proposed now. Granted, the cost "savings" for eliminating a gas burner from a packaged AC unit is pretty low. On the other hand, what price can you place on comfortable, even heat?

    My guess is that the installer loves packaged units because there is relatively little to go wrong with them. Besides a pad with some control wiring, power, and a gas line, they require little to nothing to be hooked up. Hire a crane, and you're done. That does not mean that the folks using the structure will be happy campers though. Find a professional!
  • Don Walsh
    Don Walsh Member Posts: 131

    Maybe you should suggest that all parties have a bit of "nap time" on the floor like all day care centers do. Maybe their idea of nice cold concrete floors will not be as highly regarded thereafter. Day care centers for the most part are for children, and they are as close to the floor as you can get, even adult day care centers have a desparate need for radiantly heated floors (old folks are always colder than the rest of us.) If that isn't enough to sway them, ask them to think about the airborne spread of germs in cold and flu season. One sick kid in the corner does in the whole lot of them in just a few air turnover cycles.
    I would definitly search out a competent radiant contractor to prepare a quote for the job. The price may become far more affordable than what has thus far been proposed. Sounds to me like someone is not very open minded on that design/build team.

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  • Constantin
    Constantin Member Posts: 3,796
    Allow me to disagree

    When I looked at the $Δ that a GSHP would have to cost over traditional technology (i.e. Air-Air) to justify itself, I flinched. Allow me to elaborate:

    IMHO, Geothermal systems are wonderful in markets with high energy prices because their superior COP really cuts down on the energy required to heat and cool a building (particularly on design days WRT to air-air heat pumps). On such days, the GSHP needs to do much less work per unit heat addition/extraction than a outdoor HP does.

    The savings manifest themselves in a much lower energy usage (less work = less energy required). However, the installation costs of GSHPs can be quite expensive and thus ought to only really pay for themselves when the local energy prices are high. In the referenced application, with an electricity cost of just $0.035/kWh, I doubt that the Δ$ can be made up, unless you use extremely low costs of capital.

    Let's have a go at it. Assuming you lose about 0.6MBTU on a design day and had a building in Boston, your estimated annual fuel costs using gas or electricity is about $7,000 (using the above prices).

    Now, if we install a DX system, the COP is somewhere around 4 (according to ARI). If my understanding of COP does not fail me, that would reduce your electrical "fuel needs" by a factor of 4 also. Thus, you'd save about $5,000 per year in heating costs. Sounds pretty good so far.

    Next, consider the cost of installing a 0.6MBTU geothermal heating/cooling system. I'll venture a guess... it'll be more than $100,000. If I still remember my NPV calcs correctly, even at 1% for cost of capital (less than inflation!) the NPV of $5,000 saved over 15 years (my expected life for the thing) is only $75,000. Were we to increase its life to 25 years, only a 1.5% cost of capital will result in a positive NPV.

    In a high-electricity cost area, the savings would be greater. However, other fuels would also have to feature high costs or one would simply switch to gas or oil. However, it could be possible to have savings of around $8,000 in Beantown. Thus, even a 4% loan will come out nearly positive within 15 years, while becoming NPV-positive over 25 years at almost 6%.

    Naturally, I have not considered other factors that I expect GSHP proponents to love, like a longer equipment life (lower cap costs), perhaps less maintenance (no leaves to foul the condenser), etc. However, on a straight fuel basis, GSHPs need to be carefully matched to the local environment. Perhaps that is why so many of them are designed to carry a base load while using other devices to cover peak periods.

    I'd include the NPV calc in this post, except invision seems to dislike XLS attachments. E-mail me if you want a copy.
  • GMcD
    GMcD Member Posts: 477
    Mech system costs

    For our project, we are working to a mechanical systems budget cost of approximately $18.50/SF total installed cost, in the south area of Seattle. This is for plumbing, sprinklers and the HVAC. Plumbing costs are running about $5.75/SF, Sprinklers at $1.90/SF and the heating and ventilating at $10.85/SF. The radiant floor system uses about $2.50/SF of the HVAC budget, using 5/8 tubing on 12" centres. Most of the HVAC money is spread out with HRV cost, ductwork, and heating pipe circuits/equipment. We are looking at about 9-10 floor zones. Our project has a bit more plumbing than usual due to some neo-natal care and "near hospital" requirements with on site laundry and small staff kitchen operation. No med gas, no other specialties. Wood frame building with slab on grade, two storeys, with a concrete topping for the second floor for the floor heating. Gas fired mid-efficiency boiler, with primary/secondary curcuits for the different heating zones, 2 attic mounted Lifebreath or Venmar HRV's. Client has recently come back and asked about the upcharge to go geothermal and do radiant heating and cooling system with cooling on the airside as well as the slab. Might get fun.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656

    I'm amazed that $2.50 was budgeted for the radiant side. That's below the cost of materials on any projects I've seen with Div. 15 specs. What about labor costs? Or am I missing something? Maybe for tubing in-slab only?? With boiler budgeted on the H/V cost. Curious minds inquire....I'm particularly fond of Lifebreath HRV's, and use them extensively with a radiant design. Good luck with it!

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  • GMcD
    GMcD Member Posts: 477
    Radiant cost

    Hi Paul: the $2.50/SF for the radiant is what we are getting from the local trades and construction cost consultants. That cost is for the tube and manifolds, installed cost in the concrete. Across the border here in Vancouver, BC, the average installed cost is running between $2.25CAN and $2.50CAN per SF (or about $1.75US to $1.90US per SF). We have a fairly tight envelope design on our project so we will only be using 5/8" tube on 12" centres, so for a 10,000 SF project, the total amount of tube will only be +/- 9000 feet max. Some interior zones will not have any in-floor heat and will be ventilated only (storage, linen, interior bathrooms, corridors). If you know of different pricing in the south Seattle area, please advise. [email protected]
  • S Ebels
    S Ebels Member Posts: 2,322
    80% Richard?

    If you're going all radiant why wouldn't you use a condensing boiler? 90%+ is easily attainable. Drops your per million BTU cost to about 9 1/2 bucks or less with the right boiler and system.
  • jerry scharf_2
    jerry scharf_2 Member Posts: 414
    they don't want to do it

    That's how I read it. Just because they are big doesn't mean they have these skills in thier "standard subs."

    I'm very dubious with the 18" OC tubing, it's likely to give striping. Since much of the floor is a surface that needs to be easily cleaned, it it also likely to have good emmivity and getting the heat even would be hard.

    Here are some questions:
    what is the heat loss calc per zone?
    what is the floor construction and surface?

    Here's an idea. I don't know how far away Hot Rod is from you (same state.) Why don't pull the heating from the general and have him do it for a bunch less. Or have him consult on a design and help you find a capable and affordable contractor. I've watched an owner rep do this twice on a half million sqft job. Each time he recoevered more than his owner rep fees for the project. Lets the owner know you're really working for them.

    Also, given what you're doing, there would be no reason to settle for an 80% efficiency gas boiler. There are any number of condensing/mosulating boilers and control systems that would get you well into the 90% efficiency. Now it still may not be the right thing, but it would be interesting to see the payback on 92% (brand M and others) and 95% (brand V) boilers. They actually tend to run higher than the AFUE rating in low return temp radiant systems.

    best of luck, jerry
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