Hello, I'm a new member here. We are in the very initial stages of a new construction project, and trying to decide on the radiant heat design to implement. Forced- air heat option is out. Comes down to either radiant heat hydronic floors vs. low heat water radiators. First are the specifics about our project. We are in Philadelphia, Pennsylvania suburbs. 3500 sq. ft. two-story plus basement, 2x6 frame construction, which is very typical for the region. I want hardwood floors throughout the house- possible engineered floors, maybe cork on the second floor. First question is the comparative $$ cost of the radiant floors vs. low heat water radiators. Also relative complexity of the implementation of either option. I don't think my builder has experience with either, so it's possible, that we will need to hire a third party HVAC company. So far, i talked to one HVAC guy, who reportedly has a good deal of experience with hydronic radiant floors installations, but I'm not sure he'd be the best at designing the whole system (heat load analysis, etc.) I think, i will need to hire somebody to design the whole heating (and possibly AC) systems for the house. What is the approx. cost of the design might be? Other big question is the AC- central AC vs. split- level AC, the same questions apply- cost and complexity. Please, I'm open to any alternative ideas. Thanks in advance

BTW, forgot to mention: there is no gas option in the new house, only electricity

So, how do you intend to heat the water?

Putting anything between hydronic radiant emitter and the living space can adversely affect heat transfer and significantly reduce heating system efficiency. Cork is one of the best insulators there is…so much so that it is used for spacecraft heat shields for thermal protection during reentry. We have our fees on our website, but we only operate in OR and WA. We also have free DIY analysis/design software on our website too. Lots of people have successfully used it to design hydronic radiant floor heating systems. You may find the information in the software instructions to be educational as well even if you elect to hire out the design/installation.

Electric boiler, I'd imagine

Understand about the cork floors So you saying you couldn't even do a design for me, if I wanted to hire you?

The question remains though- comparative cost of the hydronic radiant floors vs. low heat water radiators

You might be a good candidate for radiant walls and an air to water or geo heat pump.

Unfortunately, cost and contractor performance can vary significantly by geographical area. You might find Guruuno’s experience with NJ hydronic radiant contractors educational:

NJ Hydronic Radiant Experience

An electric boiler can be a good option if your electricity can be obtained at low cost. Electric boiler benefits include 100% conversion efficiency of the "fuel", ability to handle short-cycling (which avoids the need of a buffer tank when you may have small heat zones calling for heat), and is a relatively simple DIY installation. Hydronic radiant floor heating is likely the most comfortable heating option. However, if you need both AC and heating, you really should look at mini splits as they are far more efficient and avoid the need of duct work...so likely much lower HVAC system acquisition and operational costs.

Any thoughts on low heat water radiators ?

Have a look at Myson T6 flat panel radiators.
Easy instal, look good thermostatic head, bypass valve so you can throttle the radiators back if needed on a room by room basis.
We provide custom prefabricated electric boiler panels with pump or zone valves if needed. Simplify the mechanical room process.
Dan

Mari,

Your first post said it all.

We design hydronics-based radiant heating systems for retrofit and new construction for locations all over N. America and beyond. We have no prejudice or ill-conceived notions about radiators or radiant floors. In fact we are the myth-busters of hydronic radiant heating (HRH).

First, I have an engineered cork floor in my upstairs bath. Though cork is one of the best natural insulators available, all insulation is rated per-inch thickness. My cork floors are warm to the touch regardless of the outdoor temperature or condition of the boiler. We did run into a bit thicker cork floor in a new construction SIP home here in Minneapolis and after modelling the intended floor covering for the main floor decided to look to the heavenly alternative Jonr suggested. The whole main level ended up with a radiant ceiling, save the one radiant wall in the master shower.

Second, my main level powder room is covered with 3/4" oak and radiated from below.

Third, my basement 3/4 bath is covered in tile-over-concrete-slab and nearly always warm since the stat is set higher than the main basement stat and works to satisfy all.

A mini-split (I have one of those too) is a poor fit for many multi-level, multi-room designs. Yours would likely be a good candidate for a high velocity system.

Finally, it is true that anything that gets between a heat emitter and the occupants will compromise optimum heat transfer, but thoughtful design consideration makes this truly insignificant, more especially when the heat source (in your case and mine, an electric boiler) will not suffer an efficiency discount as might a condensing boiler or heat pump.

We do quite a few wall-hung panel radiator design/builds and naturally my basement entry sports a 16 x 24" panel with TRV, always operating below the European supply water temperature standard of 60°C (140°F).

Practical performance - perfect comfort.

…and if a company operates from outside the customer’s State of jurisdiction and protection, a company can pretty much sell snake oil at a profit with total impunity.

Once your hydronic radiant floor heating system is installed and operating, it can be used to access the performance of both your building design and your hydronic radiant emitter design. With regard to building design performance and with an indoor temperature of 70 degrees F and outdoor temperature of 20F, we consider a hydronic radiant floor surface temperature of 70-75 degree F as excellent performance (i.e., a low-load, energy efficient building), a floor surface temperature of 75-80 degree F as average performance, and a floor surface temperature greater than 80 degree F as poor performance (i.e., a high-load, energy inefficient building). With regard to hydronic radiant emitter design performance, we consider a 10 degree F or less temperature difference between the hydronic radiant floor heat source supply temperature and the hydronic radiant floor surface temperature as excellent performance, a 10-25 degree F temperature difference as average performance, and greater than a 25 degree F temperature difference as poor performance. One should always keep in mind that you have to live with the performance of both your building design and your hydronic radiant emitter design forever.

So you might want to get an actual performance estimate/guarantee and make sure you have legal remedy if the performance is less than acceptable or as promised. As I always discover, when considering any propaganda, always follow the money and the truth will become very clear!

Posted By Maril555 on 10 Jan 2015 04:13 PM
Electric boiler, I'd imagine

With the above average cost of electricity in Philadelphia*, that is going to be an expensive way to heat a 3500 sq ft home.  How long do you plan on living there?

*  http://www.bls.gov/regions/mid-atla...elphia.htm

Have you considered geothermal?  If you plan on being in the house for >10 years and can take advantage of the 30% tax credit for geothermal systems available through 2016, it is something to consider.  A geothermal heatpump can also provide your AC.

I fully agree Arkie, if one doesn’t have low cost electric, an electric boiler will be an expensive option. If this will be a low-load, energy efficient building, a hydronic radiant floor heating system may also not be perceived to be as comfortable as one might expect. A hydronic radiant floor typically feels “barefoot comfortable” to most people when the floor temp is between 80-85F. For a low-load, energy efficient building, the floor temp may never exceed 75F. So while the floor won’t feel cold, it likely will NOT feel “barefoot comfortable” as one might expect. One should also keep in mind that a low-load, energy efficient building will likely generally feel very comfortable no matter how you heat it.

I intent on living in that home for at least 10-15 years. Haven't considered a geothermal. Don't even have a vaguest idea of the possible cost. Still, no one has answered the most important question, I asked. Comparative cost of hydronic radiant floors vs. low heat water radiators. This is the first dilemma, I need to solve!!!

What exactly do you mean by "low heat water radiator"? Can you provide a link to an example of what you are considering here?

I should have said "low temperature water heat radiators"
http://www.hydronicalternatives.com

Your link goes to a standard flat panel euro style radiator.
These work well in a lower temp mode next to a copper fin radiator due to the size. As I understand the larger surface area provides better convection letting lower water temperatures preform well.
These are similar to the Myson T6 I mentioned earlier.
Easy install.
Radiators will cost less than a in-floor, wall, ceiling system.
Not including the boiler system or any labor and these are my best guess estimates the real numbers come out once a design is established. Your in floor materials will start sq. ft $ at about $1.50 (staple up with plates this would also be similar to a ceiling or wall system), $2.50 topping pour 1 1/2 concrete structural of the joist system will apply as well) $3.00 for a RHT floor panel system (sandwich type) $6.00+ for a warm board sub floor system. There are a host of other systems as well I am less familiar with, quick tracks, Stadler panel, Roth panel, and more.
For a "rough" cost on radiators you can use a 30 BTU per square foot value, a radiator take the floor plan sq. foot per room, then select the size radiator that will fill the required BTU load, and see the cost with related bits (bypass valve, adaptors, thermostatic head).
We have provided hundreds of homes for public housing here in Seattle using the T6 in combination with a wall hung boiler that provided both domestic hot water and heat. Affordable, the system can be run in pex, radiators can be oversized to provide low water temp option.
That said I would not rule out in-floor if it is an option or a combination of both.
Dan

In simple terms…

The first step is to determine the heat load of the room you will heat. The next step is to determine the surface area of the hydronic radiant emitter (e.g., hydronic radiant floors, radiators, etc.) that will be used to heat the room. Then the required average surface temp of the hydronic radiant emitter can be determined that will provide the required heat load. Then an appropriate design delta temp can be selected which will determine the heat source supply and return temps.

So higher room heat loads in combination with smaller emitter areas (e.g., old style radiators and new style wall panel radiators) require higher supply and return temps than lower room heat loads in combination with larger emitter areas (e.g., hydronic radiant floors). Old style, smaller area radiators used high temp steam. New style, larger area wall panel radiators use high temp water (e.g., 120F+ supply temps). Hydronic radiant floors use lower temp water (e.g., 80F-120F supply temps).