Technical Information


    Frontier Plumbing & Heating Supply is a specialty supplier of Hydronic Floor Heat systems and all the accessories, complete with experts with many years experience on staff. Our staff has been involved in projects as small as a bathroom floor or heated towel rack too as large of projects as high-rise office towers. We can do industrial design to residential homes or anything in-between.Our services are very extensive and cover all your heating needs. We also keep in inventory a large and complete selection of major components for your convenience. We can service any project no matter the budget range or the size of job.

    Some of the services provided:

    1. complete packages
    2. pre-plumbed pumping and control panels
    3. system design
    4. project design build
    5. freezer sub soil heat
    6. indoor pool dehumidification
    7. make up air system
    8. slab heat systems
    9. wood floor staple up heat system

    Radiant surface heating is an efficient, cleaner, more comfortable, and healthier method of heat distribution which effectively reduces overall fuel consumption in both residential and commercial buildings. Floor heating can save as much as 10% to better than 50% on the fuel bill.


    Radiant heat relies on the heating of entire surfaces of space which, in turn, radiate an even, comfortable warmth to the objects, occupants and surfaces of a room without first heating the air. Where conventional heating systems rely on high temperatures delivered to a few low surface area convectors, first warming the air and depending on convection to transfer the warmth for the air to the occupants, radiant surface heating provides lower level warmth to entire surfaces which in turn radiate heat directly to occupants and objects within the space. Surfaces stay warm, floor to ceiling temperatures remain more nearly constant, relative humidity remains higher, and room air feels fresher.


    Radiant surface heating is most commonly installed in floors; either within slabs, or within or under wood floors. It can also be installed within walls or ceilings.


    Full, even, surface warmth rather than isolated heating units. Heat distribution from floor to ceiling closely approaches “ideal” heat distribution. (In conventional heating, heat is stratified, concentrated in the upper third of the space height). Body warmth is retained. Heat radiates directly to occupants. Radiant heat does not create drafts, typical of conventional heating system.As drafts are less of a problem so is dust. Radiant heating does not transport dust particles, making it the choice where allergies or spread of infection are considerations. Operates at lower temperatures. Where conventional heating systems rely on high temperatures delivered to relatively small surface areas, radiant surface heat utilizes lower levels of heat over large areas. This allows boilers to operate more efficiently and with reduced fuel consumption. Lower fuel bills. While fuel efficiency and cost is specific to the installation, studies have shown radiant surface heating yielding equivalent comfort levels at substantial fuel savings. Ideal for larger, open areas with high ceilings. Because of a lower rate of convection and stratification, radiant floor heat is particularly beneficial in large open areas where heat loss to unused areas within the space create a problem for conventional heating. No restrictions on furniture placement caused by obtrusive convectors. As radiant floor heating is installed either under or within space surfaces, usable square footage is increased and furniture placement is not hampered by units within the room.


    A radiant system will only work if some careful planning is done prior to the installation. We also know that it is very hard to change a system once it is installed, we would ask then that if additional information is needed other than contained in this manual the reader would contact Frontier Plumbing & Heating Supply LTD.


    We must take in to account the amount of heat that the floor has the ability to conduct. The floor must be able to transmit enough heat to meet design heat loss condition. The less thermally conductive floors, such as thick carpets, particularly with insulating pads, may require relatively hotter water.In general the more thermally conductive floor coverings, such as tile, concrete toppings, brick, and thinner vinyl flooring will respond faster to temperature change than carpeted floors. In residential most floor coverings will work if the system is designed properly.


    There are a number of things common to the design of radiant floor heat system regardless of whether the installation is to be in a concrete slab, wood floor, wall or ceiling.


    The amount of energy a radiant floor heat system can deliver increases with the temperature difference between the radiant surface and the heated space. This amount, in B.T.U. per hour per square foot, has been found to be twice this difference.For example, if the minimum desired temperature of the heated space is 70 degrees F and the radiant surface temperature is 85 degrees F, 30 B.T.U./hr/sq.ft. can be delivered. (2 x delta T = 2 x 15 degrees F = 30 B.T.U./hr./sq.ft.)

    PLEASE NOTE: To assure occupant comfort in residential and commercial applications it is suggested that radiant floor surface temperatures not to exceed 85 degrees F. For other occupancies such as light manufacturing, factory or warehouse buildings, higher heat loads may require higher surface temperatures.


    There are a few situations in which a floor heating system may not be able to deliver enough heat. One example of this would be a greenhouse addition, with high glass walls, sunken floors, and a carpeted floor. In cases like this, or in other examples where design heat loss may exceed 36 BTU/SQ/FT/HR, the prudent contractor may have to install auxiliary heat delivery sources. Good choices include baseboard heat, fan coils, radiant wall or ceiling panels, a wood stove or other.


    A floor heat system, due to its nature, requires a longer period of time to respond to changes in its thermostat setting. However, once the thermal mass of the floor is heated, it is usually easy to maintain the desired level of comfort. This means appropriate use of floor heating is where the structure is kept a constant temperature.Because of the slower response time of radiant floor heat systems, a careful study of each project should be made. Special consideration should be given to situations such as churches and conference rooms, where sudden change in occupancy levels may cause significant changes in the internal heat gain. This sudden heat gain along with the heat output of the floor, may cause an unwanted rise in the temperature of the room. This is particularly true in rooms with relatively low ceilings. System controls that anticipate these internal heat gains may be required.



    Zones are areas of independently control temperatures. Wherever individual temperature control of an area is desired, a zone is defined. For example, a living room may be differentiated from a bedroom, a kitchen, a bathroom, a garage area, etc. Zones are physically defined by providing an individual piping circuit controlled by a pump, a zone valve, or a mixing valve depending on the circumstances. A thermostat with a sensing element located within the zone controls the pump or control valve, thus regulating the temperature in that area.

    Zones with floor surfacing that conduct heat well may require tempering to avoid overly warm floor surfaces. A surface temperature of 85 degrees F or under is generally recommended based on comfort. Differing floor coverings conduct heat differently. However, the supply temperature necessary to attain a design surface temperature in a heavily carpeted room may prove too effective in areas with more highly conductive surfaces. Areas such as these that require significantly less heat input may be separately zoned and differentiated by a tempering (mixing) valve.

    Valves and pumps can be thermostatically controlled or totally manual, whatever the choice. Whichever the choice it is important that access to control systems and headers be available.


    Surface Conductivity:

    Floor coverings with highly conductive surfaces which require significantly lower fluid temperatures to reach design floor surface temperatures than adjacent floor areas should have a zone separation. For the purpose of design, a difference in R value of one can be considered as significant. This difference will typically indicate a required heat fluid temperature difference in the area of 20 degrees F.

    In situations that a fluid would need to be 20 degrees different in one area to the next would indicate the need for water tempering equipment or a zone valve to shut off the area with the floor covering with the lesser R value. Zoning is very important in floor heating, it is the only way to prevent uneven heating in a building.

    Preference or Usage:

    Zone size, convenience, space use, degree of independence or specialty uses desired, are among the many reasons for creating additional zones.

    Each room, and in fact, discrete portions within rooms can be inexpensively independently zoned and controlled.

    Heat load:

    Areas of dissimilar heat losses of more than 5 degrees F should be separated into areas of their own zone. This again is the only sure way of controlling or balancing the heat. Mixing valves or balancing valves can be used but requires more manual input than simply adjusting a thermostat. Now that the zoning areas are determined then the proper amount of heat must be provided to each area to ensure that adequate heat is available on the cold days and not overheat the milder days.


    In general, loop lengths from a single header and multiple headers within the same zone should be equal in length to ensure equal flow in each loop and should be laid out in a uniform pattern of consistent spacing to ensure even heat distribution. The actual length of the loop is determined by the area the heat is to be provided to and by the limitations that the size of tubing will adequately handle. Each tubing we distribute has a different inside diameter, therefore they all have a different maximum length that can be used. This length is to be determined by a qualified designer that can calculate the pressure drop in the selected tubing. Radiant Design and Supply will help determine this length for each project based on the pressure drop information the tubing manufacture has provided us.Although alternative spacing are acceptable, 5 to 16 inch spacing between tubing loops are typical choices depending on the application and the heat load. A typical installation will have a closer spacing in the areas of heat losses, such as the exterior walls, windows, and doors of a building. This meaning that the tubing will be more concentrated around the perimeter of the building and become a little further apart as the center of the building is done. The only thing when doing this is to make sure that as many tubes as possible make contact with the exterior of the building, this is to even out the temperature drop in each loop of tube. The actual spacing required in any project should be determined by a qualified person in the floor heat industry and familiar with the flow capacities of the selected product. Frontier Plumbing & Heating Supply Ltd. will assist in the calculation of the proper spacing of the appropriate tubing for the job to be done.


    The flow rates of a job are determined by the heat loss of the given area, with out a proper heat loss then the flow rates cannot be correctly figured, therefore the spacing cannot be accurate. The G.P.M. of the system is determined by dividing the total B.T.U.s of the zone by the design or suggested temperature drop, then divided that by 60 minutes in an hour then that is divided by the specific heat of the heat transfer fluid. The GPM figure is then divided by the suggested tubing flow rate to determine how many runs will be required to provide the proper energy.


    Most hydronic heating systems are closed loop systems. The same water is pumped around over and over again. That being the case pumps only have to be overcome the friction of the fluid resistance through the system. The amount of force to push the fluid through out the tubing system depends on the viscosity of the fluid, the amount of water each individual tube will carry, and the total distance the fluid has to travel. You may use the following calculation to determine the pressure drop through a length of floor heat hose, as long as the loop length is known and the GPM per tube is known. P=?*x(v) 1.6xL

     P= pressure drop in feet of head
    ?*= changing multiplier based on the tubing (provided by manufacturer)
    v= flow rate per individual tube
    L= length of a loop of the selected tubing
    ()= this number is raised to the power of 1.6

    Once the flow rate of the pump circuit and the pressure drop for the zone or the pumping area is determined, a pump curve table can be used to select the proper pump. Be sure to calculate the total pressure drop by adding up all the drops due to the piping, valves, elbows, and the boiler or heat source.


    For the majority of the residential and commercial radiant heating systems with flow rates less than 15 gpm, a standard l inch diameter copper header is used. Larger diameter headers are available for flow rates greater than 15 gpm. To determine the supply and return pipe sizes required, use the following pipe sizing guide:

  19. TABLE 1

    3 to 7gpm .75 inch
    7 to 15 gpm 1.00 inch
    15 to 30 gpm 1.50 inch
    25 to 50 gpm 2.00 inch

    Multiply loop distribution and return headers should be piped in for reverse return to avoid short circuiting and to ensure balanced flow by creating an equal pressure drop across each fluid path in the zone. 


    Control system options are many but typically include tempering (mixing) valves to control the temperature of the heat transfer fluid in the system and the zone valves to control entry of heat transfer fluid into individual zones. The most desirable method of fluid temperature control for a radiant floor heat system is one which responds immediately to changes in outdoor ambient temperature. This is known as “indoor outdoor reset”. A control unit senses changes in outdoor temperature, and adjusts the boiler temperature, or the position of a tempering or mixing valve to regulate the temperature of the water supplied to the system.


    The heat transfer fluid temperature in a hydronic radiant floor heat system is generally lower than that of baseboard, radiator or coil heating system. For example, a baseboard system is most often sized for water at 180 degrees F. Floor heating systems, on the other hand, rarely require temperatures above 150 degrees F with typical operating temperatures of 100 deg to 140 deg F. This is because the heat transfer area (Floors) is very large compared to that of other types of systems. The average fluid temperature required are dependent upon the thermal resistance values of the materials between the heat tubing and the radiant surface, and the desired temperature of the heated space. Heavily carpeted floors, for example, will require higher fluid temperatures than bare floors.


    Once preliminary design is complete, heat transfer fluid temperature requirements of the zones can be approximated. The boiler will be expected to supply the highest heat required by any zone plus any contingency output desired, usually at least 10%, at the design flow rate. Tempering valves are used to de-rate areas which this highest heat requirements would prove uncomfortable warm.An alternative, and necessary adjunct to calculating and setting design fluid temperature requirements is experience in use. Assuming zoning has properly taken into account significantly divergent BTU delivery requirements, tuning of BTUs delivered and resulting surface temperatures reached are easily accomplished through adjustment of tempering in operation.

    To calculate required average heat transfer fluid temperatures for the design conditions, the total R value of the materials between the floor heat tubing and the room is multiplied by the design heat load per square foot. This figure is added to the desired temperature of the heated space. The design heat load is the rate at which energy is lost by the structure at the winter design conditions for the geographical area. Design fluid temperature = minimum desired temperature of heated space + (design heat load per square foot in BTU X sum of R values). Example = 70 degrees F. + (25 BTU/sq. ft.x 2.62R) fluid temperature = 135.5 degrees F.


    The first thing that must be done is the location of the header is to be determined, the low profile of the headers allows easy concealment within even a 2×4 stud wall. When considering header placement, a number of tradeoffs need be considered. Among these are convenience of location, accessibility, distance to supply source, tube layout and run preference, and so on. Each of these considerations is arbitrary, but each will play a role in the final placement decision, which, in a large zone, includes whether multiple header locations is preferable to ganged headers.Next is to determine the total length of materials required for the project, this is determined from the spacing of the tube plus the square footage of the zone. Refer to Radiant Design Supply for more help in this area. To determine the loop lengths within the given zone by analyzing the maximum distance the tube will have to travel based on the location of the header, this will become the run length for that zone. The pattern that the tubing takes to canvass the area to be heated plays no significant roll only the spacing between the runs of tubing. In most cases this will be relatively straight forward. In others however, there may be obstacles for direct access to some sections of the zone and the path may require ganging loops through a narrow opening, such as a doorway, before spreading into the specified spacing. You will find that the first runs to lay down around the outside of the structure will be straight and easy to place, the loop runs in the center of the area will be different in there layout because they have a lesser distance to travel, these last runs will run back and forth maintaining the proper spacing using up the required length of tubing.


    The total number of runs that will be required can be determined on the job site by cutting the runs off the roll as you go, so not to cut too many runs and just judge how many to use by determining the length of the runs. Then keeping the runs all equal length fill in the spaces to be heated with tubing at the designed spacing. The other method is to have the design heat load converted to gpm and then the number of loops can be calculated to the number of loops required as shown previously. The number of loops required to heat an area can also be determined by a detailed design provided by Frontier Plumbing & Heating Supply LTD.

    In Slab Installations:

    The slab should be prepared using good construction practice, this will result in a good radiant installation. It is recommended that all floors to be heated be insulated on the exterior, and that all slabs have vapour barrier installed to stop moisture from entering the building. It is also recommended that insulation be installed throughout the slab to help the heat system to respond to rapid heat changes. The location of the header will have to be determined, some good choices are in the boiler room, a closet, or suspended under the joist. The location of the header should also allow for the tubing to be able to reach all areas of the floor to be heated but also try and keep runs as short as possible. The header in concrete installations should never be cast into the slab, the copper manifold should remain out of the slab to stop damage from any movement the slab may undergo. The tubing materials that should be used for floor heating should always be able to take the normal movement of the slab in the event of cracking. The specified tubing can be installed either over or underneath the reinforcing steel or mesh. Placing the tubing down before the mesh will help hold the tube in place. However, placing the tubing on top of reinforcing lets you tie the tubing to the mesh or steel. The main thing to consider is that the spacing asked for is maintained and that the tubing is kept for moving around. Floor heat tubing loops should be placed from the outside toward the center. This makes sure that adequate tubing is placed around the exterior of the floor area, to ensure the heat loss to the outside is met. This makes sense because this is where the heat loss is.

    Under Wood Floor Installations:

    For installations under a joist supported floor tubing of designed spacing is installed between the joist by stapling the tube to the under side of the sub floor. This stapling is done by special staplers for this purpose. The tubing should be supported with a staple every 8 inches, to stop any sagging that may occur with the weight of the warm water. The tubing is run from one end of the zone area to be heated, from a header system of supply and return at the edge of the zone, these headers can be under the floor joist or be placed in a closet or other accessible area. Once the tubing has been installed to spacing required for the project then a foil faced insulation must be placed in the joist space below the tubing, leaving space to make sure the foil does not touch the heat tubing.

    Above Floor Installations:

    A number of methods are used to install Radiant floor heat tubing on top of existing flooring. The two most common are:

    1. installation in a layer of light weight gypsum concrete,
    2. installation between sleepers.

    Light weight gypsum based concrete normally 1.25″ to 1.5″ in thickness is used to cover the floor heat tubing. This method can be used in all types of installations and is the popular retrofit solution. This method of installation, either on a sub floor in a new construction of over an existing floor, consists of:

    1. covering the floor with water proof sealer to ensure that there is no warping during the concrete pour,
    2. fastening the tubing to the floor on 8″ centers using staples,
    3. pressure testing the tubing and maintaining the pressure during the pour.

    Another above floor installation method involves placing the radiant floor tubing at the specified spacing, between sleepers which support the finished flooring. In addition to new construction, this method is particularly suited to rehab and renovation work. Sleepers are installed on the sub-floor with a gap sufficient to accept the floor heat tubing and the tubing is laid in the space created. Alternatively, the tubing is placed down first, then the sleepers are placed between the loops of tubing. Needless to say, when securing the finish floor, care must be taken that no fasteners penetrate the floor heat tubing.