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HRH FAQ's (Hydronic Radiant Heat Frequently Asked Questions)
Can an antifreeze be mixed with water in a radiant system?
Can I use a std. Water Heater for radiant floor heat?
How many square feet can I heat with a std. water heater?
What's the difference between Manabloc manifolds and Comap manifolds?
Is an expansion tank necessary for a small radiant system?
What is the difference between the HAR and HCM crimp tools?
If I buy a MVSupply radiant package , what else do I need to install it?
Do the Screw Clips install above or below the re-mesh in my concrete slab?
What is the difference between Pex and oxygen barrier BPex?
What is the best length for the radiant tubing loops?
Should I use crimp fittings or compression fittings?
Why should I use a Comap manifold for my radiant system?
Do I need to install the foam insulation under my concrete for radiant heat?
Your price on tubing is so low...is it code approved?
Can Comap manifolds handle multiple zones?
Can I use Pex tubing instead of the more expensive BPex or PAX tubing?
How long will it take to get my order with your free std. shipping offer?
Can programmable thermostat be used for radiant systems?
What is a thermostatic mixing valve?
What is the difference between a zone valve controller and a zone pump controller?
MVSupply HRH Packages MVSupply HRH Design Guide Vanguard HRH Installation Instructions
Q. Can an antifreeze be mixed with water in a radiant heat system?
A. Vanguard has tested and approved glycol for use in Pex tubing, and recommends a 50/50 glycol/water mix for maximum freeze protection. Typical automotive antifreeze is not recommended due to the many additives in automotive antifreeze, which have not been approved for use with Pex.
Q. Can I use a std. Water Heater for radiant floor heat?
A. Yes, but check with your local code enforcement department (some require boilers only) and make sure your water heater is sized correctly for the area you are heating.
Set the water heater temperature control to high and make sure to install a thermostatic mixing valve and expansion tank.
Q. How many square feet can I heat with a std. water heater?
A. There are many variables that dramatically affect heat loss, but here are some general guidelines, based on a new construction radiant slab, well insulated (walls, ceiling and under slab), in a moderately cold winter climate area using a thermostatic mixing valve: A standard 50 gallon electric water heater with (2) 4500 watts elements and a 20 gallon per hour (gph) recovery rate can usually heat about 250 sq ft. A standard 40 gallon gas water heater with a 40,000 BTU burner and a 40 gph recovery rate can usually heat about 500 sq ft. These square footages can generally be doubled for "partially heated" areas where a 50 to 60 degree inside temperature is acceptable on the coldest days (very common for garages, workshops and storage buildings).
Q. What's the difference between Manabloc manifolds and Comap manifolds?
A. Manabloc and Comap manifolds are used for completely different applications. Manabloc manifolds are used as a distribution panel for potable water plumbing systems (like an electrical panel, but for water instead of electricity). Comap manifolds are used for hydronic radiant floor heat systems.
Q. Is an expansion tank necessary for a small radiant system?
A. Yes, an expansion tank is required for all hydronic radiant heat systems. Expansion tank size is determined by heat source size. We carry five models: Basic tanks: HRMVSEX15, HRMVSEX30, Tanks with auto fill valves: HRMVSFT109, HRMVSFT110 and HRMVSFT111.
The auto-fill valves on the HRMVSFT109, HRMVSFT110 and HRMVSFT11expansion tanks work GREAT for closed radiant systems. The auto-fill valve is the easiest way to fill the system with water AND keep it full (otherwise, you'll need to use a hose and connect to the fill-valve on the manifold which usually sprays water everywhere).
Q. What is the difference between the HAR and HCM crimp tools?
A. HAR series crimp tools are "bolt-cutter" style crimpers that require two hands to operate. The HCM series CRIMPMAKER crimp tools are compact and feature an angled head for hard-to-reach crimps. HCM crimp tools also have an "open-stop" that allows one-handed crimping. HCM crimp tools are a popular choice for professional installers. Both types of crimpers are heavy-duty, professional quality tools.
Q. If I buy a MVSupply radiant package , what else do I need to install it?
A. For the radiant packages for concrete slabs, you will need a main supply line and a main return line between your heat source and the manifold assembly, which is usually 3/4" or 1" copper, depending on the size of your manifold (for longer runs between the heat source and the manifolds, 3/4" or 1" BPex is usually used). You will also need an expansion tank that usually installs on a "Tee" fitting on your main supply line. And you will need a thermostatic mixing valve (TMV) unless your heat source can supply the lower temperature water required for radiant floor heat (generally 90 F to 110 F). If you're using a std domestic water heater as your heat source, you need to set the water heater on high and install a TMV (water heaters have zero storage capacity if you set them to low to try to avoid installing a TMV).
For sub-floor radiant packages you will also need tubing clamps or heat transfer plates, depending on your application.
Q Do the Screw Clips install above or below the re-mesh in my concrete slab?
A. Screw Clips twist into the foam-board insulation. The tubing snaps into the screw clips. Then, wire mesh (remesh) and/or rebar is laid over the tubing. When you pour the concrete, pull the wire mesh to the middle of the slab. Be careful not to pull the tubing up with the remesh when you pour. Many people prefer to use fiber-reinforced concrete so they don't have to install wire mesh.
Q. What is the difference between Pex and oxygen barrier BPex?
A. BPex is standard Pex that is manufactured with a special external coating that prevents available oxygen from permeating the tubing. Available oxygen in the water is what causes rust to form on ferrous radiant system components. We recommend BPex tubing for all radiant systems. If you use standard Pex tubing for your radiant system, instead of the recommended BPex tubing, you will need to install corrosion resistant system components (stainless steel, brass or bronze pump, boiler and fittings).
Q. What is the best length for the radiant tubing loops?
A. The absolute maximum loop length for 1/2" tubing due to pressure loss from friction is 400', but we don't recommend loop lengths over 300'. For optimum performance, keep your radiant loops short. Shorter loop lengths work much better because they provide less temperature drop in the loop. Hot-spots and Cold-Spots become very noticeable with longer loop lengths. We stock BPex in 300' and 500' coils that can be cut to the exact length for shorter loops. 300' coils work great for 290' loops with a 10' leader, or (2) 140' loops. 500' coils work great for (2) 240' loops with 10' leaders.
Q. Should I use crimp fittings or compression fittings?
A. Crimp fittings are best! They are permanent, economical and can be used throughout the radiant system. They allow concealed splices and, if properly crimped, provide the most reliable connection available. Using crimp fittings allows you to use all the tubing you purchase without having to worry about ordering the exact length needed for each radiant loop. The crimp tool required can be purchased for a little over $100 or rented, see Crimp Tool Rental
The alternative, compression fittings, are approved for use in accessible locations only and cannot be used in concealed areas (behind walls, in concrete slabs, etc.). Compression fittings need to be monitored for slow leaks.
Q. Why should I use a Comap manifold for my radiant system?
A. Comap manifolds are modular so you can easily expand the system to as many zones and loops as you need. Just add one return module and one supply module to the Comap Connection kit for each loop to assemble your own manifold. It can be configured as a single zone manifold with multiple loops or as a multiple zone manifold. Comap manifolds have balancing valves on all supply and return modules to regulate each loop for the best possible heat distribution. The manifolds assemble easily without tools and you can add as many as you need. They also include a thermometer on both the supply and return manifolds and come with an automatic air vent and fill/drain adapter.
Q. Do I need to install the rigid foamboard insulation under my concrete for radiant heat?
A. It is not absolutely required, but it will greatly increase the efficiency and performance of your radiant floor heat system. We recommend 2" foam-board insulation under all radiant concrete slabs. Most builder supply yards stock it or can order it for you. There are also many foil-faced bubble type insulations available and the manufacturers claim they work well.
Q. Your price on tubing is so low...is it code approved?
A. Absolutely! Our tubing is top-of-the-line. It conforms to CTS-OD, SDR-9 and ASTM F 876/877 standards and is NSF-pw Potable Water Listed. We purchase large quantities of tubing and pass the savings on to our customers.
A. MVSupply is a specialty plumbing products distributor. Our market focus is on contactors: General, HVAC, Plumbing and Homebuilders, but our products are available to the general public. Radiant systems can be quite complicated so you'll need the final hook-up and system start to be preformed by a licensed professional. MVSupply Tech-Reps will gladly help you design your radiant system and answer any installation questions you may have.
Q. Can Comap manifolds handle multiple zones? I need a radiant system with one heating zone for the basement (several loops) and 4 zones for my main floor (3 zones with 1 loop each and 1 zone with 2 loops). Can a Comap system handle that?
A. Absolutely. You need 2 manifolds, one single zone, three loop manifold for your basement and one three zone, four loop manifold for the main floor. The zone for your main floor that needs two loops can be configured two different ways. 1) Link the two loop actuators together so one thermostat will control both, or 2) Use a three zone, three loop manifold and "Tee" the second loop from the controlled loop.
Q. Can I use Pex tubing instead of the more expensive BPex or PAX tubing?
A. Yes, if your boiler is corrosion resistant and you use a stainless steel or bronze circulator pump and fittings, but the small additional cost for BPex is well worth the money. We recommend BPex or PAX tubing for all radiant systems.
Q. How long will it take to get my order with your free std. shipping offer?
A. We ship standard ground orders via FedEx ground. In-stock Std Ground orders ship-out within 3 to 5 business days. PRIORITY ground shipping is also available for a additional charge. In-stock PRIORITY orders ship-out within 1to 2 business days. All in-stock orders ship from West Virginia. Transit time to West Virginia is usually 1 business day, the South coast, East coast and Mid-America is usually 2 to 3 business days... West coast, usually 4 to 5 business days. If you provide your email address, you will receive a FedEx Ground tracking email when your order ships.
A. Screw Clips are used to secure the tubing before pouring your concrete slab. They twist into the 2" foam-board insulation under the concrete and the tubing simply snaps into the screw clip. We recommend Screw Clips placed every 30 inches.
Q. Can programmable thermostat be used for radiant systems?
A. Programmable thermostats can be used, but consider this: Radiant systems are designed to maintain a constant temperature. It can take quite a while to warm a room from a cold start and the system is going to use a lot of energy to heat the room. Digital thermostats are more precise than standard mercury-bulb thermostats and may cause the system to cycle too frequently. Mercury-bulb thermostats are generally the best choice for radiant systems.
Q. What is a thermostatic mixing valve?
A. A TMV is used to control the temperature of the hot water supply to the manifold. It is necessary when the design temperature is significantly lower than the supply water temperature from the heat source. The TMV installs in the plumbing supply and return lines between the manifold and the heat source. It blends return loop water from the manifold and supply water from the heat source to a manually set temperature.
Q. What is the difference between a zone valve controller and a zone pump controller?
A. A zone valve controller is used to operate motorized zone valves or loop actuators. When a thermostat calls for heat, the zone valve controller will open the motorized zone valve or loop actuator and start the circulator pump. A zone valve controller is used for systems with one circulator pump and multiple zones.
A zone pump controller is used to operate zone pumps. When a thermostat calls for heat, the zone pump controller will start the appropriate circulator pump and send a control signal to start the heat source. A zone pump controller is used for systems with multiple circulator pumps supplying multiple single zone manifolds.
Note: Comap manifold and radiant package item numbers ending with "L" require a 1/2" crimp tool. Even though Radiant systems are very easy to install, we recommend installation by licensed, experienced professional installers. Radiant systems require electrical wiring, which must be comply with the NEC and other local electrical codes, if applicable. All electrical wiring must be preformed by a licensed electrician.
MVSupply.biz is a "no-nonsense" company focused on delivering the highest professional- quality products at the lowest price. We combine incredibly low prices and Free Shipping for the best value on the web! MVSupply.biz Tech-Reps have years of experience with HRH and Manabloc systems and are just an email away from answering your questions (usually within an hour or two, not days). Just email us at sales@mvsupply.biz.