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Radiant Floor Heating

By Tim Carter
©1993-2008 Tim Carter
Summary: Radiant floor heating is so comfortable because the heat is uniform throughout a house. You can even create zones in different parts of the house. These radiant heat zones operate using separate thermostats so that you minimize energy costs.

DEAR TIM: I am giving serious thought to incorporating a new hydronic radiant heating system into my new home. Is this technology reliable or is it just a fad? Can you install these systems in existing homes? How do you size the system? What are the disadvantages if any? Alicia P., Bennington, VT

DEAR ALICIA: Next winter you are going to be as snug as a bug in a rug. Hydronic radiant heating is not new by any means. It is just a fancy word for any system that uses water to deliver heat. Radiant heating systems have been used for thousands of years. Anyone who has warmed themselves in a cave or a room with a fire has felt the natural warmth of radiant energy. Romans used a primitive radiant heating system to warm public and private baths. Your parents most likely dried their snow packed gloves on top of steam or hot water radiators. Radiant heating is not a fad. It is reliable and simply superb.

Radiant Heat – Radiant Floor Heat
Radiant Heat experts offering Radiant Heat Quotes, Loop CAD Designs, and wholesale prices on everything for your heating system. Free shipping over $300. www.pexsupply.com

There are numerous advantages to using radiant heating. It is a known fact that radiant heating systems produce higher and more consistent comfort levels than a forced air system. Hidden radiant systems that use piping inside of floors, ceilings, and walls permit unlimited design possibilities and furniture arrangements. Certain systems allow you to combine domestic hot water needs for bathing and household cleaning into your heating system. There is no need to buy a separate hot water heater. You can also easily create zones within your house. Electronic controls allow you to send heat to only those portions of the house that you occupy during the course of the day and night.

Even though your new house will have a specific heat loss that can be measured, tests over the years have shown that radiant or hydronically heated houses tend to have lower energy bills. The fans that push heated air in a forced air system pressurize the inside of a house. Heated air in certain instances can actually be pushed out of tiny cracks and holes in exterior walls and ceilings. Forced air systems tend to create layers of heat in rooms. Temperatures between the floor and ceiling can vary by more than 15 degrees. Houses heated with radiant systems tend to have uniform temperatures throughout each room.

If a friend or relative has a chronically cold room or area in their house, they can sometimes use certain radiant systems to make the trouble areas toasty warm. Some hydronic systems allow you to staple flexible piping to the underside of exposed wood floor systems. If the area to be heated is the size of several rooms, the heat source can often be a low cost hot water heater. These same systems can be used to heat entire houses. Other companies make reliable radiant nets that incorporate low temperature electric cables. These can be installed under ceramic tile, slate, or marble floors in bathrooms kitchens or entrance halls.

Hydronic and radiant heating systems are sized just like any heating system. Your heating contractor must do a heat loss calculation. The heating contractor measures the surface area of exterior walls and insulated ceilings, window sizes and glass type, thickness of wall and attic insulation, house orientation, and numerous other factors. These measurements are entered into a computer program that determines the amount of heat your house loses each hour. Based upon these calculations the contractor can select the correct sized boiler or water heater and produce the correct design of the hydronic heat delivery system. Do not underestimate the importance of this procedure. If you install a system that is too small, you will be uncomfortable. A system that is too large will waste energy.

There are few disadvantages to hydronic heating systems. If you require cental air conditioning, your overall heating and cooling system equipment cost will be higher since you have to install two delivery systems (piping for the heat and ducts for cooling). You may also find it hard to locate a qualified and knowledgeable installer. Many contractors are resistant to change and may try to talk you out of an hydronic system. Contact various hydronic system manufacturers. Ask them for a list of qualified installers in your area.

 






Comments

Nancy E
21 Jan 2008, 17:25
We are looking to build a 2 story cabin in northern WI and are looking to use Radiant heat. Since it will be a 2 story home with a large open vaulted area in the center, will it be necessary to run Radiant heat upstairs as well as down? or does the heat rise enough to not have to worry about it.
AsktheBuilder
22 Jan 2008, 08:56
Nancy,
If you hire a seasoned radiant-heating contractor, he will look at all sorts of issues and make a determination. There are too many variables for me to comment.
Robert
11 Feb 2008, 07:54
I'm in Massachusetts, in a split-entry with forced hot air via natural gas, and central A/C. I'm about to expand my house dramatically, with an in-law suite, new master bedroom and a sunroom to connect the "old house" with these new areas, all of which will be concrete slab.

The sunroom is going to be a heating challenge. It won't get much direct sunlight except through the skylights, and it's about four steps down from the existing house. I'm thinking that electric radiant heat pads on a therostat would work well for that room, assuming I use ceramic tile flooring. True?

Also, the in-law apartment will have vaulted ceiling, which I know will cause another heating problem. The majority of the flooring will be some type of woood, but the adjacent (and open) kitchen will be tile. Could radiant heat be of some benefit there too?

Estimated cost/sq ft?




AsktheBuilder
11 Feb 2008, 08:17
Robert,
You are making this all too hard. Why not in-slab radiant heating? Install three or more zones for maximum comfort, efficiency and control. Cost you ask? There is no way I can quote you a number. That can only be done looking at finished plans coupled with a site visit. There are many variables that affect pricing.
Gary Ray
11 Feb 2008, 12:54
On an exterior concrete deck of a residence, what is the miniman mortar thickness required for a glycol closed loop 1/2 inch radiant heating system. Are their standards, or do different manufactures vary. Thanks for your help.
AsktheBuilder
11 Feb 2008, 14:52
Gary,
I have no clue. Contact the Radiant Panel Association.
Roger Bombassei
29 Feb 2008, 08:42
I am in the process of installing radiant heat under the tiles in my kitchen hall and bathroom. The installer has laid down the tubing and floated morter over it.
Now I can see that the tile area of the house is going to be 2" higher than the rest of the house. Is radiant heated flooring alway this high? Do you have any recommendations about smoothing out the step where the carpet and the radiant heated tile come together?
AsktheBuilder
04 Mar 2008, 16:23
Roger,
Yes...... When installed throughout the house it is not an issue as the floors are at the same level. You will need a stone reducing threshold.
David
14 Mar 2008, 12:30
We purchased a home built in 1948 with inslab hydronic heat, and despite being 60 years old, it works as great as ever!

It's run off of a cast-iron boiler, which we run a biodiesel blend in. We'd like to swap out the boiler for something requiring less expensive maintenence (as the technicians in our area who work on boilers are commercial, and charge $80/hr minimum) and calibration - but all in all the costs are still cheaper than our neighbors - and the heat is MUCH more comfortable and dust free.
Russell
15 Mar 2008, 08:31
Hi Tim:
Are you familiar with a low voltage electric radiant element called Zmesh? In areas like Robert on 02/11 would build, it would be much more efficient and less costly to install than a Hydronic system.

There's no floor buildup and it can be stapled or nailed through anywhere without a problem. Solid hardwoods can be installed directly over the top too because it's a slow growth, even heat that won't get any hotter than 85*.

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