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.
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.
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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.
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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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