I am planning an addition to my house. Finally I have blue prints and
started talking to HVAC people about heating and A/C option for an
addition. I will be installing completely new system for an addition
independent of the existing one. I am considering multi zone hydronic
radiant heat floors as the only heating option and central A/C in the
attic as the only A/C option.
I talked last week with much known and well respected HVAC
contractors, half of my neighbors used him for several decades. I
showed him my blue prints and told him I am considering hydronic
radiant heat floors for the addition and asked his opinion. He told me
that it is luxury item and very comfortable it is much more expensive
to install (which I knew and do not dispute) and more importantly way
more expensive to heat the house then efficient forced air furnace. He
does install both forced air and hydronic heat though he said heated
floors he usually installs in $2-3 mil. houses. The fact that hydronic
heated floor is much more expensive to operate was complete surprise
to me. I always thought that in most cases hydronic heated floors
powered by natural gas that in my area (NYC metro - Central NJ) is
cheapest fuel is the most economic way to heat the house.
I tried to search online for comparison of operation cost of forced
air vs. hydronic heat floors but could not find any concrete data
supported by evidence that either proves or disproves his estimation.
Separately from that, I have troubles finding knowledgeable
contractors in hydronic heating area. Though I live in relative
affluent neighborhood (average house is ~$550K) none of my neighbors
have any heated floors, either hydronic or electric and maybe because
of this almost all HVAC referrals I got from anyone does not know much
about hydronic radiant heat. I just don't know where to find someone
who can knowledgeably and honestly tell me about various options,
It makes no sense that hydronic radiant floor heat would be more
expensive to operate than forced air heat. You do need to insulate
the floor very well below the radiant tubing. Once you've done that,
the heat loss of the building should be the same in either case. So
if your heating plant is equally efficient (the hydronic boiler versus
the furnace), the operating costs should be the same.
Sounds reasonable. I'm sure you are going to buy an efficient boiler
for the hydronic setup. I use a System 2000 from Energy Kinetics and
it saves me about 39% compared to my old boiler.
The cost of heating the house is a factor of heat loss, not type of
system. If you have an efficient boiler or furnace and put a given
amount of Btu into the building to be comfortable, that is the
determining factor of cost. Radiant heat does take a bit longer to
get started because of the mass that needs initial heating and is
slower to respond if you want changes in temperature for the same
reason. But if, say, on a given day you need 100,000 Btu of heat,
that is what fuel you burn.
My guess is that he had some bad experience with improperly installed
and insulated systems years ago and has not kept up with technology.
You will have to do some of your own research on the best way to do
When I lived with radiant I kept the temp lower at the 6 ft level ny
1-2f which is how I monitor temps in apartments. Radiant is under you,
the temp sitting at 2-3 ft is colder by maybe 1-2 degress with
radiators so you can keep the temp down. It is a more even heat
because of floor mass so temp swing is not noticed as much. With
boilers the maximum efficency for condensing boilers is under 140f, by
the time you get to 180 you might be 4-5% less efficent so condensing
units work best with radiant at 110f. There are statements-studies
that heating a house is more efficent with a lower water temp and
conrtrols are sold that do that to keep boiler temp only as high as
needed, im not sure about the savings but only radiant heats at low
temps of 110, my cast iron radiators need 140-170, some baseboard
The most efficent houses I read about have radiant underfloor. Leaks
in ductwork, heat loss of ducts in walls are a 5-15% loss issue in
average homes that few can or do fix. Radiator homes with any
radiators on outside walls must be wasting a good percentage of heat
they give off by heating an outside wall. I see so many benefits of
underfloor low temp heat, I dont even know all of them, I just wish I
had it now now im at a cast iron radiator home, but cast iron I would
rate second best to underfloor radiant and forced air last.
Electricity is another issue never thought of in the heating bill,
the several Boilers I have use a 130-175 watt water pump, Furnaces use
a minimum 375 watt blower on a small unit, ok VSDC is about 10-20%
less, but how long do they last. Furnaces cost more to maintain,
annual cleening, and filters. You dont flush a boiler and my fire box
doesnt need cleaning but every maybe 4 years. And boilers last usualy
longer than furnaces.
Thank everyone for the info. All these posts reinforced me that
hydronic radiant heat floors will be more efficient then forced air
and it will be of cause more comfortable.
I did a lot of research on various options and still do not have any
solid idea what heat source to choose and what the complete hydronic
radiant heat floors system consists of. I would be very thankful if
someone could shed clarity on this issue.
The addition is ~1500sf, I live in central NJ, the fuel is NG. Current
heating is forced air furnace, I do not want to touch it, new system
will be an addition, not replacement. The addition will include big
room on slab foundation and second story area. The house will be well
insulated: all attics R-49, walls R-19.5, floors under second story
addition will be probably R-30 and the slab will have at least
2" (R-13) foam insulation. All windows are E4 Andersen windows.
I want at least two zone hydronic system for new addition: one is for
big room on the slab and another for second story area. I intend
embedding PEX tubes into the slab, tired them to rebar, and for second
story with hardwood floors I will put plywood panels with grooves and
aluminum backing and run the PEX tube inside the grooves.
I have very limited space in my basement where new system can be
installed. So the ideal approach for me for the heat source would be
radiant heat source and water heater combination unit that does not
take much floor space. This unit will also replace existing NG water
heater and provide hot water for entire house.
I did some research on EK system 2000 and got responses from very
satisfied (low operating cost) to very unsatisfied (controller breaks,
the system uses a lot of proprietary components and require very
expensive servicing only from authorized technicians).
Yea that's the only downside of in floor heat...If you have the door open
for a few minutes to hollar at the dog or to carry something in it takes a
while to warm back up...My buddy had it put in his new body shop and he
absolutly HATES it..Everytime he opens the garage door it cools it off big
time and it takes forever to warm back up and then the door is open
again..He finally put up a large HW Modine to help it out.LOL...
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.