energy lands on every section/lot in the country to provide many
times the energy needs of a typical home."
DSHH Q&A - FAQ
Builders should be Master Builder or
certified Builders and include a comprehensive warranty for all
facets of installation.
Factory warranty applies to all parts
such as control valves, pumps, solar collectors, and pipes. Copies
available on request.
How does DSHH Underfloor Heating
In Layman's Terms
1. See diagram
: For this to work the house MUST be a thermally efficient home and
be EEH approved for energy efficient design, to work properly. The key
element in the DSHH system is the custom designed digital controller
with a large LCD display. It uses over 6 thermal sensors, and
controls various control valves and pumps to distribute heat as
2. Large evacuated “U” tube solar collectors
collect huge quantities of heat during sunny days, especially over
the summer. These types of E/T solar collectors also work well in
3.The heat is controlled by the DSHH custom
digital controller, and as required is targeted at:
a. hot water cylinder,
b. the slab floor and
c. a Solar heat containment storage area under
Thus: if not required to heat the hot water (Opt) or
house, the excess heat is dumped (Saved/stored) into a huge
in-ground thermal mass heat core storage area. The heat core is
located in the ground itself, and comprises the whole floor area
of the slab, inside an insulated wall min. 1M high,
underneath and insulated from the Slab. This in effect
encompasses the “whole-house” foundation under the slab.
4. Eventually this heat containment area
becomes saturated with heat at the top and through conduction,
permeates downwards filling the heat containment area and below.
This limited speed of conduction is what makes the system long
lasting. A long time to thermally charge up and a long time to
extract the heat.
5. As required in winter, warm water is
automatically extracted from the collectors or
heat core as required and circulated through a series of pipes
laid in the concrete slab (floors) of the rooms. These pipes form a
continuous loop and act to create a large warm surface that will
warm the room to a comfortable background temperature. In summer all
heat generated is dumped into the heat core, dramatically rising its
temperature, and providing for long term storage.
6. Concrete slab floor
temperature is limited to only a few degrees above thermostat set
point temperature, with the floor temperature nominally limited to
“Warm”. The concrete slab is also thermal mass and releases the heat
slowly over long periods of time.
7.Even in winter the U Tube
evacuated tube solar collector system generates significant heat on
cold sunny days. The vacuum tubes act much like a Thermos type
bottle; it keeps the solar collector isolated from most of the
cold. A Solar hot water system can be integrated into the package as
can a Wetback or fireplace boiler for backup.
8. 1:1 coverage is calibrated: Each
of home to be warmed, requires ~1m3 of standard
earth, hardfill, hard pan or rock for thermal storage in most of the
N Island and slightly more in the South Island.
Expectations: In optimal locations
in the North Island, excluding the plateau, design is for a standard
whole-house background temp of 18c for most of the winter, and 18c
for 75% of the winter in Southland and the plateau areas. These
figures will vary based on house design, earth, thermal mass,
temperature set point, as well as summer and winter sunshine hours.
The system will inject solar heat even in winter under freezing
conditions outside. It is anticipated the system will improve over
time as the heat core storage increases in thermal energy.
Can the DSHH underfloor heating be installed in any new building?
For optimal service it can be installed in any ‘EEH’ approved
thermally efficient design with a slab floor. Note it takes a full
summer to get a nominal heat charge in the thermal heat-core, it can
take 2-4 years to fully ‘charge’ the heat core depending upon
location and circumstances.
What about backup or Wetback/Fireplace boiler?
The DSHH has an option to integrate a wetback or some other boiler.
Like the Solar heat, the Digital controller will first heat the Hot
Water Cylinder, then the house, then dump excess heat into the core
to a maximum of 80c residual.
Will DSHH underfloor heating affect timber
The DSHH Under-slab heating will not affect wood, tile or laminate
flooring due to the low slab temperature (Max 25-28c typical) which
is less than summer heat temperatures, however; be careful with
natural wood flooring where you must ensure the moisture content is
low in the timber during installation to prevent shrinkage. Also be
aware, timber flooring acts as a partial insulator, reducing the
effectiveness of the warm slab.
Will the DSHH underfloor heating work through a carpet?
Yes but not very well for the same reason as above. The carpet will
act as an insulator; try to avoid thick carpets and underlays in
areas you want the heat to permeate. Obviously the system’s
efficiency improves without the insulating effects of a carpet
system; this can be mitigated in some areas such as bedrooms where
less heating is preferred, or carpeting is localised.
Will the rooms be warm enough?
The DSHH system was designed from the beginning to be a background
heat, to stop the house from dropping below world standard
recommendations of 16.5c, where mould and mildew spores start to
fester. It's optimal winter operational temp is 18-20c with emphasis
on preventing the serviced portion of the home to drop below 18c.
Provided that the room meets the minimum EEH insulation
requirements, plus the system is designed and installed correctly,
and reasonable care is given to ensuring continued thermal
efficiencies in the home, it will operate as per the ‘expectations’
Remember this is not a rapid heat, but is designed to provide a
continuous background heat over long periods. The engineering is
designed to provide ~18c for most of the winter. You may want some
locations warmer in winter or cooler in summer, thus it is a good
idea to have some sort of supplementary heat/cooling.
Can the DSHH underfloor heating be installed in timber floors?
Not advised, but yes it can by using heat spreader plates under the
floor. NOTE: It is not very efficient due to the insulating factors
of the timber, the relatively low heat of the operating system, and
is not fully tested at this point, nor recommended.
Will the DSHH floor get hot and what about area zoning ?
No, generally underfloor heating has a low return temperature and is
designed and limited to few degrees above the thermostat set-point
temperature: typically max 25-28c. This eliminates stress in the
concrete and reduces the time it takes to get up to temperature from
cold. The DSHH heating system is designed as a background heat.
Some Areas can optionally be Zone controlled. It is wise to advise
these areas in advance of the design phase. During the design phase
we focus the initial warmth in areas such as bathrooms and living
areas, with less heat focused on sleeping areas and hallways.
Can it be installed as a 2 stage
Yes, in order to save on
up front capital costs, it can be installed in 2 separate stages. It
imperative the heat core be installed properly, and that the heat
exchange pipes be installed at build time. Also pipes need to run
into the roof along with temperature sensor wires for future use.
This will allow the more expensive Solar collection system and
control system to installed later, perhaps when funds allow.
Note: If you are
considering a solar hot water system, we would highly recommend
you purchase the optional DSHH solar hot water materials package.
The reason is it will be compatible with the future DSHH system and
this system will not cost you any more than a decent higher quality
solar HW systems. We can supply a special solar controller that will
allow excess heat to be dumped into the heat core or slab as
required. The EEH high tech Solar Hot Water system will
actually heat most hot water tanks/cylinders to their design
temperatures by late lunch time, and then the system goes into
stasis as it tried to handle the excess heat. The DSHH controller
can direct the excess heat to the core or slab pipes, effectively
using your excess heat. This is not a huge amount of energy but can
help offset a chilled slab in winter.
Can I convert my existing
expensive to operate under floor heating to this?
The easy answer is a
Your underfloor heating is designed as a "Demand" heat system,
whereas the DSHH is designed as a background warmth system. This
means the heat is not designed to make the floor hot, in fact we
limit the slab temperature to 29c so as not to heat it in an
If you have radiators
only they will not be of much use as they are concentrated heat and
wee deal with energy not necessarily high temperature.
The Solar package
could be sized to heat your home for much of the year if you don't
have the massive thermal heat core of the DSHH, this means 2 things:
- Your heat will
be less reliable in cloudy conditions. On the + side, it will
still offset a large part of your heating costs.
- You will need
some sort of backup. We offer optional wetback integration as
well as Hot Water Heat Pumps, which can do double duty as lower
cost hot water backup as well as heating backup. Ask us if you
are not clear.
Can I use an underfloor heating system as a cooling or A/C system?
We don’t recommend it as cool air tends to stratify close to the
floor, unlike heat which tends to rise and mix. Install a quality DC
Inverter Heat Pump for your best cooling, in fact we recommend one
for backup, summer cooling, or zoned heating requirements. Remember
the size of the heat pump can be considerably smaller with an EEH
home, be sure heating contractor is aware of this.
DSHH does offer an optional 7.7, and 8.8 kW hot water heat pump with
a COP of 3.5, but this is not designed to cool.
BENEFITS OF THE EEH DSHH UNDERFLOOR HEATING
are a number of features and benefits that occur from almost free
underfloor Solar Heating.
Space & Economics
No huge ongoing and ever increasing expenses for energy in heating
for as long as you live in the home and the system operates
normally. Every square metre of your home can be fully utilized, and
Eco-Friendly, Carbon Neutral
Virtually Zero carbon emissions during the heating operation of
this system after the first year. As this reduces the need for
expensive oil imports, it becomes very close to carbon neutral.
If a PV (Photovoltaic) power station were added, the DSHH system
would easily become carbon neutral, and if increased substantially
the whole house could be designed to be energy carbon positive.
Hygiene & Health
There are huge positive health implications. For example: No dust
is generated or circulated. The heating will help asthma sufferers
as it reduces dust mites at floor level and can virtually eliminate
toxic mould and mildew. The NZ government advises that if you keep
the house above 16.5c, mould and mildew is unlikely to grow in
normal living areas in your home. No mould, no invisible allergenic
spores, & warm home = improved health..
Comfort & Intrinsic Happiness
It is pure luxury in winter to come home to a warm home. The DSHH
provides comfortable background levels.
Cost effective & Savings
Once installed, the DSHH will typically provide a heating energy
saving, from 50% to 100% over your typical NZ heating costs. The
improvement when compared to bog-standard, poorly insulated existing
NZ home can be in the hundreds of percent. Actual results will vary
and can be optimised.
Compared to forced air or radiator systems, there is no noise, no
annoying air noises or ticking as pipes expand in floor voids. The
pump is typically a 47watt unit that is virtually silent when
The DSHH is designed to heat one floor which is the equivalent of
the SqM of the heat-store area. A 2nd floor will benefit
from the DSHH system through conduction and convection. We can also
increase the size of the heat core and install a floating concrete
floor above to achieve the best results. Remember the core is
matched to the house footprint size, location, and circumstances of
your build thus expect 2nf floor and performance losses accordingly.
Integrated Wetback or other boiler heat source is simple, and only
requires a few extra components as long as the pipes are in place. A
DC Inverter heat pump is also a good investment as it provides
summer Air Conditioning as well as back up heat in winter. Note: A
heat pump should be sized according to heat loss not just as per
house SqM: thus the actual size/cost of a heat pump required is much
lower in an EEH home.
Ease of control
The DSHH is fully automated for day to day running. Set and forget
with periodical checks to ensure all is well.