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The Hybrid
HVAC System, Part I: Concepts and working systems
The Hybrid
HVAC System, Part II : Typical schematics
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Shown below in Figure 1 and Figure
2 are concept
hybrid HVAC system schematics where a fan/coil is integrated with
a heat recovery ventilator in a dehumidified mechanical
room closet; and are what we believe to be one of the
transitional solution between the past and the future in
HVAC. Before anyone panics, we know the
mechanical
closet idea is not new and is adapted here from the work of
Armin Rudd from Building Science Corporation; nor is the
integration of an HRV/ERV core with a fan/coil,
furnace or boiler new as these products are readily available from
manufacturers (see below for examples). We just don't know of anyone
as yet (summer 2011) who has specifically combined these elements.
If so - forgive us and
tell us how its working.
The principle: hydronic fan/coil
along with say a radiant
floor cooling and heating
system would be served from a storage tank connected to
a
solar or geo system or connected to a community based
district cooling and heating energy system.
Dehumidification of space air
(if required) would occur
within the closet itself. Humidification (if required)
would be done in the downstream air plenum using steam.
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Figure 1. Type 1 Hybrid - Single
fan HRV/ERV unit w/ or w/o humidity control and optional
floor cooling and heating |
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Figure 2. Type 2 Hybrid - Multi-fan HRV/ERV unit
w/ or w/o humidity control and optional floor cooling
and heating
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Off the shelf equipment: Integrated
systems |
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Figure 3. Condensing boiler integrated with HRV core, brazed
plate heat exchanger for domestic water heater and
optional radiant floor heating.
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Figure 4. Above left image is an
integrated fan/coil with a heat recovery core.
Right image is the inside view from the installation in
Figure 5.
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Installations |
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Figure 5. Above example of a traditional hybrid.
Shown are off-the-shelf fan/coils with HRV cores and a
wall mount condensing boiler for domestic water and
radiant floor heating.
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Packaged Control Appliances: Hydronics
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Figure 6. Above is an off-the-shelf factory assembled and electrically certified
hydronic control appliance with electric boiler (shown
as item 4 in schematic below) - set up
for radiant floor heating. This same type of panel could
also serve the fan/coils in addition to the radiant
system.
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The solar hybrid |
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Figure 7. We see the future in mechanical system to be
some form of a
combination of the types of equipment above -integrated
into a mechanical room closet and served by a geo*
and solar thermal system for base loads with electric or
gas fluid heaters for peak loads. Which means a whole bunch of things like
- if you do "air only" learn hydronics so you can deal
with solar and geo thermal and if you do "hydronics
only" learn air so you can do dehumidification,
deodorization and decontamination of the ventilation
air.
*Geo as in not to be confused with a
ground source heat pump, but a direct connect ground
loop system sans compression. |
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See:
The
Hybrid HVAC System, Part II : Typical schematics |
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Suggest study:
Dedicated outdoor air systems (DOAS)
The
Hybrid HVAC System, Part II : Typical schematics
Additional reading:
- Lstiburek, J.,
Residential Ventilation and Latent Loads, ASHRAE
Journal, April 2002
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