Danfoss Roof application. Frost protection Application guide

Roof application. Frost protection

Roof application.
Frost protection

Application manual

Intelligent solutions
with lasting effect

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Index

Let DEVI do the work

1. General information 4

2. System Description 5

3. Product Selection 6

4. System Design 9

5. Installation 12

6. Cases 24

DEVI - an abbreviation of Dansk El-Varme Industri - was established in
Copenhagen, Denmark, in 1942. As from January 1st 2003 DEVI has become
a part of the Danfoss Group - Denmark’s largest industrial Group. Danfoss
is one of the world’s leading companies within heating, cooling and air­conditioning. The Danfoss Group has more than 23000 employees and serves
customers in more than 100 countries.

DEVI is Europe’s leading brand of electrical cable heating systems and electric
pipe heating systems with over 70 years of experience. The production of
heating cables takes place in France and Poland while the head office is
situated in Denmark.

The value of experience

We have installed literally thousands of systems across the globe, in every
conceivable setting. This experience means that we can offer you practical
advice about precisely which components you need to get the best results at
the lowest cost.

Roof application. Frost protection

This design guide presents DEVI’s recommendations for design and
installation of ice and snow melting systems for roofs application.
It provides guidance for heating cable positioning, electrical data and system
configurations.

Our quality management

Following DEVI’s recommendations will ensure energy efficient, reliable and
maintenance free solution for constant wattage heating cables with
20 year warranty.

system
and compliances

ISO 9001 TS 16949

ISO 14001 PED

Along with full compliance with EU

directives and product approvals

3

1. General
information

DEVI’s ice and snow melting system
for roofs and roof gutters can be
applied for virtually any type of roof
constructions to prevent meltwater
accumulation in roof gutters and
to reduce damage to constructions
like frozen facades and roofs.

The ice and snow melting system
should be installed along the roof
edge or where there is a risk of
ice and snow formation. Damage
prevention in roof gutters and
downpipes is achieved by efficient
and free meltwater draining,
which typically proves satisfactory
operation of the system.

Electronic DEVIreg™ thermostats
ensure that optimal results are
achieved with the least possible
energy consumption. These results
are ensured by highly precise
readings of weather sensors and
thermostats providing automatic
on/off heating control at the right
time.

Benefits

• Enter and exit the building safely –

no risk of icicles formation or falling in
cold season causing injuries or damage
to vehicles or other property.

• Relief of roof constructions – reduces

the risk of roof collapse due to extra
snow loads or roof gutters and
downpipes damage due to ice loads.

• Cost reduction for renovation

following the winter season – by
keeping facade walls dry as the DEVI
system ensures safe water evacuation
from the roof during the cold season.

• Maintenance-free solution

with 20-year full warranty on constant
wattage heating cables includes
product price and all related
repairing costs.

The typical applications are
roof constructions, roof gutters,
downpipes, flat roofs and valley
gutters.

• Cost-effective & Energy-saving
solution – designed for various weather

conditions with automatic operation
based on 24-h monitoring and ice
and snow removal, it ensures payback
period of just one snowy winter.

4 Roof application. Frost protection · VGLUE102 · ©DEVI

2. System Description

When winter sun melts snow and
ice, it starts forming icicles on cold
roof edges and gutters which over
time can cause serious damage
to the building and constitute a
danger for vehicles and passerby.

First of all, in order to avoid all
above and manual ice removal
heating cables should be installed
in all drains such as gutter valleys,
gutters and downpipes.

Frost protection of the roof itself is
required where such problems can
exist, e.g:

• on south-faced eaves

• under skylights/roof windows

• 1-1.5 m lower the roof for older
houses, e.g. with heated attics and

Roof edge / Eave

DEVIclip™ Roof Hook
DEVIclip™ Guard Hook
DEVIfast™ & DEVIfast™ Double

Gutter valley

DEVIfast™ & DEVIfast™ Double
DEVIclip™ C-C

• on roofs where snow loads
typically exceed the capacity of
the existing roof construction.

In harsh water or water and
sludge environment DEVIsnow™
cables provide constant wattage
when appropriate, whereas
DEVIiceguard™ self-limiting cables
represent flexible small scale
installation.

Opportunities

• No winter damage costs

• Discreet UV resistant cables

• Automatic control

• Priority zones with limited power
supply

Flat roof with drain

DEVIfast™ & DEVIfast™ Double

Installation

DEVIsnow™ 20, DEVIsnow™ 30 W/m
DEVIsnow™ 30 for roofing felt
DEVIiceguard™ for small scale
solutions (< 10 m)
DEVIclip™ fixing accessories
DEVIfast™ fitting band

Performance

Save 50-80% with control by smart
DEVIreg™ 850.

Thermostat improves
DEVIiceguard™ performance with
regard to energy consumption.

Roof with baffles

DEVIfast™ & DEVIfast™ Double
DEVIclip™ C-C

Gutter

DEVIclip™ Gutter
DEVIfast™

Downpipe to frost-free well

DEVIclip™ Traverse
DEVIfast™ Double
Chain / Entlastungseil

Downpipe with open end

DEVIclip™ Relief
DEVIfast™ Double
Chain / Entlastungseil

5Roof application. Frost protection · VGLUE102 · ©DEVI

3. Product Selection

3.1 Heating elements

Heating cables DEVIsafe™ 20T and
DEVIsnow™ 30T:

Heating cable DEVIsafe™ 20T/
DEVIsnow™ 30T – a twin conductor
resistive heating cable complies with
IEC 60800:2009 and provides high
UV resistance. Ready-made set with
a connection box and 2,5 m cold
lead. Cable design provides for 230 V
and 400 V power supply and ensures
installation in a safe, efficient and
cost-saving manner.

DEVIsafe™ 20T/DEVIsnow™ 30T

3.2. Control

Heating cable DEVIiceguard™ 18:

Heating cable DEVIiceguard™ 18 is
a self-limiting parallel heating cable
(SLC) with high UV resistance. The
cable can be cut to the required
length from drum or ready made
(RM) version.

The self-limiting capability of the
cable ensures that the output of the
cable increase or decrease
according to the ambient
temperature.

The heating cable is flexible and easy
to install as it can be cut to length in
situ and can be installed directly on
the roof or in the gutter system.

Important: Always install thermostat
over 3 m far from the self-limiting
cables, this will help to prolong
cable lifetime and minimize energy
consumption in a standby mode.

DEVIiceguard™ 18

Frost protection systems are
different and require different
thermostat types.

DEVIreg™ thermostats are fitted
with a complete set of control
functions for heating systems
for ice and snow melting of any
type and allow attaching external
measuring sensors for air or ground
temperature measuring as well as
control of moisture conditions.

Electronic thermostats feature
high-speed operation and good
repeatability. Correctness of
thermostat selection and control
accuracy impact significantyly on
reliability and power consumption
of the heating system.

The thermostat product range
is designed for external systems
including the following: DEVIreg™
316, DEVIreg™ 330, DEVIreg™ 610
and DEVIreg™ 850.

DEVIreg™ 850 electronic
controller

Two-zone controller is
recommended for the installation
protection against frost.

It has external 24 V DC power
supply. Four integrated roof
moisture and temperature
sensors can be connected to
the controller providing optimal
control of the heating system.
Comparing to installations with

typical temperature measuring this
thermostat allows reducing energy
consumption costs of up to 75%
(see 3.2.1).

Moisture and temperature roof
sensor

Moisture and temperature
measuring sensor with a built-in
heating element for snow melting.
All measured values are highly
accurate, which is provided by an
integrated processor of the sensor
as well as digital, not analogous,
measurment and set-point
calculation. The sensor is equipped
with a 15 m cable for connection to
the controller.

DEVIreg™ 850 Moisture roof sensor DEVIreg™ 316, DEVIreg™ 610

6 Roof application. Frost protection · VGLUE102 · ©DEVI

3.2.1 DEVIreg™ 850 detailed
description

DEVIreg™ 850 microprocessor
controller is fully automatic,
digital electronic device. Its
operation is based on complex
digital measurements provided
by temperature and humidity
measuring sensors. Simultaneous
moisture and temperature
measuring allows controller to save
up to 75% energy comparing with
systems that provide temperature
measurements only.

Digital sensors provide much
higher accuracy than analog ones.
As a result frost protection system
operated by DEVIreg 850™ provides
higher level of functionality and
lower operating costs. Therefore
we recommend using this type of
thermostat for installations with
output capacity exceeding 5 kW or
for any smaller installations where
optimum power use is a preference.

Configuration options

DEVIreg™ 850 can control two
independent installations with
maximum 4 sensors connected
in various configurations, i.e.
two independent systems or two
zones in one system with separate
outputs.

In addition, priority setting for both
zones is possible. You can set one
zone for the higher priority and
another for the lower priority.

The zone with lower priority will
be activated following switching
off the zone with higher priority. In
this way you can reduce demand
of the available power for the frost
protection system.

Intuitive menu of the thermostat
allows simple settings. For detailed
instructions and data specifications
please refer to the safety data
catalog and installation manuals
for corresponding sensors and
controllers.

Note: When connecting more
than two sensors additional power
supply is required.

Energy consumption

Сontrol of several parameters has
an effect on energy consumption.

No energy is consumed in cold
dry weather – usage of moisture

sensors is important and enables
switching the system off in cold
dry days, so no excessive energy is
consumed.

Less energy consumption in case
of system splitting into zones with
different weather impact – splitting

area into 2 zones, e.g. North and
South, allows saving energy when
the southern side is free of ice and
snow melting runs faster by the sun
heat.

Running hours for different control systems - Example from Salzburg, Austria, winter 2005/2006.

Controller Sensor parameters Origin of data Hours Index

DEVIreg 850™ Air temperature below +3 °C and moisture Meter reading 535 1

DEVIreg 316™ Air temperature between +3 °C and -7 °C Weather data 2309 4

DEVIreg 330™ Air temperature below +3 °C Weather data 2737 5

None Constant from November to March 3624 7

* DEVIreg™ 850 is a highly efficient multizone thermostat which is equipped with a multilingual menu enabling
both temperature and humidity measuring as well as zone prioritization in case of limited power.

7Roof application. Frost protection · VGLUE102 · ©DEVI

3.3 Accessories

Roof and drain pipes plastic
fixings, plastic tape for roof drains:

Plastic material with increased UV
resistance.

Allows quick and easy installation
of cables intended for heating roof
areas with an installed protection
system.

DEVIclip™ Guardhook, Roofhook,
RX-C Roof Clip:

Enable non-invasive installation of
heating cables in tracts and areas
adjacent to roof gutter edge.

Self-limiting accessories

Refer to Installation of self-limiting
cabels.

DEVIclip™ Roofhook, Gutter, Guardhook DEVIfast™ Double DEVIclip™ C-C

Galvanized steel chain for drain
pipes and DEVIfast™ Double:

Corrosion-resistant hot-dip
galvanized steel chain for cable
installation in downpipes.

3.4 Product selection general overview table

Product Options Description

DEVIsnow™
DIN IEC 60800,
Constant wattage;

DEVIsnow™ 20T (with roofing felt)
DEVIsnow™ 30T
230 & 400 V program

Twin conductor cable, 100%
screen, UV stabilized, black

DEVIsafe™
DIN IEC 60800,
Constant wattage;

DEVIiceguard™
DIN VDE 0254
Self-limiting cable

Thermostat DEVIreg™ 850 with air & moisture sensor

Sensor Roof sensor for Devireg™ 850

Accessories DEVIfast™ Metal

20T
230 & 400 V program

DEVIiceguard™ 18T
Drum & Ready made program

DEVIreg™ 316 with min/max temp.
setting
DEVIreg™ 330, max. temp. setting
DEVIreg™ 610, max. temp. setting

Air sensor for Devireg™ 316 & 330

DEVIfast™ Copper
DEVIclip™ C-C
DEVIclip™ Gutter
DEVIclip™ Roof Hook
DEVIclip™ Guard Hook
DEVIclip™ Traverse
DEVIfast™ Double
Spaceclip
Extra 24 V PSU for Devireg 850

Twin conductor cable, 100%
screen, UV stabilized, black,

Twin conductor cable, wire
screen, UV stabilized black

2x15 A, 24 V PSU, DIN rail

-10...50 °C, 16 A, DIN rail

-10...10 °C, 16 A, DIN rail

-10...50 °C, 10 A, wall intallation

IP67 with 15 m sensor cable
IP44, 15 kΩ

C-C steps 2,5 cm
C-C steps 2,5 cm, in copper
C-C steps 1 cm
C-C steps 1 cm for gutters only
Hook for roof edges
Hook for snow fence
For downpipe hole
For cable loop in downpipe
SLC Relief for sharp edges
Needed with 3-4 sensors

For self-limiting cables DEVIchain™

DEVIdrain™
Connection box
Connection box kit
Cold tail connection kit
End termination
Connectors

8 Roof application. Frost protection · VGLUE102 · ©DEVI