6
System should be designed as primary/secondary piping
and to operate with a maximum output temperature of
180ºF or lower and a temperature rise across the unit
of 20ºF or lower. Refer to tables below and Figures 2
& 3.
“AT” Series - 2 Element Boiler
KW Capacity
Minimum Flow Rate (GPM)*
6
2.0
8
2.7
10
3.4
12
4.1
“AT” Series - 4 Element Boiler
KW Capacity
Minimum Flow Rate (GPM)*
12
4.1
16
5.5
20
6.8
24
8.2
* Flow rate based on 20°ΔT
CONNECTINg SUPPLy AND RETURN PIPINg
1. Maintain minimum clearance of one inch to hot
water pipes.
2. Hot water boilers installed above radiation level must
be provided with low water cutoff device either as
part of boiler or at time of boiler installation.
4. Suggested plumbing arrangements are illustrated in
Figures 2 & 3. Inlet or return pipe is located at bottom
of unit. Reverse flow will result in noisy operation
and cause very early element failure. Drain cock is
to be located at lowest point of piping.
5. Outlet or supply pipe line to radiation is located at top
of unit. Combination temperature pressure (altitude)
gauge is provided with each unit and should be
installed close to boiler outlet. It is important gauge
sensor be completely immersed in flowing water
to assure correct temperature readings. Manual or
automatic water make up supply may be located in
this area below. Circulator pump should be installed
on supply side (pumping away).
6. Install gate valves at locations shown in Figures 2
& 3, so any boiler servicing requiring removal of
water can be done quickly and easily. Not illustrated
but recommended is installation of air vents at high
points of hydronic system. Devices will reduce initial
start up time and help avoid element burnout during
entire life of heating system.
7. Pressure relief valve is supplied with each Electric
Hydronic Block and should be installed at the location
and discharge direction shown in Figure 1, using
pipe nipple and elbow supplied. Piping should be
added so that any water discharged will not damage
boiler or other system components.
PLUMBINg AND
ACCESSORy
INSTALLATION
8. For further piping information refer to Hydronics
Institute (I=B=R) manual 200 (Installation guide
for Residential Hydronics).
figurE 1
3. When boiler is connected to heating system utilizing
multiple zone circulators, each circulator must be
supplied with flow control valve to prevent gravity
circulation.
dEsign of WATEr circuLATing sysTEm
NOTICE
Return water temperature must be higher
than room temperature in which boiler is
installed to prevent condensation.
NOTICE
In some states low water cutoff device
(LWCO) may be required. Check your local
codes.
NOTICE
Reduced pressure back flow preventer must
be present under provisions required by
Environmental Protection Agency, (EPA).