12
7. Boilers may be factory
packaged with a tankless heater coil
see figure below. This
coil provides instantaneous heating of water for domestic use - if proper burner and
water supply line controls are used. Tankless coils are meant to provide domestic hot
water for intermittent draws, not continuous flow.
IMPORTANT
Do not use a tankless coil if your water is excessively hard with
lime or other deposits which will accumulate inside the coil.
When using a tankless coil, the boiler has been configured so the Honeywell L8124C
Combination Hi/Low Limit Aquastat Relay mounts on a thermowell (provided) which
needs to be installed in the 3/4" tapping on the tankless coil. By mounting the aquastat
on the coil, the tankless coil performance is maximized by making the burner respond
more quickly to a call for domestic hot water. A tempering valve (mixing valve) is also
recommended as shown in figure below. A flow restrictor may be required on the
tankless coil inlet piping so that flow rates are matched to boiler heat input (see table
below).
Boiler
Burner Firing
Input
Tank less
Model
Rate (gph)
(MBH)
Rating (gpm)‡
3EW.65T
0.65
91
2.90
3EW.75T
0.75
105
3.00
3EW1.00T
1.00
140
3.25
4EW.90T
0.90
126
3.15
4EW1.25T
1.25
175
3.50
4EW1.50T
1.50
210
3.75
5EW1.20T
1.20
168
3.45
5EW1.75T
1.75
245
4.00
5EW2.00T
2.00
280
4.25
‡ Gallons of water per minute heated from 40°F to 140°F with
200°F boiler water temperature, intermittent draw
