AUTOFLAME Mk7 User Manual

6.2.2 Heat Flow Metering Calculation
Set out below is an example together with relevant calculation, these calculations are embedded in to
the software in the Mk7 version of the expansion PCB.
Example
A boiler firing at 75% has an input of 20,472,840 BTU/Hr (6MW). The temperature of the flow (MM
Temperature detector) out is 185°F and the temperature of the return T1 is 167°F. The combustion
efficiency is 82% (Mk7), Radiation losses are 1% at maximum continuous rating.
Description Imperial units Metric Units
Firing rate 75% 75%
Input 20.47 MMBTU/HR 6MW
Return Temperature 167°F 75°C
Flow Temperature 185°F 85°C
Sp Ht water 1.0 BTU/lb/°F 4.18KJ/KG/°C
Density Water 60.68lb/cuft @176°F 972 kg M³ @80°C
Combustion Efficiency 82% 82%
Efficiency%100%

18%
1%100
75%

80.67%
UsefulHeatintoWaterTotalHeat
Efficiency
100
20,472,840
80.67
100
16,514,440BTU/hr


VolumeFlowinlbs/hr
16,515,440
1
󰇛
185167
󰇜


917,524.4lbs/hr


VolumeFlowincuftHr
VolumeFlowinlbs hr
⁄
DensityofWateratReturnTemperature



917,524.4
60.68
15,120.7cuftHr

VolumeFlowinUSG.P.M.15,120.7cuftHr0.1246761,885.2USG.P.M.
It can be seen from the above that by adding the expansion P.C.B. and a return temperature detector
to the Mk7 M.M. system that you get the following additional useful information.
“Useful heat into water” (BTU/hr) &
“Volume flow” (US G.P.M)
This is displayed on the screen of the Mk7 M.M.
The direct benefit is that you have a “Heat meter” and “Flow meter” for any hot water boiler.
6 Steam and Heat Flow Metering
Page 110
Mk7 Manual: Expansion Board Set-Up Guide
October 2014

AUTOFLAME Mk7 Specifications

General

Brand	AUTOFLAME
Model	Mk7
Category	Measuring Instruments
Language	English