N.H. Code Admin. R. Puc 2506.04 - Metering of Sources that Produce Useful Thermal Energy

(a) Sources producing useful thermal energy shall comply with this part in metering production of useful thermal energy.
(b) Sources shall retain an independent monitor to verify the useful thermal energy produced.
(c) Sources shall take data readings for the measurement of useful thermal energy at least every hour. The useful thermal energy produced shall be totaled for each 24 hour period, each monthly period, and each quarter.
(d) Sources shall install heat meters to measure thermal energy output in accordance with the manufacturer's specifications and as specified in this part. The heat meters shall operate within the conditions for which the meter accuracies are guaranteed.
(e) Large thermal sources using a liquid or air based system shall measure the useful thermal energy produced using one of the following methods:
(1) Installation and use of heat meters with an accuracy that complies with European Standard BS EN 1434-1 (2015 edition) published by CEN, the European Committee for Standardization, available as specified in Appendix B, and that complies with paragraph (k), (l) or (m). The heat meter shall have the highest class flow meter that will cover the design flow range at the point of measurement and a temperature sensor pair of Class 5K or lower. Compliance shall be confirmed by a professional engineer licensed by the state of New Hampshire and in good standing;
(2) Installation and use of meters that do not comply with subparagraph (e)(1), provided that the manufacturers' guaranteed accuracy of the meters is ±5.0% or better, and provided that a professional engineer licensed by the state of New Hampshire and in good standing confirms that the meters were installed and operate according to the manufacturers' specifications and in accordance with paragraph (k), (l) or (m); or
(3) Use of an alternative metering method approved pursuant to Puc 2506.06, provided that the accuracy of any such method is ±5.0% or better, and provided that a professional engineer licensed by the state of New Hampshire and in good standing confirms that the source implemented the alternative method as approved by the commission and certifies that the alternative method achieves the stated accuracy of ±5.0% or better.
(f) Large thermal sources using a steam-based system shall measure the useful thermal energy produced using one of the following methods:
(1) Installation and use of meters with accuracy of ±3.0% or better, which compliance shall be confirmed by a professional engineer licensed by the state of New Hampshire and in good standing and in accordance with (m) below;
(2) Installation and use of meters that do not comply with the accuracy of subparagraph (f)(1), provided that the manufacturer's guaranteed accuracy of the meters is ±5.0% or better, and provided that a professional engineer licensed by the state of New Hampshire and in good standing confirms that the meters were installed and operate according to the manufacturer's specifications and in accordance with (m) below; or
(3) Use of an alternative metering method approved pursuant to this section, provided that the accuracy of any such method is ±5.0% or better, and provided that a professional engineer licensed by the state of New Hampshire and in good standing confirms that the source implemented the alternative method and confirms that the alternative method achieves the stated accuracy of ±5.0% or better.
(g) Small thermal sources shall measure useful thermal energy produced using one of the following methods:
(1) For any small thermal sources, the methods described in (e) or (f) above;
(2) For small thermal sources using solar thermal technologies, the method described in (h) below;
(3) For small thermal sources using geothermal technologies, the method described in (i) below; or
(4) For small thermal sources using thermal biomass technologies, the method described in (j) below.
(h) Small thermal sources that elect pursuant to (g)(2) above to measure useful thermal energy pursuant to this paragraph shall calculate useful thermal energy produced by small thermal sources using solar technologies as follows:
(1) "Q" means thermal energy generated, stated in Btus;
(2) "R" means the Solar Rating and Certification Corporation (SRCC) OG100 rating on Medium Radiation (1500 Btu/ft2.day) C (36º F) Conditions, stated in thousands of Btus per day;
(3) "L" means the orientation and shading losses calculated based on solar models such as Solar Pathfinder, T-sol, Solmetric, or another functionally equivalent solar model, converted from a percentage to the equivalent number less than one;
(4) "t" means the total operating run time of the circulating pump as metered, stated in hours;
(5) "h" means 11 hours per day to convert the SRCC OG100 rating to an hourly basis, the conversion factor; and
(6) To calculate Q, the useful thermal energy produced by small thermal sources using solar technologies, the source shall compute the product of R, t, 1,000 and the result of 1 minus L, and divide the result by h, as in the formula below:

Q = [R * t * 1,000 * (1 - L)] / h

(i) Small thermal sources that elect pursuant to (g)(3) above to measure useful thermal energy pursuant to this paragraph shall calculate useful thermal energy produced by small thermal sources using geothermal technologies as follows:
(1) "Q" means thermal energy generated, stated in Btus;
(2) "HC" means the Air Conditioning, Heating and Refrigeration Institute (AHRI) certified heating capacity at part load, stated in Btus per hour;
(3) "COP" means the AHRI Certified Coefficient of Performance;
(4) "t" means total operating run time of the heat pump when operating in heating mode, stated in hours; and
(5) Small thermal sources using geothermal technologies shall calculate Q, the useful thermal energy produced for each heat pump, by multiplying heat pump HC by the difference between heat pump COP and 1, multiplying the result by t, and dividing the result by COP, as in the formula below:

Q = [HC * (COP - 1) * t] / COP

(j) Small thermal sources that elect pursuant to (g)(4) above to measure useful thermal energy pursuant to this paragraph shall calculate useful thermal energy produced by small thermal sources using thermal biomass renewable energy technologies as follows:
(1) "Q" means the thermal energy generated, stated in Btus;
(2) "D" means the default pellet density, which shall be 0.0231 pounds per cubic inch;
(3) "R" means the auger revolutions per hour;
(4) "V" means auger feed volume, stated in cubic inches per auger revolution;
(5) Small thermal sources shall assume that V equals one of the following:
a. 5 cubic inches per revolution for augers with a 2-inch inside diameter;
b. 20 cubic inches per revolution for augers with a 3-inch inside diameter;
c. 50 cubic inches per revolution for augers with a 4-inch inside diameter;
d. 95 cubic inches per revolution for augers with a 5-inch inside diameter; or
e. 150 cubic inches per revolution for augers with a 6-inch inside diameter;
(6) "EC" means the default energy content of pellet fuel, which shall be 7870 Btu per pound;
(7) "ASE" means the default thermal efficiency expressed as a percentage based on the manufacturer's warranty of average seasonal thermal efficiency, or based on a default thermal efficiency of 65%;
(8) "t" means the total auger run time in hours as metered;
(9) The estimated amount of fuel burned, that is, the product of D, R, V and t, shall be verified by the fuel purchase records and fuel inventory; and
(10) Small thermal sources using thermal biomass renewable energy technologies with wood pellets as the fuel source may calculate Q, the useful thermal energy produced, by computing the product of D, R, V, EC, ASE and t, as in the formula below:

Q = (D * R * V * EC * ASE * t)

(k) Large thermal sources, and small thermal sources that elect pursuant to (g)(1) above, using solar thermal technologies shall calculate useful thermal energy as follows:
(1) "Qg" means the heat generated in the collector loop, stated in Btus;
(2) "dm/dt" means the mass flow of the collector working fluid measured near the inlet to the solar storage tank, stated in pounds per hour;
(3) "cp" means the specific heat of the collector fluid, stated in Btus per pound of mass, degrees Fahrenheit (Btu/lbm-°F);
(4) "Ti" means the collector loop inlet temperature measured near the outlet of the solar storage tank, stated in degrees Fahrenheit;
(5) "To" means the collector loop outlet temperature measured near the inlet to the solar storage tank, stated in degrees Fahrenheit;
(6) "t" means the frequency at which data readings are recorded, stated in hours;
(7) Meter sensors shall be installed on the collector loop as close to the water storage tank as practical and in accordance with the meter manufacturer's guidance; and
(8) Thermal sources using solar thermal technologies shall calculate Q, the useful thermal energy produced, by calculating the product of dm/dt, cp, the difference between To and Ti, and t, as stated in the formula below:

Qg = (dm/dt)*cp *(To -Ti) * t

(l) Large thermal sources, and small thermal sources that elect pursuant to (g)(1) above, using geothermal technologies shall calculate useful thermal energy as follows:
(1) "Qg" means heat generated in the ground loop, stated in Btus;
(2) "dm/dt" means mass flow measured near the outlet of the ground loop, stated in pounds per hour;
(3) "cp" means specific heat of the working fluid, stated in Btu/lbm-°F;
(4) "t" means the frequency at which data readings are recorded, stated in hours;
(5) "Ti" means ground loop inlet temperature measured at the inlet to the ground loop, stated in degrees Fahrenheit;
(6) "To" means ground loop outlet temperature measured at the outlet from the ground loop, stated in degrees Fahrenheit;
(7) Bleed points, supplemental boilers, and cooling towers shall be excluded from the calculation;
(8) Meter sensors shall be installed on the ground loop as close to the ground loop inlet and outlet as practical and in accordance with the manufacturer's recommendation; and
(9) Thermal sources using geothermal technologies shall calculate Q, the useful thermal energy produced, by calculating the product of dm/dt, cp, the difference between To and Ti, and t, as stated in the formula below:

Qg = (dm/dt) * cp * (To -Ti) * t

(m) Large thermal sources, and small thermal sources that elect pursuant to (g)(1) above, using thermal biomass renewable energy technologies shall calculate useful thermal energy as follows:
(1) "Qg" means the thermal energy generated from biomass, stated in Btu;
(2) "dmout/dt" means mass flow metered upstream of distribution and downstream of parasitic loads, stated in pounds per hour;
(3) "hout" means the specific enthalpy at the metering point determined by temperature data and, for superheated steam, by pressure data, stated in Btus per pound;
(4) "dmin/dt" means mass flow of water into the feedwater or condensate pumps, stated in pounds per hour;
(5) "hin" means the specific enthalpy at the metering point which will be a function of the enthalpy of incoming condensate and make-up water prior to the first condensate or feedwater pumps, stated in Btus per pound;
(6) "t" means the intervals at which readings are recorded, stated in hours;
(7) All metering systems shall measure boiler feedwater flow, pressure, and temperature as close to the first feedwater pump inlet as possible, thereby excluding the deaerator;
(8) Metering for systems that produce hot water shall include sensors for temperature and hot water mass flow placed as close as possible to the boiler hot water distribution header inlet;
(9) Metering for systems that produce steam shall include sensors for temperature, pressure, and steam flow placed as close as possible to the steam distribution header inlet and thereby prior to distribution to process loads;
(10) For saturated steam systems, pressure and temperature shall be measured to verify the absence of superheat at the measurement point;
(11) For superheated systems, both pressure and temperature measurements shall be required;
(12) Regardless of phase, the enthalpy under the measured conditions shall either be calculated using the formulas in The International Association for the Properties of Water and Steam (IAPWS) Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam, August 2007 revision, http://www.iapws.org/relguide/IF97-Rev.pdf, as specified in Appendix B, or taken from IAPWS or derivative steam tables; and
(13) Thermal sources using thermal biomass renewable energy technologies shall calculate Q, the useful thermal energy produced, by calculating the product of dmout/dt, (hout), and t, and subtract from that number the product of dmin/dt, hin and t, as stated in the formula below:

Qg = [dmout/dt *(hout) * t]-[dmin/dt*(hin) * t]

Notes

N.H. Code Admin. R. Puc 2506.04
Derived from Volume XXXV Number 01, Filed January 8, 2015, Proposed by #10741, Effective 12/5/2014. Amended by Volume XXXVIII Number 06, Filed February 8, 2018, Proposed by #12473, Effective 2/1/2018, Expires 2/1/2028.

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