CFM UVHK29MN, UVHK36MN, UVHK23MP, UVHK31MP Gas Pressure Check, Gas Inlet Pressure Natural Propane

Gas Line Pipe Sizing

NOTE: To determine the size of the branch gas line from the main gas line to the fireplace, enter the tables below (for iron pipe or copper tubing) using the distance from the gas meter or second stage regulator to the furthest appliance on the gas system. Select a pipe or tube diameter which has enough capacity to meet the maximum input requirement of the fireplace. Regardless, do not use less than 1/2” diameter for the branch line. For any distances required longer than shown in these tables, refer to the National Fuel Gas Code.

NOTE: There may be a local gas utility requirement specifying a minimum diameter for gas piping. All units require a 1/2 inch pipe con-

nection at the gas valve.CAPACITY OF PIPING

Cubic Feet per Hour based on 0.3” w.c. Pressure Drop

Specific Gravity for Natural Gas - 0.6 (1000 BTU/Cubic Foot) Specific Gravity for Propane Gas - 1.6 (2550 BTU/Cubic Foot)

Length			Nominal Inches for Iron Pipe Sizes (1,000s BTU/hr)
of	1/2” D		3/4” D		1” D		1¹⁄₄” D		1¹⁄₂” D
Pipe	Natural	Propane	Natural	Propane	Natural	Propane	Natural	Propane	Natural	Propane
20’	92	143	190	296	350	546	730	1135	1100	1711
30’	73	115	152	237	285	444	590	918	890	1385
40’	63	97	130	202	245	380	500	778	760	1183
50’	56	87	115	179	215	334	440	683	670	1043
60’	50	79	105	163	196	304	400	622	610	949
70’	46	71	96	151	180	280	370	576	560	872
90’	40	61	84	130	160	250	320	497	490	763
100’	38	59	79	122	150	235	305	474	460	717

Outside Diameter Copper Tubing, Type L (1,000s BTU/hr)

Tubing Length	1/2”	5/8”	3/4”	7/8”
Feet	0.43	0.545	0.666	0.785
10	110	206	348	536
20	76	141	239	368
30	61	114	192	296
40	52	97	164	256
50	46	86	146	224
60	42	78	132	203
80	36	67	113	174
100	32	59	100	154

WARNING: Use only internally tinned copper tubing. If correct copper tubing is not used, tubing can deteriorate and develop gas leaks.

Gas Pressure Check

Check the inlet pressure to the appliance to ensure that it is as shown in Table 1. Also check the incoming gas pressure where the field installed gas line connects to the gas logs.

The manifold pressure is controlled by the regulator and should be checked at the pressure test point located downstream from the regulator on the control valve body. Access to the pressure test point is obtained by removing all logs and the heat shield on the right hand rear side of the base. The pressure test point 1/8” NPT plugged tapping is located on the rear face of the control body. (Fig. 5)

The pressure should be checked with the appliance burning on high (highest setting) and all other gas appliances turned on. One must then read the manometer and if pressures are not 10” w.c. for LP or 3.5” w.c. for natural gas, then the inlet pres- sure must be adjusted or increased until the proper pressures are attained. If these pressures are greater than 10” w.c. for LP or 3.5” w.c. for natural gas, contact your gas supplier before operating the appliance.

The pressure regulator is preset and locked to prevent tamper- ing. If the pressure is not as specified, replace the regulator with part # 73332 (for natural gas only), or part # 73333 (for L.P. gas only).

Table 1

Gas Inlet Pressure	Natural	Propane
Max.	10.5” w.c.	13” w.c.
Normal	7” w.c.	11” w.c.
Min.*	5.5” w.c.	11” w.c.
Regulator Pressure	3.5” w.c.	10.0” w.c.

*Minimum inlet supply pressure for the purpose of input adjustment.

After measuring the pressure, replace the test point plug and check for leaks. Replace the control box cover and the two phillips head screws.

CAUTION: If the appliance’s operating pressures are not checked and adjusted, improper combustion may result in soot being produced.

Test Point

T126

12 Fig. 5 Pressure test point.