Weil-McLain SB0203 Referenzhandbuch

Subject: Water Boiler Installations with Three-Way Valves

Number: SB0203 (Page 1 of 2)

Date: November 22, 2002

Primary/Secondary pumping is the preferred method for system temperature modulation in

commercial hydronic heating installations. Three-way valves are also used on many

installations for this purpose. Without proper system design and control, three-way valves

can cause cold system water to be returned to a hot boiler. This condition could lead to

boiler thermal shock, creating a potential for section failure. With minimal equipment

investment, thermal shock conditions can be reduced on three-way valve installations.

Weil-McLain makes the following design recommendations.

Piping Selection:

1. Use by-pass piping arrangement – See Figure 1 or 2.

2. Follow basic boiler piping instructions in the boiler manual.

Three-Way Valve Selection:

1. Use valves with minimum timing of four minutes from one extreme position to the other.

2. Size to circuit design requirements. Follow manufacturer’s recommendations. Normally

valve will be one or two pipe sizes smaller than recommended boiler piping size.

3. Avoid oversizing to prevent poor control of mixed water.

4. Pressure drop across the valve should be high enough to provide accurate control

without “hunting”.

Circulator Selection:

1. Size system circulator to circuit flow characteristics. Specify gpm and head requirements.

2. Size each by-pass circulator as follows:

1 .

# of boilers used

[1/4 to 1/3 flow (gpm) of system circulator] X

3. All circulators must run at the same time.

EXAMPLE: Specify equipment to by-pass one 1,000,000 btuh Weil-McLain boiler.

Piping: (1) tee, (1) ell, (1) 45° tee (By-pass size and length will vary on each installation.)

Circulator:

1,000,000 btuh .

10,000 btuh

System flow rate with 20° ∆T through boiler = = 100 gpm

1 .

1 boiler

By-pass flow rate = 1/4 X 100 gpm X = 25 gpm

In most cases a standard booster pump can provide the necessary flow at by-pass gpm and

head requirements.

www.weil-mclain.com.

Technical Services Bulletin No: SB0203 (Page 2 of 2)

Subject: Water Boiler Installations with Three-Way Valves

Date: November 22, 2002

BOILER

SYSTEM

VALVE

3-WAY

PUMP

10 TO 20

PIPE

AT LEAST

DIAMETERS

PUMP

FROM SYSTEM

Figure 1

By-Pass Piping Using Three-Way Valve – Single Boiler

10 TO 20

AT LEAST

DIAMETERS

3-WAY

VALVE

SYSTEM

TO P1

BOILER

PUMP

PIPE

PUMP

BOILER

PUMP

AT LEAST

10 TO 20

DIAMETERS

PIPE

FROM SYSTEM

Figure 2

By-Pass Piping Using Three-Way Valve – Multiple Boilers

Inhaltsverzeichnis

Andere Weil-McLain Kessel Handbücher

Weil-McLain

Weil-McLain LGB Series 2 Bedienungsanleitung

Weil-McLain

Weil-McLain UltraOil 2 Series Bedienungsanleitung

Weil-McLain

Weil-McLain Evergreen EVG 220 Bedienungsanleitung

Weil-McLain

Weil-McLain 550-141-829/1201 Bedienungsanleitung

Weil-McLain

Weil-McLain GV90+ Leitfaden

Weil-McLain

Weil-McLain CGi Series 2 Bedienungsanleitung

Weil-McLain

Weil-McLain SVF 725 Benutzerhandbuch

Weil-McLain

Weil-McLain VHE Series 3 Gebrauchs- und Wartungshandbuch

Weil-McLain

Weil-McLain PD Gas Series 3 Bedienungsanleitung

Weil-McLain

Weil-McLain 5 Series Bedienungsanleitung

Weil-McLain

Weil-McLain ULTRA299-S4 Bedienungsanleitung

Weil-McLain

Weil-McLain Ultra Series 3 Bedienungsanleitung

Weil-McLain

Weil-McLain GV90+ Leitfaden

Weil-McLain

Weil-McLain WMB-155C Bedienungsanleitung

Weil-McLain

Weil-McLain CGA 2 Series Produkthandbuch

Weil-McLain

Weil-McLain UO-3 CV Bedienungsanleitung

Weil-McLain

Weil-McLain EG-30 THRU -75 Gebrauchs- und Wartungshandbuch

Weil-McLain

Weil-McLain Gold GV Series 4 Bedienungsanleitung

Weil-McLain

Weil-McLain GOLD CGI 550-110-710/0107 Bedienungsanleitung

Weil-McLain

Weil-McLain CGi Leitfaden

Weil-McLain

Weil-McLain LGB-4 Bedienungsanleitung

Weil-McLain

Weil-McLain HE (Series 2) Bedienungsanleitung

Weil-McLain

Weil-McLain WM97+ Aqua Logic Bedienungsanleitung

Weil-McLain

Weil-McLain SVF 1500 Bedienungsanleitung

Beliebte Kessel Handbücher anderer Marken

Vaillant

Vaillant uniSTOR VIH SW GB 500 BES Bedienungsanleitung

Radijator

Radijator BIO max 23.1 Bedienungsanleitung

Brunner

Brunner BSV 20 Bedienungsanleitung

Buderus

Buderus Logamax GB062-24 KDE H V2 Bedienungsanleitung

Potterton

Potterton 50e Datenblatt

UTICA BOILERS

UTICA BOILERS TriFire Bedienungsanleitung

Joannes

Joannes LADY Series Handbuch

ECR International

ECR International UB90-125 Gebrauchsanweisung

Froling

Froling FHG Turbo 3000 Bedienungsanleitung

Froling

Froling P4 Pellet 8 - 105 Bedienungsanleitung

U.S. Boiler Company

U.S. Boiler Company K2 Bedienungsanleitung

Henrad

Henrad C95 FF Bedienungsanleitung

NeOvo

NeOvo EcoNox EF 36 Bedienungsanleitung

Potterton

Potterton PROMAX SL 12 Bedienungsanleitung

Eco Hometec

Eco Hometec EC 25 COMPACT Bedienungsanleitung

Viessmann

Viessmann VITODENS 200 Leitfaden

Baxi

Baxi Prime 1.24 Bedienungsanleitung

REXNOVA

REXNOVA ISA 20 BITHERMAL Bedienungsanleitung