Weil-McLain SB0203 Manuel de référence

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

Table des matières

Autres manuels Weil-McLain Chaudière

Weil-McLain

Weil-McLain EVERGREEN PRO 1 EVG-110 Mode d’emploi

Weil-McLain

Weil-McLain LGB Manuel utilisateur

Weil-McLain

Weil-McLain 380 Manuel utilisateur

Weil-McLain

Weil-McLain HE (Series 2) Manuel utilisateur

Weil-McLain

Weil-McLain BSC Manuel de service

Weil-McLain

Weil-McLain LGB-4 Manuel d'utilisation et d'entretien

Weil-McLain

Weil-McLain GV90+ Mode d’emploi

Weil-McLain

Weil-McLain UltraOil Manuel utilisateur

Weil-McLain

Weil-McLain GOLD CGt SERIES Mode d’emploi

Weil-McLain

Weil-McLain Gold GV 3 Series Manuel utilisateur

Weil-McLain

Weil-McLain PD Gas Series 3 Manuel utilisateur

Weil-McLain

Weil-McLain Ultra 80 Manuel utilisateur

Weil-McLain

Weil-McLain SVF Series 1 Manuel utilisateur

Weil-McLain

Weil-McLain Evergreen 220 Mode d’emploi

Weil-McLain

Weil-McLain CGi Mode d’emploi

Weil-McLain

Weil-McLain AFG Manuel utilisateur

Weil-McLain

Weil-McLain CGi Series 2 Manuel utilisateur

Weil-McLain

Weil-McLain CGM (Series 7) Manuel utilisateur

Weil-McLain

Weil-McLain SlimFit 550 Mode d’emploi

Weil-McLain

Weil-McLain SlimFit Manuel utilisateur

Weil-McLain

Weil-McLain RS Manuel utilisateur

Weil-McLain

Weil-McLain Series 4 Manuel utilisateur

Weil-McLain

Weil-McLain CGM (Series 9) Manuel utilisateur

Weil-McLain

Weil-McLain Ultra Electric Water Heater Manuel utilisateur

Manuels Chaudière populaires d'autres marques

Vaillant

Vaillant uniSTOR VIH SW GB 500 BES Manuel utilisateur

Radijator

Radijator BIO max 23.1 Manuel utilisateur

Brunner

Brunner BSV 20 Manuel utilisateur

Buderus

Buderus Logamax GB062-24 KDE H V2 Manuel utilisateur

Potterton

Potterton 50e Fiche technique

UTICA BOILERS

UTICA BOILERS TriFire Manuel utilisateur

Joannes

Joannes LADY Series Manuel

ECR International

ECR International UB90-125 Manuel d'instructions

Froling

Froling FHG Turbo 3000 Manuel utilisateur

Froling

Froling P4 Pellet 8 - 105 Manuel utilisateur

U.S. Boiler Company

U.S. Boiler Company K2 Manuel utilisateur

Henrad

Henrad C95 FF Manuel utilisateur

NeOvo

NeOvo EcoNox EF 36 Manuel utilisateur

Potterton

Potterton PROMAX SL 12 Manuel utilisateur

Eco Hometec

Eco Hometec EC 25 COMPACT Manuel utilisateur

Viessmann

Viessmann VITODENS 200 Mode d’emploi

Baxi

Baxi Prime 1.24 Manuel utilisateur

REXNOVA

REXNOVA ISA 20 BITHERMAL Manuel utilisateur