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AR Gas Valve Replacement

Technical Bulletin Radiant

Ref GB/TB/043/0412 AR Sigma 840 Gas Valve Change

Note: Bulletin to be used in conjunction with the various Operating and Installation manuals for Radiant and Herringbone heaters.

This bulletin describes the procedures to be carried out when replacing obsolete or redundant gas valves fitted to AR burners. See photo's below


Honeywell VR4705 series AmbiRad no. 2046/3187


Black Teknigas 2443212-45 AmbiRad no. 2032


SIT 830 Tandem AmbiRad no. 2052

The replacement gas valve is a SIT 840 Sigma, AmbiRad part no.201857, which will be supplied together with a mini harness AmbiRad part no. 900375. See photo's below.
No additional gas pipe fittings are required to change this gas valve.


SIT 840 Sigma AmbiRad no. 201857


Sigma valve lead AmbiRad no. 900375

In addition and depending on which valve is being replaced, the following tools and equipment maybe required. Note: Gas valve and mini harness supplied together.



PROCEDURE

Removing old valve

Ensure that both the gas and electricity supplies are isolated from the burner.

1: Remove combustion chamber cover and hinge down the control housing cover.

either
2a: Remove the electrical push on connections from the existing valve
or
2b: on newer models, unplug the mini harness from main harness.

3: Using stilsons, remove the external flexible gas feed hose from the burner.

4: From within the combustion chamber, remove the burner head.

5: The gas valve can now be removed from the controls compartment as a whole assembly.

either
6a: On older models and using stilsons, unscrew the 90° malleable elbow complete with injector and retain for re-use.
or
6b: on newer models remove the aluminium 90° elbow casting and ‘O ring complete with injector by unscrewing 2 small and 4 large screws and retain all parts re-use.

either
7a: On older models remove the aluminium casting/double ended gas inlet plug and ’O’ ring by unscrewing 4 screws and retain all parts for re-use.
or
7b: on newer models remove the aluminium gas inlet support block and ’O’ ring by unscrewing 4 screws and retain all parts for re-use.

Fitting new valve

All threaded pipe joints should be sealed using a suitable jointing compound.

either
1a: Refit the original aluminium casting/double ended gas inlet plug and ’O’ ring to the new gas valve using the 4 screws ensuring it is positioned correctly on the inlet side of the valve!
or
1b: refit the original aluminium gas inlet support block and ’O’ ring to the new gas valve using the 4 screws ensuring it is on the correct inlet side of the valve!

either
2a: Refit the aluminium 90° elbow casting complete with injector and ’O’ ring to the outlet side of the gas valve using 2 small and 4 large screws.
or
2b: using stilsons and a suitable jointing compound re-screw the 90° malleable elbow complete with injector to the outlet side of the gas valve .

3: Refit the new valve assembly complete with injector within the controls compartment.

4: Replace the burner head ensuring it’s position in-line with the support casting and a tight fit onto the injector carrier.

5: Using stilsons, replace the external flexible gas feed hose.

either
6a: On newer models insert the new mini harness plug onto the new valve, then re-connect the three pin plug into the main wiring harness.
or
6b: on older models and using wire cutters, remove the electrical push on connectors from the main burner harness. Remove the 3 pin plug from the new mini harness supplied. Using a suitable mains terminal block, rejoin all 3 connections. Red to Brown (live), Blue to Blue (neutral) and Earth to Earth.

7: Replace the combustion chamber and control housing covers.

Following this procedure the burner MUST be tested for gas soundness then re-commissioned.

 

Click on link below to follow the step by step instructions.

document added 12/04/12

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Article Attachments
706043 TB043 AR Gas Valve replacement ARAD EN 1412 A3F TB.043.0412.pdf

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Last Modified on 12/07/2016.
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