Low Water Cut-Offs

RonF

Hello,
I have a Weil_McLain Series 3 GV-4 boiler. The boiler currently does not have a low water cut-off installed on it. I purchased a McDonnell & Miller MM- 238 (F) Model # RB-122 low water cut-off (guard Dog). According to the manual, if the boiler does not draw more than 5.8 amps I can wire it using option # 1, if the boiler draws more than 5.8 amps I need to wire it using option # 2. Can anyone tell me if the series 3 GV-4 boiler draws more than 5.8 amps? I looked in the boiler manual and could not find any information on start or running amp loads. Has any one here used this LWCO on this boiler before? What wiring scheme should I use?

LWCO location
I am planning on placing the LWCO in a T on the supply of the boiler. Is this a good location? Thank you for any information that you can provide.

Steamhead

Use a snap-on ammeter

to determine the load while the boiler is running, then wire according to the correct diagram.

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Al Letellier

MM238 on GV

Not sure about the MM238 wiring as I don't have a manual on that one. The WM literature makes no mention of the current draw in any of my books. Mount the LWCO anywhere ABOVE the crown of the boiler and wire into the 120 volt circuit in series with all your safety switches. That how we do it with almost any LWCO we use. We use the Safeguard OEM170 the most and have little or no problems.
Hope this helps. Good luck

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