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Sea Chest Clog Alarm


Karen Smith
 

Those of you who have a newer SM with the switch that triggers the alarm for a clogged seachest:  

Does anybody know the pressure setpoint of this switch?


Alan Grayson
 

I believe it is a vacuum activated switch as I remember doing to some work on the A/C unit that required the seacock to be closed. When I fired it back up with the sea cock closed it activated pretty much straight away


From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> on behalf of Karen Smith via groups.io <karenharmonie@...>
Sent: Saturday, 28 November 2020 3:24 AM
To: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io>
Subject: [AmelYachtOwners] Sea Chest Clog Alarm
 
Those of you who have a newer SM with the switch that triggers the alarm for a clogged seachest:  

Does anybody know the pressure setpoint of this switch?


 

Karen,

I do not have the precise vacuum, but I imagine that Amel probably adjusts the vacuum switch when it is installed. Here is the information I have in my book. The source of this information was Amel:
The Amel Sea Chest has an Amel innovative Vacuum Switch attached
via a hose to the Sea Chest Manifold. The Vacuum Switch is located
above the sea chest. Sea Chest blockage will create suction inside the
Sea Chest, which closes the switch, activating an alarm. Test this alarm
switch by closing the Sea Chest valve for up to 8 seconds while the engine
is running.

The internal part of the switch can get clogged as well as the curved
copper pipe. If the alarm isn't working, check for clogs.
To adjust the sensitivity of the vacuum switch, remove the top screw, then
using a jeweler's flat head screwdriver, inserted into a tiny, concealed
adjuster screw adjust the sensitivity. Turning the small screw clockwise,
increases sensitivity and the alarm comes on. Anticlockwise and the alarm
stops. Through trial and error, you will find the ‘sweet spot’ by running
the fridges, AC, engine, and generator at the same time. NOTE:
Adjusting sensitivity doesn't require the removal of the Vacuum Switch.

image.png

Also, if you order the sensor from Amel and have the one below on the left, you will find it has changed to the one below on the right.
image.png
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Sat, Nov 28, 2020 at 5:18 AM Alan Grayson <bazgrayson@...> wrote:
I believe it is a vacuum activated switch as I remember doing to some work on the A/C unit that required the seacock to be closed. When I fired it back up with the sea cock closed it activated pretty much straight away

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> on behalf of Karen Smith via groups.io <karenharmonie=yahoo.com@groups.io>
Sent: Saturday, 28 November 2020 3:24 AM
To: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io>
Subject: [AmelYachtOwners] Sea Chest Clog Alarm
 
Those of you who have a newer SM with the switch that triggers the alarm for a clogged seachest:  

Does anybody know the pressure setpoint of this switch?


Roque
 

Karen,

I just ordered mine from Amel, $60,62 euros each, adaptor included (ex-Vat & shipping). Hasn't arrived yet. 

As far as I know, they are are made by Elettrotec – Italy (http://www.elettrotec.com/US/Vacuum_Switches.asp).

The adjustable pressure range (Elettrotec), depending on the model, is from  -200 to -900 mbar. 

Roque
Attika A54 # 117
Paraty- Brazil


Karen Smith
 

Thanks, all!  

I was not looking to install one, just get a feel for the setpoint.  A minimum setpoint of -200 mbar gauge (80 inches of water) tells me what I need to know.  That's a significantly higher vacuum setpoint than I expected.  I would have thought something like 20 instead of 200.

For our raw water system, (which is a lot simpler than a later model SM) the AC units quickly shut down on high pressure if there is insufficient water, the genset quickly shuts down on high exhaust temperature if it lacks water. Adding a high wet exhaust temperature alarm to the main drive engine will cover pretty much all the cases.

Bill Kinney
SM160, Harmonie
Fort Lauderdale, FL, USA