[RE-wrenches] wrenches] Battery Off Gassing and CO Detectors

[John DeBoever]

Very risky proposition...
Battery room/enclosure shall be well ventilated. Any fan system shall have a normally open position in case of fan failure, with adequate natural air flow.
John

From: Kent Osterberg [mailto:kent at coveoregon.com]
Sent: Friday, February 03, 2012 01:35 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] wrenches] Battery Off Gassing and CO Detectors

Fellow wrenches,

Most CO sensors will be sensitive to both hydrogen sulfide and to hydrogen. Here's a link to a typical sensor<http://www.alphasense.com/pdf/COAX.pdf>. While the unintended sensitivity to hydrogen and hydrogen sulfide may cause false alarms to CO, does anyone know if these devices alarm before there is an explosive concentration of hydrogen? Sounds like recommending them for that purpose is risky.

Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com<http://www.bluemountainsolar.com>


On 2/3/2012 8:23 AM, john wrote:
Rich,
   I have found that having the CO detector anywhere nearby seems to pick up the battery gasses.  I had a problem with one customer's battery box (built by their carpenter) made of pine boards tightly fitted together. It was leaking gasses thru the crack between the boards on the top near the vent.  I put electrical tape on the crack and the problem was solved.  The vent fan was working fine but did not have enough volume to keep the gasses from escaping upward and out of the crack. A good reason to use plywood or something else other than multiple boards.  I would definitely agree with Bob that the CO monitor does work to indicate a bad fan.   I have had them go off when the voltage set point on the dux relay was set too high to catch the early stages of gassing.

John
CVSolar


-----Original Message-----
From: Rich Nicol <rich at solartechvt.com><mailto:rich at solartechvt.com>
To: 'RE-wrenches' <re-wrenches at lists.re-wrenches.org><mailto:re-wrenches at lists.re-wrenches.org>
Sent: Thu, Feb 2, 2012 9:40 pm
Subject: [RE-wrenches] Battery Off Gassing and CO Detectors

Wrenches
I understand that battery gassing of Hydrogen Sulfide can set off CO detectors.  A new customer who I am about to replace a large battery bank for had his furnace tech on site today to check for proper operation of the furnace since his CO detector was going off, the tech found the high levels of CO were coming from the battery bank. I recognize its not actually CO but rather it’s hydrogen sulfide since his generator had recently been running to charge the batteries and I assume that the detector couldn’t differentiate the Hydrogen Sulfide from the carbon monoxide. Does anyone have any insight into the mechanism that CO detectors use to detect the gas and secondly could they be used reliably to detect battery gassing that isn’t being evacuated from the battery enclosure such as when a power vent fails? Maybe a CO detector could be located near enough to the vent hole in the Zephyr fan to detect high levels of Hydrogen Sulfide that aren’t being pushed out when the fan fails to operate and open its damper? Power vent failure is a fear that a number of customers have expressed, maybe this could be  a method of alerting the homeowner that there is an issue.
Thanks
Rich


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