Aqualarm raw water sensor failure

[Brian B]

In Jan 2016 Knotflying and myself installed the Aqualarm raw water sensor on our boats. In March 2019 they both failed. Symptoms were intermittent or no alarm at the helm. We called Aqualarm and spoke to Rodney. He suspected the reed switches have failed and was very surprised that they did. I mailed my unit to him and he replaced the reed switch free of charge and promptly mailed the unit back to me. Knotflying is waiting to send his unit back. If you have these installed and an issue arises give the company a call and see if they will help with the issue, ours were out of warranty.

 

[captstu]

How did you know they failed? I don’t know an easy way to test the Shearwater’s float switch.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[Brian B]

How did you know they failed? I don’t know an easy way to test the Shearwater’s float switch.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

No alarm or warning light at the helm when engine is started.

 

[baz]

FYI....

I have a brand new AquaAlarm Model 306-13209 in original box with instructions etc. I bought this for my R21 EC but never did install it. It's been collecting dust for awhile now. It has the 85dB buzzer and helm alarm plate ENGINE RAW WATER decal for mounting.

It's available to anyone who cares to PM me. 🙂

 

[BB marine]

Brian, I have been contemplating installing a exhaust temp alarm. Where is this installed before the seawater pump or after? If it is flow it probably doesn't matter. I actually like the idea of this better then the exhaust temp. I have concerns when launching that I am not picking up water immediately and running the pump dry or when running in areas with a lot of vegetation floating. The alarm reaction would be quicker with this then exhaust temp alarm. Does the alarm start to sound at engine start up each time until it senses flow? Would you still recommend this unit after having a reliability issue.

 

[Brian B]

Brian, I have been contemplating installing a exhaust temp alarm. Where is this installed before the seawater pump or after?

Between the sea strainer and the pump.

If it is flow it probably doesn't matter. I actually like the idea of this better then the exhaust temp. I have concerns when launching that I am not picking up water immediately and running the pump dry or when running in areas with a lot of vegetation floating.

We actually have had this happen and the alarm sounded.

The alarm reaction would be quicker with this then exhaust temp alarm. Does the alarm start to sound at engine start up each time until it senses flow?

Yes it sounds at startup for a second until it senses flow.

Would you still recommend this unit after having a reliability issue.

Yes, it’s a nice feature to have. The company stepped up when they didn’t have to.

 

[ALICE J]

I broke a belt to the raw water pump, alarm sounded, thought it was the impeller, fearing to crawl into the engine cavern as rhe last resort because of a bad impeller , a strong flash light revealed a missing belt from the impeller pump. The cause was a knicked pulley caused by a mechanics that used a metal screw driver to replace the original belt. Lessen learned, only use a plastic or wooden tongue depressor to pull the belt off the pulley. With out the alarm only the engine over heat might have shut the engine down, but with the raw water alarm alarm, the problem was immediately to shut down the engine and diagnose the problem. As a back up I also have a hot water sensor on the exhaust hose. It has a only shown the green light at the console. When the belt broke there was a red light showing and an alarm sounding but would have thought a broken impeller :roll: . But checking revealed the real issue !

 

[NorthernFocus]

I also had a sensor failure a couple of years ago. But mine was bad right out of the box. Unfortunately I didn't do a simple test before installation so when it didn't work I spent an hour or so troubleshooting the whole circuit before it occurred to me to test the sensor(simple continuity test).

I highly recommend this simple alarm device with one caveat. One needs to understand how it works and therefore what it does and doesn't do. It is a simple switch that indicates flow/no flow. It does NOT indicate LOW flow. If you have low flow due to partial blockage of the intake/strainer or a damaged impeller the Aqualarm will not pick that up. It takes a very small amount of flow to open the switch(silence the alarm). We picked up enough grass in the intake such that the engine overheated at anything above 1200 rpm and the Aqualarm was perfectly happy. Visually there was a very small flow going through the seachest, maybe 1/4 gpm.

For DIY installations I would also recommend purchasing the switch only and fabricating the fitting. One reason is that the hose barbs supplied by the factory are oversized and a real bugger to install. Also the factory glues the fittings which necessitates replacing the whole thing if the switch fails. Unfortunately I did not have the foresight to do this myself but will certainly correct that error if I have another switch failure. Replacing the switch could take a few minutes rather than half a day.

 

[BB marine]

I'm adding this to my to do list. I like this option. I like Dans DIY idea. Although the fittings if done in bronze could be as much as the sensor in cost. The advantage would be removal of sender, a pipe plug installed for inspection or replacement. It could done in plastic pipe at a reduced cost I suppose ??. I looked at the water flow alarm setting on the Aqualarm 10235 water flow detector. It goes open ( sounds alarm) at 3 to 4 gallons per minute. The D3 water pump is designed to move 7 gph at 700 rpm. 20 gpm at 2000rpm, 30gpm at 3000rpm so Dans point would also valid on the D3. There needs to be a significant restriction to sound the alarm at higher rpm.I feel even at 4 gpm the alarm will protect the impeller but the engine or exhaust could be getting into an over heat situation. I feel it is an advantage to have the raw water sensor. I'm installing one in along with the Exhaust temperature sender. This will cover both ends of the spectrum. Thanks for the post Brian, Dan, AliceJ.

 

[NorthernFocus]

...the fittings if done in bronze could be as much as the sensor in cost. The advantage would be removal of sender, a pipe plug installed for inspection or replacement. It could done in plastic pipe at a reduced cost I suppose ??..

Sure plastic/nylon would work fine. That's what comes with the switch if you purchase the complete unit. Brass would probably be fine too and cost a lot less than bronze. Different people have different philosophies on material selection.

 

[ALICE J]

Brass may be fine in freshwater, but a BIG NO-NO in salt water, brass will fail caused by dissimilar metals caused by salt connecting the bronze intake strainer, the metals in the engine with the brass in the middle. Prudence is the best insurance, do not by fron the big box stores any metal fittings for your Tug, pay the piper and get them from a reputable boat yard or the jewelry story-Westmarine.

 

[knotflying]

When I installed my sensor (after struggling with Gansetts install) I blunted the ends on the barbed fitting, put the switch in ice water, heated the hose ends in hot water, applied a little soap and they just slipped right on. May be a little more difficult to remove.

 

[Brian B]

To add to Knotflying’s post and what we learned from experience. When I recently removed the sensor the only way I could get the hoses off the sensor barb fittings without damaging them was to cut them off with a hacksaw. The hose is metal reinforced thus you have to cut through the stainless wire in the hose. I purchased new 1 1/4” I.D. Hose at W.M. I placed both hose ends in boiling soapy water for 5 minutes, at the same time I iced the sensor barbs. I applied soap to the barbs and the hoses went on fairly easily. A little soap to the other two ends of the hose and slip the assembly in place.

 

[NorthernFocus]

Brass may be fine in freshwater, but a BIG NO-NO in salt water, brass will fail caused by dissimilar metals caused by salt connecting the bronze intake strainer, the metals in the engine with the brass in the middle...

Bronze and brass are very similar metals with very little difference in potential. The engine has an anode in it.

 

[mjq1987]

Brian, I think you are right about covering multiple potential problems with the water flow and temperature sender. Which temp sensor/sender are you planning to use?

Thanks,

Mike

 

[BB marine]

Brian, I think you are right about covering multiple potential problems with the water flow and temperature sender. Which temp sensor/sender are you planning to use?

Thanks,

Mike

I was looking at Borel manufacturing, it has a alarm setting of 165 F exhaust temp. The sensor is located on the exhaust hose just below the hose clamps and just down stream of the raw water injection point. Boral advertises as a USA product. After the discussion of the Aqualarm Raw water flow sensor on TugNuts. I looked at Aqualarm Website and saw they too have an exhaust temp sensor. It has an alarm set point 35 degrees higher at 200 F. Given the fact that I had engine compartment air temperatures of 158 degrees last fall while cruising the Tennessee river I possibly could get a false Alarm with the 165 F set alarm. ( I did increase the ventilation in the engine compartment significantly over the winter so I am still contemplating the Borel) The Aqualarm has a two function panel that combines the raw water flow sensor and the exhaust temperture sensor. This feature would be nice for a clean looking installation and ease of installation. I'm going to call Aqualarm and speak to a representative about the DIY water flow installation and get some more information about their Exhaust sensor options. this may be the direction I go.

 

[Red Raven]

Brass may be fine in freshwater, but a BIG NO-NO in salt water, brass will fail caused by dissimilar metals caused by salt connecting the bronze intake strainer, the metals in the engine with the brass in the middle...

Bronze and brass are very similar metals with very little difference in potential. The engine has an anode in it.

Unfortunately Brass and Bronze are not similar enough. Yes, both are copper alloy’s and both alloys have similar galvanic potential, but brass is typically made with up to 39% zinc. The galvanic potential between the copper (-0.30 to -0.57 volts) and the zinc (-0.98 to -1.03 volts) in the brass creates a strong galvanic cell within the brass itself! The zinc will sacrifice itself in seawater turning the brass into the consistency of a sponge. Bronze however, is made of copper and tin which are right next to each other in the galvanic series. Bronze has excellent performance in salt water. Don’t use brass outside on a boat for anything other than decoration and never under saltwater. (Ref. The Boat Owners Guide to Corrosion, by Everett Collier)

 

[Cutwater28GG]

this looks like a simple install.

Brian is this just on the exhaust pipework as it comes out of the engine before it gets to the waterlock/muffler?

 

[mjq1987]

I was looking at Borel manufacturing, it has a alarm setting of 165 F exhaust temp. The sensor is located on the exhaust hose just below the hose clamps and just down stream of the raw water injection point. Boral advertises as a USA product. After the discussion of the Aqualarm Raw water flow sensor on TugNuts. I looked at Aqualarm Website and saw they too have an exhaust temp sensor. It has an alarm set point 35 degrees higher at 200 F. Given the fact that I had engine compartment air temperatures of 158 degrees last fall while cruising the Tennessee river I possibly could get a false Alarm with the 165 F set alarm. ( I did increase the ventilation in the engine compartment significantly over the winter so I am still contemplating the Borel) The Aqualarm has a two function panel that combines the raw water flow sensor and the exhaust temperture sensor. This feature would be nice for a clean looking installation and ease of installation. I'm going to call Aqualarm and speak to a representative about the DIY water flow installation and get some more information about their Exhaust sensor options. this may be the direction I go.

Thanks, Brian. I am thinking about installing a temperature sensor that provides a gauge display rather than just the alarm condition. I am leaning toward this one: http://www.yachtd.com/products/thermometer.html. I am planning to attach it to the exhaust hose downstream of the water injection point with a hose clamp, similar to how the Borel and Aqualarm sensors work. Although the measured temp would not be the true wet exhaust temp, I was hoping I would be able to figure out a normal max based on RPM/water temp and that having a temperature trend readout might help to detect flow degradation before an alarm would initiate. Not sure if this is overkill or would even be effective in detecting the onset of a flow degradation problem, but I like the idea of it being NMEA 2K and the ability to read it on the chartplotter.

 

[BB marine]

this looks like a simple install.

Brian is this just on the exhaust pipework as it comes out of the engine before it gets to the waterlock/muffler?

Gavin, yes it is a simple install. Basically a hose clamp with a temp sensor attached to it. The sensor is installed at 3 o'clock and the hose clamp/sensor or strap goes around the exhaust hose just down stream of the raw water injection point. The hardest part and not bad with C26 or C28 is running the sender wires to the helm. In my case it will be Both raw water sensor wires and the temp sensor wires.



Mike, I like the fact that the sender is N2K compatible.Having a value to the exhaust temperature could be a quicker warning of an issue. For me seeing incremental increases may give me some anxiety though. We boat in different areas, mostly Lake Michigan. The exhaust temperature would mostly remain close to the same or gradually increase as the summer progresses and the lake warms up to it's warmer temperature of 70F. When we get off the lake and head down the river the temperature would make a quick increase of 15 F degrees higher. As long as you are aware of ambient water temperature change in different waterways you will get use to the fluctuation. If you are use to seeing 120 F exhaust temperature and then see 135 F it may give you a few moments of anxiety.