Wet exhaust alarm

[Waltthesalt]

I’m replacing a raw water cooled A-4 with a fresh water cooled Beta 16. This includes replacing the wet exhaust with fiberglass (Centek) elbows and rubber exhaust hose. The question is whether to install a exhaust temperature alarm.

With the raw water system if flow was lost I would get an immediate engine temp alarm. With a fresh water system there will be a delay before the fresh water system heats up and alarms. Meanwhile, without water injection, the exhaust temp will increase to temperatures above what the fiberglass and rubber can handle. Theoretically they may fail before we are alerted and shut down the engine.

Borel, Vetus and AquaAlarm make exhaust alarm units. Does anyone have any advice or experience on whether or not this is worthwhile to do

[Minnewaska]

Just another thought. I have a flow sensor connected just after the strainer and before the impeller. Theoretically, it should alarm at the first sign of reduced flow, rather than wait for temp changes. That could keep you from eating the entire impeller first.

[dieseldrifter]

a exauhst temp sensor is never a bad idea and very simple to wire in. if mounted on a relitivly thin piece of pipe it should alert within 30 second of raw water flow lose. the flow sensor are nice but they have two disadvantages #1 it is two more hose joints in the raw water system I like to keep those to a minimum and #2 it can be impeeded by groth and lead to false alarms. as to keeping an impellor from coming apart and going into your raw water system i could see that but i think a exauhst skin sensor would alert soon enough.

[casey1999]

I have bought the aqua alarm exhaust alarm but have not had a chance to mount it. I also purchased some additional temp switches to mount at locations on the engine to warn of high temp (again not had a chance to install).

[haffiman37]

Take the exhaust bend to a machine shop, drill and weld on a nut and install the temp switch just after where the water enters the bend.

[Borel]

We have been selling raw water failure alarms for over 10yrs and this is what we have learned.
Although a flow sensor would make the most sense, in reality, over time they have a tendency to clog up and stop working or give false alarm.
We have also had several customers report the raw water injection hose broke off. In this case a flow sensor would not indicate loss off cooling water to exhaust gases. Thermal sensors are the easiest to install and get the job done. Weather you buy ours or from another supplier, wet exhaust alarm is a wise investment.
You are protecting a very expensive piece of equipment for very little cost or time to install.
We talk to owners all day who have either burned up their exhaust system or damaged their engine due to loss of raw cooling water.

Borel Manufacturing

[Minnewaska]

Borel. Thanks for the food for thought. I'm beginning to think that both would be a good idea.

[Stu Jackson]

If you have an engine temperature gauge and alarm, why would you need another one? Just a contrary approach.

[Minnewaska]

Originally Posted by Stu Jackson

If you have an engine temperature gauge and alarm, why would you need another one? Just a contrary approach.

I have a temp gauge, but it's near my ankle. No way I would notice it in time. I've seen many configurations like that. Not good, but common. If you only have a temp alarm, you will likely already have eaten the impeller or done some heat damage by the time it goes off. The flow alarm says you lost flow before she heats up or eats the rest of the impeller (in theory, as Borel explains above). Both sounds like a winner to me.

[MastUndSchotbruch]

Originally Posted by Minnewaska

I have a temp gauge, but it's near my ankle. No way I would notice it in time. I've seen many configurations like that. Not good, but common. If you only have a temp alarm, you will likely already have eaten the impeller or done some heat damage by the time it goes off. The flow alarm says you lost flow before she heats up or eats the rest of the impeller (in theory, as Borel explains above). Both sounds like a winner to me.

I agree, one does not stand in for the other.

I plan on installing a wet exhaust alarm and I am trying to decide between the Aqualarm and the Borel. What I like about the Aqualarm is that I do not have to cut a 2" hole, I believe that it is surface-mount (correct me if I am wrong). However, I wonder if it is loud enough. It says it uses a 'buzzer' and I am concerned that I will not be able to hear it in the cockpit if it is installed in the cabin (or vice-versa). In particular when the motor is running.

Does anyone know how loud the Aqualarm is? Is the Borel substantially louder?