Hot water tank

[bwasileski]

Hi.
Looking for some ideas. I have Beneteau 423 and I just replaced the 11gal Seaward hot water tank. Heats from the engine or the electrical. The installation went straight forward without any issues. Tested it out while at the dock hooked to shore power. Seemed good.

Now that I'm at the mooring (i.e. no shore power) the expectation was the motor would heat up the water. Unfortunately it's not. I thought there might be an airlock in the antifreeze lines to/from the motor so I cracked the fitting to the tank and let some antifreeze run out....Still no hot water.

Then I disconnected the lines from the motor, poured antifreeze in the feed line while holding it higher that the return and immediately antifreeze came running out. Did this twice. So there's no air in the between the motor feed and return. I let the thing run for almost an hour and still no hot water. before Installing the new tank, the hot water used to heat up in about 15min running the motor - enough to take a shower.

Anyone have any ideas of what to check next? This is purely mechanical system heat via convection - what could go wrong? Yeah, that's what I thought.

Thanks in advance.
-Bryan

 

[jssailem]

Brian.
Your motor has a thermostat. The engine needs to run hot enough and long enough to open the thermostat to get the coolant to flow through the lines. Did you see the engine temp up above the opening temperature of the thermostat?

You can measure (using an infrared temp sensor) the temp of the fitting at the water heater to see the in going temp and at the return to engine temp to see what is happening.
Sealand is a good average unit with not a lot of insulation, so expect the unit to get to temp when running the engine then cooling reasonably quickly when at rest (no coolant running through the WH)
Here is a pretty good primer on Water Heaters.
http://stevedmarineconsulting.com/water-heater-primer/

 

[arf145]

After I changed out the coolant last time, I found out that it takes a *very* long time to get my Yanmar 3GM30F hot enough to start circulating coolant when the engine isn't under load. Even in gear in the slip it took quite a while. So, if your test didn't include running under a good load, all might be just fine.

 

[cymeyer]

Hi.
Looking for some ideas. I have Beneteau 423 and I just replaced the 11gal Seaward hot water tank. Heats from the engine or the electrical. The installation went straight forward without any issues. Tested it out while at the dock hooked to shore power. Seemed good.

Now that I'm at the mooring (i.e. no shore power) the expectation was the motor would heat up the water. Unfortunately it's not. I thought there might be an airlock in the antifreeze lines to/from the motor so I cracked the fitting to the tank and let some antifreeze run out....Still no hot water.

Then I disconnected the lines from the motor, poured antifreeze in the feed line while holding it higher that the return and immediately antifreeze came running out. Did this twice. So there's no air in the between the motor feed and return. I let the thing run for almost an hour and still no hot water. before Installing the new tank, the hot water used to heat up in about 15min running the motor - enough to take a shower.

Anyone have any ideas of what to check next? This is purely mechanical system heat via convection - what could go wrong? Yeah, that's what I thought.

Thanks in advance.
-Bryan

Hi Bryan,

Are you sure this is heated from the engine? We have a B321 and believe the water heater only works with shore power.
Chris

 

[NYSail]

I have same set-up on our 423..... have not replaced but have been considering it if for nothing else a good excuse to clean underneath the tank. Our tank is same way though..... takes a while for the engine to heat up the water. Was told it’s just due to size. On my old boat I had a 6 gallon raritan on a 3HM35f yanmar. Water would be HOT in 10 minutes of running engine under load.
Good luck

Greg

 

[bwasileski]

There's really no readable thermostat on the motor, only a indicator light/horn if it starts to overheat. I ran the motor for an hour at 1500 rpm. Should have been more than enough. I had the same problem last year with it after I installed it and motored quite a long way under full load....never warmed up.

 

[bwasileski]

It's the exact same unit. The previous on heated up in about 15-20 minutes

 

[bwasileski]

Hi Bryan,

Are you sure this is heated from the engine? We have a B321 and believe the water heater only works with shore power.
Chris

I'm certain.

 

[jssailem]

Have you seen these infrared temp gauges. You can point it at a hose and get a temp reading .

Box store, Costco, Amazon, even Harbor Freight sell them $35-$50. I use it all the time on the boat to give me an indication of how systems are working.

Point it at the engine to get a base line temp. Point it at the WH coolant hose connection on the engine. Should read nearly the same temp as the engine. You know the coolant is getting heated. Point it at the WH coolant input. Is it the same or different from your engine reading. Point it at the WH coolant out connection. You should see a little difference. Not much. Point it at the connections in and out of the Heat Exchanger. Then check the temp of the coolant return to the tank. If you get funny readings anywhere along the way that is where you start your inspection.

If the Coolant "Heating" part of the system is good then your next step is to check the supply line connections to your sink faucets. It is a process of elimination. The temp gauge just saves you the time and work of disconnecting all of your hoses, lines and fittings to find your problem.

 

[jviss]

After I changed out the coolant last time, I found out that it takes a *very* long time to get my Yanmar 3GM30F hot enough to start circulating coolant when the engine isn't under load. Even in gear in the slip it took quite a while. So, if your test didn't include running under a good load, all might be just fine.

So, before you change the coolant it didn't take a long time? Was the coolant the only difference?

When you say "start circulating coolant" do you mean through the block and heat exchanger, or through the water heater?

I suspect you have an air-lock in the water heater since you changed the coolant. Make sense?

 

[jviss]

There's really no readable thermostat on the motor, only a indicator light/horn if it starts to overheat. I ran the motor for an hour at 1500 rpm. Should have been more than enough. I had the same problem last year with it after I installed it and motored quite a long way under full load....never warmed up.

I suspect an air lock. I think I have the same problem. I'm going to try to bleed mine tomorrow.

 

[jviss]

Box store, Costco, Amazon, even Harbor Freight sell them $35-$50.

I got mine on eBay for $11, shipped!

 

[NYSail]

On my feed hose I have a bleed value installed to make sure all air is out of the hw loop.


Greg

 

[arf145]

@jviss, I had no air lock. I was using an infrared temperature gauge and I could see that the engine just wasn't hot enough and the thermostat hadn't opened. Since I was in my slip, I had to put the transmission in gear and run the engine over 2000 or so to warm it up.

 

[twx]

There's really no readable thermostat on the motor, only a indicator light/horn if it starts to overheat. I ran the motor for an hour at 1500 rpm. Should have been more than enough. I had the same problem last year with it after I installed it and motored quite a long way under full load....never warmed up.

As far as engine water temp, I got a water temp kit from West Marine and installed a T fitting where the light sensor is. I then put the light sensor in one leg of the T and put the new heat gague sensor in the other side, mounted the gague in the cockpi instrument package. I now have the light and a gague.