Water Heater Access

[KenKrawford]

I’ve never poked around in the bowels of my boat before but need to do some checks on my water heater. Is the locker on the swim platform the easiest/best access point? I sure hope not cause it looks really tight.

[remote779]

That’s it!

[remote779]

But lots more room inside

[Interlude35]

I usually access the hot water (HWH) thru the stern port hatch - it is a bit tight. Another alternative is via port hatch in the cockpit ( requires removal of four screws and removing the storage shelf). Once below, I access the HWH by sitting on port side and reaching over.

[KenKrawford]

Thanks for the info. In case the problem is a blocked check valve, does anyone know the inside diameter of the coolant hose?

[Bob_A]

Ken,
They should be 3/4"

[Interlude35]

HI Ken- per the Seward Owner’s manual the coolant is 5/8” ID Hose. I could not find the water hose size - manual mentions 1/2” NPT fittings. John

[Bob_A]

My apologies Ken,
The hose are indeed 5/8" ID
Mine lead aft to a small heat exchanger prior to the HWT due to the hydronic heating system.

[KenKrawford]

Thanks for the info. Kudos to John Ferguson. I removed the shelf from the port cockpit locker and had tons of room to work. MUCH better than the swim platform locker. I didn't find the check valve. The only thing I saw on the coolant hose was the drain petcock located on the end of the nylon T just before the coolant hose attaches to the heater. Am I in the wrong area?

[Olivia Mae]

Ken, that sounds like what we have on our boat. I'm not aware of any check valve on the engine cooling lines to the water heater. What problem are you chasing? Do you have no hot water when the engine is running but hot water when the boat is plugged in to shore power?

[KenKrawford]

Scott That's exactly what's going on - tepid hot water after motoring, normal hot water when plugged in. I have bled coolant out of the valve by the heater and on the engine manifold but still no change. I was working on this a couple of days ago and looked high and low for the check valve mention but I'm convinced there isn't one on my system. I'm glad you confirmed this.

[Interlude35]

Hi Ken -Our Seaward hot water heater (HWH) never really produced hot water from the engine yet it was great when heated by the AC electrical power. I tried bleeding the system but the HWH performance never changed.

The Universal Diesel Operators Manual on page 33 states “If any portion of the heating circuit rises above the engine closed cooling system pressure cap, then a pressurized (aluminum) remote expansion tank (Kit # 024177) must be installed in the circuit to become the highest point.” I believe the hot water heater and connection hoses are about 3” higher than the engine closed cooling system pressure cap which could cause the HWH to become air-bound.

I decided to install a remote expansion tank to solve the problem. At the same time I replaced the HWH with a Isotemp HWH that has a Thermostat Mixer Valve. The Isotemp HWH is smaller and better insulated. I was concerned if remote expansion tank solved the HWH performance issues, the potable water temperature could become very hot. The Thermostat Mixer Valve regulates/limits the potable water temperature preventing a possible injury from excessively hot water.

The changes solved the problem. I think the remote expansion tank being the high point in the cooling loop prevented the HWH from becoming air bound. Since I changed the HWH at the same time I cannot be 100% sure. I have a write-up on the details I would be happy to sent to you. John

[Olivia Mae]

I would agree that the water heater may be higher than the engine by a little bit. The last time I changed coolant in the engine, I had to bleed the system at both the engine and water heater. That said, we have always gotten very hot water out of ours when motoring so not sure what to suggest as you've already bled any air out.

[wolfe10]

Yup, put a rag under the bleed at the water heater and start the engine. Leave at idle.

Open the bleed valve at the water heater and let it run until all the air is out of it.

No question, with circulation, the water WILL be hot after motoring.