Water Heater Coolant Line Questions

[apweng]

Good day,

Coolant lines running from engine to water heater were chaffed to near breaking level and I'm replacing them. Unfortunately when disconnecting coolant lines I didn't note which was the coolant supply and coolant return on the water heater. The heater is about 5 gallons and cylindrical in shape and probably 30 years old - sorry make and model unknown.

First Question
Does a water heater typically have specific supply and return connections? I don't see any markings on the water heater that indicate direction of flow. I'm heading to boat later this morning and can take pictures of the water heater if that helps.

Second Question
As mentioned the water heater is old, and I'm concerned for a rupture inside the water heater resulting in coolant leakage and overheating of the engine. There's a valve on the coolant return on the engine, but it doesn't look like a shutoff valve (maybe some sort of bleeder valve). This is shown in the image below. Also, in the event of a rupture to the coolant line in the water heater, I don't see anything that would allow me to bypass the water heater.

1. Is an inline valve recommended and if so would I put this on the supply side? I suppose in a pinch I could bypass the water heater and just connect the coolant supply to the return on the engine. If a valve was installed would that still mean that coolant would circulate properly to keep the engine running?

2. Is it possible to identify the type of valve in the picture below please?

Thanks!

[stormalong]

Originally Posted by apweng

First Question
Does a water heater typically have specific supply and return connections? I don't see any markings on the water heater that indicate direction of flow. I'm heading to boat later this morning and can take pictures of the water heater if that helps.

Second Question
As mentioned the water heater is old, and I'm concerned for a rupture inside the water heater resulting in coolant leakage and overheating of the engine. There's a valve on the coolant return on the engine, but it doesn't look like a shutoff valve (maybe some sort of bleeder valve). This is shown in the image below. Also, in the event of a rupture to the coolant line in the water heater, I don't see anything that would allow me to bypass the water heater.

1. Is an inline valve recommended and if so would I put this on the supply side? I suppose in a pinch I could bypass the water heater and just connect the coolant supply to the return on the engine. If a valve was installed would that still mean that coolant would circulate properly to keep the engine running?

2. Is it possible to identify the type of valve in the picture below please?

Thanks!

1) Mine is marked in and out but I doubt there is a difference.

2) Don't drink heated water, washing with it would not harm you. IMO it is far more likely that the tank will rust and leak before the heat exchanger would.

3) That valve looks like a petcock for bleeding air. It is often difficult to get air out of the engine coolant loop when it is plumbed to a water heater. An air bleed is best at the highest point in the cooling system

4) At one time I had a valve to stop the coolant from going to the water heater. It was installed by the PO. I never used it so when I repowered I took it out. If you are putting one in to stop a coolant leak at the the water heater you will need to put valves on both hoses.

[apweng]

Cruisers forum is amazing - thank you very much sir!

Scouring the innerweb for a few hours and came up with squat. Post a question to CF and I get my answer in 20 minutes - fantastic!

Now I can complete my project this weekend - thanks again!