Hot Water Tank

[hcarmich]

Hi Guys,

My 28 Riv has a hot water tank that can be heated with shore power or by one of the water cooled engines - through the heat exchanger. We think there is a break in the heat exchanger and that water is escaping.

Here is our plan, but I need some help.

1. We plan on disconnecting the hoses from the engine at the hot water tank heat exchanger connections.
2. We will install 2 valves on the connections on the hot water tank for the heat exchanger (this will close things off).

Question. Can I cap off the two hoses to/from the engine or do they need to be in a loop? The problem is it is pretty tight in there and connecting the two hoses in a loop is pretty challenging.

Really appreciate the help

thank you

[Viper]

Don't cap them off, loop them.

[hcarmich]

Ok - Can I use PVC for the loop, or brass? I don't have hose - or pex tool so looking for simplest solution.

thank you

[km1125]

You can cap them off or loop them, it doesn't matter. Do whatever is easiest just make sure you do good connections so something doesn't pop apart when you least expect it.

Do not use regular PVC... it's not rated for HOT water.

[Viper]

Looping them will make life easier come winterizing time.

[tomschauer]

Actually if you think there is a leak in the heat exchanger, pull the engine hoses off and turn on dockside water to the heater.
If there is a leak water will definitely come out of the exchanger inlet/ outlet. The dock water is 3x pressure or your engine coolant.
As such, if your problem is losing engine coolant its not there. You would be gaining coolant from the higher pressure potable water system.

[Viper]

Ya removing the one or both engine lines off the heater and turning on the water pressure will reveal if you have an exchanger leak in the tank. That's about the only water to tell in a raw water cooled engine as there's no coolant level to check.

What makes you think you have a leak there? Are you loosing water from your water tank? If so, have you eliminated other possibilities? Is there water in the bilge?

[hcarmich]

Hi Viper.

To summarize, our problem is that when we fill the water tanks (2), turn on the water pump, we are losing water. No leaks around the pump/hot water tank, no additional water in the bilge(s). All taps closed, pump turns on to pressurize the line, shuts off, then after about 4 minutes, comes on again after losing pressure. Eventually, no water left.

We suspect the heat exchanger might be the culprit.

[tomschauer]

It's possible, but i doubt it is the heat exchanger. Are your engines freshwater cooled? if so you would be overfilling the coolant and spilling out the overflow bottle.

[Viper]

From the first post, it sounds to me like it's raw water cooled engines.

A sure test would be to remove the engine lines from the hot water tank and turn on the water pressure. If water continues to run out of the exchanger ports on the tank, then you've found your leak.

When you say "no additional water in the bilge" is there ANY water in the bilge, and if so, how sure are you that there's no additional amount that is periodically being pumped overboard by the bilge pump? If there's water in the bilge, vacuum it out, turn on the pump and monitor the bilge for water accumulation. If you see water slowly accumulating, you could have a plumbing leak instead.