Hot Water Tank
- bud37
- Admiral

- Posts: 5182
- Joined: April 23rd, 2015, 10:22 pm
- Has thanked: 604 times
- Been thanked: 1312 times
Re: Hot Water Tank
See all the previous responses in the other thread " Riviera Bilge Question ". He now has a list to one side ??
FWIW.....The above is just my opinion.
- PaulH
- Scurvy Dog

- Posts: 5
- Joined: May 21st, 2022, 8:14 pm
- Vessel Info: 1997 Carver 355 Motor Yacht, with two Mercruiser 7.4 L, MPI inboard engines.
- Location: Port Credit
- Has thanked: 5 times
- Been thanked: 1 time
Re: Hot Water Tank
I believe that I might have a similar problem. I have checked all of the onboard water connections (hot and cold) and don’t find any leaks, but my pressure water pump continues to come on every three or four minutes to restore the pressure. This happens most frequently when the hot water heater is turned on. I think that there is a crack in the hot water heat exchanger and water pressure is being lost by water escaping through the cracked heat exchanger into the raw water cooled engine. The hot water tank is 25 years old, so there could be corrosion cracking or possibly the winterization wasn’t sufficient.
How could I confirm the hot water tanks heat exchanger is the problem?
How could I confirm the hot water tanks heat exchanger is the problem?
- km1125
- Admiral

- Posts: 3657
- Joined: February 28th, 2017, 6:04 pm
- Has thanked: 81 times
- Been thanked: 1114 times
Re: Hot Water Tank
The heat exchanger is easy enough to test. Just pull the hoses off (coming from the engine) and loop them together so you can still run the engines. Then, you can either leave the heat exchanger ports open and see if any water starts leaking out, or you can put a "jumper" hose across them to seal the system. If the potable water stops its periodic pumping then you've found the cause.. if not, then continue looking. Could just be some debris in the valves of the pump too that's causing some leak-back when it's not running. For that, you can disassemble, clean and reassemble.PaulH wrote:QR_BBPOST I believe that I might have a similar problem. I have checked all of the onboard water connections (hot and cold) and don’t find any leaks, but my pressure water pump continues to come on every three or four minutes to restore the pressure. This happens most frequently when the hot water heater is turned on. I think that there is a crack in the hot water heat exchanger and water pressure is being lost by water escaping through the cracked heat exchanger into the raw water cooled engine. The hot water tank is 25 years old, so there could be corrosion cracking or possibly the winterization wasn’t sufficient.
How could I confirm the hot water tanks heat exchanger is the problem?
- PaulH
- Scurvy Dog

- Posts: 5
- Joined: May 21st, 2022, 8:14 pm
- Vessel Info: 1997 Carver 355 Motor Yacht, with two Mercruiser 7.4 L, MPI inboard engines.
- Location: Port Credit
- Has thanked: 5 times
- Been thanked: 1 time
Re: Hot Water Tank
I believe I have a leak through the heat exchanger. When the hot water tank is connected to the freshwater system the pressure pump keeps coming on every few minutes to top up the pressure. When I isolate the hot water tank from the fresh water system the pressure pump works correctly. The hot water tank heat exchanger is directly connected to the raw water cooling for the engine, so no water is coming into the inside of the boat!
- km1125
- Admiral

- Posts: 3657
- Joined: February 28th, 2017, 6:04 pm
- Has thanked: 81 times
- Been thanked: 1114 times
Re: Hot Water Tank
Did you see the previous post?PaulH wrote:QR_BBPOST I believe I have a leak through the heat exchanger. When the hot water tank is connected to the freshwater system the pressure pump keeps coming on every few minutes to top up the pressure. When I isolate the hot water tank from the fresh water system the pressure pump works correctly. The hot water tank heat exchanger is directly connected to the raw water cooling for the engine, so no water is coming into the inside of the boat!
Do you have freshwater or rawwater cooled engines?