Does using hot water when at anchor (and there is no source for additional hot water) cause the hot water tank to fill with fresh (cold) water, thus cooling the remaining hot water in the tank? It seems it would be best for the tank to not take on any additional water until the tank could heat it. We’d like to have hot water as long as possible while at anchor and don’t know the best practice in this regard.
Hot water tank use when at anchor
- Thread starter skunther
- Start date
When you turn on the hot water faucet, the water pump detects low water pressure and pumps fresh cold water into hot water tank. This is the only way that water comes out of hot water tank. It is similar to your house hot water tank. If you need to heat the water you will have to run the engine.
If you add a valve to incoming cold water to hot water tank and close the valve you will not get any water out.
If you add a valve to incoming cold water to hot water tank and close the valve you will not get any water out.
Yep, the water in the tank is replaced with cold water. This is not all bad as the water in the tank may be as hot as 180° F. A little hot water goes a long way.
A tempering valve should be installed on the outlet side of the tank. This will mix cold water with the hot as it comes out of the tank, effectively increasing the amount of hot water that can be used.
A tempering valve should be installed on the outlet side of the tank. This will mix cold water with the hot as it comes out of the tank, effectively increasing the amount of hot water that can be used.
If it helps you sleep better at night, take some comfort in the fact that the cold water comes into the bottom of the tank and sits on the bottom of the tank and pushes the hot water out the top of the tank. There is limited mixing of cold and hot water in the tank.
Your cold water inlet and hot water outlet ARE correctly installed ARE they not ? Just a thought
.
Your cold water inlet and hot water outlet ARE correctly installed ARE they not ? Just a thought
.
Your source of hot water can be running your engine. It takes very little time to heat the contents of your tank. I'm usually running out of water and never worried about the hot water depletion. Besides, if the pump isn't replenishing the water in the tank, you aren't getting any water, hot or cold, out of the tank.
In our temperate climate our hot water lasts 3 days with one of us taking a "navy" shower and me rowing ashore for a shower every day. Rarely do we sit in one place for longer. Takes a long time for my engine to warm up while not under load so I use a Honda generator into the shorepower to heat another tank if required.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,877
If there is adequate sunshine one of the 3 gallon camp shower bags can help.
Then there is the Grand Shower bag.
10 Gallons so you have enough for friends. Make it a party.
Then there is the Grand Shower bag.
10 Gallons so you have enough for friends. Make it a party.
I'm always amazed how long the water stays hot after the engine heats up the water in the tank and we shut it down. Never been an issue for us.
Our small 4 gal. tank is well insulted, but the real "hot" water is mostly gone by late the next morning. OTOH, running the engine at a fast idle will bring it back up again in about 25 minutes.
And, yup, those "solar shower" bags will heat the water enough to hurt you, on a sunny day.
And, yup, those "solar shower" bags will heat the water enough to hurt you, on a sunny day.
My tank is extremely warm the next morning from being heated the previous day by its heat exchanger.
Interesting idea! Can you estimate how much time your Honda needs to warm up the tank and what's the power of your Honda? What's the tank capacity and approximate initial water temperature?
6 gallon Seaward heater, Honda 2000 generator, tank water probably starts in the 60's (Fahrenheit) and maybe 45 minutes or so ? I'm really guessing at the time and temp.
First thing I did on our "new" boat was to remove the 6 gallon hot water tank.
It impeded engine and thruhull access. We have a black bag but looking at the post above I think I have 3 gallonitis.
It impeded engine and thruhull access. We have a black bag but looking at the post above I think I have 3 gallonitis.
The 1500W electric element REQUIRES a Honda 2000, the 1000 will not support the load. Otherwise, using a H2000 is just like shorepower. 30-45 minutes to get to ~140, input water can be anywhere from ~60 to ~80s, that's why it's not an exact time.
Your hot water heater has two chambers. One for the fresh water sourced from your water tank and the other is attached to the cooling system of your inboard motor. When at the dock, and plugged into shore power, there is a heating element that sticks into the fresh water half of the water heater which, when the switch is on, heats the water. You NEVER want to empty that water out of the heater and leave the switch on, or that will burn out the element. When you are underway, the engine cooling system (which gets hot) runs through the second chamber in the water heater. The hot water, next to the chamber with the fresh water, heats the fresh water, which is plumbed to the hot side of your faucets, shower, etc. When you are at anchor, and the cooling system of your engine cools, it no longer heats the fresh water side. To heat the fresh water side, you have to start the engine and get it up to operating temperature so that it heats of the fresh water. Or, if your boat has a generator, then you can start that up and the heating element in the water heater will heat up your fresh water. Alternatives are on demand water heaters that are available in electric or propane systems.
looks like everyone has assumed that you have a fresh water cooled engine and the heater is connected to your engine heat exchanger. If this is the case then you probably have a five gallon hot water tank. Yes cold water is pumped from the main water tanks into the hot water tank every time the faucet is opened. However if the hot water tank is looped to the engine heat exchanger it doesn’t take long to re heat five gallons of water while the engine is running. Approximately five to ten minutes.
The hot water tank is insulated pretty well and should hold temperature for about eight hours with minimal heat loss. You can also add more insulation if you want.
if your hot water tank is not looped to the engine then as someone posted you can get a camping shower bag that is heated by solar which works quite well. We used to have two that we tied to the deck during the day and then place them into a insulated cooler with a few hand warmers and they lasted about twelve hours until morning.
The hot water tank is insulated pretty well and should hold temperature for about eight hours with minimal heat loss. You can also add more insulation if you want.
if your hot water tank is not looped to the engine then as someone posted you can get a camping shower bag that is heated by solar which works quite well. We used to have two that we tied to the deck during the day and then place them into a insulated cooler with a few hand warmers and they lasted about twelve hours until morning.
Yup, we have a solar shower for backup. Boat has a 6 gallon hot water tank, heated by element under shore power or freshwater cooling from engine heat exchanger while underway. It does keep heat well for a day or so, just thinking of those additional days. I have yet to turn on the engine to heat up more, but that may be the simplest way to go, burn less than 1/4 gallon of diesel at 30 minutes of 1500rpm. I wonder - we have plenty amp hours, maybe I can use the inverter to heat up the element? It seems not to be wired in this configuration, but I’d like that option as well. We plan to add solar, and that would likely more than make up the difference.
