Relocating a hot water heater?

[HeadedToTexas]

I am the sort who showers aboard every night as opposed to in the marina or not at all. To that end, optimizing my hot water is important to me. As built, the water heater on our mariner 37 is clear back in the lazarette. We waste several gallons waiting for the water in the line to heat up enough to shower.

While we use some hot water at the galley sink, the overhwelming majority (and most important) hot water use is in the shower forward off the master state room. We virtually never use the day head shower and have yet to use hot water at the cockpit shower.

What would it take to move and relocate the water heater to the space in the engine room forward of the workbench? Is it as simple as disconnecting power and water, moving and mounting the unit to stringers forward, then routing and reconnecting the power and water?

 

[psneeld]

I would start by looking at bigger better water heaters based on what real estate I had in the engine room for the move.

In a perfect world...I would just plumb the other in and keep that one as a spare with shutoffs.

Just this week I thought I was going to be without hot water due to a heater failure on a relatively new unit.

 

[Comodave]

I am the sort who showers aboard every night as opposed to in the marina or not at all. To that end, optimizing my hot water is important to me. As built, the water heater on our mariner 37 is clear back in the lazarette. We waste several gallons waiting for the water in the line to heat up enough to shower.

While we use some hot water at the galley sink, the overhwelming majority (and most important) hot water use is in the shower forward off the master state room. We virtually never use the day head shower and have yet to use hot water at the cockpit shower.

What would it take to move and relocate the water heater to the space in the engine room forward of the workbench? Is it as simple as disconnecting power and water, moving and mounting the unit to stringers forward, then routing and reconnecting the power and water?

Well, yes it is that simple, or maybe not so simple depending on how good access you have to the areas. I absolutely hate doing plumbing work, it always leaks and takes multiple tries to stop the leaks. I replaced the shower head faucet in our last boat. The darn thing leaked where I hooked it to the old plumbing. I took it apart at least 6 times and put it back together, still leaked. A plumber friend came over took it apart and put it back together exactly as I had done and no more leaks. Hum…

 

[rslifkin]

Relocating closer will definitely help. You could also put in a bypass to dump water from the hot water line back to the tank so you don't lose the water you run through to get the line hot.

 

[HeadedToTexas]

I've done my share of plumbing in industrial and commercial environs over the years and have gotten pretty comfortable with that. Less so with electrical, but it's just 120 VAC with the water heater. That said, while going to the trouble, why not take the opportunity to increase capacity?

Our current one is 11 gallons. What's the difference between a $500 Kuuma and a $1000 Raritan heater?

 

[HeadedToTexas]

Relocating closer will definitely help. You could also put in a bypass to dump water from the hot water line back to the tank so you don't lose the water you run through to get the line hot.

Sort of a hot water recirculation system? That would be good, but necessitate a valve in the shower area or a trip down into the engine room to actuate it so the hot water side heats up before turning on the shower, right?

 

[rslifkin]

Sort of a hot water recirculation system? That would be good, but necessitate a valve in the shower area or a trip down into the engine room to actuate it so the hot water side heats up before turning on the shower, right?

Yeah, you'd want a valve near the shower I'd think. Or an electric solenoid valve mounted somewhere convenient with a momentary switch near the shower.



As far as choosing what water heater, I've been shopping to replace mine (an aging, not well enough insulated 12 gallon Raritan with a kinda rusty looking tank). From what I've found, the Isotemp models are the best insulated ones you can buy (and the form factor is pretty easy to add more insulation if desired). I'm probably going with the 11 gallon Spa 40 for my boat.

 

[Comodave]

If you have room for a larger heater then I would do it. Keep in mind that it will take longer to get the water hot. If it is only 120 volt and doesn’t have a heat exchanger then it will be much easier to do. I would not bother trying to reroute the water back since it will make the plumbing more complicated. Maybe the most difficult part will be getting the power wiring to the new location, depends on access in your boat. But the wiring itself is pretty easy.

 

[Scottwb96]

Another added benefit of putting in the engine room, you could also plumb off the engine to help heat it. Use that "free" heating source.
The recirculation pump is also an interesting idea. We have one in our master bedroom at our house, happens to be the furthest point from our tankless gas heater. You could probably connect one at the shower location, or possibly the furthest point in the boat and it would prime the entire hot water lines. BUT, I think you would need to plumb it directly back to your tank. The water pump and/or accumulator tank may not like having that dumped right back into the pressurized system. So a "simple" return line back to your main tank would take care of that. Below is the unit we put in, I think at the time ~3 years ago I paid around $400 for it? Comes with a bush button activator and shuts off once the hot water is sensed at the unit. WORKS GREAT!!!

https://www.homedepot.com/p/Taco-Co...th-Undersink-Kit-008-CT-USK/206500089#overlay

 

[psneeld]

Actually a well insulated larger water heater even with only a 750 Watt element heats faster.

My 8 gallon Isotemp Spa with a 750 Watt element heats faster than my old 6 gallon whatever cheapo with a 1500 Watt element. Benefit...less load on the circuits so less worry about load sharing.

It also will keep water warm enough for 2 or more showers or 2 days in warmer weather such as summer cruising.it supplies enough hot water for 2 pretty long hot showers at a time...with warm enough water left over to reheat fast or do other things like dishes. That is also the way it works with engine heating during a days run.

 

[Lepke]

I recirculate hot water so it's not wasted getting a shower or sink up to temp. I use a push button at each location to turn on a circulation pump for a couple minutes using a timed relay. There's also valves so I'm not heating plumbing where there's no demand. All controlled by the buttons and relays.
Ships have constant circulation in their hot water lines.

 

[HeadedToTexas]

Recirculating hot water is common practice in land based buildings as well. Sound science.

 

[Comodave]

Yes it is in a home, but in a boat there isn’t too much to be gained unless it is a large boat. A .5” ID pipe 40’ long only contains about .4 gallons of water. Not really worth the extra effort IMO.

 

[O C Diver]

A larger water heater is beneficial if you have the space. Mine is a Raritan 20 gallon. For me, after a few hours of cruising with the engine making hot water through the heat exchanger in the water heater, I have enough hot water for 2 evenings of showers and doing dishes. I installed a tempering (mixing valve) to keep the extremely hot water at a safe level at outlets. When connected to shore power or the generator, the electric element heats to a much lower temperature (by my choice). The greater the delta between the temperature in the water heater and outside the water heater, the faster the hot water cools. Simply, it's more energy efficient to keep more stored hot water at a lower temperature. While the tempering valve makes it seem like there's no difference between engine heated water and electricly heated water in my boat, there is little cold water added through the tempering valve on electricly heated water.

My original plan was to tee the hot water line at the shower (furthest outlet from the water heater), install a valve, and then run a line to one of the water tanks. The idea was to quickly purge the hot water line into the water tank before taking a shower. Open the valve, feel the pipe, when warm close the valve and have hot water without wasting time (purging the line would be much faster than a flow restricted shower head) and water. Apparently it hasn't reached the top of the "to do list" as I think about it every time I wait for hot water before showering.

Ted

 

[Mako]

To simplify and reduce costs, instead of installing a recirculating loop with pump, you can install a valve in the shower hot water line, that when opened, runs water back into the fresh water tank.

That way you are not wasting any water at all - it is recaptured.

Some pipe and a valve. Probably $20 worth of Home Depot materials.

 

[rslifkin]

To simplify and reduce costs, instead of installing a recirculating loop with pump, you can install a valve in the shower hot water line, that when opened, runs water back into the fresh water tank.

That way you are not wasting any water at all - it is recaptured.

Some pipe and a valve. Probably $20 worth of Home Depot materials.

Agreed. The system is drawing from a tank, so need for a circulating pump to avoid waste. Just create a valve-controlled leak back to the tank.

 

[wkearney99]

Another added benefit of putting in the engine room, you could also plumb off the engine to help heat it. Use that "free" heating source.

Yeah, and if that loop fails you risk destroying an engine.

We had the elbow on the starboard C12 in our EB47 fail. It puked 12 gallons of antifreeze (at $20/per) out all over that side if the engine room. Fortunately we caught the issue right away when the heat spiked. Thankfully it's run three years since with no issues. But I'll never, ever have that setup again on any boat I own. I don't need the heat recovery enough to have that risk.

 

[Helmsman]

Hmmm….HtT, do you have the one or two state room model? If you have the one stateroom model the storage locker might be the place to put the hot water heater.. The water to the galley might have a little farther to go, but the the bathroom sink and the shower would be closer.

I wonder if insulating the hot water run from the water heater to the shower might also help.

 

[HeadedToTexas]

The two stateroom model? Can't say I've seen that floor plan nor what might be called a storage locker. Our's is a 2007 Mariner 37 and hull #3; definitely just one stateroom. Is the storage locker in the engine room through the day head? Only thing I can think that fits that description.

In my mind, our 11 gallon Seaward would fit conveniently forward of the work bench on the starboard side of the engine room. Speaking of what may be the storage locker, I have seen a picture (or Photoshop?) of a washing machine mounted in that doorway. Very cool, but how would you access the space to outward of the machine, between the machine and the port hull? There are two through hulls there that need attention from time to time.

 

[Helmsman]

The two stateroom model? Can't say I've seen that floor plan nor what might be called a storage locker. Our's is a 2007 Mariner 37 and hull #3; definitely just one stateroom. Is the storage locker in the engine room through the day head? Only thing I can think that fits that description.

In my mind, our 11 gallon Seaward would fit conveniently forward of the work bench on the starboard side of the engine room. Speaking of what may be the storage locker, I have seen a picture (or Photoshop?) of a washing machine mounted in that doorway. Very cool, but how would you access the space to outward of the machine, between the machine and the port hull? There are two through hulls there that need attention from time to time.

Here is a link to Helmsman’s site for the 37. They show both a 1 stateroom and a 2 stateroom model under the layout. Perhaps that is something that has changed in the intervening years. https://www.helmsmantrawlers.com/helmsman-trawlers/37-sedan-2/

As to the washer/dryer, that is offered as an option on the 38E. That picture isn’t photoshopped, but is a picture of the WD setup on the 38. The door where the WD is in the picture you attached is an additional engine room hatch when you don’t install a WD. I am not sure about access to the through hulls. Perhaps those are in a different place in the newer models.

 

[HeadedToTexas]

Ah-hah, the Mariner 37 became the Helmsman 38, not the Helmsman 37. Totally different boats. I see what you mean about the two stateroom 37. Also a nice boat.

As for the washer/dryer in the day head engine room access hatch blocking access to through hulls along the port hull, moving them would make sense, but the location of the washer/dryer still leaves a significant vacancy with very difficult access. Is there an additional hatch in the pilothouse sole near the port side door to access that space?

 

[Helmsman]

Ah-hah, the Mariner 37 became the Helmsman 38, not the Helmsman 37. Totally different boats. I see what you mean about the two stateroom 37. Also a nice boat.

As for the washer/dryer in the day head engine room access hatch blocking access to through hulls along the port hull, moving them would make sense, but the location of the washer/dryer still leaves a significant vacancy with very difficult access. Is there an additional hatch in the pilothouse sole near the port side door to access that space?

Yep, you are right on the Mariner 37. I learned that nomenclature early but completely forgot about the naming change.

Just the access through the pilot house center walkway. I don’t think there is a hatch access on the port side. I am not sure what the access to the back side of the W/D area would be once you are in the engine room.

 

[HeadedToTexas]

I really wanted to use the day head door for access to the engine room, but entering through the pilothouse sole is far easier on my back and knees. It has now been many months since that day head door has been opened and that has me thinking about optimizing that space. To port of that door is good bin space, but at maybe 5 feet wide, using that whole "aisle" for bin storage is a bit cumbersome. Perhaps shelves or something on the forward bulkhead?

 

[Helmsman]

I really wanted to use the day head door for access to the engine room, but entering through the pilothouse sole is far easier on my back and knees. It has now been many months since that day head door has been opened and that has me thinking about optimizing that space. To port of that door is good bin space, but at maybe 5 feet wide, using that whole "aisle" for bin storage is a bit cumbersome. Perhaps shelves or something on the forward bulkhead?

I would make anything there removable. That way you can leave the area available for a WD in the future if you ever choose to put one in. That also would be a selling point for future buyers, I think.

 

[HeadedToTexas]

Makes a lot of sense. That is certainly how that space is currently.

 

[rwidman]

Your water heater has not only the electrical connections and the potable water in and out connections, it has hoses to and from the engine so the water is heated by your running engine as well as electricity. You would have to extend these hoses as well.

 

[HeadedToTexas]

All true, but in my case every hose would get shorter with the water heater up in the engine room beneath the pilot house.

 

[Phase3]

Our boat is a 2007 Mariner 35. One stateroom. Our hwt was also in the laz.
Last year we ended up moving it to the engine room on the aft port side. We chose the ISO temp with two heat exchangers and one heater coil. Exchanger one runs to the engine coolant and the other to the Espar hydronic heater.
We have hot water anytime we want. If at anchor for more than two days and we need hot water, we simply turn on the Espar for 15 minutes.
So far it has worked flawlessly.
Also can change the fuel to the Espar so that we can select either diesel or kerosene

Brent

 

[CarlF]

Shortening the engine hoses is a plus. Try to mount the heater so it is lower than the pressure cap on the engine. This will avoid air lock problems and make it much easier to bleed.

Plumb a standard household tempering valve at the water heater that mixes in cold water and then turn the water heater temperature to maximum. This will make your hot water last about 30% longer.

 

[HeadedToTexas]

Last year we ended up moving it to the engine room on the aft port side. We chose the ISO temp with two heat exchangers and one heater coil. Exchanger one runs to the engine coolant and the other to the Espar hydronic heater.

That sounds like a great setup, Brent. So you have two heat sources, the main engine and the Espar diesel heater, and each has a heat exchanger. The main engine has coolant on the "engine side" of the heat exchanger; does the Spar have heated air on the non-domestic water side? I'm not familiar with that component.

Shortening the engine hoses is a plus. Try to mount the heater so it is lower than the pressure cap on the engine. This will avoid air lock problems and make it much easier to bleed.

Excellent point, Carl. Mine definitely will be below the main engine pressure cap in its new location, but I hadn't thought of that. Thank you.