What size hot water heater?

O C Diver said:

...pay someone to do the bleeding and only do the parts (plumbing and electric) that don't leave scars.

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I hear ya. But in my best Hal impression, "I'm sorry Dave, I'm afraid can't do that."

I just need to do the things I can do myself. It's the only way to know they're done right and the only way to know exactly what the issues are and how to handle anything else that might happen with the system. I definitely bring in mechanics when it's something above what I have experience with, but pity that poor mechanic who has a multi-hour session with me hanging over asking 400 questions. Some love it and some can't handle it.

I once had a John Deere mechanic come on to replace the oil cooler under warranty. He told me that I wasn't allowed to be in the engine room while he was working on the engine. I escorted him off the boat. The next guy had no problem with me being the little obnoxious brother.

I have a 11.5 gallon Attwood that is 27 years old, had to replace the pressure safety valve a couple of years ago. That is the only repair, we've never run out of hot water even with 4 adults and 3 Grandkids onboard. I liveaboard most of the year so it gets used a lot more than a weekender would use one. We don't have a washer but do have bathtub that my daughter used for the the kids when they were babies. Good luck

I vote for the 11G. Beyond the blood loss (I can relate!) is the issue of carrying around an extra 9G of water you may never use.

If you're cruising, you're either underway, at the dock, or at anchor. Underway the water is always hot when you arrive (you DO heat it off the main, right?) At the dock you're paying for electric already, may as well use it. At anchor you will probably be running the genset for at least an hour, once or twice a day. If after all that you STILL run out, just flip on the genset for a half hour.

Beyond the blood loss (I can relate!) is the issue of carrying around an extra 9G of water you may never use.

Actually if you run your FW tanks dry , most FW pumps will push enough air to be able to use the water in the HW system as an emergency supply.

Or you could man up, strap on the knee guards, elbow guards, steel mesh gloves, gird your loins, and HAVE AT THE BARSTARD, and get that 20 gal sucker in there..!

As a follow up to my thread, I finished the new water heater installation today. In the end, I decided to put in the exact same 20 gallon unit that was there previously. I figured that keeping the same one would mean a day of difficult installation. Reducing the size might mean many days of reduced hot water.

The installation was really hard. I re-fiberglassed and painted the shelf it sits on since it had gotten a little waterlogged as the previous tank started leaking. It doesn't really fit in the area - the A/C insulation needs to be compressed by 1/2 inch to give enough width. It couldn't tilt at all because it would hit the ceiling. It took all day but it's heating up water now.

This one better last 12 years and become the headache of the next owner...

Nice work ?!


1983 Present 42 Sundeck
Twin Lehman 135's

Jeffrey S said:

As a follow up to my thread, I finished the new water heater installation today. In the end, I decided to put in the exact same 20 gallon unit that was there previously. I figured that keeping the same one would mean a day of difficult installation. Reducing the size might mean many days of reduced hot water.

The installation was really hard. I re-fiberglassed and painted the shelf it sits on since it had gotten a little waterlogged as the previous tank started leaking. It doesn't really fit in the area - the A/C insulation needs to be compressed by 1/2 inch to give enough width. It couldn't tilt at all because it would hit the ceiling. It took all day but it's heating up water now.

This one better last 12 years and become the headache of the next owner...

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Well done.By the way did you ask one of the mods for the forum member's DIY band aids that you are entitled to. They are embossed with the Trawler Forum logo and depending on the difficulty of the job are usually awarded in packs of six.

Andy G said:

By the way did you ask one of the mods for the forum member's DIY band aids that you are entitled to.

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I definitely earned a pack of them. Three cuts on my legs, one burn on my knee (heat gun needed to remove old plumbing stuck on old tank), two punctures on fingers, and a slice across my right bicep that I have no knowledge of and my wife claims no involvement with...

Good job!

WE wash at the laundromat when cruising as it is the least hassle.

But the bride uses cold water , so the size of the HW heater would not be an issue.

Dishwasher might be a different HW requirement tho.

Complaints you will never hear:

We've got too much hot water.

No but run out of hot with a big water heater and only 120V to reheat and the recovery time can make having hot water again an eternity...

Too big a heater is just as bad as too small of one if you don't still plan a little bit.

And please don't take my word on it...there's countless pages of debate on it in the RV forums (maybe a little in the boating world but I haven't seen as much)...it's the same issue there. The debate on recovery time versus total gallons is a lot more evenly split.

I agree with the psneeld on this.

I changed a hot water system a while back and because of other modifications I had made in the ER I had to downsize to a smaller unit. At first I was not happy having to do this , however after using the new unit I realised the benefits of a quick recovery outweighed the larger capacity of the older unit with its greater down time.

As usual it's horses for courses.

By the way there is more information in the archives on this subject for anyone interested.

BandB said:

Complaints you will never hear:

We've got too much hot water.

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Quite!!

I had a 40 gallon household W/H on my boat, electric only with no heat exchanger. Well insulated with a blanket. Plenty of hot (and then warmish) water for a days of cruising without having to turn on the genset.

If I had to do it again, I would buy another large, domestic unit designed for solar purposes (built in heat exchange loop) and not spend the money on a marine unit. Of course have to add the insulation blankets.

Rheem makes GRP tanks that do not rust out and claim to loose only 5 deg F in 24 hours .

WE use a 50G in out home and it seems fine.

Any HW tank can now be converted to a heat exchanger style with an aftermarket kit.

Get the double wall style anti-freez can kill.