Instant Hot Water-(again)

[PP]

Thanks again for all the good information, especially Sean and Ruthi. Between the two of you, we've decided against the electric instant hot water heaters and are now seriously considering the Seaward or a conventional 10 gal (just 1 Tom). On the road when we need hot water and can't just heat up some on the stove, I don't mind running the jenny, since that's about the only time we run it anyway. All our other electrical needs are handled through the inverter except for the AirCond. Will and Wife

[Scott & Heather]

I'll throw in again that we ordered a 30gal 110v single element unit from Sears that has excellent long-term ratings, and we've been using it while on 30 amp service without an issue. It fits in the bay along with my 100 gallon black/grey and 100 gallon fresh tanks with room to spare. Took me just a couple of hours to plumb in and get set right. We've never run out of hot water...and my wife and I take long hot showers through a 2.5 GPM head. Unit was $299 and even looks nice under there. If you're paying nearly the same amount for a 10 gallon, why not bring it up a bit? Just a thought...we're new to this, so take what we say with a teeny tiny grain of salt 

[Sean]

.. If you're paying nearly the same amount for a 10 gallon, why not bring it up a bit? ...

Lots of reasons:

1.  The element is the same wattage, so starting from a cold start, it will take more than three times as long (and three times the energy) to get the water up to working temperature.

2.  The extra 20 gallons will add 170 pounds of weight (plus the additional weight of the larger tank) to your coach, bay floor, etc..  Water in the water heater is "inaccessible" in the sense that it does not add anything to your usable tank capacities (no way to get it out without putting more in).

3.  Depending on tank shape and orientation, that extra 20 gallons will also take up an additional 4-6 cubic feet of space, which will not then be available for other storage.

4. The larger the tank, the greater the heat losses in the system, so for a given amount of hot water usage, it will take more energy to use a tank this size.

Now, if you have a large family and your on-board water system is going to need to provide, say four or five showers a day, plus dishes, etc., then it does make sense to increase the size of the system.  But in seven years of full-timing, even with occasional guests on board, we have never, ever run out of hot water from our 11-gallon system.  In fact, I consider it rather luxurious in comparison to the 6-gallon model that my old S&S rig had.

On top of all that, a marine type unit such as the 11-gallon Seaward I mentioned gets you free hot water while you drive.  Now if all you do is go from pole to pole, that probably does not mean much, but if you do any dry camping at all, this can be a big boon.  So, yes, I'd much rather pay $300 for an 11-gallon hydronic/electric model than the same $300 for a 30-gallon electric-only household model.

FWIW and YMMV.

-Sean
http://OurOdyssey.BlogSpot.com

[Oonrahnjay]

I'm sorry that Ruthi has had such poor service from a "flow-through" water heater.  I had an "emergency replacement" of my home water heater about New Years; I went with a gas-type, externally mounted flow-through heater and have loved it.  Mine is a low-tech unit but it's provided just about perfect hot water under all the conditions that we've needed.  There is a simple heat control on it and I found that I needed to switch that "dip-switch" to the hotter position but it's always worked perfectly low-flow or high-flow.  (What may be important to know is that there's only the two of us there and we're pretty gentle with water use; a larger family may find different results, but in the seven months we've had it, the unit has worked just as we'd wanted it.)

(Also, don't know how this will translate to use in a bus conversion, but my home-use experience has been highly satisfactory.)

[Fred Mc]

Ruthi, most of these work on the pressure principle. When you open the tap the water pressure goes down, the water starts to flow and the heater comes on. If you have a shower saver head it works by restricting the water, hence the pressure remains high and the unit thinks you have turned the tap off so the heater goes out. When you adjust the tap for more hot water the same scenario repeats itself. Try taking the shower head off and you will notice that there is no fluctuation. Probably the same problem in your kitchen.

Regards

Fred Mc.

[robertglines1]

Biggest problem in our buses is constant pressure with these heaters. The surge of the pumps screws the sensors in these heaters up. The gas ones might work better. Or they might work better with a minimum of a 5 gal per minute pump and a expansion tank.  Just a observation.   Bob ps if your hooked up to city water all the time that's a differant story.

[Scott & Heather]

.. If you're paying nearly the same amount for a 10 gallon, why not bring it up a bit? ...

Lots of reasons:

1.  The element is the same wattage, so starting from a cold start, it will take more than three times as long (and three times the energy) to get the water up to working temperature.

2.  The extra 20 gallons will add 170 pounds of weight (plus the additional weight of the larger tank) to your coach, bay floor, etc..  Water in the water heater is "inaccessible" in the sense that it does not add anything to your usable tank capacities (no way to get it out without putting more in).

3.  Depending on tank shape and orientation, that extra 20 gallons will also take up an additional 4-6 cubic feet of space, which will not then be available for other storage.

4. The larger the tank, the greater the heat losses in the system, so for a given amount of hot water usage, it will take more energy to use a tank this size.

Now, if you have a large family and your on-board water system is going to need to provide, say four or five showers a day, plus dishes, etc., then it does make sense to increase the size of the system.  But in seven years of full-timing, even with occasional guests on board, we have never, ever run out of hot water from our 11-gallon system.  In fact, I consider it rather luxurious in comparison to the 6-gallon model that my old S&S rig had.

On top of all that, a marine type unit such as the 11-gallon Seaward I mentioned gets you free hot water while you drive.  Now if all you do is go from pole to pole, that probably does not mean much, but if you do any dry camping at all, this can be a big boon.  So, yes, I'd much rather pay $300 for an 11-gallon hydronic/electric model than the same $300 for a 30-gallon electric-only household model.

FWIW and YMMV.

-Sean
http://OurOdyssey.BlogSpot.com

Ohhh. Ok. This makes perfect sense...I like the concept of Hydronic heat from the engine. It is wasted heat otherwise....We're pole-to-pole people mostly so in some respects our needs are different. We love our unit, but again, our needs are different. But the unit really doesn't take up what I consider an unacceptable amount of space in the bay. 170 lbs. isn't going to cause us grief since we're weighing in at 27,000 lbs at the moment and a bit underweight (coach rides rough) and I had noticed that a few individuals have plumbed twin 10 gallon 1500 watt units in series and I figured those used more power (3000 watts total v.s. 1650 on our single element unit) and were more work..but I know they have a place too. To each his own I guess.  We have different needs since we'll hardly boondock....so I guess we have it a bit easier.

[PP]

I checked out the Seaward water heaters and I really like the stainless 11g model. (I have a thing about stainless) But the biggest benefit is its size--it should fit in nicely beside the jenny where the existing is currently habitating and I can take advantage of the heat exchanger without too much plumbing. Must admit, I'm a little nervouse about splicing into a perfectly good (ie-non leaking) cooling system. But it's all good. Thanks for the info Sean.
Fresh, I'm assuming your 30 gal is a std round home style heater. The space that I have available for my heater is square, unless I give up the slider shelf above it, but that's where I store my towbar and mounting brackets when not in use (along with emergency road flares, etc). Even then, I think a round 30 is more than we need and too wide for the space. All the same, I appreciate your input, Will

[Scott & Heather]

Yes sir...home unit. Short cylinder. I'd love to see a photo of where your Seaward will go...I'm trying to envision in near the genny...and we're new to this, so we're not necessarily utilizing our space as efficiently as we should be...

[PP]

Scott and Heather, it must be nice to not have to worry about space constraints LOL
Will  
I will get you a picture in the near future and post it for you.

[PP]

Scott and Heather, I checked out your bus on the other thread, WAY COOL! The slide show brought back memories of when the wife and I did our Skoolie way back in the .....
Anyway, here are the pictures I promised. In the second one you can see where the circuit board is melted. Will

[Scott & Heather]

Great pics! I didn't realize for some reason that you had a Prevost. Typically, the bay MCI's use for the genset wouldn't be shaped quite like yours. Now I get it *smacks forehead with hand*.  From the looks of the pic, you'd never want a house-type unit. Would love to see a pic of the new stainless 11g when you get it. Maybe one day we'll get one when we buy a weight bench and install it on a slide-out tray where our old 30 gallon water heater was