Hot Water Heater Options

richard5933 · January 01, 2018, 06:02:34 PM

Quote from: luvrbus on January 01, 2018, 05:58:44 PM
I saw a Truma water heater in a high dollar RV that was vented through the floor,doesn't seem like it would be that hard to vent any brand out the bottom of a bay with a little sheet metal work.
People told me I had to have a propane fridge on outside wall with the ugly vent that didn't happen no way was I going to cut a hole in the side of the bus for a vent, that fridge is still in the middle of the bus and always worked too

Do you know if the water heaters have any type of fan to move the exhaust or are they strictly gravity? If they don't have a fan, then how well would one vent down? I'd be willing to give it a go, but it would seem that something must be done to get the hot exhaust to vent downwards when it wants to vent upwards.

Fred Mc · January 01, 2018, 08:43:44 PM

I have a Paloma demand lp hot water heater mounted to a bay bulkhead adjacent to the bay door. To exhaust the hot gases I fabricated a 4" vent tube that exits the top and goes horizontally approx. 1 ft thru a hole in the bay door.This hole is covered by a 4" round screen. Has worked fine for 30 years.

Scott & Heather · January 01, 2018, 09:44:57 PM

Richard I went through this same annoying search when building our second coach. I wanted a short stubby gas water heater. They used to exist but are now against code so they are gone. I finally went with a 40 gallon rheem with two 2000 watt heating elements. I can't help you in this department except in my case once the water is heated to the 150 degrees my thermostat is set to, I can turn both elements off and have three to four days of hot water if I'm careful. It doesn't lose much if any through the insulated casing.

Sent from my iPhone using Tapatalk Pro

chessie4905 · January 02, 2018, 04:22:47 AM

A small water heater with two big elements you can turn on at same time will heat water very quick, minimizing any generator time to every couple of days for about an hour. That amount of generator time should be tolerable and minimize extra systems. A marine heater with coolant loop are great too. But somewhat pricey. We had one in our 4104 and only occasionally needed to run the generator.

buswarrior · January 02, 2018, 05:21:15 AM

Hold on... Is there really a problem?

Have you done any temperature drop-down tests on the existing 6 gallon tank?

If you have it up to temp, via an inverter underway, or plugged in ahead of the journey...

What is the water temp in 12/24/36/48 hours?

What is the external temp of the water tank casing? Is the tank insulated well enough?

There's a lot of money can be wasted, or saved, on this....

With winter visiting most busnuts... carving holes in the door of the water bay presents new challenges in freeze protection...

so many conflicting options....

happy coaching!
buswarrior

Oonrahnjay · January 02, 2018, 05:24:52 AM

Quote from: chessie4905 on January 02, 2018, 04:22:47 AM
A small water heater with two big elements you can turn on at same time will heat water very quick, minimizing any generator time to every couple of days for about an hour. That amount of generator time should be tolerable and minimize extra systems. A marine heater with coolant loop are great too. But somewhat pricey. We had one in our 4104 and only occasionally needed to run the generator.

A comment I posted in the other thread:

" I have an Atwood 10 gallon water heater. It heats off a 120V coil, propane, and has a heat exchanger coil. If you keep the electric or propane switched on, it will rise to about 190º internal temperature. It has a built-in "tempering valve" that mixes outside water with water from the heater tank to supply water at a temperature of about 118º. I'm not sure how many mixed gallons I get, but it's a lot. Also, the hot water from the heat exchanger is "free" heat if it's come from the engine cooling system while traveling; since it's also regulated to 190º, there's no difference to the temp of the water inside the bus, no subjective feel that there's any difference, and the same amount of mixed-temp water. It also seems to be insulated pretty well.
(Washing machine manufacturers recommend a temperature of about 160º for sanitizing during washing cycle with antiscald or tempering valves at other fixture locations but I don't have a washing machine on my bus. I like the 118º setting OK.)
This works well for me; since I'm often alone or only with my wife, it would probably be different for larger families or others may need or prefer something else, but that's "doing it my way".
HTH. BH NC"

I don't remember exactly what I paid but it seemed reasonable for the capability that the Atwood gives. I remember that the step from 6-gallon to 10-gallon was a slight higher price, but once I decided to have the three inputs for heating energy, I think that the extra for heating from 120V and the heat exchanger was only about $75 more than the basic propane-only unit.
I like the heat exchanger but since in real life most of us aren't on the road enough to make it useful every day, I find that (conditions permitting) firing up the generator before breakfast, running the coffee maker and breakfast cooking, doing a battery recharge, and heating water (wife prefers a shower after breakfast anyway) works for us. We have plenty of battery for rest-of-day (not counting A/Con of course) but heavy loads are carried by the generator. Works for us, anyway.

Geoff · January 02, 2018, 06:04:23 AM

If you take the sheet metal off the exhaust you should see a round exhaust coming out of the water heater. That is where you hook up an exhaust pipe out the floor.

luvrbus · January 02, 2018, 06:19:29 AM

I have seen solar on buses for water heaters ,they say it works good we heated our pool with it and it was ok saved us a lot of money till it froze and broke

TomC · January 02, 2018, 07:19:06 AM

I saw a 4108 once that I went up to look at. When I was right next to it, I walked by the generator exhaust and discovered the generator was running only by having the exhaust hit me in the leg. The exhaust was virtually silent, and I only knew the generator was running when I put my ear on the bus and could faintly hear the generator running. It is possible to get the generator to run just about silently (think on site portable studio generators). I'm aiming at my generator in my truck to be that quiet. The big key is to have a remote radiator with electric fan and to have the generator sealed with forced air venting.
Then you can continue to use your existing electric water heater.
When we're boon docking, we run the generator 2 hours in the morning for coffee, heat the water, charge the batteries. Then sometimes again 2 hours at night. Carrying more than 2-8D batteries for house isn't an option-we don't have the room. Good Luck, TomC

Iceni John · January 02, 2018, 07:27:29 AM

Quote from: luvrbus on January 02, 2018, 06:19:29 AM
I have seen solar on buses for water heaters ,they say it works good we heated our pool with it and it was ok saved us a lot of money till it froze and broke

I plan on also having solar water heating - I've left space for two 20 sq.ft. panels that should be able to supply all my hot water in the summer, and to preheat the water in the winter so I use less propane. From what I've read, the water may get too hot in the summer, so I may need some type of thermostatic drainback system.

John

richard5933 · January 02, 2018, 07:29:35 AM

Quote from: TomC on January 02, 2018, 07:19:06 AM
I saw a 4108 once that I went up to look at. When I was right next to it, I walked by the generator exhaust and discovered the generator was running only by having the exhaust hit me in the leg. The exhaust was virtually silent, and I only knew the generator was running when I put my ear on the bus and could faintly hear the generator running. It is possible to get the generator to run just about silently (think on site portable studio generators). I'm aiming at my generator in my truck to be that quiet. The big key is to have a remote radiator with electric fan and to have the generator sealed with forced air venting.
Then you can continue to use your existing electric water heater.
When we're boon docking, we run the generator 2 hours in the morning for coffee, heat the water, charge the batteries. Then sometimes again 2 hours at night. Carrying more than 2-8D batteries for house isn't an option-we don't have the room. Good Luck, TomC

Maybe I should ask a different question... How do I silence a 44-year-old generator?

In the meantime, I am doing what I can to minimize its use.

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

luvrbus · January 02, 2018, 07:33:07 AM

I have 2 of the Sealand heaters with heat exchangers and electric I bought from Gary @B&B if anyone is looking contact me I am looking just to get my money back

buswarrior · January 02, 2018, 07:48:10 AM

Silencing a generator requires the building of a closed box, lined with sound proofing, fan-forced cooling air driven around purposefully built baffles both intake and exhaust, radiator mounted remotely with a big squirrel cage fan, ideally with 2 speed motor and somewhat under-driven for less "whoosh", the radiator air similarly re-directed through sound proofing baffles. Look up "hospital grade mufflers" for exhaust silencing purposes.

The box may be arranged such that the one squirrel cage does all your air movement through both sections. Some put the generator in one bay and the radiator next bay over through the wall.

Don't even think about this with an air-cooled unit...

Some proper calculations and measuring in sizing the airflow path so accidental flow choke points are avoided, a system of temperature measurement and alarms inside the box as well as engine parameters, a thought to fire suppression, even if it is only a well placed hole to direct a fire extinguisher into, would be important considerations.

It takes some space, and some expensive bits, but silence costs...

happy coaching!
buswarrior

oltrunt · January 02, 2018, 09:26:31 AM

I've had good luck with my air cooled genny in a sound proofed box but it did require both a pusher fan coupled to a thermostatically controlled puller fan and the remote positioning of the muffler outside of the box. I did many trial runs taking temp readings under various load levels before settling on the final design. I installed a high (200 degree) oil temp shutdown switch which as of yet hasn't activated. Sure are a lot of ways to skin a cat. Jack

lvmci · January 02, 2018, 09:52:15 AM

Hi Richard, I have had a Paloma and an EZ tankless propane water heaters. The venting I originally designed was thru the bay door, but the mechanism of bay door closure on my C3, made the exhaust venting difficult, Gary & Vans solution was thru the floor and out the billboard next to the propane heater exhaust, not a difficult venting route and there hasn't been any problems, lvmci...