Can I instal a water heater? What Kind is best?

[John and Dana]

I have just replaced my flat plate because I had water feed backward through the hot water faucet and freeze cracking the heat exchanger. I did not have time to move mine because I was getting ready for a trip when I found the problem.

Sportsmobile does not mount the flat plate inside because they are concerned that a coolant hose will break spraying steam or scalding coolant into the passenger compartment. I am sure there are some rules they must follow as a RV manufacturer on this.

I do have a suggestions that could easily allow the flat plate be mounted inside without the concern of the coolant lines. Johnny are you listening. What I would do is mount the flat plate inside with solid pipe running down through the floor of the van and then install a hose nipple under the van for the coolant lines. This would be no different from how a heater core is installed under the dash. All rubber heater lines are outside and all fresh water lines and the heat exchanger are inside. A insulated cover would probably need to be fabricated as well to keep the heat exchanger from heating up the cabin during warm weather.

I think all of us who have had to go out every night in cold weather while camping to drain the heat exchanger would agree that finding a way to mount the flat plate inside would be a significant design improvement.

John

[LanduytG]

The Flat Plate heat exchangers we have are 12 plate 3/4 male pipe for connections. Same as SMB uses.

Double wall or single if they are not drained you run a big risk of freezing. It would be a very easy thing to install a drain valve as well as well as open the sink so the system can get air to drain. When people drain them they often do not open the sink to allow air in the system. If air is not allowed to enter it will not drain completely and will leave water. I would not put one inside either just because of safety concerns. Nothing worse than a blow hose and 180* pressurized water inside the van.

Greg

[deminimis]

Thanks for all the replies on this revived thread. Lots for me to think about. The coolant heater is probably more hassle and $ than I want to mess with (you can buy a lot of Wet Ones for $1,000).

[John Kalmbach]

SMB installed the Flatplate on the exterior to minimize occupant exposure to scalding hot engine coolant in the event of a hose rupture. I've heard of folks mounting it inside in an enclosure, which is not a bad idea. Keep in mind that unless the cabin area is always above freezing temperature, having it mounted inside will not really help any, which is also a reason SMB opted for the exterior mount.

I know it can be an issue to drain the Flatplate, if you don't have the Espar Hydronic coming on occassionally to prevent freeze damage. Once the potable water in the Flatplate is drained completely, including opening the faucet valve to allow the hot water going to the faucet to drain too, then closing all the drain valves to trap air in the hot water line will prevent water from migrating into the Flatplate whenever you use the cold water at the faucet.

The coolant lines routing to the Flatplate should be in series (spliced into the engine coolant line) from the engine to prevent any disruption to the engine coolant flow for the engine.

I hope this helps.

John K.

[AndrewST]

To have hot water and air, the SMB's have 2 devices.

I am planning having one device doing both... thank to Webasto who developped the DualTop recently.
Unfortunatelly for you, it seem's to be available for time only in Europa

The dualTop has a ~3 gallon boiler, provides hot air with an autodrain and antifreeze mode.
It can be mounted outside or inside...
Forgot to mention Diesel fired.

More under:http://www.webasto-dualtop.de/index_uk.html

Hope it helps.

[monkeyboy]

Originally Posted by AndrewST

To have hot water and air, the SMB's have 2 devices.

I am planning having one device doing both... thank to Webasto who developped the DualTop recently.
Unfortunatelly for you, it seem's to be available for time only in Europa

The dualTop has a ~3 gallon boiler, provides hot air with an autodrain and antifreeze mode.
It can be mounted outside or inside...
Forgot to mention Diesel fired.

More under:http://www.webasto-dualtop.de/index_uk.html

Hope it helps.

I hoped to get one of these in my SMB Sprinter for the exact reasons you mentioned. Unfortunately it aint gonna happen (so I am going with Airtronic/Hydronic/flat plate). Here is what I got back from the SMB folks upon asking about Webasto products:

"# The Webasto dual top is unfortunately not UL listed and therefore cannot be installed in US made RVs. We can do the cooktop…just not the dual top.
# The Webasto stove would be doable. It just got approved for use in the US. I am waiting for shipment of our first unit. I expect it to cost between $2500 and $3000 installed."

[deminimis]

Originally Posted by monkeyboy

# The Webasto stove would be doable. It just got approved for use in the US. I am waiting for shipment of our first unit. I expect it to cost between $2500 and $3000 installed."

That's a lot of sushi!


Right now, the front runner for me is the Raritan marine water heater with exchanger. The 6 gallon unit is most likely, but will go with the 12 gallon unit if I can make it fit. I've got some measuring to do. I've discovered some lost space in my fridge cabinet that I would like to have used (was thinking flat plate), but this (or similar) marine unit might work best for me under the sink or in the next cabinet. The additional gallons of stored water would be very nice. The only thing that's holding me back right now (besides $) is determining the exact power consumption on 120v. If the van is running, and its sunny, I can run my microwave indefinitely, so will use that as a base line for comparison purposes I suppose. Not sure how well it will heat using the exchanger only. My guess it wouldn't be as efficient as one of the flat plates, but I would think we'd arrive at our destinations with at least 6 gallons (or 12) of warm/hot water. I need to find some real world experience regarding how quickly the unit heats water when idling and using 120v.

[Angel]

I wanted to get a PRECISION TEMP RV 500 tankless water heater from Houseneeds.com (on demand hot H20 using propane) like a friend has in a motor home. SMBW could not fit it under the sink, in my lay out, due to RV regs as to where propane is vented. My sink is in front of a door. They could have put it under my bed if they raised the bed/bench up 3 inches because the heater was 3 inches too tall. I did not want to do that. It may work for you.

Angel

[John and Dana]

John K.

I used to close the exterior drain valve on the flat plate which is how I ended up with mine freezing. My suggestion is to leave the exterior open that way any water that back feeds though the faucet can drain out. In my case water flowed though the faucet and then could not flow out because I had closed the drain valve. After a week of camping in freezing conditions and not using the flat plate it had collected enough water to freeze and crack. The most important think to do after draining, if you are using the van, is to close the hot water tap and not open it.

John

[John Kalmbach]

Yes, if you open the hot water valve at the faucet, water will migrate into the Flatplate, only the cold water valve should be used once the Flatplate is drained. Because what you experienced had happened in the past, an inline shut-off valve on the hot-water line was added on the hot-water line under the sink. With this valve "off", there was no risk of getting water into the Flatplate by accidently opening the hot-water valve at the faucet. There should also be an inline shut-off valve on the cold-water line before it goes through the floor to the Flatplate.

Be careful if you decide to install a water heater "tank" that is heated by the engine inside your SMB. I remember one having to be isolated with a valve because the amount of heat it induced into the interior was unbearable to the occupants. The reason the Suburban works so well with the motor-aid feature is because it is well insulated and vents to the exterior.

More food for thought...

John K.