Water & Heating System - help with our design/diagram?

[Jocke]

Hi all,

This is my first post here, so I think it's appropriate to first say thanks to everybody who's posting and replying to posts. There's so much information to digest and this site is truly valuable. Thank you all!

I've been lurking, reading, researching, searching, etc and I've done an attempt in designing our water and heating system. This is based on so many resources on the net and books that it all makes my head spin.

I'd love to hear your thoughts on our diagram - attached as PDF and PNG. I think I've got many "in theory" parts figured out but there's still some practical points that I haven't figured out fully. Also we're very keen on hearing your thoughts of what components to use, or even more important, which ones not to use. So all info and tips are greatly appreciated!

The idea is to build an Overland Camper based on an ex-Bundeswehr Unimog U1300L. As it's an old vehicle and we might end up in colder climates, we want to be able to heat the engine (maybe truck cab and even truck batteries). We're also planning a shower so we need hot water for that. For heat distribution we're thinking of underfloor heating, a fan assisted water-to-air heat exchanger, (maybe a towel rail too). Powered by a diesel heater such as an Eberspacher Hydronic unit - to be decided.

The things that I haven't really figured out yet.
1) Where to plumb into the engine? I thought that the hot return pipe between the engine and the radiator would be a good idea. But then, when heating the engine from the camper heater we'd be losing heat through the radiator. Or where's the best spot to plumb in?
2) I'm assuming the engine water loop needs a pump so that we can force the water round the block?!
3) Will heating the block, with the aforementioned pump, also heat the truck cabin if I switch on the truck cab heater and power up the truck cab fan?
4) I've specced a two-coil calorifier (with electric heater element), one for the engine heating loop and one for the camper heating loop. The idea is to keep the camper heating circuit separate from the truck engine heating circuit. I've also added a plate heat exchanger between these two loops. Is this required or have I over-engineered it all? If so, which components are superfluous?
5) I'm also assuming that the truck engine loop should be turn-off:able with some valves so that a) the engine can heat up properly before putting heat into the calorifier and/or camper, but also in the other direction; b) to not waste heat on the block when stationary for longer periods? I've specced two valves there. Is that how it's done?
6) I'm also assuming the camper heating loop needs a safety valve and an expansion tank?!
7) Naturally all parts need to be able to be drained and bled of air.
8) What philosophy should I adapt with regards to pumps? Where do I position them? Are they needed?

Like I said, my head's spinning from all this (and the electrical diagram too!) I'm sure I've got tons more questions, but one step at a time.

And thanks again for all your insights and any tips and thoughts you might have.

 

[NatersXJ6]

So... I’ve never done what you are trying, but... the reliability engineer in the back of my head says try for a more simple system.

Use a single heater that ties into the block and have a valve to cut off the camper heat loop when not wanted. Either use a heater with a pump or get a separate electric pump. You won’t need a huge pump because you are not cooling from multiple hundreds of degrees down to 200 or so, you are instead heating from maybe -20 to 130 or so. Huge difference in total heat movement. Will you lose heat from the radiator? Yes, but not very much because there will be no airflow. Still concerned? Get a snap on winterfront. Cycle the heat in the right order, and you can probably get away with very small heater. I couldn’t see your diagram but I think I would flow through the block, then the floor, then the water heat exchanger, and not worry about a towel rack. Heating the block will allow the blower to heat the air flowing through the normal vents, but I’m guessing a heated floor will make all of that unnecessary. You could go from hot water heater to a water/air exchanger with a separate fan for the camper if you wanted to be certain. It sounds like fun. There will be lots of covered/hidden piping, so make sure to use high quality materials that are compatible with your antifreeze technology. Not a good time to get surprise corrosion, gelling, or precipitates!

After reading my post, I realized that you won’t want a hot floor in summer, so maybe water heater, then floor, you can short circuit back to block and keep the floor cool.

 

[Jocke]

So... I’ve never done what you are trying, but... the reliability engineer in the back of my head says try for a more simple system.

I've never done this before either. But I do agree with you that simplicity is very important. Complications are failure points.

Use a single heater that ties into the block and have a valve to cut off the camper heat loop when not wanted. Either use a heater with a pump or get a separate electric pump. You won’t need a huge pump because you are not cooling from multiple hundreds of degrees down to 200 or so, you are instead heating from maybe -20 to 130 or so. Huge difference in total heat movement. Will you lose heat from the radiator? Yes, but not very much because there will be no airflow. Still concerned? Get a snap on winterfront.

I thought of wrapping the radiator in a blanket or some other material. Few pieces of cardboard would probably stop heat loss in howling wind..
As for block heating, I'm thinking that from ~ -20ºC up to +10ºC is enough to get an old 'Mog engine fired up. It's a big lump of metal though.

Cycle the heat in the right order, and you can probably get away with very small heater. I couldn’t see your diagram but I think I would flow through the block, then the floor, then the water heat exchanger, and not worry about a towel rack. Heating the block will allow the blower to heat the air flowing through the normal vents, but I’m guessing a heated floor will make all of that unnecessary.

As this would have a separate (with a hatch) camper from the truck cab, having heat in the truck cab all the time would be a waste of energy. However, thawing and de-misting the windows whilst heating the engine block would be very beneficial for cold morning starts. This is why I'm wondering whether I need to have anything else connected to enable truck cab heating? I think it would be very easy to add a secondary power supply to the truck cab heater matrix fan to enhance the flow from the heater matrix to the air. However, what I don't know is whether the hot coolant from the block will reach the truck cab heater matrix by itself or do I need to add a pump or extra plumbing (I should probably ask this on the Unimog forum).

You could go from hot water heater to a water/air exchanger with a separate fan for the camper if you wanted to be certain. It sounds like fun. There will be lots of covered/hidden piping, so make sure to use high quality materials that are compatible with your antifreeze technology. Not a good time to get surprise corrosion, gelling, or precipitates!

Yes, I do not want water leaks... like, never ever.

After reading my post, I realized that you won’t want a hot floor in summer, so maybe water heater, then floor, you can short circuit back to block and keep the floor cool.

Regardless, I think every heating element (floor, radiator, towel rail, whatever's installed) would need their own thermostat so that we don't get sautéed in the desert.

One thing that worries me a bit with the simplicity vs. complexity is that if there's only one water circuit, then damage to the one water circuit might leave us without the ability to run the engine (and get out of trouble). This is partially why I specced a separate circuit for the truck engine and the camper.

Thanks for your input!

 

[Joe917]

1.The heater installation manual gives all appropriate attachment options, Webasto, Espar etc. Closing a valve on one side of the loop to the ebgine will stop coolant circulating through the block. Leaving the other side of the loop open allows the camper loop to expand into the vehicles expansion tank. There is no heat loss through the radiator(the thermostat will be closed at heating temps). the block is a huge point of heat loss so you need to avoid running heated coolant through it unless it is for starting preheat. NEVER use cardboard to block airflow through a radiator. It quickly brakes down and permanently impairs radiator performance. It also does nothing if thermostat is working correctly.
The only pump required is the one that comes with the heater. The engine pump will circulate the coolant when the engine is running the heater pump will do it during the heat cycle. You only need a pupm for the engine if you separate the engine and camper loops with a heat exchanger, I believe an unnecessary complication.
4. over engeneered waste. one coolant system one coil calorifier.
Attached is our simple Webasto plan (Webasto Italy) This has been in operation in our truck for 25 years. The Webasto unit (now Thermotop C) was replaced approx 4 years ago. All Camper pipes are PEX with crimp fittings. Controlled by Heatmiser Slimline thermostat.

 

[grizzlyj]

Hi

If you are having a plate exchanger between engine and camper circuit then turning off the engine pre-heating pump will stop camper heat getting into the block, valve not needed? Or if it is you only need one to stop the flow at least.

What is the normal starting temperatures a Mog is designed to start down to? -20C? So pre heating isn't normally needed. It will help, and minimise smoke on start up, but not needed.

When we had a D5WS Eberspacher on a U1300l the heater was behind the front right bumper where the hydraulic tank might be, with connections into the cab heater matrix smaller pipes (I think). Pipes followed the chassis rail then up through the front right camper floor corner. There will probably be specific bits recommended by Eber to connect to that quite common engine? The water pump for an Eber like that may well be attached to it?

If you are separating engine and camper circuits then having both still going through the calorifier is a bit ott? We were told to use a twin coil but with the one heater circuit to go through twice for a quicker heat up. Wether that actually is the case I don't know yet because this install is not yet complete.
If you are having a crawl through then with a toasty camper in the morning before a drive, just open the door before leaving to assist cab warmth and demist? One thing you may end up addressing is how quickly the truck air system loses pressure once turned off. But when you start up from zero pressure you will sit there 5 mins waiting for the pressure to come up before driving off.

I know a lot of people talk about under floor heating in a camper, but someone on here actually worked out how much heat it could release for a given area vs how much needed for a given level of camper insulation. It will make the floor feel nice but even if you heat the whole floor I don't think there's enough area? And I still don't get how you can blend the hot water down to a comfortable temperature to stand on if mimicking a domestic set up? Or do you just need an air cushion between 90 degree pipe and where your feet are?

Or, with a twin coil calorifier, could you make use of that as the plate heat exchanger between the two water circuits? Or would that be really inefficient?

A purifying water filter will slow down water flow, and maybe you could just filter a feed to a dedicated tap for drinking? Then leave the pump to provide max flow for showering? (Have a look here for given flow rates through Katadyn filters varying through one filter housing (1h), up to four (4h) You need 0.2 micron to purify https://www.famous-water-shop.com/e...ies/Wasser/waterjack/waterjack_fresh_assembly)

The thermostat on the air blower would be to turn the fan off not the water input?

Why do you have a non-return valve at the camper water pump? The water that could flow back will only be clean from what you've drawn?

The Surejust calorifiers that I've mentioned before on here do suggest an expansion tank is required near to the calorifier, and have suggestions on size. Their calorifiers do have a pressure release valve too though.

If the water tanks are inside then they won't need heating while you're using the camper, but everything will need draining if you park it up un heated for a while, so I don't think water heaters in the tanks are worth it?

I would like a towel rail to dry towels (!) or rain coats without having the fan blowing. I was going to bend 22mm copper to form one to suit one bit of space until my better half requested more cupboard space instead.

And as I often do, I'd suggest looking at Ulrich Dolde's book which can be a pdf download. And have you seen Atkinson Vos now sell an empty camper box to suit a U1300l? Looks nice.

Good luck!

 

[Plumb Bob]

I'm also working out options for my heating systems and redundancy. I'm a plumber and boiler installer by trade, so I understand heat loads and heat transfer with fluids. My 10 foot camper works out to a 5200 btu/ hr load, approx 1.5 KW, maintaining 70F at 0F outdoor.
With only 80 square feet of available floor space, radiant floor heat alone is not an option, it would require 62 BTU/ sq ft, typical radiant floors output mid to high 20's BTU/ sq ft.

My first heat source is a small wood fired heater I have a Cubic Mini out of Canada. Sits on countertop next to sink for easy clean up. I added a homebuilt copper tube heat exchanger to the outside for heating domestic water, it heats the 6 gallon Dometic LP water heater. Burning scrap lumber I can raise the camper from around 20F to 70F in about 1 hour. Probably not safe or practical to run the wood stove while traveling down the highway however.

* Please invest in a top quality CO detector when burning any fuel inside, including wood.

My 2K generator will run an electric space heater of around 1K, or from shore power.

I'd like to heat from the Fuso diesel also, I'll try a flat plate HX in the coolant loop, and a small forced fan convector in the camper. 12V DC circulators are available, I use the B&G/ Laing DS solar version, it runs off my solar PV or truck batteries. This small circulator flows the PG fluid to various heater options. The heat exchanger will keep the truck coolant separate form my heating circuits, now the ability to regulate is on the camper side of the HX, more control options this way, I feel. If the truck coolant temperature is too low, a snap disc thermal control will drop power to the D5 circulator.

I'm still noodling some sort of HX to wrap around the outside of the exhaust pipe, lot of energy goes out there, and it is right under where I need it I don't think running down the road I could recover much, but standing still I think I could find 1- 1.5 KW of exhaust energy?

Once you have your thermal energy in a fluid, I use non toxic PG glycols, now you have many options from air coils, towel bars, panel radiators, floor, ceiling and wall radiant, etc.

I built a 8X20 tiny home and cover the load with radiant floors and radiant walls. It has much better R-value however, my camper is 1 and 1.5 foam in walls and ceilings and single pane windows.

 

[Plumb Bob]

Some additional heater thoughts and prototypes. This is a common kick space forced convectors. Used to add additional heat to a kitchen for example, fits in the toe kick space, ties into a hydronic, hot water, boiler system.
I added q 120V 1KW element into a copper tube so it could be powered from my generator, or shore power. It will also be heated from the copper wood stove heat exchanger and possibly the HX in the diesel coolant circuit. So this give me multiple heat sources and fuels. As much as I hate blower noice, these kickspace heaters are fairly quiet, much quieter the any electric space heater I've found. For quick heat up you really need a fan forcing convection, radiant or panel rads are to slow for a quick morning warm up. For me anyways.

 

[Jocke]

1.The heater installation manual gives all appropriate attachment options, Webasto, Espar etc.

Cool! Makes sense, however, I don't have a manual yet because I don't know what to buy because I don't know how they connect which is in the manual which I don't have...

Closing a valve on one side of the loop to the ebgine will stop coolant circulating through the block. Leaving the other side of the loop open allows the camper loop to expand into the vehicles expansion tank.

That makes so much sense now when you've typed it out! Thanks!

There is no heat loss through the radiator(the thermostat will be closed at heating temps). the block is a huge point of heat loss so you need to avoid running heated coolant through it unless it is for starting preheat.

Check!

NEVER use cardboard to block airflow through a radiator. It quickly brakes down and permanently impairs radiator performance. It also does nothing if thermostat is working correctly.

Got it! I was merely thinking of preventing a gale howling through the radiator core whilst the engine warms up, but if there's no need, then there's no need. However, must say I've used cardboard during winter hours in temps at around -10ºC to -25ºC on other vehicles.

The only pump required is the one that comes with the heater. The engine pump will circulate the coolant when the engine is running the heater pump will do it during the heat cycle. You only need a pupm for the engine if you separate the engine and camper loops with a heat exchanger, I believe an unnecessary complication.

Good points! I would have thought that "just t-ing off the engine coolant" wouldn't have enough flow from the engine water pump, but I might have too little knowledge and/or misunderstood something. I also think I've read somewhere that additional pumps have been needed, I'll have to go back to those forum posts and re-read. I find that I need to do that as my understanding grows anyway.

4. over engeneered waste. one coolant system one coil calorifier.

Check!
However, is there any issues with potentially damaging the coolant loop and thus losing both heating and the ability to drive? Or am I being overly cautious?

Attached is our simple Webasto plan (Webasto Italy) This has been in operation in our truck for 25 years. The Webasto unit (now Thermotop C) was replaced approx 4 years ago. All Camper pipes are PEX with crimp fittings. Controlled by Heatmiser Slimline thermostat.

Thanks! Much appreciated. I'll stick the words through Google Translate next to make sure I understand it. Looks very simple, I like that.


Thanks for your reply!

 

[Jocke]

Hey!

If you are having a plate exchanger between engine and camper circuit then turning off the engine pre-heating pump will stop camper heat getting into the block, valve not needed? Or if it is you only need one to stop the flow at least.

Well, this is where I need the wisdom of the esteemed panel. Personally I like valves so that I can shut off circuits if needed. Keep in mind that my plumbing expertise only includes relocating a radiator, installing taps and such. Nothing complicated, in other words.

What is the normal starting temperatures a Mog is designed to start down to? -20C? So pre heating isn't normally needed. It will help, and minimise smoke on start up, but not needed.

I am indeed worried about smoke. If we'd be starting up in a location where there's other people then I don't want to suffocate them for 15 minutes to get going.

When we had a D5WS Eberspacher on a U1300l the heater was behind the front right bumper where the hydraulic tank might be, with connections into the cab heater matrix smaller pipes (I think). Pipes followed the chassis rail then up through the front right camper floor corner. There will probably be specific bits recommended by Eber to connect to that quite common engine? The water pump for an Eber like that may well be attached to it?

Got it! Interesting. So through the cab heater matrix to the engine?
I'm all for moving stuff out of the camper as it'll be small as it is without too much technical gubbins in there.

If you are separating engine and camper circuits then having both still going through the calorifier is a bit ott? We were told to use a twin coil but with the one heater circuit to go through twice for a quicker heat up. Wether that actually is the case I don't know yet because this install is not yet complete.

Good idea to use two circuits to get quicker heat transfer.
I don't know if the two coils in the calorifier are designed for different heat sources, I obviously thought they are. The reason why I specified the two circuits is a) it seemed logical , b) keeping things separate seemed like a good idea , c) I dunno, I'm just overthinking things. d) see c).

If you are having a crawl through then with a toasty camper in the morning before a drive, just open the door before leaving to assist cab warmth and demist? One thing you may end up addressing is how quickly the truck air system loses pressure once turned off. But when you start up from zero pressure you will sit there 5 mins waiting for the pressure to come up before driving off.

Yeah, we're planning a crawl through. However, I wouldn't think it would be enough to just open the hatch and thaw a few centimetres of snow off the cab. And it'll make it cold in the camper anyway.

I know a lot of people talk about under floor heating in a camper, but someone on here actually worked out how much heat it could release for a given area vs how much needed for a given level of camper insulation. It will make the floor feel nice but even if you heat the whole floor I don't think there's enough area? And I still don't get how you can blend the hot water down to a comfortable temperature to stand on if mimicking a domestic set up? Or do you just need an air cushion between 90 degree pipe and where your feet are?

The underfloor heating is purely a comfort an luxury item. If we are going to build all this from scratch on our own, then I want the luxury of warm and toasty feet. I think it'll be there only to maintain a bit of heat, rather than actually raise the temperature up. I also want it on the floors inside the cupboards, benches, and perhaps even in the garage, to keep moisture away (along with ample ventilation).
The temperature would be controlled just like regular radiators with a thermostat.

Or, with a twin coil calorifier, could you make use of that as the plate heat exchanger between the two water circuits? Or would that be really inefficient?

No idea again. I'm just assuming that the heat transfer between coil 1 and coil 2 through the hot water wouldn't be enough, which is why I specced the plate heat exchanger in the diagram.

A purifying water filter will slow down water flow, and maybe you could just filter a feed to a dedicated tap for drinking? Then leave the pump to provide max flow for showering? (Have a look here for given flow rates through Katadyn filters varying through one filter housing (1h), up to four (4h) You need 0.2 micron to purify https://www.famous-water-shop.com/epages/62572049.sf/en_GB/?ViewObjectPath=/Shops/62572049/Categories/Wasser/waterjack/waterjack_fresh_assembly)

Yes, I've been considering using only purified water in the kitchen and toilet sink. Or even have a separate drinking only tap. Again, I need to go back to the Famous Water site now when I have a slightly better understanding of things. However, from Ulrich's book, I understood that he's filtering everything through the Famous Water filters, which is why I just copied it and stuck it in my diagram.

The thermostat on the air blower would be to turn the fan off not the water input?

My intention was to control the water temperature, but it might not be necessary. My reasoning was that if we're in a hot area, then we don't want any hot water in the blower's matrix to, even passively, heat the camper up. We still might want hot water for washing the dishes though.

Why do you have a non-return valve at the camper water pump? The water that could flow back will only be clean from what you've drawn?

A (house) plumber friend of mine recommended this. It seemed like a good idea to me too, as I wouldn't want water running "backwards" on principle.

The Surejust calorifiers that I've mentioned before on here do suggest an expansion tank is required near to the calorifier, and have suggestions on size. Their calorifiers do have a pressure release valve too though.

Good info, thanks!

If the water tanks are inside then they won't need heating while you're using the camper, but everything will need draining if you park it up un heated for a while, so I don't think water heaters in the tanks are worth it?

I think you're right on this. It could be phase 2 if needed. I don't think it would be too complicated to do a supplementary install to heat water tanks if needed.

I would like a towel rail to dry towels (!) or rain coats without having the fan blowing. I was going to bend 22mm copper to form one to suit one bit of space until my better half requested more cupboard space instead.

Yeah, I've come to appreciate dry towels so that's why we're toying with the idea of a towel rail, but space is at a premium so it might not fit.

And as I often do, I'd suggest looking at Ulrich Dolde's book which can be a pdf download. And have you seen Atkinson Vos now sell an empty camper box to suit a U1300l? Looks nice.

Got Ulrich's book, and I keep re-reading parts of it as we progress. The AV box is not only expensive, but also just a composite sandwich design which means no motorbikes or spare tyres on the back (both of these items are still being determined). This is why we're planning a steel box section skeleton (yes, I'm aware of thermal bridging, etc, etc).

Good luck!

Thank you! Might need a heap-load of that! Thanks for your reply! Much appreciated!

 

[Jocke]

I'm also working out options for my heating systems and redundancy. I'm a plumber and boiler installer by trade, so I understand heat loads and heat transfer with fluids. My 10 foot camper works out to a 5200 btu/ hr load, approx 1.5 KW, maintaining 70F at 0F outdoor.
With only 80 square feet of available floor space, radiant floor heat alone is not an option, it would require 62 BTU/ sq ft, typical radiant floors output mid to high 20's BTU/ sq ft.

Thanks for replying! Good to have a plumber around!
Very interesting re the calculations. I kind of had the idea that the underfloor heating would not be the primary source of heat. I just really hate cold floors and cold feet, and as I've said above, I would like to heat the floors in the cupboards, etc from the underside to avoid moisture collecting, but primarily it's comfort. The water-to-air heat exchanger(s) will be the main source of raising and maintaining the heat.

But still, very interesting that you've done the calculations. Thank you!

My first heat source is a small wood fired heater I have a Cubic Mini out of Canada. Sits on countertop next to sink for easy clean up. I added a homebuilt copper tube heat exchanger to the outside for heating domestic water, it heats the 6 gallon Dometic LP water heater. Burning scrap lumber I can raise the camper from around 20F to 70F in about 1 hour. Probably not safe or practical to run the wood stove while traveling down the highway however.

I'd love a wood fire, but I think we won't have the space. Interior design hasn't started yet, so if I find that there's is a small nook where it can go, then I'll definitely put one in.

* Please invest in a top quality CO detector when burning any fuel inside, including wood.

Yes, we're thinking of having two, just for redundancy.

My 2K generator will run an electric space heater of around 1K, or from shore power.

We are hoping to do without a generator (and shore power for most of the time).

I'd like to heat from the Fuso diesel also, I'll try a flat plate HX in the coolant loop, and a small forced fan convector in the camper. 12V DC circulators are available, I use the B&G/ Laing DS solar version, it runs off my solar PV or truck batteries. This small circulator flows the PG fluid to various heater options. The heat exchanger will keep the truck coolant separate form my heating circuits, now the ability to regulate is on the camper side of the HX, more control options this way, I feel. If the truck coolant temperature is too low, a snap disc thermal control will drop power to the D5 circulator.

Interesting, thank you! A vote for separate circuits.

I'm still noodling some sort of HX to wrap around the outside of the exhaust pipe, lot of energy goes out there, and it is right under where I need it I don't think running down the road I could recover much, but standing still I think I could find 1- 1.5 KW of exhaust energy?

I do think it's a wasted heat, indeed, however with the engine coolant being easier, I don't know how much bang-for-the-buck it would yield?!

Once you have your thermal energy in a fluid, I use non toxic PG glycols, now you have many options from air coils, towel bars, panel radiators, floor, ceiling and wall radiant, etc.

Yup!

I built a 8X20 tiny home and cover the load with radiant floors and radiant walls. It has much better R-value however, my camper is 1 and 1.5 foam in walls and ceilings and single pane windows.

Ah, right. Again, very interesting. We're thinking 50-60mm foam insulation in the walls, probably a bit more in the floor, and Outbound windows/doors. Still to be determined though.

Thanks for your reply!

 

[Jocke]

Some additional heater thoughts and prototypes. This is a common kick space forced convectors. Used to add additional heat to a kitchen for example, fits in the toe kick space, ties into a hydronic, hot water, boiler system.

Very interesting! This has given me some ideas. Maybe just to create a heat barrier at the door and the crawl through...

I added q 120V 1KW element into a copper tube so it could be powered from my generator, or shore power. It will also be heated from the copper wood stove heat exchanger and possibly the HX in the diesel coolant circuit. So this give me multiple heat sources and fuels. As much as I hate blower noice, these kickspace heaters are fairly quiet, much quieter the any electric space heater I've found. For quick heat up you really need a fan forcing convection, radiant or panel rads are to slow for a quick morning warm up. For me anyways.

Very neat, and yes, I wasn't expecting "regular radiators" or the underfloor heating to raise the temperature quickly, but maybe maintain it a bit to prevent instant drop, especially when sleeping and you don't want fans running.

Thanks!

 

[grizzlyj]

How will you control camper coolant water temperature?
You seem to suggest doing that for the air blown heater inlet and for the underfloor? As far as I know a domestic underfloor heating system has the hot water from whatever source blended down to the required temperature with mains cold water. A hydronic heater produces water at maybe 90 degrees C, and cycles on and off to maintain that within it's set range. Not 40 degrees down one pipe, 90 down another. I know a 12v Webasto a year or two ago did have a low temperature circuit for underfloor heating, and normal campers at the higher end seem to have it, but I don't know how?

Eberspacher air heaters are "allowed" in the living compartment water heaters are not because if they fail you might get fumes inside from what they told me.

You can google the fitting and user instructions for Ebers.

A U1300l has at 7500kg gross about two tons of payload up from a bare chassis. Some get uprated to 8500kg (I'm not sure what if anything needs changing on the chassis? Brakes?) but in the EU you then need a Class C licence which is cost and time but well worth it. Those two tons will get eaten up in a heartbeat unless you keep every spare kg out. You may find a motorbike on the back is impossible without overloading the back axle unless you minimise the rear extent of the camper box. A U1300 for instance (no l) has a tiny rear chassis overhang to allow carrying heavier stuff off the back (3 point linkage etc). AV may have designed their camper like that because they know putting all that weight on the back is not good. Ulrich Dolde suggested an assembled F&F cabin without sloping section, or subframe or windows/doors was €23,440 at 4.5m long (too big for a U1300l), is AV more than that?

Our Mog steel framed camper box was built too heavy by a UK body builder, and had a pair of 14.50R20 spares mounted on a frame within the camper walls. Because of it's excess weight we swapped the camper over onto a U1700 and chose to have bigger heavier tyres. To carry those spares A Vos extended the chassis to the back of the camper for them to sit on.

You may not easily get answers, but once we discovered how overweight our U1300l camper was (made and fitted out by the last owner and snapped up by us thinking it was a bargain rather than self build ourselves), and you start looking at how tail down a lot of them are, and asking the weight of those who have one or of ones for sale, you realise how many are a ton plus too much, ours was about a ton and a half too much empty. Or maybe a better way of looking at that is every single one is overweight unless it was built with weight in mind from day 1, or is tiny. If you really want a Mog and a bike, unless your box will be tiny and light, you may want to look at a bigger Mog. A 7.5 ton U1300l with standard hp won't keep up with most traffic either. Slightly higher fuel comsumption and the licence are the major downsides to a bigger Mog, dimensionally they can be pretty much the same. Our 1700 was much nicer to drive than the overladen 1300.

How much height will your under floor heating take up? If you are piping 90 degree water throughout, and you have an airspace to give a bearable temperature on your feet will your floor be 100mm thick, and so your vehicle travelling height will go up accordingly?

Ending up discovering how much weight our camper was carrying, and then deciding to resolve that rather than carry on regardless, made a huge difference to what we had planned to do with it, so maybe I bang on a bit but starting off with a big truck and bolting everything you want to it might not end up with what you hope for

 

[Jocke]

How will you control camper coolant water temperature?
You seem to suggest doing that for the air blown heater inlet and for the underfloor? As far as I know a domestic underfloor heating system has the hot water from whatever source blended down to the required temperature with mains cold water. A hydronic heater produces water at maybe 90 degrees C, and cycles on and off to maintain that within it's set range. Not 40 degrees down one pipe, 90 down another. I know a 12v Webasto a year or two ago did have a low temperature circuit for underfloor heating, and normal campers at the higher end seem to have it, but I don't know how?

I'm aware of this, but I don't have all the knowledge to confirm or discard that it's doable - that's why I'm here asking these "silly questions" innit.
Even if 90ºC water was piped through the heating pipes in the floor, the floor would only reach 90ºC if the hot water would be allowed to circulate and the floor could not dissipate the heat. Which is why a thermostat is crucial.

Eberspacher air heaters are "allowed" in the living compartment water heaters are not because if they fail you might get fumes inside from what they told me.

Yes, I've understood that, and that Webasto waterborne heaters are allowed in the living space. However, the location is to be determined regardless of what configuration we end up with.

You can google the fitting and user instructions for Ebers.

Eventually I'll get to that situation that the chosen components will be researched to the max, including spec sheets and installation manuals.

A U1300l has at 7500kg gross about two tons of payload up from a bare chassis. Some get uprated to 8500kg (I'm not sure what if anything needs changing on the chassis? Brakes?) but in the EU you then need a Class C licence which is cost and time but well worth it. Those two tons will get eaten up in a heartbeat unless you keep every spare kg out. You may find a motorbike on the back is impossible without overloading the back axle unless you minimise the rear extent of the camper box. A U1300 for instance (no l) has a tiny rear chassis overhang to allow carrying heavier stuff off the back (3 point linkage etc).

I'm aware of the weight constraints. It's a big issue and we are recording the weight every item we're speccing in the spreadsheet. We are choosing items based on weight. And so forth. Weight is a concern. Loading the rear is a concern. However, except for a wheel on the roof and some boxes under the camper, there's no other space for big stuff. We'll stay under the 7,500kg for many reasons.

AV may have designed their camper like that because they know putting all that weight on the back is not good. Ulrich Dolde suggested an assembled F&F cabin without sloping section, or subframe or windows/doors was €23,440 at 4.5m long (too big for a U1300l), is AV more than that?

The box, with apertures for doors and windows is £10,000 + VAT. There's nothing more than a SIP box. The design is simply because embedding structural members in the SIPs would be very complicated.
And yes, loading stuff on the back is a bad idea, the more weight the worse the idea. Which is why this is a very important part of the consideration of all aspects.

Our Mog steel framed camper box was built too heavy by a UK body builder, and had a pair of 14.50R20 spares mounted on a frame within the camper walls. Because of it's excess weight we swapped the camper over onto a U1700 and chose to have bigger heavier tyres. To carry those spares A Vos extended the chassis to the back of the camper for them to sit on.

So what weight are you on now?

You may not easily get answers, but once we discovered how overweight our U1300l camper was (made and fitted out by the last owner and snapped up by us thinking it was a bargain rather than self build ourselves), and you start looking at how tail down a lot of them are, and asking the weight of those who have one or of ones for sale, you realise how many are a ton plus too much, ours was about a ton and a half too much empty. Or maybe a better way of looking at that is every single one is overweight unless it was built with weight in mind from day 1, or is tiny. If you really want a Mog and a bike, unless your box will be tiny and light, you may want to look at a bigger Mog. A 7.5 ton U1300l with standard hp won't keep up with most traffic either. Slightly higher fuel comsumption and the licence are the major downsides to a bigger Mog, dimensionally they can be pretty much the same. Our 1700 was much nicer to drive than the overladen 1300.

If I wanted easy I'd be talking to Bimobil, Earthroamer, etc, etc. However, money is a factor, and "just upgrading" to the next involves a lot of money. Money that we're already planning on spending which can't just be magically increased. So we're dealing with compromises.

How much height will your under floor heating take up? If you are piping 90 degree water throughout, and you have an airspace to give a bearable temperature on your feet will your floor be 100mm thick, and so your vehicle travelling height will go up accordingly?

I don't know, at this stage, what the floor thickness is going to be, but I fail to see how the underfloor heating will actually take up any space, as in my head the water pipes will be routed into the foam insulation that's already in the floor.

Ending up discovering how much weight our camper was carrying, and then deciding to resolve that rather than carry on regardless, made a huge difference to what we had planned to do with it, so maybe I bang on a bit but starting off with a big truck and bolting everything you want to it might not end up with what you hope for

I appreciate your concerns, and I don't want to extinguish your willingness to help, but every person I talk to about this camper project is in turn projecting their fears and experiences on me. I've heard anything from "you don't want that, you want a Hilux" to "I don't think having a camper is going to solve anything" to "A Leyland-Daf is less than £5,000, why would you pay that?!", etc, etc.

Thanks for your input, it might not seem like it, but I am storing all the opinions and options. There's just so much to take in.

 

[grizzlyj]

Hiya
Our U1700 two person camper with 395 tyres ended up at about 9500kg loaded and with two spares tyres, no motorbike . Now there are three of us we no longer have a Mog. Ages ago in a UK 4x4 magazine was a feature on a Mog camper with a bike plus sidecar on the front bumper! Probably nicely balanced axle weights.
I suppose I am pushing my view, and four of the U1300l campers I discovered were overweight were steel framed, but there's no reason not to end up under 7500kg starting fresh. I love Mogs and won't be suggesting anything else!
I look forward to seeing your underfloor design

 

[grizzlyj]

To be slightly back on topic, while the Katadyn Ceradyn and Carbodyn filter elements that Famous Water use are not too costly, their housings soon add up! Housing them in something else might be an idea if you aim to have them in parallel for higher flow rates.