Diesel hot water systems

[ersatzknarf]

<snip>
The last common option is to run a Dual Top. We haven’t used one yet but I’m sure they have a place. They don’t run coolant at all and heat the water directly. Also they have 2 hot air outlets that can be ducted into the vehicle for space heating. So a bit of co-generation going on there. Very compact and have a tank built in.

Some other points to make here are that the calorifiers all have an electrical heating element built in so that if you pull into a vanpark or a mates’ place you can run off electricity for awhile and the other point for now is that if you are going to run a calorifier especially plumbed into the engine then fit a thermastically controlled temperature kit to it as a safeguard. These are an adjustable valve that goes on the hotwater outlet of the calorifier and mixes with coldwater to give set output temperature..Very simple to set up but well worth it. If the engine has provided the heat the temps can get very hot and vary so its’ not as simple as dialing down the thermostat on the furnace.

<snip>
Regards John.

Hello John !

Since this thread came back to life, I wanted to ask if you folks had installed a Webasto Dual Top, yet ?

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Of course, it will likely come down to which set-up I can fit in the space available.

Thanks !



Cheers,
Frank

 

[whatcharterboat]

Hello John !

Since this thread came back to life, I wanted to ask if you folks had installed a Webasto Dual Top, yet ?

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Of course, it will likely come down to which set-up I can fit in the space available.

Thanks !



Cheers,
Frank

Hey Frank. Always a pleasure.

As a matter of fact, we are just in the final few days of one of those large MAN dream rigs which has our first Dual Top. We haven't fired it up yet but it's all in place bar the fuel tank pick up. Everything went together really well but I'm not sure if we'll do it again. Perfect for a sealed road 2wd whale type motorhome. Perfect. But if you're putting together an outback tourer where extreme dust is a concern and space is at a premium I think the more conventional Webasto furnace/calorifier/space heater(s) combination is more adaptable and can certainly be designed to do so much more. So in our situation we can put in a space heater and plumb the coolant lines to it rather than ducting 90mm or 75mm pipe work throught cupboards etc. We were also concerned with deep water fording so we mounted the Dual Top in a cupboard inside the vehicle rather than under it. It was still a neat install but for an expedition camper I think it's useful if you can utilize the engine heat for initial hotwater heating. So as an example, if you pull up for an overnight stay your furnace may not even need to turn on so your fuel consumption will therefore be optimized.

Please don't take this the wrong way. The Dual Top is an excellent bit of kit(as with any of their products) but it just doesn't suit our trucks like the old system. For a first time home builder, a Dual Top would be a very good choice but carefully plan ( and do it early) for the necessary ductwork, location,etc.

Seeing as how the thread has been re ignited, I'll follow up with some pics soon.

Seawali. Got your PM re: this thread too. Will reply soon. Thanks for you patience.

 

[whatcharterboat]

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

We don't use the dual circuit type. If you do, it means you need a separate header tank. Through some tricky valving, we get away with a single circuit tank and you can preheat the motor with the furnace if you need to. Haha, as I sit here sweating away in a heatwave. Price wise, the extra you pay for the dual circuit tank is about the same as 2 solenoid valves but a proper header tank maybe another couple of hundred bucks. Just a thought. Do the math. I looked at dual circuit tanks years ago and thought maybe>>> just never went down that road. Plenty to think about heh?

We even built a Round The World truck at work some time back that had no calorifier. Instead it just had a tiny heat exchanger that made instant hotwater from a larger Webasto furnace (with selectable engine preheat and a space heater). It worked fine too.

 

[whatcharterboat]

I am still going back and forth between that and the Isotherm calorifier (which I just read can have dual heating circuits to be able to use not only engine coolant heat but a separate hydronic heater, if I read it correctly).

Hey Frank, while I think of it >>> a little tip with the Isotherm units that you may not realize is that they should be mounted with the bolt holes at the bottom. For anyone who doesn't have a clue what we're talking about >>> Isotherm calorifiers look like a "stretched D"- shaped tank and should be mounted with the flat section to the bottom. Now you could in fact mount them with any orientation you desire as the mounts are certainly strong enough to hang upside down, say from under the floor but the reason I say this is that the insulation is actually much thicker at the top than the bottom. So for it's for efficiency sake that I make this comment as I have seen them mounted incorrectly in the past when guys have just said "She'llberightmate" and you certainly wouldn't know about the insulation thickness just by looking at them. Something to remember when it's time.

Again >> a very good product. Good backup electrical elements in them too.

Oh and make sure you fit a thermostatically controlled valve to the hot water outlet to be on the safe side.

John.

 

[jesusgatos]

Another thought I had in my notes: The tank for a heater could be a jerry can. I have heard of people doing this and have ran across caps for jerry cans that have fuel pickups and fill volume senders already installed in them. I figured I'd just make my own cap/pickup unit when the time came.

Like this?

 

[ersatzknarf]

Hey Frank. Always a pleasure.

As a matter of fact, we are just in the final few days of one of those large MAN dream rigs which has our first Dual Top. We haven't fired it up yet but it's all in place bar the fuel tank pick up. Everything went together really well but I'm not sure if we'll do it again. Perfect for a sealed road 2wd whale type motorhome. Perfect. But if you're putting together an outback tourer where extreme dust is a concern and space is at a premium I think the more conventional Webasto furnace/calorifier/space heater(s) combination is more adaptable and can certainly be designed to do so much more. So in our situation we can put in a space heater and plumb the coolant lines to it rather than ducting 90mm or 75mm pipe work throught cupboards etc. We were also concerned with deep water fording so we mounted the Dual Top in a cupboard inside the vehicle rather than under it. It was still a neat install but for an expedition camper I think it's useful if you can utilize the engine heat for initial hotwater heating. So as an example, if you pull up for an overnight stay your furnace may not even need to turn on so your fuel consumption will therefore be optimized.

Please don't take this the wrong way. The Dual Top is an excellent bit of kit(as with any of their products) but it just doesn't suit our trucks like the old system. For a first time home builder, a Dual Top would be a very good choice but carefully plan ( and do it early) for the necessary ductwork, location,etc.

Seeing as how the thread has been re ignited, I'll follow up with some pics soon.

Seawali. Got your PM re: this thread too. Will reply soon. Thanks for you patience.

Hi John,
Thanks.
Same here - always a pleasure

Glad to hear that you've done an installation of a Dual Top, but can understand well that it might not be the best choice for an overlander, compared to installation in a more "traditional" RV...
If we were to go with one, it would almost certainly need to be under the car and although Webasto say it is designed for it, I can't imagine they were thinking about deep water fording. I also had the same concerns about routing the furnace ductwork and how to fit that along with everything else.

So, the alternative for us looks to be the Webasto Thermo Top "C" that can do either engine heating or cab heating (through the car's heater vents) and I think we can fit one of those square Isotherm calorifier units up in front of a rear tire between the outer and inner wheel arch bodywork, but if that won't work, I think we can find space for one of the standard, round ones.

Regardless, I am anxious to see photos


Cheers,
Frank

 

[ersatzknarf]

We don't use the dual circuit type. If you do, it means you need a separate header tank. Through some tricky valving, we get away with a single circuit tank and you can preheat the motor with the furnace if you need to. Haha, as I sit here sweating away in a heatwave. Price wise, the extra you pay for the dual circuit tank is about the same as 2 solenoid valves but a proper header tank maybe another couple of hundred bucks. Just a thought. Do the math. I looked at dual circuit tanks years ago and thought maybe>>> just never went down that road. Plenty to think about heh?

We even built a Round The World truck at work some time back that had no calorifier. Instead it just had a tiny heat exchanger that made instant hotwater from a larger Webasto furnace (with selectable engine preheat and a space heater). It worked fine too.

Hi again John,

Ah, hah ! That's right about the extra plumbing required. I was reading the posting by "jammyauto" about his Sportsmobile and recall reading that a dual circuit Isotherm was being used with one circuit plumbed to the engine and the other to an Espar hydronic unit.

"Haha, as I sit here sweating away in a heatwave." LOL ! Yes, I forgot our seasons are opposite ! Trade ya' !

Since we are building on a much smaller scale, I think we'll be fine with the more simple approach.

I keep getting carried away with all the neat bits that can be fitted and have to rein myself in and regain focus of the design, but that is actually part of the enjoyment...

The idea of "instant hot water" from the heat exchanger sure sounds nice. I think if we just keep it simple, the Webasto Thermo Top "C" (Caravan) and the Isotherm should do us fine. That way, we'll have engine preheat/calorifier heating and cab heating. We'll have a back-up catalytic heater as well, since we'll have a small outside tank for an outside-use gas cooker.


Cheers,
Frank

 

[ersatzknarf]

Hey Frank, while I think of it >>> a little tip with the Isotherm units that you may not realize is that they should be mounted with the bolt holes at the bottom. For anyone who doesn't have a clue what we're talking about >>> Isotherm calorifiers look like a "stretched D"- shaped tank and should be mounted with the flat section to the bottom. Now you could in fact mount them with any orientation you desire as the mounts are certainly strong enough to hang upside down, say from under the floor but the reason I say this is that the insulation is actually much thicker at the top than the bottom. So for it's for efficiency sake that I make this comment as I have seen them mounted incorrectly in the past when guys have just said "She'llberightmate" and you certainly wouldn't know about the insulation thickness just by looking at them. Something to remember when it's time.

Again >> a very good product. Good backup electrical elements in them too.

Oh and make sure you fit a thermostatically controlled valve to the hot water outlet to be on the safe side.

John.

Hey again John,
Thanks for that tip on the orientation of the "round" Isotherm - I did not know that at all, but it makes perfect sense.

Yes, I recall reading about the thermostatically controlled valve (that is an option ?) being a very good idea to avoid scalding ! 8^O

Thanks for that reminder. I need to make doubly sure to do that.

(I think I might have seen one on an Isotherm and it's really just a valve marked "hot" with an arrow pointing the way ?)

Cheers,
Frank

 

[egn]

We also use an Isotemp water storage together with a Webasto diesel furnace. It works fine for us, we have warm water about 2 days. To heat it faster we use the model with the two heat exchangers. The temperature controlled valve doesn't work that good together with the temperature controlled shower. So we opened it fully all the time.

 

[ersatzknarf]

Thanks for the reply on that, Emil.
In the photo, there is a valve at the bottom of the tank. That is the "thermostatically controlled valve," isn't it ? There looks to be another control near there (a blue/grey box with a control lever). Is that related to the water temperature control ?


Cheers,
Frank

 

[dzzz]

Great thread well worth reviving.

The isotherm does come with a mixing valve. I ordered the Basic 40 Double Coil which is an 11 gallon unit.
The isoterms I looked at also have a 750w heater, which may have some use. The double coil increases cost a bit, but separates the systems. I will need a little expansion tank and probably a pump. My truck already has an cab/engine webasto, but I'll add a second unit for cabin heat. My only concern with webasto is that the units are too high powered for heating small spaces. I prefer the smaller Espar units, but I'm not going to run two brands.

In the first part of this thread there was a discussion on propane. I would not use propane on a boat (a sealed bowl). But I am using it for cooking in a camper. I don't like diesel cooktops.

 

[charlieaarons]

The 5kw Webasto is not too high powered for a camper. The 9kw for the engine/cab is 9kw in order to heat things up in 1hr. The camper takes at least several hrs, as much as 8hrs, in order to get thoroughly warm from -15 F. Even with R13 insulation. Not just the air but the solid objects like the camper batteries, which are hidden away under a sub-floor.

Charlie

 

[ersatzknarf]

Great thread well worth reviving.

The isotherm does come with a mixing valve. I ordered the Basic 40 Double Coil which is an 11 gallon unit.
The isoterms I looked at also have a 750w heater, which may have some use. The double coil increases cost a bit, but separates the systems. I will need a little expansion tank and probably a pump. My truck already has an cab/engine webasto, but I'll add a second unit for cabin heat. My only concern with webasto is that the units are too high powered for heating small spaces. I prefer the smaller Espar units, but I'm not going to run two brands.

In the first part of this thread there was a discussion on propane. I would not use propane on a boat (a sealed bowl). But I am using it for cooking in a camper. I don't like diesel cooktops.

Agreed ! This is a great thread !

Glad to hear that the mixing valve comes with the Isotherm. I was wondering about that.

11 gal. would be wonderful to have but I think tough for us to fit.

With the cab/engine Webasto, how well does it work for heating the "cab" area do you feel ? Our arrangement is open from the cab all the way back...

For the space we have, I am thinking that we can hide the "Slim Square" (4.2 gal.) in the back, because it can also be stood on its side, which will allow us to tuck it into the empty space between the inner and outer bodywork.

Cheers,
Frank

 

[dzzz]

.............

With the cab/engine Webasto, how well does it work for heating the "cab" area do you feel ? Our arrangement is open from the cab all the way back...

............

From my limited experience with a separate cab/chassis, it works very well. But I'm unclear what configuration we're talking about. On the one end there's Charlie's completely seperate two boiler system. On the other is FusoFG with a single boiler and one system with the ability to turn off flow to the engine.
I'm installing a hybrid, where the two systems can exchange heat through the water heater (calcifier).

 

[ersatzknarf]

From my limited experience with a separate cab/chassis, it works very well. But I'm unclear what configuration we're talking about. On the one end there's Charlie's completely seperate two boiler system. On the other is FusoFG with a single boiler and one system with the ability to turn off flow to the engine.
I'm installing a hybrid, where the two systems can exchange heat through the water heater (calcifier).

Oops ! You're right, I think we got a little confused there. I was referring to the Webasto Thermo Top "C" and when I read "cab/engine webasto," I thought it was the same thing... The plan is to use that for engine and cab, etc. heat with the side benefit that it will heat the Isotherm and if I understood Charlie's post correctly, the "C" should handle our needs. Since we'll be using an outside-mounted propane tank for an outside-use camp stove, we're looking at a small catalytic heater for back-up.


Cheers,
Frank