Hydronic Heat, Hot water, and Engine Pre-heating

[Korey H]

Thanks mog for all the info. Personally I am not a big fan of running the engine coolant through the entire vehicle.
Therefore planning a heat exchanger combined with a circulation pump inside the engine bay and install the water heater(s) in the back.
Also, nowadays diesels don`t leave much room for these kind of auxiliaries.

Do you have any info or links on what you’re using? I’m still figuring mine out. Would like the insurance of a engine pre heat, planning a heat exchanger with mixing valve for water then maybe a floor loop and or tank loops. Thank you


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[pgeering]

Korey H, same here, still figuring things out myself. I know what my final goal is; one person, off-grid for 14 days, taking 30min showers every day. Obviously only works with a re-circulating shower. I am extensively pre-testing everything before installing it into my vehicle. Here I am testing my dual pump shower setup; https://www.sugarsync.com/pf/D3733953_169_6356102818

As an automation engineer I am not shy of using a professional grade PLC to control all my gimmicks. I will start a build thread / you tube channel at some point showing implemented solutions/products which work for my final goal.

 

[Peter_n_Margaret]

I have a Webasto Thermotop C in our OKA motorhome that has one significant difference from the systems described here.
The calorifier has 2 separate heat exchange circuits. One is used by the Webasto and the central heating radiators and the other is used by the engine circuit.

22 litre horizontal twin coil Surecal calorifier

SureCal boilers are made of the finest quality materials, which guaranteeing the ultimate performance and reliability. In addition the drop coil technology and finned surface heat exchanger used in the boiler provides unrivaled heat recovery. The units also come in twin coil version for use with...

www.surejust.co.uk

Both circuits have auxiliary circulation pumps in the lines which can be manually switched.
If I heat the calorifier water with the Webasto and run the engine circuit auxiliary pump, then the engine gets heated.
When driving, the engine glycol circulates through the calorifier by default and we have 22L of hot (85C) water within 30 minutes.
If when driving I also run the Webasto circuit auxiliary pump then the central heating can operate (without running the Webasto).

The calorifier also has a 1000W immersion heater that we can power via an inverter from solar power/batteries when camped up. I deliberately kept it small so as not to use up all the available solar.

There are no pre heaters and the glycol buffer tank is about 2L with no overflow on the Webasto circuit and I do not circulate the glycol through it. It simply catches any air bubbles. The level only varies a tiny bit from one extreme to the other and from one month to the next.
There is nothing else on the engine circuit except the engine and its normal bits.
There is an expansion tank on the hot water line.

The other useful feature is we have 2 independent central heating radiator/fan units, one of which heats the bathroom (it gets its "cold" air from the living area and blows it into the bathroom) and with the door closed and the window open a tad it operates as a VERY effective cloths drying room without heating the rest of the living space.

Yes kerosene works fine. I usually add 10% to the diesel to increase its cold weather performance to stop gelling.
Cheers,
Peter
OKA196 motorhome

 

[pgeering]

Peter, thank you very much for all the helpful information. Very nice setup you have going here. I will definetely look into this twin coil hot water tank. A bit concerned with the pressure rating of the tank as my two water pumps put out up to 4.2bar max. But then planning on running them on a PWM module to be able to control flow and pressure.

Philipp

 

[Iceabenezer]

I have a Webasto Thermotop C in our OKA motorhome that has one significant difference from the systems described here.
The calorifier has 2 separate heat exchange circuits. One is used by the Webasto and the central heating radiators and the other is used by the engine circuit.

22 litre horizontal twin coil Surecal calorifier

SureCal boilers are made of the finest quality materials, which guaranteeing the ultimate performance and reliability. In addition the drop coil technology and finned surface heat exchanger used in the boiler provides unrivaled heat recovery. The units also come in twin coil version for use with...

www.surejust.co.uk

Both circuits have auxiliary circulation pumps in the lines which can be manually switched.
If I heat the calorifier water with the Webasto and run the engine circuit auxiliary pump, then the engine gets heated.
When driving, the engine glycol circulates through the calorifier by default and we have 22L of hot (85C) water within 30 minutes.
If when driving I also run the Webasto circuit auxiliary pump then the central heating can operate (without running the Webasto).

The calorifier also has a 1000W immersion heater that we can power via an inverter from solar power/batteries when camped up. I deliberately kept it small so as not to use up all the available solar.

There are no pre heaters and the glycol buffer tank is about 2L with no overflow on the Webasto circuit and I do not circulate the glycol through it. It simply catches any air bubbles. The level only varies a tiny bit from one extreme to the other and from one month to the next.
There is nothing else on the engine circuit except the engine and its normal bits.
There is an expansion tank on the hot water line.

The other useful feature is we have 2 independent central heating radiator/fan units, one of which heats the bathroom (it gets its "cold" air from the living area and blows it into the bathroom) and with the door closed and the window open a tad it operates as a VERY effective cloths drying room without heating the rest of the living space.

Yes kerosene works fine. I usually add 10% to the diesel to increase its cold weather performance to stop gelling.
Cheers,
Peter
OKA196 motorhome

Hey Peter, I know this is an old topic, but I'm currently looking at installing a similar setup on my rig, which has a 2001 7.3 Powerstroke. Two questions I have when looking over this post are where you tied the calorifier into the engine coolant system, and the same with the auxiliary pumps. I've been trying to figure out how to install the aux pumps without restricting coolant flow when the pump isn't running but the engine is. I also want to make sure that enough of the coolant gets to the block when the pump is switched on and the engine is off. It looks like these are mostly used as pumps that are running when an engine computer tells them too, and on this setup I'd only be running it when the engine is off.

Any feedback would be super helpful as I plan this out. Thanks in advance!

 

[Peter_n_Margaret]

Hey Peter, I know this is an old topic, but I'm currently looking at installing a similar setup on my rig, which has a 2001 7.3 Powerstroke. Two questions I have when looking over this post are where you tied the calorifier into the engine coolant system, and the same with the auxiliary pumps. I've been trying to figure out how to install the aux pumps without restricting coolant flow when the pump isn't running but the engine is. I also want to make sure that enough of the coolant gets to the block when the pump is switched on and the engine is off. It looks like these are mostly used as pumps that are running when an engine computer tells them too, and on this setup I'd only be running it when the engine is off.

The calorifier is teed into the heater coolant circuit (both in and out) near the engine.
The auxiliary pumps are manually switched. They offer little resistance to coolant flow when not running.
Cheers,
Peter
OKA196 motorhome

 

[awheeler]

Received the two electronic valves to control the water heater loop and the summer loop. These have four allen-head bolts where the motor drive can be removed in case of failure and replaced with a manual lever.
View attachment 498804View attachment 498805

The shower fixture coming from England next week. it will mount to the exterior of the van and when the rear hatch is lifted, it will attach there. Imagine unlimited warm showers
View attachment 498825
Here is the flow-restrictor when you have to run from stored water. It goes between the shower head and the hose.
View attachment 498828

Could you share where you got those valves? I'm doing a similar setup but using primarily Rixen stuff for it.

 

[javajoe79]

I've been following this thread and wanted to put in some info that I've been working with. I recently rewired the entire cab of my NPR using a PDM, power distribution module, from Hardwire. They offer 10, 15 and 25 circuit PDMs. It's all programmable and solid state. It accepts analog and canbus inputs as well as raw sensor data and uses that to switch the outputs. It will do normal on and off, PWM, timers etc.. Any of the input channels can be programmed to effect any of the output channels. I am going to purchase another PDM for the camper box when I'm ready. Anyway, the reason I mention this is because my plan is to control my Espar using the PDM. It doesn't seem like anyone is doing stuff like this yet. The PDM is a decent expense but it will eliminate the need for a variety of other components and vastly simplify the wiring of the entire truck. I'll be able to control the espar, external pumps, fans, valves etc. plus lighting and other power needs, all from one small box. The possibilities are limitless really. Anyway, check them out here https://www.hardwire-electronics.co.uk/

 

[pgeering]

I've been following this thread and wanted to put in some info that I've been working with. I recently rewired the entire cab of my NPR using a PDM, power distribution module, from Hardwire. They offer 10, 15 and 25 circuit PDMs. It's all programmable and solid state. It accepts analog and canbus inputs as well as raw sensor data and uses that to switch the outputs. It will do normal on and off, PWM, timers etc.. Any of the input channels can be programmed to effect any of the output channels. I am going to purchase another PDM for the camper box when I'm ready. Anyway, the reason I mention this is because my plan is to control my Espar using the PDM. It doesn't seem like anyone is doing stuff like this yet. The PDM is a decent expense but it will eliminate the need for a variety of other components and vastly simplify the wiring of the entire truck. I'll be able to control the espar, external pumps, fans, valves etc. plus lighting and other power needs, all from one small box. The possibilities are limitless really. Anyway, check them out here https://www.hardwire-electronics.co.uk/

Interesting and good to learn someone else is using programmable equipment. My setup uses the following industrial grade IP69x rated PLC: https://www.br-automation.com/en-gb/products/plc-systems/x90-mobile-control-system/

The unit uses CAN for communication and I will see if I can talk to the PDM you are using. In my case the PLC controls a lot more than my aux heater. I am still at an early stage of programming but what I have implemented so far works flawless. I will do a dedicated built thread at some point.

 

[javajoe79]

Interesting and good to learn someone else is using programmable equipment. My setup uses the following industrial grade IP69x rated PLC: https://www.br-automation.com/en-gb/products/plc-systems/x90-mobile-control-system/

The unit uses CAN for communication and I will see if I can talk to the PDM you are using. In my case the PLC controls a lot more than my aux heater. I am still at an early stage of programming but what I have implemented so far works flawless. I will do a dedicated built thread at some point.

I'm traditionally anti tech but the way I see it, using the pdm simplifies everything to a degree that I'm ok with it and in the event of a malfunction I can easily jumper vital circuits directly to the battery cable lug on the pdm if needed.

 

[goneagain]

This is a fantastic thread. I am building a very similar system.

What is the advantage of using a HW holding tank vs simply running the system as an on-demand straight from the exchanger?

Is it simply the ability to extend the useful working time of the heated water, without firing the furnace unit, or is there other advantages?

 

[Joe917]

This is a fantastic thread. I am building a very similar system.

What is the advantage of using a HW holding tank vs simply running the system as an on-demand straight from the exchanger?

Is it simply the ability to extend the useful working time of the heated water, without firing the furnace unit, or is there other advantages?

Heat transfer is not instant so "on demand" is not an option. For hot water you need to heat a hot water tank.

 

[goneagain]

Heat transfer is not instant so "on demand" is not an option. For hot water you need to heat a hot water tank.

I guess Im spoiled then, because my coil exchanger is exactly that. On-demand hot water. I have never use a conventional plate exchanger, I assumed they were the same.

 

[Alloy]

This is a fantastic thread. I am building a very similar system.

What is the advantage of using a HW holding tank vs simply running the system as an on-demand straight from the exchanger?

Is it simply the ability to extend the useful working time of the heated water, without firing the furnace unit, or is there other advantages?

Without a tank it depends on what you call on demand. If the system has cooled on demand will mean waiting for the system to heat up.

On demand saves weight but it waste water when the water is run to check for hot water.

My 10g tank is insulated with 1" EPDM. It takes about 12 hours to go from hot to warm.

 

[goneagain]

Without a tank it depends on what you call on demand. If the system has cooled on demand will mean waiting for the system to heat up.

On demand saves weight but it waste water when the water is run to check for hot water.

My 10g tank is insulated with 1" EPDM. It takes about 12 hours to go from hot to warm.

Looking at the calorifier options available, once your tank capacity is used, with the heating coil running, will the system act in an on-demand manner?

I see a 2.5 gallon tank available, and 2.5 gals won't go far in a shower. Ive placed emails to the manufaturer, but have not received a response.