Integrated RV HVAC system with hydronic heating and 12V A/C

4621 Views 34 Replies 9 Participants Last post by eranrund, Mar 25, 2022

kvanner

Discussion Starter · Mar 5, 2021

I’m new to the forum and plan to order a Transit Cargo van, 144” wheel base, dual rear wheels, high roof, extended/long body, AWD and convert it to a class B RV. I've spent the last 2 months on this to develop requirements and come up with a conceptual design of the system. For the HVAC system, I plan to run a hydronic heater and an under van mounted 12V compressor & condenser for HVAC use with a rear heater/A-C unit (not coupled with the vehicle) when not driving. The heater would also provide hot water through a heat exchanger. The compressor would be powered by a 600 AH 12 volt lithium battery bank and about 800W of solar on the roof. Don't really want to put AC on the roof. Has anyone on this forum already done this on a Transit? Any suggestions or advice? I am really lacking geometric information of the underside of the van to place the A/C components - and tanks for that matter. There is a separate topic for tank placement that I have started to sort through.

1 - 20 of 35 Posts

ArgonautVans

· #2 · Mar 5, 2021

You could mount the compressor unit in front of the spare. Lots of room, deep cavity. There are also big cavities next to the fuel tank and muffler on the sides.

I'd recommend going to a ford dealership with a cardboard sheet so you can crawl under and get the measurements you need.

If you can find a Hr Extended in stock anywhere.

binaryagent

· #3 · Mar 5, 2021

Any info on the "12V compressor & condenser" you are looking at using?

Also, what advantages do you see in hydronic heating over diesel air heater and electric water heater? I have been leaning toward the latter for simplicity and longevity. The diesel heaters seem to have a limited lifetime but are cheap to replace.

Have you considered the resale value of the van if you go with a custom "non serviceable" HVAC solution?

carringb

· #4 · Mar 5, 2021

I don’t think the OPs system needs to be considered “non-serviceable”.

Webasto make complete systems for the Transit including underbody condenser. The only thing their package lacks is the 12-volt compressor, but they sell those as well, so I suspect it would be easy to get them to modify the standard package to include that compressor.

Ford Transit Vans

Webasto Brochure

Reactions: 3

ArgonautVans

· #5 · Mar 5, 2021

How are those Webasto systems offering 32K-42k btu of cooling and heating with such low amp draw?

Considering other AC’s I see with 13,000 btu are 5-6x the amperage ?

eranrund

· #6 · Mar 5, 2021

Curious which AC you are going with, @kvanner

carringb

· #7 · Mar 5, 2021

Muggydude said:
How are those Webasto systems offering 32K-42k btu of cooling and heating with such low amp draw?

Considering other AC’s I see with 13,000 btu are 5-6x the amperage ?

The webasto compressor is normally engine driven so the quoted amps is just the blower and condenser fans.

Reactions: 1

nealcallan

· #8 · Mar 6, 2021

In our van we have a Rixen hydronic heat system for hot water and air. For AC we use Cruise-&-Comfort 12v system. The Rixen system works very well at high altitude and sea level. We will be testing the AC system this summer. I calculated if you run the AC system for 3 hours at 40 amps draw will drain 120Ah. Important to size your system for the typical needs. Our insulation is, thinsulate with EZ cool air gap on ceiling, and ceramic coating on all windows.

Reactions: 1

binaryagent

· #9 · Mar 6, 2021

12V/24V Electric air conditioning for buses,truck, engineering vehicles, excavators, harvesters and agricultural machines

kvanner

Discussion Starter · #10 · Mar 10, 2021

Muggydude said:
You could mount the compressor unit in front of the spare. Lots of room, deep cavity. There are also big cavities next to the fuel tank and muffler on the sides.

I'd recommend going to a ford dealership with a cardboard sheet so you can crawl under and get the measurements you need.

If you can find a Hr Extended in stock anywhere.

Thanks, I plan on doing this.

kvanner

Discussion Starter · #11 · Mar 10, 2021

nealcallan said:
In our van we have a Rixen hydronic heat system for hot water and air. For AC we use Cruise-&-Comfort 12v system. The Rixen system works very well at high altitude and sea level. We will be testing the AC system this summer. I calculated if you run the AC system for 3 hours at 40 amps draw will drain 120Ah. Important to size your system for the typical needs. Our insulation is, thinsulate with EZ cool air gap on ceiling, and ceramic coating on all windows.

Thanks, I am looking a the Rixen system also. Are you using the the VES-12s or VES-12L Classic? Does the blower assy come with or can you add a heater core to it? Or is the heater core integrated with the Rixen system? I'm trying to avoid 2 blower fans.

kvanner

Discussion Starter · #12 · Mar 10, 2021

eranrund said:
Curious which AC you are going with, @kvanner

Not sure yet, but Proair makes them also.

Reactions: 1

kvanner

Discussion Starter · #13 · Mar 10, 2021

nealcallan said:
In our van we have a Rixen hydronic heat system for hot water and air. For AC we use Cruise-&-Comfort 12v system. The Rixen system works very well at high altitude and sea level. We will be testing the AC system this summer. I calculated if you run the AC system for 3 hours at 40 amps draw will drain 120Ah. Important to size your system for the typical needs. Our insulation is, thinsulate with EZ cool air gap on ceiling, and ceramic coating on all windows.

Thanks. A few more questions:
1)what is your fan set up?
2) do your windows open for ventilation?
3) Do you have solar on the roof?
4) What color is the van, I think this matters for the thermal model. White vs. color vs. black. Not sure how to evaluate, but a test would be worth a lot.

kvanner

Discussion Starter · #14 · Mar 10, 2021

carringb said:
I don’t think the OPs system needs to be considered “non-serviceable”.

Webasto make complete systems for the Transit including underbody condenser. The only thing their package lacks is the 12-volt compressor, but they sell those as well, so I suspect it would be easy to get them to modify the standard package to include that compressor.

Ford Transit Vans

Webasto Brochure

Just talked to a Webasto rep and they only offer engine driven compressors, which does not meet requirements for this application.

kvanner

Discussion Starter · #15 · Mar 10, 2021

binaryagent said:
12V/24V Electric air conditioning for buses,truck, engineering vehicles, excavators, harvesters and agricultural machines

Thanks for the link and the price is tempting, but I don't think I'm going there.

kvanner

Discussion Starter · #16 · Mar 10, 2021

binaryagent said:
Any info on the "12V compressor & condenser" you are looking at using?

Also, what advantages do you see in hydronic heating over diesel air heater and electric water heater? I have been leaning toward the latter for simplicity and longevity. The diesel heaters seem to have a limited lifetime but are cheap to replace.

Have you considered the resale value of the van if you go with a custom "non serviceable" HVAC solution?

The main reason for not relying on electric for hot water is the power draw when off grid. With hydronic heating, most of the energy comes from the gasoline which is already on-board and more cost effective than battery storage as a source. With electric heating, raising 7 gallons of water from 70 to 120 F would pretty much draw down a 12V 100 AH Lithium battery to 28% and it would take 36 minutes with (my 1440 watt) electric heater to heat it . This all assumes perfect efficiencies which there never are. I do plan using an electric heating element if we are connected to shore power.

The second reason is that I can use the AC blower and ducting to more evenly distribute the HVAC airflow. I think it's going to be quieter, but I'm not sure. I'm looking for some noise info, but haven't tallied it yet.

The third is to consider using the heater to freeze-proof the fresh water tank via a little recirculation, not something I would want to do with batteries. In cold climates this could seriously impinge on remaining battery capacity.

I don't consider the A/C system non-serviceable because there are nationwide service centers for it. The heating system's core is from Eberspacher, which I don't consider non-serviceable. The jury is out on the surrounding other heating components, potentially from Rixen's. It looks like they make quality stuff though, just not sure about servicing yet. I haven't talked to them.

Nevertheless, I don't put resale value high on my priority list. I've been camping all my life in multiple setups and plan on keeping this conversion until it is almost fully depreciated / worn out. I do agree though, that this should be considered in case something unexpected happens, just not giving a lot of weight right now. I would rather get what I want to use than sacrifice for what might happen in the future.

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nealcallan

· #17 · Mar 11, 2021

kvanner said:
Thanks. A few more questions:
1)what is your fan set up?
2) do your windows open for ventilation?
3) Do you have solar on the roof?
4) What color is the van, I think this matters for the thermal model. White vs. color vs. black. Not sure how to evaluate, but a test would be worth a lot.

the C&C system we have is : HD-12L Mobile 12 Volt DC Air Conditioner split system. 8k
Fan system - maxxair as far forward as possible
Tern Overland roof hatch
Windows - AMA half sliders on driver and passenger
200 watts of solar. 2 - 100W renogy panels.

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Reactions: 1

eranrund

· #18 · Mar 11, 2021

nealcallan said:
the C&C system we have is : HD-12L Mobile 12 Volt DC Air Conditioner split system. 8k

Fan system - maxxair as far forward as possible

Tern Overland roof hatch

Windows - AMA half sliders on driver and passenger

200 watts of solar. 2 - 100W renogy panels.

View attachment 149030

How do you like the CNC AC?

kvanner

Discussion Starter · #19 · Mar 11, 2021

eranrund said:
How do you like the CNC AC?

Thanks for the info. Learning a lot here.

nealcallan

· #20 · Apr 16, 2021

Just started my C&C install. Mounted the condenser where the spare tire was. (Spare is now mounted on a rear door tire rack and ladder combo for aluminess). I set the condenser at 20Deg angle, the minimum is 15 deg. Used 3/16" aluminum stock and bent it to the correct angle. Attached to van with 5/16" bolts and Rivnuts. Took a little while to make sure I could route the refrigerant lines up to the evaporator, but will work. Overall took me two half days to complete the install. I will put some metal screen in front of the condenser to stop any road debris from damaging the heat exchanger fins.

Tire Wheel Car Vehicle Table

Tire Wheel Vehicle Car Hood

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