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Discussion Starter · #1 ·
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.
 

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Discussion Starter · #10 ·
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.
 

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Discussion Starter · #11 ·
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.
 

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Discussion Starter · #13 ·
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.
 

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Discussion Starter · #14 ·
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.
 

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Discussion Starter · #16 ·
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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Discussion Starter · #21 ·
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.

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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.

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Nice! Thanks for the info. Will be interesting to see how it works out for you. Keep us posted.
 

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Discussion Starter · #22 ·
Hi, any thoughts on how this is working out in terms of cooling capacity and power consumption. Does it seem that it was sized right in terms of cooling capacity and efficiency. The reason I'm asking is that I was planning a similar capacity system, but had an up-fitter tell me that I need a 3 ton unit for the van. That's the size of the one in my house! Seems like overkill and I think would cycle on and off too much, not to mention the power consumption and weight.
 

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Discussion Starter · #24 ·
3T is 36,000 BTU. That would be a freezer in an insulated van. The carrier Reefers uses for refrigeration put out less BTU's than that. I can't imagine this outfitter is well versed with A/C systems.
I'm not familiar with the carrier Reefers, but another benchmark is that typical sedan AC systems are about 3T capacity according to here's a paper I'm going to read to try and get some insight. It's not directly answering my question but it gives general ideas of automotive AC power consumption scenarios: https://www.sae.org/standardsdev/tsb/cooperative/mobile_ac.pdf. So bottom line is that I was skeptical when told I needed 3T but am looking for some "science" in the thought process. Benchmarks are a big help and actual results in real world systems are very useful.
 

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Discussion Starter · #25 ·
I'm not familiar with the carrier Reefers, but another benchmark is that typical sedan AC systems are about 3T capacity according to here's a paper I'm going to read to try and get some insight. It's not directly answering my question but it gives general ideas of automotive AC power consumption scenarios: https://www.sae.org/standardsdev/tsb/cooperative/mobile_ac.pdf. So bottom line is that I was skeptical when told I needed 3T but am looking for some "science" in the thought process. Benchmarks are a big help and actual results in real world systems are very useful.
By the way thanks for the link, looks like useful stuff. I have not had much luck in getting quotes for parts I need.
 

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Discussion Starter · #27 ·
Automotive A/C engine drive AC systems are designed to cool your vehicle very quickly after it has reached some really high internal temperatures, as a result once temp is achieved the compressors cycle heavily.
Standard 110V rooftop A/C are around the 15,000BTU/hr range and do not cycle very much on a hot day, they just run full blast.
It completely depends on what you are trying to achieve.
Thanks, this makes sense. I don't plan to cool the RV quickly as when you get into a hot car. The use case for us is that we plan on being outside usually during the day and using the vent fans to keep it at ambient or slightly above. The need for the AC will be mostly at night to have a reasonable sleeping temp in hot/humid climates. We also hope to use the AC to get the humidity out in cooler . rainy weather just as a car AC helps defog the windshield. The van is the silver ingot color so not as cool as white, but hopefully not too bad.
 

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Discussion Starter · #34 ·
Hi! I'm new to this forum as well and am contemplating my first van build. Have you seen this YT? The way he put it together is pretty slick.
I just watched this. Haven't seen it before, but I usually learn something every time. This is one of the better configurations I've seen for a AC powered split system.
 
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