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Twist on AC/Heater?

Brett Proctor

Well-known member
OK guys work with me on this.:D

This may make it real simple to have AC/heater in your car regardless if its air or water cooled.

It may have already been done.

What about building a heat pump??

It would give you ac in the summer and a heater in the winter.

Its just a thought at this point but I don't see why it wouldn't work.

Some of you guys out there that are smarter than me may be able to shed some light on this.

In my journeys through the junk yards I've seen alot of condensers that could be used for this.

I think the only draw back is the condenser/evaporator have to be mounted in two separate locations(or do they)



Heat-pump-cooling-heating-reversing-valve.JPG
 

letterman7

Honorary Admin
Never thought in that direction... interesting. Someone more versed in HVAC might be able to shed more light on this...
 

Peter

Active member
Hmmmm, why not?
This might help.
The Homemade Heat Pump Manifesto - Page 107 - EcoRenovator

I'm still thinking of a DC driven compressor though as I don't want one on the engine.

Inside unit would of course be inside and blowing into distribution system, (hot or cold), outside unit would be outside and it will change from blowing hot and cold air I wouldn't run it in front of the radiator as with an AC condenser but behind it or separately, even better
 
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Brett Proctor

Well-known member
On the honda the fan for the condenser bolts right over it so it has a tight seal.

Running the lines to and from would be easy also.

AC fan.jpeg

I'm still thinking of a DC driven compressor though as I don't want one on the engine.
A good option

Inside unit would of course be inside and blowing into distribution system, (hot or cold), outside unit would be outside and it will change from blowing hot and cold air

Correct. I wasn't awake and thinking on all cylinders when I posted that*nothing to see* Still not totally awake:D
 

ratrog64

Well-known member
Being a home inspector I said the same thing about a heat pump years ago. A simple reversing valve in the system could be a simple solution however here is the problem -
Heat pumps typically do not work with temperatures below say 40 degrees F. That's why they are not effective methods of heat in the northern states but work well here in Florida where our cold days are usually right around 40. So it would work in a car very well until the temps dropped below 40. Then the evaporator and condenser coils and ref lines would ice up and the compressor head pressures would rise and you'd kill your compressor.
 

Peter

Active member
Peter do you know of a supplier

This is the sort of thing I had in mind to be used in conjunction with the normal stuff. There are quite a few types about.
Mini cooling unit 12 volt condenser unit air conditioner portable refrigerator compressor, View Mini cooling unit 12 volt condenser unit air conditioner portable refrigerator compressor, BOYANG/LANHAI Product Details from Lanhai Compressor Co., Ltd. !

or

12V TRUCK AIR CONDITION COMPREASOR - AIR CONDITIONER

My domestic appliance man says many freezers are 12V with a transformer so they don't run 220V mains, worth a thought.

OR a 10HP motor driving a small car compressor either parallel by belt or in-line coupling.
Just thoughts*hmmm*.
 

Brett Proctor

Well-known member
Being a home inspector I said the same thing about a heat pump years ago. A simple reversing valve in the system could be a simple solution however here is the problem -
Heat pumps typically do not work with temperatures below say 40 degrees F. That's why they are not effective methods of heat in the northern states but work well here in Florida where our cold days are usually right around 40. So it would work in a car very well until the temps dropped below 40. Then the evaporator and condenser coils and ref lines would ice up and the compressor head pressures would rise and you'd kill your compressor.

Edit:
Thought about my previous comments and edited this post

Heat pumps typically do not work with temperatures below say 40 degrees F.

Good info to know.

I guess you need to weigh the good and the bad of the system

I don't think anyone here is going to be driving their sterling in freezing weather.

The system may just get you by in the winter but in the summer your going to have AC also.

I doubt anyone here is going to build it anyway but if they did it would be a nice compact system that would fit under the dash of a sterling. There wouldn't be much to it. One set of lines to run to it and you have heat and AC.

It would be interesting for someone to build this just to see how well it works.
I know it works great in a house. If it keeps the house cold here in over 100 degree temps then a scaled down version should work good in a car

Not sure how you would control the temperature. I guess the reversing valve would control that.
 
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ratrog64

Well-known member
Put it where it would get some heat from the motor.

Plus how many of you are going to be driving your sterling in freezing temps with ice and snow on the ground.

Lets not over think this. Take it for what it is.

This system could be made really compact. It doesn't need a heat exchanger for heat. You can make it very basic where there is no need for blend door actuators. The heat vents and cooling vents are the same.

I think the main issue is the compressor. The guys with VW power need something that wont drag the motor down, so a 12V DC powered compressor would seem the way to go if one is out there that won't kill the battery when turned on and is small enough to fit.


If you put it where is would get heat from the motor then in the summer months it might struggle to work well in the cooling mode.

I agree, most wont be driving on the freezing days just like most won't be driving in the rain so why do an intermittent wiper system?

I just offered up some basic information on how heat pumps work and what some of the limitations are. I'm not over thinking anything really, I was just answering a question.

It can be made as simple or as complicated as a person wants. It all boils down to, do you want to have a simple car you can drive as it was intended to be or do you want to continue to over complicate a very basic car with systems you more then likely will not need or use in the short treks to the local restaurant or car show you attend once a month or so?

Most of today's modern AC compressors either scroll or piston do not require the same hp as those from days past. I was told by the owner / engineer of the company who has the system I installed made (in China), that it takes about 1.5 hp to drive the compressor. Cold Master, Largo Florida
The owner is a super cool guy who has designed several of the products they sell. They primarily do larger systems in buses and large commercial vehicles.

To further answer the question, the evap and cond coil would still be mounted the same if its a cool only or heat pump. They just trade roles when in the heat pump mode.
The reason heat pumps are not used in vehicles is because most vehicles are used and need heat in temps below 40.
So do you over complicate or "over think it" by trying to create / engineer a heat pump system for a car or just get heated seat cushions and a small electric plug in heater since the car is not going to be used in freezing temps anyway?
 
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ratrog64

Well-known member

Edit:
Thought about my previous comments and edited this post

Heat pumps typically do not work with temperatures below say 40 degrees F.

Good info to know.

I guess you need to weigh the good and the bad of the system

I don't think anyone here is going to be driving their sterling in freezing weather.

The system may just get you by in the winter but in the summer your going to have AC also.

I doubt anyone here is going to build it anyway but if they did it would be a nice compact system that would fit under the dash of a sterling. There wouldn't be much to it. One set of lines to run to it and you have heat and AC.

It would be interesting for someone to build this just to see how well it works.
I know it works great in a house. If it keeps the house cold here in over 100 degree temps then a scaled down version should work good in a car

Not sure how you would control the temperature. I guess the reversing valve would control that.

Temperature would have to be controlled by cycling the compressor on and off (handled by the thermostat).

Unlike a residential type system where the system only creates a temperature differential of about 20 degrees - lower (in cooling mode) or higher (in heat pump mode) from where it starts (temperature in the house), an automotive type system creates cold air at about 36 to 38 degrees regardless of the temperature inside the vehicle. As you said, in a modern car, the air is blended with cabin air or air through the heater core by regulating a damper system. In aftermarket stand alone systems, they just blow as cold as they can and we regulate the temp by turning the blower up or down or the thermostat on the unit will also cycle the compressor on and off as needed to regulate temperature. The compressor in a car can be short cycled because they bleed off pressure more quickly then a residential type unit and they also have all the horse power they need to start again from the cars motor where as in a residential unit has an electric motor with a predetermined hp rating. That's why they have a timed delay when they are short cycled. It gives them a change to bleed off pressure so they don't get damaged and so the electric motor will have the power to spin them up again.
 

ydeardorff

New member
Another thing to consider is a the HVAC teacher I talked to.
It has to do with climate,...
Heat pumps work well up here in the my temperate climate, but they are much less functional in desert climates. Thats why you see more humidifyer systems, and full blown AC systems than heat pumps. I hear they have started working that problem out, but a system like that may not function well enough in your climate.
 

ratrog64

Well-known member
Another thing to consider is a the HVAC teacher I talked to.
It has to do with climate,...
Heat pumps work well up here in the my temperate climate, but they are much less functional in desert climates. Thats why you see more humidifyer systems, and full blown AC systems than heat pumps. I hear they have started working that problem out, but a system like that may not function well enough in your climate.

This is true, it really is a balancing act. In the dry desert climates, swamp coolers work well for cooling and cost much less to run then a typical air conditioner. Heat pumps have to work harder to heat when humidity levels are extremely low.
 

letterman7

Honorary Admin
Or, simply supplement the heat mode with the OE stale air heating system.. unless you're running watercooled, then the entire discussion is moot :D.
 

Brett Proctor

Well-known member
I'm a little confused. Does everyone here live in Death Valley.

I live in Las Vegas and my house has one of these systems in it and it has no issues keeping the house cold in the summer and hot in the winter. Granted you guys North and East/West of us get worst weather.

The unit has been in the house for 15 years and has had no issues.

Plenty of negative input out there of why it wont work considering nobody has done it.

While your at it why don't you do the math on it.

How many square feet of condenser/evaporator area is there in a house unit and how many square feet of house does that heat and cool. I think you'll find that the area of the condenser/evaporator that is used for a car is way over kill so the unit shouldn't work as hard.

Just forget I brought it up.

Peter:
Did some research on that 12V compressor and it doesn't look like they are that good.

I can post one article I found on it if you would like to read about them.
 

Peter

Active member
Peter:
Did some research on that 12V compressor and it doesn't look like they are that good.

I can post one article I found on it if you would like to read about them.

As I said Brett, *oh my* lots of different ones out there from coke can size upwards, but I am sure you are right, I haven't read up on any reports for them so there must be some duff ones out there, and I hope some good ones too but don't forget we are only talking about 30 cubic feet at most, half a normal car's interior and a lot of that taken up by the driver.

I did look at the Peltier element electronic coolers as used in cooler boxes and small fridges, (I have one in my workshop for summer drinks), but they take 20 minuets to get down to about 5c and not very effective on a big enough scale for a car's interior, also use a fare bit of juice, like 80W.

Also in Oz' they like the ice water coolers with fans in the lids, OK for half an hour or so but heavy and a 'cooler' rather than a 'chiller' and of course it has to be in the cabin, not remote.

I looked at the idea of freezer gel packs in a cooler box with a 1/2" coiled copper pipe in it running through a normal matrix between my fan and the ducts in the cabin circulated by a small 12v pump, re-usable freezer gel packs would last well and maybe with a Peltier unit in the lid to slow down the melting they could be useful and last an hour or so. *hmmm*

Lots of ideas but you seem well into your AC system and very innovative it is too.*rock on*
 

Brett Proctor

Well-known member
Here's the write up on them Peter. It'll give you something to read while you heal:D

http://www.vintageair.com/Tech Articles/Electric Compressors/Electric Compressors.pdf



I agree, most wont be driving on the freezing days just like most won't be driving in the rain so why do an intermittent wiper system?
Because it was an option that already existed on the controls and instead of having a dead circuit on the controls I wanted it to work. Makes it look like a more professional job was done on the system than a half ass one and everyone knows there's a big difference between it raining outside and a light sprinkle which would be when the intermittent option would be used.
Using that thinking then why even wire in the wipers.

I believe this system would work in our cars. Nobody has proven it wont. It would give those air and heat that have nothing and it is more compact than other systems. The biggest problem is what to use for a compressor. Newer compressors are more efficient but when you have an engine that produces only 40 hp every bit counts.
The only other issue is how much heat it would produce. Apparently everyone is in agreement that it would work for cooling.

I don't think the unit would have to produce as much heat as the oem units because nobody would be driving the car in freezing temps, but it would produce enough heat for the temps that the car would be driven in.

Building a simple prototype would answer most questions.
 
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Brett Proctor

Well-known member
These heat pump systems are being used now in EV's.

Don't know any specifications of them but they are being used.
I wonder if those engineers are monitoring this site.
 
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