# MasterFlux BLDC Air con system



## Vortex (Aug 17, 2012)

I purchased a MasterFlux compressor and 4 way reversing valve to run a RC air con system in my EV. However the Subaru Vortex donor car was never fitted with AC although it was an option. So I need to build from scratch. My intention was to buy the a condenser and evaporator for a similar sized car from the wreckers. I also understand I can't use a standard expansion valve as they are a one way device and I must use a fixed orifice tube instead. Has anyone attempted this and could they pass on some experiences and advice


----------



## Roy Von Rogers (Mar 21, 2009)

Vortex said:


> I purchased a MasterFlux compressor and 4 way reversing valve to run a RC air con system in my EV. However the Subaru Vortex donor car was never fitted with AC although it was an option. So I need to build from scratch. My intention was to buy the a condenser and evaporator for a similar sized car from the wreckers. I also understand I can't use a standard expansion valve as they are a one way device and I must use a fixed orifice tube instead. Has anyone attempted this and could they pass on some experiences and advice


 
It doesnt matter if you use an expansion valve or a fixed tube, you must have a bypass at evaporator in order to use it as a heatpump and must have the same at the condensor plus a metering device. You need to realize in heatpump mode the condensor is the evaporator and evaporator the condensor (giving heat). 

Btw there is no such thing as a four way reversing valve, its just a reversing valve wich needs 4 tubes to do the reversing.

Roy


----------



## acarstensen (Sep 4, 2012)

You will need something like this valve from Sanhua:

http://www.zjshc.com/Esanhuaweb/productsdetail.asp?id=105

Also, the heat pump mode is not really effective in cold climates.


----------



## acarstensen (Sep 4, 2012)

You may also want to look at this link:

http://www.refrigerationbasics.com/RBIII/heat_pumps1.htm

Tony


----------



## Vortex (Aug 17, 2012)

Thanks Roy. I agree on the valve name but thats what Danfoss call it.


----------



## Vortex (Aug 17, 2012)

I already have a Danfoss reversing valve. Thanks for the refridgeration link, havent seen it before and its very good.


----------



## Nathan219 (May 18, 2010)

Have you talked to Master flux? They don't recommend heat pumps for vehicle applications. If you are dead set on a heat pump, go for it, but a resistive heater would be more efficient option. Good luck, keep us posted!


----------



## Roy Von Rogers (Mar 21, 2009)

Vortex said:


> Thanks Roy. I agree on the valve name but thats what Danfoss call it.


Dont know the reason they call it 4 way, if they do want to use that it would be more like 2 way...lol

Let me explain a bit so you know how heatpumps operate in a home enviroment.

In heat mode the outside (condensor) gets cold enough to were it frosts up, to the point it needs to be defrosted. They determine that it needs to be defrosted with a sensor. So they turn the unit in to cool mode without running the outside fan, in order to defrost the condensor coil. 

In order for the inside unit not to throw cold air in to the house, they have an electric heating element, to offset the cooling at the time of defrost. In other words, they use the inside heat to defrost the outside coil.

To use such a system in an EV one has to account for what is needed to make it operate properly, as mentioned above.

One could use a large drop in interior temperature output at evaporator to accertain it needs defrosting and reverse the unit, and if the air outside is above freezing, turn of interior airflow and let the unit defrost via plain driving airflow across condensor coil, or have some other meachanism to transfer heat to the condensor coil and use heat from interior to defrost when outside temps dont allow. But what does one use to keep interior from getting too cold ?? You will still need some kind of heatsource to negate from getting interior cold airflow.

As you can see, there is a lot of mechanism's involved, and as a professional in this discussion, I have to agree that using some other source of heating, would be prudent. I wouldnt attempt it, but then again I live in Florida, so heating is not a large concern.


Roy


As you can see


----------



## Maury Markowitz (Jul 6, 2012)

Nathan219 said:


> Have you talked to Master flux? They don't recommend heat pumps for vehicle applications. If you are dead set on a heat pump, go for it, but a resistive heater would be more efficient option. !


Really? I was under the impression that a HP was about three to four times as energy efficiency as resistive heating.


----------



## Nathan219 (May 18, 2010)

Efficiency was a poor choice of words. Size your components to avoid Ice over of the heat exchangers. keep us posted.


----------



## Maury Markowitz (Jul 6, 2012)

Nathan219 said:


> Efficiency was a poor choice of words. Size your components to avoid Ice over of the heat exchangers. keep us posted.


So why do they suggest not using them then?


----------



## Vortex (Aug 17, 2012)

Nathan219 said:


> Have you talked to Master flux? They don't recommend heat pumps for vehicle applications. If you are dead set on a heat pump, go for it, but a resistive heater would be more efficient option. Good luck, keep us posted!


I looked at their site 12 months ago but didnt seen that comment. I planned to go with both heat sources. Initially use a ceramic cartridge heater in place of the heater radiator (it was U/S anyway) and then upgrade to A/C. As I live in a predominately hot climate, cooling is needed a lot more than heating. If I go with RC the evap unit can easily be added inside without removing the dash again and the heater cartridge can stay.


----------



## Vortex (Aug 17, 2012)

Roy Von Rogers said:


> Dont know the reason they call it 4 way, if they do want to use that it would be more like 2 way...lol
> 
> Let me explain a bit so you know how heatpumps operate in a home enviroment.
> 
> ...




Roy,

I live in West Australia where the climate is dry, humidity low and it briefly gets below freezing overnight in some areas one or two times a year. Ive never seen a split system A/C ice up here. As I plan to have a cermanic cartridge element installed anyway (phased approach) I can always fall back on that.


----------



## acarstensen (Sep 4, 2012)

The issues with using compressors as heat pump is related to low temperature climates. You dont want the refrigerant to migrate back to the compressor which can damage the compressor. Typically, heat pump systems are not used in temperatures where it can get into the 30's F. In some cases, there is a belly band heater applied to the compressor to heat it up and boil off the refrigerant out of the compressor prior to it running. I am fromMasterflux and this is the recomendation from us.


----------



## Maury Markowitz (Jul 6, 2012)

acarstensen said:


> Typically, heat pump systems are not used in temperatures where it can get into the 30's F. In some cases, there is a belly band heater applied to the compressor to heat it up and boil off the refrigerant out of the compressor prior to it running.


I'm in Toronto, and it gets into the 0's here (rarely, but at least once a year).

But the vast majority of the heating load happens at temperatures between 35 and 55.

In this case, would I not save considerable energy by using a pump, rather than solely relying on a resistance heater?

And if so, is the solution you note here one that you *do* recommend?

I wouldn't mind having to install a secondary heater - my home is also pumped and has just such a solution.


----------



## acarstensen (Sep 4, 2012)

Maury,

Yes. You would save on power with a heat pump but there is only so much you can get at low temperatures. As the temperatures go down, the effectiveness of the heat pump system also goes down. I'm just not sure you would be happy with the performance. I am in Michigan so I know what the weathe in Toronto can be. I would much rather have resistive heating than relying on a heat pump. however, you can use both and just switch to the resistive heating when the temperatures get too low.


----------



## Roy Von Rogers (Mar 21, 2009)

Considering the extra complexity involved in doing a heatpump system on an electric vehicle, a resistive resolution is highly recommended.

I'm in Florida and a HVAC professional, and I wouldnt even attempt such an installation.

Roy


----------

