ReplyWouldst it be impossible to size the single cap tube for proper pressure in heat and cool?
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If a heat pump utilizes a single capillary tube for metering to both coils, would 2 filter/driers be required? I would assume you would need one at each end of the cap tube with a bypass on each filter/drier.
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Wouldst it be impossible to size the single cap tube for proper pressure in heat and cool?
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One biflow drier in the liquid line should be all you need
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I would tend to agree with you because you'd be using less of a charge in heat mode.Originally Posted by SBKold
Doug
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Here's the deal. I'm designing a heat pump that has a manually operated valves for the RV. Trying to keep it as simple and inexpensive (value engineering) as possible. I was thinking if I used 2 coils of the same size with a cap tube in between them it would make the concept of reverse flow easy to understand. It will be a fractional horsepower compressor from a Coke machine. Maybe I should just use 2 cap tubes, each with a filter/drier and check valves?
Wisdom has been chasing you, but you have always been faster.
In your darkest hour, when the demons come, call on me brother and we shall fight them together.
A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii
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Yes u would need two driers if u only have one cap tube
But single cap tube theory will not work
Cause indoor and out door don't have the same load.
I'm not sure where would u put ur manual change ove reversing valve?
Fractional HP will not work
Not enough btu capacity
Professional Member
With a single cap tube(which I don't think it would be possible), you would have to use a bi-flow filter as their wouldn't be any check valves and you would only have one path for the liquid
Professional Member
Shaka, all I'm trying to accomplish with this "test" model is theory reinforcement. A fractional hp compressor will do absolutely fine. All I'm hoping for is a cold coil and a warm coil. Not really desiring great amounts of heat transfer. I did this drawing in Paint. Let's see if it will work. By closing one of the valves in the discharge line and one of the valves in the suction line, I should be able to manually control the direction of flow.
Last edited by doc havoc; 03-27-2013 at 05:24 PM. Reason: Changed diagram to reflect closed valves.
Wisdom has been chasing you, but you have always been faster.
In your darkest hour, when the demons come, call on me brother and we shall fight them together.
A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii
Professional Member*
looks good to me doc.
put 2 biflow driers on either side of tube or just even strainers since its just a model.
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My bad
It's a learning apparatus
In that case it looks good
Why not just use a real RV
So they can understand it on the bench.
If u ask me those shut off valve cost more that RV.
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Just use one drier and add it onto discharge right after compressor. York did it for years.
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Sort of like a small condensing unit and evap. I always tell the customer to think of a window AC turns around.
Shaka, all I'm trying to accomplish with this "test" model is theory reinforcement. A fractional hp compressor will do absolutely fine. All I'm hoping for is a cold coil and a warm coil. Not really desiring great amounts of heat transfer. I did this drawing in Paint. Let's see if it will work. By closing one of the valves in the discharge line and one of the valves in the suction line, I should be able to manually control the direction of flow.
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Just make sure its a quality solid core one from sporlan though!
Not a bad idea though....then just use a couple strainers at the cap tube. Guess the only downside is the strainers will release any debris whenever it switches.
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I did not know they used drier on discharge line
It seems like repeated pulsation will break it down.
I guess it would also act like a muffler the same time.
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won't the heat of the discharge gas prevent it from trapping and holding any moisture?
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If it's purged with nitrogen and evacuated well enough, the amount of moisture left in the system should be negligible?
I have cut-away reversing valves and functioning heat pumps in the lab for actual experience. Not all people learn the same way. I figure, the more options I can give them, the better off they will be.
While the individual valves are probably more expensive than a reversing valve, I happen to have enough of them laying around to make this work.
Wisdom has been chasing you, but you have always been faster.
In your darkest hour, when the demons come, call on me brother and we shall fight them together.
A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii
Professional Member*
^^^what he said
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McQuay's cap tube heat pumps have only a strainer at the capillary connection. If you really want a filter drier, install a suction drier before the comp. With nothing to clean it will dry the system and not have to be removed.
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why dont you just use a biflow txv? like they do on majority of wshp's and install biflow drier on liqiud line in cooling thats what trane used to do if you use single cap tube you could end up with a lot of coiled up copper tube.I believe it was lennox years ago(like 30)that they had systems like that but there was a lot of coiled copper in the condenser on split systems that were close to each other
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Trying to build this with stuff we have laying around the shop. We have lots of cap tube, but not so many TXV's. Especially biflow TXV's. Remember, this is a fractional horsepower system. It will be using a 1/3 HP compressor from a Coca Cola machine along with two evaporator coils from similar Coke machines. The cap tube won't be much longer than probably 8 feet (depending on the I.D. of the tubing).
Wisdom has been chasing you, but you have always been faster.
In your darkest hour, when the demons come, call on me brother and we shall fight them together.
A Veteran is a person, who at some point in their life, wrote a blank check payable to the United States of America for payment up to and including their life.
Gene Castagnetti-Director of the National Memorial Cemetery of the Pacific in Hawaii
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