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Old 06-28-13, 11:53 AM   #21
thumperoo
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Default Open Loop, Open Loop, Open Loop !

Open loop is way easier, cheaper and THE most efficient way to go. We use 1/2 HP jet pump to feed a Trane water source heat pump (24000 BTU) to heat and cool a 2600 Sq Ft house. Saves us tons o money! Our water temp varies between 46-49 deg F. Reject into a grey water weeping field. In your case back to bayou. Coils in the ground or in the water too costly and innefficient. Keep it open loop man, especially if you have well nearby. Thumperoo

The unitís internal heat exchanging water coil is engineered for maximum heat transfer.The coil is a tube within a tube design.The inner-water tube contains a deep fluted curve to enhance heat transfer and minimize fouling and scaling. It is available in either copper or cupro-nickel (selectable option) coil.The outer refrigerant gas tube is made from steel material.

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Old 06-28-13, 11:58 AM   #22
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We bought our trane water source heat pump for $1200 on Kijiji. Just saw plug in water source heat pump on E-bay. Just saw a trane for $950.

Thumperoo
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Old 06-28-13, 12:43 PM   #23
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You can also look at these marine units. Self Contained Marine Air Conditioning Systems - Prices & Specifications
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Old 06-28-13, 12:53 PM   #24
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You can also look at these marine units. Self Contained Marine Air Conditioning Systems - Prices & Specifications
They run on water pumped from sea (saltwater and crap from harbour). They just have good quality strainers and baskets to filter out nasties. Look at the condenser (tube in tube) at bottom of web page link - looks like what you are trying to do.
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Old 07-02-13, 09:19 AM   #25
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Originally Posted by thumperoo View Post
You can also look at these marine units. Self Contained Marine Air Conditioning Systems - Prices & Specifications
They run on water pumped from sea (saltwater and crap from harbour). They just have good quality strainers and baskets to filter out nasties. Look at the condenser (tube in tube) at bottom of web page link - looks like what you are trying to do.
Those guys are the exact reason I started this though (hopefully physical soon) journey. I figure that if I run more feet of similar exchanger I should be able to up heat transfer, but large copper is $$$, so add feet with PEX around small copper carrying the refrigerant.
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Old 07-02-13, 09:20 AM   #26
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We bought our trane water source heat pump for $1200 on Kijiji. Just saw plug in water source heat pump on E-bay. Just saw a trane for $950.

Thumperoo
Wild! have any links?
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Old 07-02-13, 09:49 PM   #27
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Ok, so I see you've decided how to do this project. You're going to draw well water to feed your condenser and discharge it into the bayou. For heat exchange, you plan on doing a tube-in-tube or tube-in-shell design. You plan on keeping the capacity under a ton (12kbtu) for each unit and you're not combining compressors for some kind of multi-capacity staging. You may hack multiple units, but each will have its own supply of cool water from the well. Am I right?

To address your concerns about the condenser, a single tube or coil of copper inside plastic will do fine. You're not going to melt or burn up pex or pvc pipe with a half-ton compressor unless you lose your water jacket. The compressor would surely trip out on its own overload many times before the discharge line got hot enough to melt anything. If in doubt, just use iron pipe.

The only real choice to make in the condenser design is the length. If you can deal with a big loop, you can use 1/4 inch annealed refrigeration tube (don't get icemaker line) inside 1/2 inch pex and just make a couple of large loops. If you need something short, you can wind the copper into a coil and put larger pipe around it. For 15 feet of 1/4 inch tubing, this is way more than a ton of capacity with any substantial amount of water flow. What comes to mind here: using a 3/8" iron pipe as a form, the coil would fit inside a piece of 1-1/2" pipe 3' long; using a 1" pipe as a form, the coil would fit inside a 2" pipe 18" long.

If you were planning on a larger (~20kbtu or more) condenser, a more elaborate condenser (with better flow and heat transfer) would be needed to get ultra-high efficiency. Lucky for you, because your setup is small enough to be simple.

TX valves can be found cheap every day on ebay, here's one today:

1 ton (12k btu)
http://www.ebay.com/itm/AAS-1-HC-Eme...item35c9359d0b

You can also surf to surpluscityliquidators.com and find everything you might need cheap.

They have a 1 ton turbotec coax coil for $31.00 today:
http://surpluscityliquidators.com/vi..._TON_COAX_COIL

Last edited by jeff5may; 07-02-13 at 10:37 PM.. Reason: info
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Old 07-03-13, 12:21 AM   #28
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Originally Posted by jeff5may View Post
Ok, so I see you've decided how to do this project. You're going to draw well water to feed your condenser and discharge it into the bayou. For heat exchange, you plan on doing a tube-in-tube or tube-in-shell design. You plan on keeping the capacity under a ton (12kbtu) for each unit and you're not combining compressors for some kind of multi-capacity staging. You may hack multiple units, but each will have its own supply of cool water from the well. Am I right?
You are correct. I'd like to keep each unit separate for a) zoning and b) reliability of always having a working unit.


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To address your concerns about the condenser, a single tube or coil of copper inside plastic will do fine. You're not going to melt or burn up pex or pvc pipe with a half-ton compressor unless you lose your water jacket. The compressor would surely trip out on its own overload many times before the discharge line got hot enough to melt anything. If in doubt, just use iron pipe.
Awesome on the non melting temperature, that will reduce complexity, cost, and have less points to fail. That said, I'm still dead set on having an over temp shutdown in case of water flow failure.

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The only real choice to make in the condenser design is the length. If you can deal with a big loop, you can use 1/4 inch annealed refrigeration tube (don't get icemaker line) inside 1/2 inch pex and just make a couple of large loops. If you need something short, you can wind the copper into a coil and put larger pipe around it. For 15 feet of 1/4 inch tubing, this is way more than a ton of capacity with any substantial amount of water flow. What comes to mind here: using a 3/8" iron pipe as a form, the coil would fit inside a piece of 1-1/2" pipe 3' long; using a 1" pipe as a form, the coil would fit inside a 2" pipe 18" long.
Wow, way way less than I thought I would need.
What is your estimate of required water flow? I'd like to keep the pump small so as not to drain all of my efficacy gains away in pump watts. I really need to do some testing, I think I only have to pump 4-6 feet of lift with my site, but I need to verify.

Quote:
Originally Posted by jeff5may View Post
If you were planning on a larger (~20kbtu or more) condenser, a more elaborate condenser (with better flow and heat transfer) would be needed to get ultra-high efficiency. Lucky for you, because your setup is small enough to be simple.
Small is the name of the game at the camp, everything is moderately sized, sure makes things simple and easy.
QUOTE=jeff5may;30499]

TX valves can be found cheap every day on ebay, here's one today:

1 ton (12k btu)
Aas 1 HC Emerson Alco TXV Expansion Valve R22 | eBay

You can also surf to surpluscityliquidators.com and find everything you might need cheap.

They have a 1 ton turbotec coax coil for $31.00 today:
TUROTEC | COILS, STEAM & WATER | 1 TON COAX COIL | Surplus City Liquidators[/QUOTE]

I can't remember, I want to run a TXV that is larger, or smaller than compressor capacity?
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Old 07-03-13, 08:38 PM   #29
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Ideally, you want to find a TXV that is rated the same btu capacity as your compressor, at the same temperature range, with the same refrigerant type, with the right sensing bulb gas, with the same size connections as your unit dictates. To put a TXV in a stock unit, the manufacturers say it must be the same as what came out or it will void your warranty.

For us, some of these rules can be bent. For instance, you can go up or down 1 size in capacity and the unit will still do its job well if you don't go out of its range. In your situation, a water-cooled condenser will develop a gob of subcooling during normal operation. This drives down your head pressure, so the TXV would open wider than it would with an air-cooled condenser to let through the same amount of liquid refrigerant. So you would want to go up one size if you can't find a cheap TXV the same capacity as your unit. That way, when you arrive to a hot home and start the unit, it could "follow the evaporator air temperature up" by opening wide without maxing out its flow.

Some of the rules should be obeyed, though. You want to get a valve the same type as your refrigerant. You want to stick with a high-temperature unit that's not made for a blast freezer or a cryogenic unit. Unless you like making and assembling flare fittings, find a valve with sweat fittings. The discharge side will likely be too large, but that's ok. Sweat some "too big" tubing into the valve and run it close to the evaporator before reducing the size. It will act as an expansion chamber, allowing your refrigerant to vaporize better in the evaporator.

Last edited by jeff5may; 07-03-13 at 08:55 PM..
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Old 07-03-13, 08:57 PM   #30
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Here's an article that explains TXV's practically:

http://www.emersonclimate.com/Docume...re-article.pdf

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