Results 101 to 130 of 130
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03-02-2011, 07:03 PM #101
Re: Home made swimming pool heat pump
Ok, just watched a video on TXV's and their construction. Looks like it'll be an interesting addition. So, as usual some questions;
1. What rating of TXV do I need
2. Do I need one that has the ability to be externally equalized
3. At what point on the suction line does the bulb need to be placed.
4. How do I attach the bulb, a jubilee clip/tie wraps/tape?
Thanks to all!
Nigel
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03-02-2011, 08:41 PM #102
Re: Home made swimming pool heat pump
1. I'd base the TXV capacity on the cooling duty of the original air con system.
2. Externally equalised would be best.
3. Just after the outlet of the evaporator. The equalising line is piped to just after the bulb.
4. The valve should come complete with a clamp, but a jubilee clip will get you going. The bulb needs to be insulated too.
Most TXV's have an instruction sheet in the box or printed on the box itself.
Jon
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03-02-2011, 09:28 PM #103
Re: Home made swimming pool heat pump
The clean copper in your system could also be due to the water scouring the metal and slowly erroding it. If the Ph is low, say less than 0.7 there will be a tendancy for the water to leech metal components. Hence shiny copper.
Oxide layers that form on copper in pool atmospheres are usually "Verdi Gris" which does not provide a protective layer. Over time pin hole penetration will occure, and with the refrig pipework, oil will slowly weep through causing the verdis gris to become pasty to touch.
On another note, There is now a following of operators using Copper ionisation in the pool water instead of chlorine. I believe it's a cheaper method. I have no invormation but yuo can search and find many sites that sell this product.Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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03-02-2011, 09:32 PM #104
Re: Home made swimming pool heat pump
I've no idea what that was, there is no label or anything. Only the model number and initial charge. The compressor is 3Kw and a COP of 3 so what would I expect, 9Kw cooling? From the video they talked about 'tonnes', how does this relate? What measurement do TXV's come in? Kw/Tonnes/something else?
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03-02-2011, 09:35 PM #105
Re: Home made swimming pool heat pump
I have come across many situations simillar to that you mention. We find if we test the water the PH tends to be down below 0.7. At this level the water leeches all metal components. In some cases I've had to return and redo the whole wash out within months of the first repair. One guy was an industrial chemist and thought checking his water 6 monthly would be adequate? every week is essential at the min.
I find worse case is when there are lots of children using the pool for other than swimming. Air born Chloramines rot all the metal work, stainless as well.Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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03-02-2011, 09:48 PM #106
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03-02-2011, 09:51 PM #107
Re: Home made swimming pool heat pump
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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04-02-2011, 07:12 AM #108
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04-02-2011, 05:34 PM #109
Re: Home made swimming pool heat pump
Ok, went to the wholesalers to ask what they had. The units they sell are Danfoss TX2 devices. He asked which one and I had no idea! So, over to you guys!
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04-02-2011, 05:53 PM #110
Re: Home made swimming pool heat pump
Your unit is rated at 7.2Kw nominal cooling so your TEX2-(N) needs to be externally equalised with a No.4 orifice (8Kw nominal)
The valve body is the DAN112. The orifice is a DAN208.
The valve will have 3/8" and 1/2" flare connections. The equalising port will have a 1/4" flare connection.
Do you have a flaring tool?
Don't buy the TX2 as this is internally equalised
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04-02-2011, 06:01 PM #111
Re: Home made swimming pool heat pump
Yes, have a flaring tool so no problem. Will go and see if they have this one in stock in the morning and get it installed if they do.
Work interrupted pleasure today so I'll be building the second heat exchanger tomorrow. Have the unit turned off at the moment as I don't want to damage the compressor with excessive heat.
Beautiful sunny weather here at the moment so the solar panels are working hard.
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05-02-2011, 08:12 AM #112
Re: Home made swimming pool heat pump
What part numbers? There are several, I can't find any that has a reference of DAN112 or DAN208, the orifice I guess is part 68-2007.
http://www.kulde.org/CH8/TE2.pdf
Thanks!
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05-02-2011, 11:14 AM #113
Re: Home made swimming pool heat pump
Based on your compressor model. The compressor duty at
4.5 barg suction
18 barg disch
has a duty 7.8kW. R22
Expansion valve required
Danfoss TEX2N (without MOP) has duty of 8.9 kW with press drop of 10 b evap at 5C. when using orifice No 03.
As you're able to braze then the better option of valve would be one you can braze into the sytem.
TEXN part number 068Z328400 (solder)
plus
Orifice 03 Part number 068 209300
plus 3/8 solder adaptor 068 206066
There is a 25% leaway with these valves on their duty and of course you may need to adjust the superheat once up and running.
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 11:20 AM #114
Re: Home made swimming pool heat pump
Sorry to butt in here Frank.
I think you may be quoting nominal duty for the orifice wich is only based on a 2 bar dp across the valve. this application is most likely to have 10 bar dp across the valve. in that case an orifice No. 03 would be most suited as it's duty is 8.9 kW Whereas the no.04 orifice will have a duty of 13.3 kW ... too high I think.Last edited by nevgee; 05-02-2011 at 11:29 AM. Reason: typo correction
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 11:27 AM #115
Re: Home made swimming pool heat pump
links where you can get details of the Danfoss valves.
http://www.ra.danfoss.com/TechnicalI...AA0A402_T2.pdf
http://www.ra.danfoss.com/TechnicalI...CPDAA0A402.pdfReality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 11:30 AM #116
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05-02-2011, 11:46 AM #117
Re: Home made swimming pool heat pump
This link may be helpfull ... Danfoss "Fitters notes" gives instructions on Expansion valves and setting them up.
http://ra.danfoss.com/TechnicalInfo/...chapter_01.pdfReality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 11:56 AM #118
Re: Home made swimming pool heat pump
I think you're quite right here. Does Acuario have the necessary information to pipe up the second condenser, taking into consideration the gas flows to ensure even balancing and equal flow through both condensers?
Perhaps someone has got some typical pipework arrangements that he could follow. Otherwise I fear he may hook up the 2nd condenser and find his gas flows are wrong.
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 12:08 PM #119
Re: Home made swimming pool heat pump
Attached Danfoss pages with TEX selection data
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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05-02-2011, 12:48 PM #120
Re: Home made swimming pool heat pump
I was using the RPW Catalogue
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05-02-2011, 01:34 PM #121
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05-02-2011, 02:13 PM #122
Re: Home made swimming pool heat pump
Well I opted for Heat Exchanger MKII instead of a second MKI in parallel, I could always parallel them up if necessary.
MKII has more coils; 3 to be precise, coil 1 wound on a 32mm former, coil 2 wound on a 50mm former and coil 3 wound on a 75mm former. All then fitted one inside the other and linked at either end. The pipe in each coil is 1/4" diameter. Coil 1 is about 6m long, coil 2 about 9m long and coil 3 about 15m long (now you're going to tell me they should all be the same!).
They are all contained in a 110mm diameter pipe 68cm long.
As I write I'm waiting for the glue to finish drying. I'll post pictures later.
My supplier isn't open saturday afternoons so I'll go and order/purchase the TXV on monday.
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05-02-2011, 06:08 PM #123
Re: Home made swimming pool heat pump
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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08-02-2011, 01:37 PM #124
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09-02-2011, 12:48 AM #125
Re: Home made swimming pool heat pump
If you are able to ensure roughly even flow over each of the coils, they should be of roughly equal lengths of tubing although, I believe, the coil with a larger helical diameter will have a slightly smaller pressure drop.
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05-03-2011, 10:50 AM #126
Re: Home made swimming pool heat pump
Here we go again, a disaster, bad weather and work got in the way but at last I'm off again..
The disaster - I managed to leave a small unbrazed hole in HX MKII and flooded my evaporator etc . I also managed to dump my charge of R22 into the pool at the same time . So, a change of refrigerant and a bit of a clean up was in order..
Blew everything out with Nitrogen and it is up and seems to be running again. As there was no refrigerant left, and I was concerned about any moisture in the compressor (I'm sure there was) I added a filter dryer and at the same time cut out the capillary and installed a TXV.
The TXV is a Danfoss TX2, 068Z3206 and I fitted orifice No. 03, but without filter as that was all he had.
So, it's running again with a new refrigerant, RS44 (R424A), slightly different PT characteristics but it's a drop in replacement.
Measurements are (fan at full speed):
Compressor exit temperature: 53.5'C
Pressure 112psig
Condensor entry 53.1'C
Condensor exit 16'C
TXV entry 14'C
TXV exit (evaporator entry) -1.8'C
Evaporator exit 5.9'C
Suction pressure 37psig
Tuning advice welcome!
Nigel
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05-03-2011, 12:07 PM #127
Re: Home made swimming pool heat pump
Last edited by Gary; 05-03-2011 at 12:23 PM.
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05-03-2011, 01:01 PM #128
Re: Home made swimming pool heat pump
I had a small leak so had to remove the gas, fix it and re-gas. Obviously readings changed...
I also spotted I put a wrong value - too many scribbles on my bit of paper!
A new bit of paper so no confusion!
Readings are:
Ambient: 15'C
Water: 20'C
Exit pressure: 167psig
Exit temp: 64'C
Condensor entry: 61'C
Condensor exit: 26'C
Evap exit: 11'C
Suction pressure: 38psig
So, following the above I have subcooling:
32.2 - 11 = 21.2K
Is this too high? Should I try to reduce it?
NigelLast edited by Acuario; 05-03-2011 at 03:28 PM.
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05-03-2011, 07:11 PM #129
Re: Home made swimming pool heat pump
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08-03-2011, 10:27 PM #130
Re: Home made swimming pool heat pump
38psig = 2.6 barg = -9C sst Too low
super heat -9 -11 = 20C Far too high
Add gas as Gary suggests and open TX valve to reduce Sh. approx one full turn counter clockwise will give 4 C .. so 2 to 3 full turns might do the trick. Check instructions on box. Do it at 1 turn at a time and allow 10 - 15 mins for the system to settle down each time.Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
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