Pool heat pump set up help please. retired eng.

I am a retired commercial refrig eng [health reasons] and have not touched a system for the past 13 years. Many things have changed in that time, gauge's, gas etc.
I have recently bought a cheap and cheerful air source heat pump for my small pool. It arrived well packed and I was surprised by the quality, it is very well made and has a Toshiba rotary comp. Because it was cheap, the setting up instructions are not all that good. It gives basic parameter settings on the digital display, but that is all.
What I need to know is how to set up the water flow rate to get maximum efficiency. I have a bi pass kit to control the water flow. I do not have any of my old gauge's, however there is a built in gauge on the side.<br><br>This gauge reads Kg-cm2&nbsp;&nbsp; 0 to 55
and MPa &nbsp; 0 to 5.5, plus temperature in both f &amp; c.<br>Gas used is R410A. It is a bit different from the PSIG ones I am used to, so if any one can help please bear this in mind, my little grey cell is not what it used to be.<img smilieid="1" class="inlineimg" src="http://www.refrigeration-engineer.com/forums/images/smilies/happy.png" border="0"><br>Until I have a look inside I don't know if the gauge is linked to the suction or discharge. This does not really matter so long as I have one or the other.<br><br><br>My filter/pump can handle 1600 gals/hour, [7.2 cubic metres] the heat pump is rated to handle 1.5 - 2 cubic metres hour so I would imagine the flow rate will have to to be throttled back using the bi pass valves. Any help as the best way do do this will be greatly appreciated.<br><br>Basically, what would be an 'average' suction / discharge pressure/temp to adjust the water flow to. I know water and air temps will have a bearing on the pressures, so&nbsp; 'average'&nbsp; readings would give me something to work with.<br><br>I think I have covered all that is needed, any further info reqd please ask.<br><br>southcoaster.<br>

FROM SOUTHCOASTER.

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RE WRITTEN WITHOUT TEXT FORMATING

I am a retired commercial fridge eng [health reasons] and have not touched a system for the past 13 years. Many things have changed in that time, gauges, gas, etc.

I have recently bought a cheap & cheerful air source heat pump for my small pool. It arrived well packed and I was suprised by the quality, it is well made and has a Toshiba Rotary comp. Because it was cheap, the setting up instructions are not all that good. It gives the basic parameter settings for the digital controller/display, but that is all.

What I need to know is how to set up the water flow rate to get maximum efficiency. I have a bi pass kit to control the water flow. I do not have any of my old gauge's, however there is a built in gauge on the side.This gauge reads Kg-cm2, 0 to 55 and MPa 0 to 5.5, plus temperature in both f & c. Gas used is R410A. It is a bit different from the PSIG ones I am used to, so if any one can help please bear this in mind, my little grey cell is not what it used to be. Until I have a look inside I don't know if the gauge is linked to the suction or discharge. This does not really matter so long as I have one or the other.

My filter/pump can handle 1600 gals/hour, [7.2 cubic metres] the heat pump is rated to handle 1.5 - 2 cubic metres hour so I would imagine the flow rate will have to to be throttled back using the bi pass valves. Any help as the best way do do this will be greatly appreciated. Basically, what would be an 'average' suction / discharge pressure/temp to adjust the water flow to. I know water and air temps will have a bearing on the pressures, 'average' readings would give me something to work with.

I think I have covered all that is needed, any further info reqd please ask.

southcoaster.

.

Hello Mr Coaster.

a Mpa (Megapascal) = about 150 psi so the 0 to 5.5 Mpa gauge would be
0 to 750 psi = discharge gauge I would say.

410a is a higher pressure refrigerant than you will be used to and it would
easily run at 200 to 300 psi dischage (13 to 22bar new money).. Suction at 0 deg C
would be 4 bar (60psi )..

So for a pool water heatpump with a water temp at about 15 deg C your suction would
be about 5 / 6 bar ( 75 to 100psi) and the delivery of 25 deg C, the discharge would be at
about 15 / 16 bar (200 / 250 psi). 410a Can run with a lot higher a discharge so don't be afraid
if it looks high.


Cheers

taz

.

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Oh and by the way...

If you have not worked with the new refrigerants for a while

DO NOT fit a set of gauges to it. Leave well alone because the
pressures are higher, the fittings are differant and the charge will
more than likely be so small that if you accidently lost (vented) any
while connecting or disconecting you might not have enough to work
the system...

taz

.

Many thanks for the info taz. It will give me something to work with.

It will be a couple of days before I can get it up and running weather permitting, as I am still waiting for some parts. I will let you know the outcome, and perchance you should see a 5kw heat pump passing overhead at a great rate of knots you will know that things did not go quite according to plan.

southcoaster.

Maybe try setting it up like you would with a pool gas boiler.

Start with the bypass closed and measure the water temperature with the unit OFF. Now start the unit and see what the water temperature is.

Open the bypass valve until you get the temperature rise across the heat exchanger that it is designed to do.
+
if you want a very good conversion software tool then download Uconeer, it's free and a lot of us use it.
http://www.softpedia.com/get/Others/.../Uconeer.shtml

Have downloaded the program Brian, it is just what I have been looking for.

Your suggestion of getting a TD across the heat exchanger is what I originally thought of doing. The problem with this method is under certain circumstances the TD can be as low as 1 degree, this could possibly give the impression that there is a fault with the heat exchanger.

Just a point of interest. If I started with the bi pass valves fully open, would this not bring the discharge temp down too low as the heat exchanger is only meant to handle 1.5 to 2 cubic metres an hour, not the 7 cubic metres the filter pump is capable of delivering. I suppose I could start with them open and then throttle slowly to reach the desired discharge temp mentioned by taz. My thoughts are the more water flow through the heat exchanger the lower the head pressure, the same as air passing through a condenser, if I remember rightly if air flow through a condenser is restricted, it causes high discharge temps. If I have got this wrong please correct me; as I have said before my little grey cell is not as it was.

Any comments are most welcome southcoaster.

southcoaster

Yes, you can start with the bypass open, I only suggested it as a way of measuring the existing pool water temperature, assuming a single measuring station.

Too, as you say the unit is only meant to add heat to a percentage of the total circulating water.