First Heatpump project

[stef110]

Yes i have a bending iron, all the pipes are 22mm iron pipes. I love to do the bending, on daily bases i am an electrician, over here in Holland we also do every thing with plastic pipe witch involve also lots of bending.

stef

[Mikesolar]

haha, is that hemp I see on some of the pipe threads? I use it all the time but the younger dudes here have never see it used.

[stef110]

Yes it is, i use it one almost all the screw-joints never ever had a leak on them.

[stef110]

small update on the programming:



This small program show you the values of the sensors, power usage, cop and relay statuses.

stef

[stef110]

Today i fit the temperature sensors in the outside unit and screw it back to gather. And already moved it to the roof of the garage. Where it will be placed on a backed on the wall so it won't stand on the roof it self.

On the general purposed heat pump controller topic, I saw ac_hacker ordered two flow sensors. I also ordered them and today i did some tests.
I mounted two valves on eater side of the sensor, one to adjust the water flow and one to just turn on of off the water. I get a water measure cup (don't know how you call it in English).
I filed the cup for exactly 20 seconds and looked how much get in.
Then calculate how much Liter per minute the flow was.
After that i just let the water flow in a bucked and looked what the software say's that the flow would be.
The calculation from the measure cup was 2,1 liter per minute.
The software say's 2,08 - 2,28 liter per minute.
I will adjust the sample time to increase the accuracy of the sensor but overall not bad!







I also have a other question about the defrost function. This is the case:

Below zero outside and there is a heat request
HP will start and the refrigerant will start to flow around.
I have two sensors one on input of the condenser and one on the output
The hp controller notice that the delta T is to low on the condenser.
This maybe will be caused by a frozen radiator so the defrost mode needs to be run.
In this case can I just switch the 4-way valve while the compressor is running?
I also will stop the fan, and let the heat do the rest.
After a certain amount of time. The radiator will be frost free and i will switch the valve back and restart the fan. And heat mode is back up.



stef

[stef110]

In the last 2 days a lot is happened, I placed the outdoor unit outside en made the cooling lines. Yesterday i brazed everything en put it under pressure this morning it was still on same pressure so the vacuum pump is running at this moment.

here are a few pic's of installation:



























stef

[stevehull]

Very nice! I wish I could do brazing that well.

Question on the flow sensor. If I recall, the Hall effect has square wave output with frequency of pulses being proportional to flow.

Is there a simple converter that would allow me to use my Fluke multimeter as an output? Counting square waves is tedious . . . .

There are a number of places on the farm where a temporary "check it" water flow sensor would be big help. Currently, I use a 5 gallon (20 L) plastic bucket and a watch . . . .

Thanks! Keep up the excellent work.

Steve

[AC_Hacker]

Originally Posted by stef110

I also have a other question about the defrost function. This is the case:

Below zero outside and there is a heat request
HP will start and the refrigerant will start to flow around.
I have two sensors one on input of the condenser and one on the output
The hp controller notice that the delta T is to low on the condenser.
This maybe will be caused by a frozen radiator so the defrost mode needs to be run.
In this case can I just switch the 4-way valve while the compressor is running?
I also will stop the fan, and let the heat do the rest.
After a certain amount of time. The radiator will be frost free and i will switch the valve back and restart the fan. And heat mode is back up.

Stef,

Defrost is a problem. Sounds like you are using the 4-way valve to do the defrost work... a very good idea, it should be fast and efficient.

Your scenario started, "Below zero outside and there is a heat request...".

The problem with frost build-up is that it can happen any time the evaporator coils go below freezing (0 C.), not necessarily the ambient temperature... and it get worse as the ambient temp gets lower.

Your idea of two temperature sensors on the evaporator is good, with the exception that the sensors will be most sensitive to change (temperature difference) when the evaporator coil is nearing 100% frost coverage... this will be too late for best efficiency.

In my opinion, you will need to study the physical progression of frost build-up. I think that you will see it spreading from the part of the condenser HX that is nearest to the entry of the cold gases, and spreading out from there.

On the air conditioners and de-humidifiers that I have de-constructed and studied, I have noticed a thermistor that is fixed to the evaporator coil between the fins, at a place that is only a modest distance away from the point of entry of the cold gases.

And I have seen in operation, that when the frost pattern advances to, and slightly past the thermistor, the de-frost cycle commences.

I can only surmise that the thermistor registers an abrupt temperature drop that is the signature of frost build-up at that point.

On the units I have studied, the frost pattern is not allowed to advance more than 10 to 15 percent of the total evaporator HX area.

Using the thermistor approach, you can change locations of the thermistor, and thereby determine the optimum point where your de-frost cycle commences. If you design for zero frost, your de-frost cycle will run too often, and you will lose efficiency. If you design for maximum frost, your evaporator HX will be obstructed and you will lose efficiency. So the "sweet spot" will likely be between the extremes, probably in the 5 to 20 percent range.

I hope this gives you some useful ideas...

Best,

-AC

[stef110]

Ac thanks for the tips. Yesterday after a vacuum session of 8,5 hours i reached 200 microns. And after that I released the refrigerant.
Today i did my first test run on heating the building.
I have some questions about the readings of my gauge set, I have a temperature sensor of gas and on liquid line. On the picture with the gauge i have two cheapass simple digital temperature sensors. On the inside of the unit i have two ds18b20 sensors. The gas sensor reached about 69 degrees and then stabilized. But when the temperature inside started to rish it finaly crossed the 70 degrees and my controller cut the compressor down. Now is the question i need to calculate super heat to know is there is enough refrigerant or there is to less. When i use the readings on the picture. Witch values do i need to take the pressure of the low side? and the temperature of that? or do need to take this measurement on cooling function?




bigger picture: http://gallery.svitterzon.nl/cache/a...2011.40.10.jpg


bigger picture: http://gallery.svitterzon.nl/cache/a...2011.53.16.jpg

stef

[Mikesolar]

If you are heating, take the measurements on heating. I installed a HP a month ago and I set it up for cooling but I know when heating season comes, I will be back to look at it again. If there was an accumulator and receiver, I wouldn't have to do this.