Problem

[Peter_1]

Tuesday, I visited a HP air/air monobloc.


Scroll Manuerop inside SZ090 on R407c, 3 phase.
Started up in heating mode: 3,3 bar LP (45 psi), 24.5 bar HP (355 psi)
Outside temperature 11.3°C (52°F)
Discharge temperature: 111°C, (232 °F) liquid 46.5 °C (116°F) suction right after the evaporator was 7°C (44.6°F)
Turbine Nicotra over the condensor 12/9.

Measured airvolume over condensor 2.400 m³/u (1413 cfm)

Opened valve till SH of +/- 7K
3.6 bar (52 psi) / 26.2 bar (380 psi) discharge 96 °C (205°F), liquid 53°C (128°F)

The unit works with a bad COP.

This machine is a replacement for a Carrier 50HS060

Inside is a liquid receiver without valves. I suppose both tubes are going to the bottom of the receiver. Otherise, I do'nt see how they circulate the liquid when reversing.

Complaints: client monitored power consumption since 1999 with the Carrier which was allways around 32000 kWh/year. Now this is increased to 43000 kWh/year.

When the units was just started, he had to reset the HP once a day, seems that this happened mostly after a defrost?
There's no suction accumulator.

Most important complaint is that during the coldest days, it took hours and hours to raise the temperature from 19°C to 20°C (66.2°F--> 68°F)
Reaching 22°C (71.6 °F) inside wasn't possibel when it was -3°C (26.6°F) outside.
The old Carrier HP could reach easily 25°C (77°F ) inside.

The old ductwork is still the same and in very good condition.
The ductwork is made of PU plates (alu foil inside) of 4 cm thick.

The suction on the condensor leaves the coil on the upper side of the coil. This seems strange for me...what about proper oil return?

Comments please .
NoNickName!

[NoNickName]

It's common for some units, for example Climaveneta chillers with heat recovery, to have HP problems on cycle reversal or when heat recovery ends. This is because of the way they use the high pressure, in parallel to main condenser.
This bluebox is an example: to have high water temperature, they kill the compressor with a 110°C discharge temperature. The result is a bad COP and a prone to failure compressor.

I wouldn't compare an old R22 with a R407c unit, some loss of performance is expected in the change.

A 7°C after the evaporator with 11°C outside is not bad, that means a 0°C evaporating temperature, which is quite common for cheap heat pumps. I don't understand why the heat is not released in the recirculation... did they left some fresh air intake open while warming up?

The other thing is the condenser: it is not proper to have liquid exit on the top. It means that the coil is flooded with liquid and that would explain an extremely high pressure with few kW released.
For me, it was mounted upside down.

[Peter_1]

Thanks NoNickName.
As far as I remember from my last visit to Intherm and X-Change, Intherm is making the coils for Climaveneta.

Can you explain why you think is the reason why Climaveneta chillers with heat recovery or others trip on HP problems after cycle reversal or when heat recovery ends?
I thought this was because they don't have a suction accumulator.
They solved it now by programming a timer after every switch over of the 4WV.

What do you mean with "This is because of the way they use the high pressure, in parallel to main condenser"


This bluebox is an example: to have high water temperature, they kill the compressor with a 110°C discharge temperature. The result is a bad COP and a prone to failure compressor
It's an air/air unit.


I wouldn't compare an old R22 with a R407c unit, some loss of performance is expected in the change.
I agree with you but the client insisted when they replaced the Carrier unit that the new one should perform at least the same as the old one and in fact, that it could perform even better then the Carrier unit He expected with the new techniques, the new compressors, the electronics they have today that it should run even much cheaper then the old one.
This is a reasonable thinking for me for a non-tech.

A 7°C after the evaporator with 11°C outside is not bad, that means a 0°C evaporating temperature, which is quite common for cheap heat pumps. I don't understand why the heat is not released in the recirculation... did they left some fresh air intake open while warming up?


The other thing is the condenser: it is not proper to have liquid exit on the top. It means that the coil is flooded with liquid and that would explain an extremely high pressure with few kW released.
For me, it was mounted upside down.

I think I explained it not very well, the way it was working when I visted it was in heating mode.
So the coil with the tube going upwards was on that moment evaporator.
Hadn't the opportunity to see the other coil inside the unit with the centrifugal fan.
I will go back next Wednesday and I will take some pictures of it.

I think there's something wrong with the condensor coil, blocked circuits, wrong soldered (have seen this on a Kuba and Roller evaporator), airflow over the condensor seems a little bit low or perhaps simple designed far too small.

I insisted Blue Box that they give me this week the dimensions of the coil.
If I have them, I will post them here to check these.

It's almost impossible to measure temperatures on the coil while running because when you open the access cover, you short circuit the air over that condensor.

[Lc_shi]

Hi peter,
What the nominal heating capcity by the unit?
You measured the condenser air flow 2400m3/h, and you can calculate the heating capacity by in/out air temp and humidity. Maybe you can find the problem. It has liquid receiver and no suction accumulator, i think it's a not too good design:)the opposite is acceptable. But it's without problem if programming proper protection ways

only for your ref

good luck
LC

[Peter_1]

BESCie, what do you think about the compressor parameters?

[NoNickName]

This is interesting, but I have customers today and I can't take care of this.
Will look into it tonight.

[BESC5240]

BESCie, what do you think about the compressor parameters?
Hi Peter,
I don't know what the suction temperature is at the compressor inlet. But if you have (in these conditions) more then 5K superheat in the suction line, you are already outside the operation envellope of the compressor. So your really on the limits of use of the compressor. (I suppose from time to time it goes out on it's internal protection).
Another thing that strikes me is the large subcooling : 11 to 15 K. That's a lot for this kind of unit. Propably partly due to the construction of the condensor. Like no Nickname said: 'flooded with liquid', so stay a long time in contact with the air flow over the condensor. (Too much refrigerant in the system?)

[NoNickName]

Now, a standard Nicotra 12/9 (let's say a 1.1kW) is capable of deliverying 3500/3800 m3/h with a static pressure of 240/280 Pa.
So, I don't know the static of the duct, but I think that you are missing a bunch of m3/h.

I see it's a rooftop, my mistake, but the point stays. How could be acceptable a 110°C discharge temp. It's out of the envelope, probably because of the high suction temp (which is not the case, since it's just 7°C).

For the receiver, they don't circulate liquid when reversing, they use the receiver as strainer (which is bull****).

[Renato RR]

Maybe the static pressure from Carrier was greater.Or maybe you have rotation of condenser fan in wrong direction.Maybe bad belt.

Something missing in this picture.

Renato:rolleyes:

[Peter_1]

This is the manual of the old Carrier
http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/50hs-1si.pdf

And this is the new machine. http://www.blueboxgroup.it/pdf/uk/2_gamma-1.pdf

Airflow and static seems the same
Turbine is direct drive and running the right way.

I wonder if the outlet of the other coi is also faced upwards.

We haven't installed these units, I'm only called try to find the cause(s) of the problems.

[Renato RR]

Carrier:
830 in.wg. =...........Pa ?
CFM = m3/s?
I dont know how to change this values in SI units.

Best regards,
Renato

[Peter_1]

I use the free conversion software from http://www.katmarsoftware.com/uconeer.htm

[NoNickName]

1.153 m3/s are 4150 m3/h, and not 2400 like you measured.
And 1995 cfm are 3391 m3/h

The two units don't have the same design air flow, and the new one is not correctly installed.

[Peter_1]

1.153 m3/s are 4150 m3/h, and not 2400 like you measured.
And 1995 cfm are 3391 m3/h

The two units don't have the same design air flow, and the new one is not correctly installed.

NoNick name1.153 x 3600 s.h = indedd 4150 m³/h.
Where have I said 1.153?? :confused:

And where is the 1995 cfm coming from.
This is realy a confusing post for me.

[Peter_1]

Forgot to say that it is a Cariier type 60.

I measure allways in m/s, multiply with meters, so, there must be a misunderstanding.

[NoNickName]

In the first post you said it's a carrier xxxxxx60, and for that model, on the catalogue you posted it says 1995 cfm

On the blue box catalogue, the air flow is 1.153 m3/s

And in your post you measured 2400 m3/h

[Peter_1]

Seems that the Carrier gave at 150 Pa design static (0.6 mmH2O) a flow of 3609 m³/h (2120 cfm)

So I measured +/- 2400 m³/h which didn't correspond with the AMPS the fan pulled.

I measured an average airflow (measured on 20 spots) of 3.5 m/sec over the central suction filter of 31 x 61 cm, locatd +/- 7 m from the machine.
The return duct is one straight end to the duct (I could see the machine through the suction grille)

I will go back Tusday to measure:
Static, DP over the fan, AMPS of the centrifugal, take some pictures of both coils especially the outlets, take some dimensions of the coils, add smoke in the ducts with a smoke generator, measure the flow coming out each grille and add those all together, ...

Any other things you think on?

I think I will let it run for some time with an open outlet (not connected to the pusion duct and monitor of course running current).
Then I eliminate the complete possible pulsion duct problem.
The importer suggested that there could be an obstruction in the pulsion duct (an outlet vane that has loosen in the duct)

Like you and BESC5240 said, 110°C is outside the compressor envelope.

Anyway, this machine should be desigend so that it can handle to my experience 150 Pa static pressure.


NoNickName, no I see wher you got the 1,153 m³/s; from the BlueBOx brochure.
Sorry.
Well how I read these numbers: the max airflow this machine can give is +/- 4.300 m³/h with 0Pa and it can deliver max 150 Pa at 0 m³/s.
I don't think that the 1,153 m³/s is valid at 150 Pa.

And now I also see why you thought it was an air/water, the brochure speaks about a waterflow of 0,613 l/s.
On the first page, they speak about an evaporator and a condensor with copper tubes and aluminum fins :confused:
It's indeed confusing.

[Peter_1]

Our posts cross-posted.

I think the unit can give +/- 4.300 m³/ h at 0 Pa and +/- 2.400 m³/h at the pressure (say 150 Pa) it was running when I measured the flow.

Anyhow, the machine must be able to handle a certain duct pressure - and for me 150 Pa seems normal - without coming into the problems we encounter now.

[NoNickName]

Oh, what a mess of a plant.

Anyhow, for me it's 150 @ 4300, because this is how we make our catalogues, don't know bluebox, though.

[Peter_1]

Was back on the site this forenoon.
Re-mesaured and datalogged many variables.

Heatpump mode: air entering condensor was 21.7°C (71.06 °F) (room temperature) , leaving air at 45.5°C (114°F)

Evaporating at 4,48 bar (65psi) and condensing at 27,5 (399 psi) to 28 bar (406 psi). Outside temperature 23.3°C (73.94°F).
Discharge was +/- 95 °C.(203°F)
LIquid at 57°C ( 134.6°F)

Static pressure of the Nicotra turbine (12/9 6P 900 RPM / 1100 W) varied from 145 to 155 Pa. AMPS were 2.2 A on the 3 lines (measured in the main duct +/- 2 m after the turbine)
Air velocity at the main suction grille +/- 3600 m³/h (2148 cfm) measured 3 times (3620 - 3590 - 3630)

Outside coil is 1000 x 1000 x 130 mm and fin spacing of 2.1 mm
Inside coil is 1000 x 750 x 130 mm, fins pacing 1.8 mm.
Tubes 3/8 and 30 x 30 pattern I think (forgot to measure the pattern)

Temperature of the room rised to 22.6 °C (72.7°F) and machine cut out at 28 bar (407 psi)

[Peter_1]

Some more pictures
Static pressure 1.57 hPa
Inside coil, the tubes coming out are positioned at the tubes on the other side.
I think they make it this way so that they can use it in both directions.
Tubes are coming out at +/- half the coil height

[NoNickName]

http://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=960&d=1147882040

This is f..ing stupid. Vapor can enter at any point, but liquid can't enter or especially exit at the middle. Is This evaporating or condensing? How do the circuits close if there are manifolds on both sides of the coil?

http://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=955&d=1147881969

More f..ing nonsense. How can liquid go up unless drowning the condensing coil?
And when it goes up, then it overflows and doesn't feed the TXV properly.

Oh, by the way: you made an encounter with a green GMC filter (look at the other thread).

[Peter_1]

NoNickName,

It's possible that on the coil itselves the tubes are located at the right position but that they were extended to have a better location for soldering.

Unfortunately, I can't see the other end of the inner coil.

One of the tubes will be lead to the distributor and therefore it's possible that it is located higher.
Just thinking loud :)

I wasn't also able to measure all the bends if all were condensing and on the other coil (evaporator) if they were fed with same amount of vaporsing liquid.

What do you think about the coil dimensions on the first sight?
The outher coil is with an axial fan. I'm waiting for the specs of this fan.

[Peter_1]

Perhaps they're soldered a T-junction on the main tubes leading to the coil, facing left and right so that they can use it in other machines??

To avoid misunderstanding: the coil you see with the grey foam around it is the coil inside the machine and is the condensor in the heating mode.

You can also see the electrical heaters
Compressor was running with a COP of +/- 1.8 in heating mode this noon where it should be with the conditions of today 4 or even more.

[NoNickName]

Perhaps they're soldered a T-junction on the main tubes leading to the coil, facing left and right so that they can use it in other machines??

Doesn't sound good to me. If the coil has to be used left-hand and right-hand, there's no use in having twice the manifolds. I would prefer, and actually we DO, have the vapour in the middle (and it stays in middle also upside down) and two liquid lines on both ends of the collector. We open the end that we use, whether it is left or right, so that when it is upside down the closed end is on top and the open end is on the bottom.
Otherwise, how could liquid exit the coil?




To avoid misunderstanding: the coil you see with the grey foam around it is the coil inside the machine and is the condensor in the heating mode.

:eek: :eek: :eek: :eek: :eek: :eek:



You can also see the electrical heaters
Compressor was running with a COP of +/- 1.8 in heating mode this noon where it should be with the conditions of today 4 or even more.

Or should be off at all. If evaporating fan is axial, is it turning freely? Did they connect it to star instead of delta? Or is the right number of poles?
When you need data for fans, any fan any brand, just let me know. I have all catalogues. I will scan a page and send it to you straight away.

[Peter_1]

NoNickName,

If I may ask you a favour: knowing the specs of this unitBox, can you determine with the Coil software package you have what you should install for this setup?
Limit is a finned width of 1000 mm so height and thickness has to be choosen.
Let's say we take a face velocity of max 2,0 m/s (what do you take) for the condensor (axial fan) and the actual flow over the evaporator (turbine) is now exactly 1 m/s.

I have serious doubts - in fact already since my first visit - that these coils not only are wrong fabricated but that they're also far too small for thsi application.

They give me tomorrow the specs of the axial fans: it's a monophase, triac controlled (I saw a triac on a cooling fins without an brand name on it)
See picture

I don't know if I said this previously but the axial fan is making an annoying noise, like there is a baffle wrongly positioned which causes a lot of turbulence.

[Peter_1]

Or should be off at all. If evaporating fan is axial, is it turning freely?

First of all I forgot, I appreciate your help.

Well, I asked the owners to set their T-stat at 30°C so that it ran continuously so I could check everything.

Under the conditions of today (inside +/- 21°C), the temeprature they want in winter, so also +/- same condensing pressure as in the winter but I had expected a much higher evaporating temperature with outside conditions almost equal to outside conditions.

If it ran now just below freezing, what should I have measured when it was outside 10°C or even 0°C?
The evaporator ran today with a DT of more then 20 K!

[NoNickName]

I don't know if I said this previously but the axial fan is making an annoying noise, like there is a baffle wrongly positioned which causes a lot of turbulence.

Looks like a 4 or 6 Amps MCHRTF from Carel, a microchiller single phase chopper. When those triac fails, the result is a noisy fan. That would make sense because if I'm not wrong, I saw a microchiller display in one of the photos you posted.
Next time you are there, bypass the MCHRTF, just put the inlet on the outlet and supply 220V direct to the fan.
If the noise persists, it is the fan, otherwise the triac is out of sync and it means that probably it went to heaven.
When triacs are out of sync, they induce vibration on rotors because of impulses on stators, which would explain the noise.

Tomorrow, I will calculate the coil in the office. Let's see.

[autt]

I have not finished reading the posts at this time, I will continue with them after work tonight.

As NoNickName said "Flood", it will decrease ref side heat transfer coefficient(That remarkably reduce the total coefficient), and then the total heat tranfer of condenser. So the outlet refrigerant not complete condensed and lot of gas before expansion valve, flow resistance rising in which, consequently the pressure outlet compressor. Is this cause problems?

regards

[NoNickName]

Peter, I have the pdf of the condensing coil ready, but the size exceeds the max allowable here.
Please let me have your email address, or being a mod I think you can increase the max size of the attachment.

In general, a 1000x800 x 4 rows, 2.1mm fin pitch, 50°C average cond temp, 24°C entering dry bulb, 4300 m3/h air flow, would give a condensing capacity of 26kW approx

[Peter_1]

Increasing the max size of attachment is only possible by Webram.
You can send it to ...

Thanks, I'll be back around noon, have 2 service calls this morning.
Thanks anyway for this again very fast answer.

Peter

[autt]

As NoNickName said "Flood", it will decrease ref side heat transfer coefficient(That remarkably reduce the total coefficient)

I have a mistake, it's ususlly not correct.

I don't have a R407c properties calculation, so i use a substitute of R22 for approaching, it was said that they have similar properties.

1000X960X130mm, 32X5 Rows, 8 Branches, which looks like in pic, 50C cond temp, 24 C air inlet temp, Air flow 4300m3/h by NoNickName, air velocity 1.28m/s, DP 16.7Pa, Capacity 34kw

[Peter_1]

NoNickName and Autt,
Thanks for the selection you both made.
NoNickName, i see on the pdf file your PM'ed me that you have a capacity of 11 kW.
The machine is a 22 kW machine.
Are your calculatiosn still correct?

[NoNickName]

NoNickName and Autt,
Thanks for the selection you both made.
NoNickName, i see on the pdf file your PM'ed me that you have a capacity of 11 kW.
The machine is a 22 kW machine.
Are your calculatiosn still correct?

Isn't it 26kW? My input was not based on the unit, but just a reversed calculation on the size and average conditions. That is the result: I didn't force it for specific match.
Anyway, I made it with a common 4 row coil, but maybe it is actually a 6 row...

[Peter_1]

So, if I understood you correctly, the coil inside the unit is capable of handling 11,4 kW under more standard conditions.
I need a condensor of almost double the surface.
Am i correct?

NoNickName, say we have the machine with the given specs I send you, what coil do we need then?
Outside conditions 5°C, inlet condensor = 20°C (temperature of the house), 20,1 kW heating capacity and 5.1 kW compressor power input (which is a COP of 4)

It bothers me also that the manufacturer still hasn't send me the specs of these coils like I asked him, now more then a week ago.

[NoNickName]

Well, my selection is far from being conclusive. It was based on fragmentary data, and as such I wouldn't dare drawing conclusions.
Anyway, tomorrow I will select a coil, 20°c db inlet. I'll see at what combined Te and Tc conditions that compressor is giving 5.1kW in and 20.1kW out. Based on those data, I will select the condenser for 25.2kW.
And for the specs of the original coil, don't expect any answer. That is normal policy for manufacturers, also for us. If you'd ask me, I wouldn't give it to you.

[NoNickName]

I can't select Manneurope, because my selection program expired.
The same scroll for Copeland (ZR90) will give 21.10kW and will absorb 6kW at +5/+48 (average glide, mid point) R407c.
The selection I gave you yesterday is approx for 26kW therefore the system can work.

[BESC5240]

The Maneurop selection program can be downloaded freely from your local danfoss-site or from cc.danfoss.com. The software is called 'Foresee'.
See results in attachment:
at +5/48°C : Qc = 24,8 kW (Qo=19,2 kW)
at conditions of your first post : Qc = 20,5 kW (Qo=12,6 kW)

[Peter_1]

Bruno,
What's your opinion in this?
Did you see the pictures?
I wjust mailed you the selection I got from Blue Box on your email address at work

[Peter_1]

...Anyway, tomorrow I will select a coil, 20°c db inlet. I'll see at what combined Te and Tc conditions that compressor is giving 5.1kW in and 20.1kW out. Based on those data, I will select the condenser for 25.2kW.
....
May I ask, have you found some time for this calculation NoNickName?
Thanks.

[NoNickName]

not yet, I will follow up shortly as soon as my customers leave me alone for a bunch of seconds.