daikin suction pressure!

[totalacedude]

hi all, im not an engineer, just interested in learning, practice and theory, but have a question thats been niggling me!

my mum has a daikin inverter system, because the indoor unit has an electronic tev would the suction pressure stay the same regardless ?

and even if not what would the pressures be?

can ne 1 explain??

many thanks ian

[totalacedude]

forgot to say its 1 r410a system

[Yuri B.]

I would say at 25C ambient the suction pressure will be kept about 10 bar and at 18C about 7.5 bar.

[totalacedude]

well i got that totally wrong...

assumed the return tempwouldnt vary ie txv controlling it, because the temp is known the pressure would be as well?

pls help me get my head around this lol
v confused, ian S

[Gary]

The pressures vary according to the temperature and volume of the air flowing through the coils.

[Yuri B.]

While the return air temp is not changing, the quantity of the boiling refrigerant in the evaporator will not be changing (so, pressure).

Becomes return air temp lower, the metering system let less refrigerant into the evap (both leading to suction pressure falling); becomes higher, let more (pressure rising).

[totalacedude]

right.. im totally head mashed!

1st of all im not so good at getting over things that i mean.. lol

i was actually going on about the line (pipe) temperature

and 2nd the way i was lead to believe the system works (its an inverter)
is that the compresser monitors high pressure side and varys the speed of it to keep the pressure constant (ie more demand = more speed at compressor needed.

some 1 told me that because the system is an inverter with an electronic tev that the suction pressure should remain constant..
(is this bulls*#t ??)

his explanation being that cos the tev monitors evap coil exit temp and keeps that constant?!? that the temp will be known to!!!!!

i am not sure, but i tend to think not!
can any 1 help?

he is a refrigeration engineer, but to be honest i cant get this into my head!!!

begging to think im gleaming snippits of info off the worng person!!

cheers guys

ian

[nike123]

and 2nd the way i was lead to believe the system works (its an inverter)
is that the compresser monitors high pressure side and varys the speed of it to keep the pressure constant (ie more demand = more speed at compressor needed.

Wrong! Compressor is governed by complex algorithm.

some 1 told me that because the system is an inverter with an electronic tev that the suction pressure should remain constant..
(is this bulls*#t ??)

Yes!

his explanation being that cos the tev monitors evap coil exit temp and keeps that constant?!? that the temp will be known to!!!!!

Wrong! Electronic TEV keeps evaporator superheat (not temperature/pressure) as complex algorithm requires.

he is a refrigeration engineer, but to be honest i cant get this into my head!!!

begging to think im gleaming snippits of info off the worng person!!

If your interpretation of his words are correct then you "gleaming snippits of info off the worng person".

[Yuri B.]

Difference inverter/non-inverter - the former more energy efficient.

Non-inveter copmpressor pump around refigerant with almost the same power consumed at 30C room temp and at 20C room temp - let's say, 5A and 3,5A respectively.

Inveter compressor's power consumed will be reduced to, let's say, 1.5A at 20C room temp (from the 5A at 30C).

I believe suction pressures still differ at 30C and at 20C on inverter.

[totalacedude]

well im glad i came here ans started asking questions!!!

any good sources of info flying around net any where??? for me to peruse and learn CORRECTLY!!!

CHEERS IAN