Chillers over VRV

[sam_mac05]

It is my understanding that where chillers are planned, it is FCUs one should deploy and that VRV would not be an economically prudent option. Would like feedback please.

[Brian_UK]

What type or size of building are you thinking about ?

[frank]

There are pro's and con's to both arguments.

There are other indoor appliances that operate on chilled water other than FCU's, such as chilled beams/ceilings, close control cabinets or even AHU/duct mounted coils.

One of the drawbacks of a chiller for air conditioning purposes is that you must run the whole circuit down to temperature even if you only want to cool one room.

With VRV/VRF, one room can be cooled/heated while the rest of the system remains in an 'Off' state.

To me, they both have advantages, but for part load, I consider that VRV/VRF would be more economical to run

No doubt other members will be along to add their thoughts.

[superswill]

i also guess plant area space in the building will play a factor a 100kw chiller will take up far less space than its VRV equivalent

[JacksonBall]

Hi guys, we build only Turbocor chillers with variable speed compressors that can turn down radically - the 90TR down to 12TR and the 150TR down to around 40TR if you know how to do it. And this is per compressor, so you could have a 540 ton chiller that can operate down to 12, drawing only the kW required to meet the load. The problem comes in the water side. How can you turn down water flow consistent with what these marvelous compressors can do? Well, you go either parallel units that you can isolate water, or get creative in how you select the heat exchangers, or both. So, it does very much depend on how large the building load is, the load profile and even IF variable flow is desired or practical. Also, many of our customers build variable speed plants and integrate wide flow rates across the chillers and provide critical zone monitoring and controls. A couple of tricks involve the use of pressure independent flow control valves at each AHU Flow Control Industries in Seattle makes a nice valve. These can squeeze performance out of the coil regardless of the pressure against the valve diaphram. You can also go with a true VFD plant control system, like the Kiltech CPECS to optimize everything and correlates it with the chiller head pressure and anbients in real time, and can monitor up to four critical CW zones. Here is a link to the CPECS flyer. OOPS, Site would not let me post the link... shoot me an email to jackson at jacksonball.com and I will get them to you.

I believe there is also a great future of integrating VRF with the oil-free Turbocor system. This could avoid the oil velocity issues and get the best of VR to multiple TX valves. Cheers...

[Greengrocer]

It is my understanding that where chillers are planned, it is FCUs one should deploy and that VRV would not be an economically prudent option. Would like feedback please.

The bigger and more diverse the system or application is, the more it would suit a chilled water system. Long pipe runs are easier to deal with for chilled water systems. Couldn't somehow see something the size of Disneyland using anything other than a central chilled water system. Having said that, multiple de-centralised VRF systems might be an option - all depends on the type of building.
Another factor is system complexity. VRF systems require specialist installers. Chilled water systems can be installed by most mechanical engineering companies.

[Thermatech]

A little story from the archive.

In about 1995 we were at the back end of the VRV installation on a new build 200 bedroom hotel.
I was carrying out the final commissioning when a director from the main contractor responsible for the construction of the complete building started asking allsorts of questions about the VRV installation.

He was really very impressed with the VRV installation to the point that he considered that they would never again use traditional chiller & FCU system due to the advantages of the VRV system.

The carpets were down & the ceiling tiles were up.

His words were
Normally we would have water leaks all over the place & we would have to replace carpets & ceiling tiles & also be looking at penalty charge for late handover.
With this system all the trades can concentrate on getting their own job complete on time without any worry about water leaks.

He went on for ages about how much better the refrigeration pipe was & how much more disruption was caused by installing larger steel water pipes all around the building.


Then the senior consulting engineer arrived & the director of the main contractor told the consultant exactly the same story.

[chillerman2006]

Hi all

The advantage of a chiller & fcu's over vrv or vrf, looked at from an health & safety side ( as HSE is king these days with environment being put 1st is now EHS) is a leaking fcu results in water leaking which is a little safer than refrigerant and probaly preferable to a sleeping hotel customer.

A leaking fcu may cause more damage (unless asphyxiation takes place) but to the EHS the risks are far lower to the occupent

[THE WOMBAT]

VRV's are the best efficiency, two phase changes per pumping cycle of the refrigerant. problems are too many moving parts to break. I have 300kw worth of units old toshi 14 years old. no end of drama. With dyno doc, my thermal camera i have been slowly getting to the bottom of these problems.

I believe that a chiller with hot water output and chilled water is far better for servicing as all the plant is in one spot. Have 2 port valve system for chilled and 3 port valve for heating coils. The return chilled line will then lead into dry coolers on the roof for free cooling in winter. N+1 on chillers so no rush job break downs.

I think the effiencey will still be the same, but you wont be desk surfin over office staff cause some ****** installed a multi controller flat to the ceiling!!!

There is alway inherent risk as far as ohs rubber cops are still in business, so they could be drowned, or gassed to death.

Water the only way!

[Lowrider]

on a properly designed system with chillers and variable flow across the building only the water that is needed in the coils will run through the system, not all the water!

The chillers, pumps and even cooling towers can be set up in in N+1 system, perhaps with freecooling.

For a system of over 100 kW the amount of floor space the equipement uses is far less then that of VRV systems.

On VRV systems multiple units will have to run for just one indoor unit and consuming far more power than a chilled water system.

As to the leaks, the leaks all depend on the quality of the one who instaled them. Water leaks on VRV systems are more commen than in chilled water systems because the isloation is usually less taken care off than in chilled water systems and should a leak in the pipe accour the dangers involved in gas coming out faroutway that of water!

[Petko Stoyanov]

For me VRF systems are the future they are more flexibility, more efficiency with better control

[Lowrider]

On average a VRV/VRF has a lower COP then our chillers, aspecially on large systems over 1MW!!

And usually no free cooling with a VRV/VRF! Again, not so efficient!

As to the control, a VRV/VRF always has a minimum operation capacity. A fancoil does not! Therefor a fancoil has an operation range of 0 to 100% whilst a VRV/VRF doesn't!

[Thermatech]

VRF has instant heat recovery from one indoor unit in cooing to another indoor unit in heating
Due toUK building regulations heat recovery ventilation is required for most projects & VAM / Lossnay ventilation energy recovery can be interlocked to work with the VRV / VRF systems providing direct free cooling.

Having said that I dont think VRV / VRF are going to chalange M watt centrif chillers for a while yet

VRV / VRF has become very popular with consultants & endusers mainly due to the exceptional energy saving provided by these systems.

Personally I was working on hybrid chillers with free cooling back in the mid 70's so nothing new there.

[CoolMike]

Modern VRF's run at high pressures, that can test the installers flare/brazed joins to the max. Whilst there are many VRfs out there that run leak-free for a long time, a lot of them either leak or are a leak waiting to happen. With long pipe runs, it can be a nightmare looking for leaks. At the moment I am a bit anti-VRF and pro chiller.

[Sridhar1312]

Yes working pressures are in the range of 500 psi and there is acute shortage of skilled manpower to do proper brazing of copper pipes especcially in INDIA. With VRF we have found small hotels say 30 to 50 rooms have been found to be convenient but am not sure whether power efficient or not.

[Sridhar1312]

For what size of Air conditioning capacity VRV or VRF is most appropriate.To the best of my knowledge for bigger system more than 200 TR Chiller is best.

[Thermatech]

In this months Consulting Engineer magazine there are two case studies of VRV instalations.
One is 285 bedrooms on 18 floors of a tower block in Manchester & about 500kw cooling capacity.
The other is a retro fit of a 24 story office block in Croydon with about 700kw cooling capacity.
In this case the Consultant is quoted that a conventional chiller / LPHW & 4 pipe fan coil system would not have met Part L carbon emission building regulations without major redesign of the building.

We regularly commission VRV / VRF systems with a total of 500 to 1000kw cooling capacity for hotels & office blocks.
Consulting engineers design these projects & use VRV / VRF because they consider it to be the best option.

[THE WOMBAT]

Yes ease of installation, lower cost pipe work, thats it.
Its all about what size pipe will fit into a hole in the wall.

Consultants gotta love'em, as there is so many glossy brochures about how efficienant they are ,as a 'stand alone installation'

Catalog consultants i call them. How easy is it for the consultant when there given a heat load program that even select the correct indoor / outdoor units by the manufactures trying flog there stuff.

The amount of core engineering skills needed to work out pipe flow rates, plumbing hydraulics, unit selection of indoor, chiller arrangements, free cooling,
All this is pushed aside for a quick, easy consult job with a guaranteed working system! as the install contractor does all the risky bits
Consultants has no real liability, only if the donut undersizes the unit!

Until some idiot installs a 410A system with crap pipe work joints and it explodes in a hotel room, i'd take a water leak any day

You may commission them but i bet you wouldn't dare repair them, i'd rather pop my eye out with a desert spoon! Or give myself rectal prolapse trying to push one of these suckers off a roof


The Modern face of consultancy

[nike123]

Yes ease of installation, lower cost pipe work, thats it.
Its all about what size pipe will fit into a hole in the wall.

Consultants gotta love'em, as there is so many glossy brochures about how efficienant they are ,as a 'stand alone installation'

Catalog consultants i call them. How easy is it for the consultant when there given a heat load program that even select the correct indoor / outdoor units by the manufactures trying flog there stuff.

The amount of core engineering skills needed to work out pipe flow rates, plumbing hydraulics, unit selection of indoor, chiller arrangements, free cooling,
All this is pushed aside for a quick, easy consult job with a guaranteed working system! as the install contractor does all the risky bits
Consultants has no real liability, only if the donut undersizes the unit!

Until some idiot installs a 410A system with crap pipe work joints and it explodes in a hotel room, i'd take a water leak any day

You may commission them but i bet you wouldn't dare repair them, i'd rather pop my eye out with a desert spoon! Or give myself rectal prolapse trying to push one of these suckers off a roof


The Modern face of consultancy

And they generate themselves a new job every 5-7 years in contrary with hydronic systems.

You took the words from my mouths!

[papasaway143]

Can someone know how the 3hp becomes 2.5tons..????

[manender]

hi,
vrv is better than chillers always,,,,,if you want to know more abt vrv , search on google.

[nike123]

hi,
vrv is better than chillers always,,,,,if you want to know more abt vrv , search on google.

I love your argumentation, it is so enlightening.

[Lowrider]

Yes ease of installation, lower cost pipe work, thats it.
Its all about what size pipe will fit into a hole in the wall.

Consultants gotta love'em, as there is so many glossy brochures about how efficienant they are ,as a 'stand alone installation'

Catalog consultants i call them. How easy is it for the consultant when there given a heat load program that even select the correct indoor / outdoor units by the manufactures trying flog there stuff.
The amount of core engineering skills needed to work out pipe flow rates, plumbing hydraulics, unit selection of indoor, chiller arrangements, free cooling,
All this is pushed aside for a quick, easy consult job with a guaranteed working system! as the install contractor does all the risky bits
Consultants has no real liability, only if the donut undersizes the unit!

Until some idiot installs a 410A system with crap pipe work joints and it explodes in a hotel room, i'd take a water leak any day

You may commission them but i bet you wouldn't dare repair them, i'd rather pop my eye out with a desert spoon! Or give myself rectal prolapse trying to push one of these suckers off a roof


The Modern face of consultancy

Designing a good hydraulic setup is really not that difficult! But the number of good consultants out there are outnumbered by the bad ones!

We do, mostly, datacentres and hospitals. Just try and see how much VRV systems one would need for a datacenter with a load of 35MW! Just the footprint of the machines needed! And the amount of ***** pipes!

The law in Holland states that they have to use as less as refridgerant as possible, for starters! There is no way all those VRV's needed for 35 MW will have less refridgerant than the 10 chillers we have there! And energy consumption will be way more! So VRV better than chillers? Not in bigger installations and not when only cooling is needed!

[frank]

To use an old saying ' Horses for Courses'.

VRV/VRF will not be best suited to EVERY situation and likewise, chillers will not be best suited for EVERY situation.

A good designer will consider all of the options and 'hopefully' come up with the best solution.

It has been said earlier, there are good and 'not so good' Consultants, so there will always be installations where the most suitable equipment has been overlooked in favour of the 'preferred'.

[mfakazi]

Personally I would go for chillers...but because of all these energy savings **** vrv seem to be getting more popular with consulting engineers but thats not suprising anyway at the end of the day these gus don't repair these equipments so they jump on anything ...I'm currently working on 30year chillers very very good equipments when maintained by competent engineers..Yes vrv very clever kit but too many things do go wrong especially pcb's,leaks...I think they way less reliable then chillers.