410a or 407c ACCU selection

[DrRTU]

I am in need of a recommendation on a 410a or 407c 12 ½ ton or 25 ton air-cooled condensing unit. Carrier, Trane, York and McQuay do not offer these products yet. Standard comfort CV use with operation down to 40 degrees F.

 

[AbbyNormal]

I did a project in 2002, client's home office was the UK. They were dead set against R22. Back then I could not find anything over 5 tons capacity that was 410A.

I looked at the following options

1) Using European Carrier that was 407C, but electrically would be a nightmare in a 60 Hz place.

2) Going custom built, which would be expensive, company like Engineered Air.

3) Field converted from 22 to 407C, which I felt would be an accident waiting to happen

4) Paying York extra money to factory convert their equipment to 407C.


It was moving to option 4, then the client caved in and accepted R22. Money talks.

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[DrRTU]

This is a LEEDs project in the Midwest. I do not want to modify or have a factory modification. The unit will be coupled to a CV AHU for a museum storage area with a very tight environmental spec.

 

[NCDesign]

I spoke with my Trane rep recently about this same issue. We had just sat through a very good presentation regarding energy conservation and LEED. I noticed one thing that was not touched on was the refrigerant issue. I inquired and was told that higher tonnage alternate refrigerant machines were supposed to be leaving the factory by the end of this year. I am a little skeptical because I have not seen anything official.
Something you might want to look at are the City Multi units from Mitsubishi. They are available in R410A. It is a "zoned" mini split system that you can apply in some really unique and helpful ways. For something of your size you would have a single heat pump condensing unit with multiple indoor units. It will work like a water source heat pump unit in that if you have interior spaces needing cooling and exterior spaces needing heating it will take the waste heat from the interior spaces and use that for the exterior spaces. It obviously isn't right for every application, nothing is, but it's something else to look at. City Multi. If you can take advantage of the multi zone aspect of it, it is extremely energy efficient.

 

[DrRTU]

The space is a museum storage area attached to a new public works building. The complete project will be LEEDs certified. The building has a mix of CV and VAV rooftops. We will not be taking points for EA (Energy Performance) but I need to meet the prerequisite Fundamental Refrigerant Management - zero use of CFC. The spec. for the museum space requires 95 % filters, humidification, dehumidification and natural gas heating. I have designed a central station AHU with supply and return fans, electric steam generator. I will use multiple SS duct furnaces in the leaving air. DDC controls. My preliminary design utilized 5 13 seer residential ACCUs but I would like a more industrial approach and it would simplify the coil selection. The major equipment will be McQuay or Trane. If the office VAV rooftop is converted to multiple CV RTUs then Carrier equipment could be used. I would like to use one major equipment vender. The space can economize so low ambient is not a big issue. York has a 407c unit but it is over 100” tall on rails. The ACCUs for ductless splits is a good idea, but they get very expensive and even higher with the larger ones with inverters.

 

[NCDesign]

If you ditched a split system concept and went with chilled water you could get a small York chiller that uses R410 in the tonnage you are talking about, or a McQuay using R407C. Carrier and Trane's units are still R-22.

Good luck it! It sounds like a very interesting project.

 

[DrRTU]

This is a very nice design / build specification. Chillers and boilers were not allowed as per the bid specifications

 

[NCDesign]

I assumed you had checked, but McQuay lists their 10-39 ton ACZ-A condensing units as being available with R407. I had missed it when I was double checking the chillers. Maybe they can get you out from between that rock and hard place your stuck in at the moment.

 

[DrRTU]

I will have to back to my McQuay rep. he said they did not have a 407c or 410a on this tonnage ACCU. Thank you

 

[AbbyNormal]

hmm tandem scrolls

Take the "V" out of HVAC and you are left with a HAC(k) job.