Electrical engineer with HVAC difficulties,Help plz!!

[T83]

Hi !!

I need some help,I am a fresh electrical engineer & I have been given a drawing for HVAC & I am having some difficulties.

First of all, if I have a compressor written next to it "2 Nb. compressor" & it is feeding two Evaporator mini split,then does it mean I have two air conditions here fed from one compressor?am I interpreting right?

Second of all,I was given BTU/hr but I don't care about that all i care about is electrical watts and not thermal watts so that I can calculate the current but i can't find a way to convert from KWth to KWe or from BTU/HR to KWe all i found was to multiply by 0.2931 which would give me thermal watt.I have 36000,24000,18000,12000,& 9000 BTU/HR & I want their current for a single phase 240V system,how can I get the values? does anyone have a table or website they can recommend???

Thx a lot!!

 

[T83]

Hello again,

I just found out that I can convert the BTU/hr to ton & then use an estimate of 1.5 to 1.7 KVA/ton for a good estimation.

So can somebody simply answer at the first part of my post.

Thank you!

 

[imok2]

Yes is the answer

 

[hepa99]

do you have the name of manufacturer and model #.

go to their website and download the electrical data. it should give you information of breaker size or amp. load requirement of the equipment.

 

[AbbyNormal]

as an electrical engineer you would probably be more interseted in the RLA of the gear for your load calc, the MCA for your wire size and the MOCP.

power consumption for an energy calc is a lot smaller than the load calc needed for electrical drawings

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

 

[trashcanman]

Also, tell the ME who did the drawing to provide the electrical data you need.

 

[TwinScrew]

Mitsubishi split?

http://www.mitsubishielectric.ca/ductless/P_Series.html

May be of use to you in the future for literature, etc.

 

[ChasBean1]

For electrical, you can get elec. watts by converting the BTU/hr to watts and just dividing the thermal watt value by the COP (coefficient of performance), which is typ. between 3-4 for these systems. Use 3.5 for an estimation.

OR just divide the BTU/hr value by the EER (energy efficiency ratio) which will give you watts and accounts for the conversion.

This is if you don't have elec. data (better bet always to do what Hepa99 indicated using manufacturer tags).

CB

 

[willard3]

Let me suggest that you return to the person who gave you this project and suggest that a ME be given this assignment as you are unsure how to proceed.

If there are no ME's on staff, hire a consultant. Trying to fake this will cause trouble.

 

[sailcat753]

I have no idea what Nb means. Must be a Daikin or Mitsubishi or Sanyo unit. Time to ask some more questions.

 

[DuctPipeMan]

The mechanical designer should give you data. At a minimum, Mfg, and Model# so that you do not have to read his mind.

Relating power consumption to performance is so varied that I would only use that kind of methodology for budgets and planning. For actual design and sizing of electrical, use real data.

 

[T83]

Hello,

Thank you guys a lot,I didn't know this thread was still going,I ended up contacting the mechanical people & they sent me the electrical data,it turned out they just put numbers without backing them with anything,I mean usually I am either given a table with minimum specifications of the system or at least the model, anyway they sent me the electrical data,Nb also turned out to have some meaning don't remember what it was.Also,the 1.7 KVA/ton gave an extremely close estimate.

Anyways,thank you all of you!!!

 

[HG1234]

I think "Nb" stands for number. u already mentioned that you have 2 no. evaporators, so these each will be feeding seperately from the correspong compressors.

Then for converting Btu/h to kW, u can use 1kW=3412 Btu/h.