Generator Question - What Size?

Soul Siesta · Mar 15, 2007

Now that I've decided on using a generator for my power needs, I need your help/suggestions on the size generator to power the following items....all of which could be on at any given time:

* 4 ceiling fans
* 4 refrigerators
* 12 - 12,000 BTU a/c's
* 4 - 9,000 BTU a/c's
* 4 - 36,000 BTU a/c's
* standard lighting & comfort and convenience items for 4 - 1200 square
foot apartments (radio, tv, dvd player, computer, etc.)

I was thinking 40 or 50 kw? Your suggestions are greatly appreciated.

Hillbilly · Mar 15, 2007

Unless you turn on all of your a/c units at the same time, you can probably do with a 30 KW unit.
However, I will consult with my technician, just to be sure and get back to you tomorrow morning early. Okay?

You have to figure that the most important part will be the automatic transfer installation. If it ain't done right, it don't matter how much KW you have...

We'll help you with that, too.

Hang on, I'll get back to you.

HB

Rocky · Mar 15, 2007

To be sure, you need only do the following.
Turn everything on that you might ever run at the same time, and put an ampmeter to the lines, and double that amount.
In other words, if your draw on one line was 30 amps and 40 on the other, then you would need to supply 70 amps at 110v, 35 at 220v.
With the above example, you would need a 15K generator.
To be doubly sure that it is sufficient, you would turn absolutely everything on, including any water pumps that go on and off all the time, then measure again.
The max, should not exceed 85%.

Rocky · Mar 15, 2007

Soul Siesta said:
Now that I've decided on using a generator for my power needs, I need your help/suggestions on the size generator to power the following items....all of which could be on at any given time:

* 4 ceiling fans
* 4 refrigerators
* 12 - 12,000 BTU a/c's
* 4 - 9,000 BTU a/c's
* 4 - 36,000 BTU a/c's
* standard lighting & comfort and convenience items for 4 - 1200 square
foot apartments (radio, tv, dvd player, computer, etc.)

I was thinking 40 or 50 kw? Your suggestions are greatly appreciated.

I just reread your post, and that's one heck of a lot of merchandise.
Do you happen to know the amps of those AC's?
If they are the new type that take less electricity, with some type of rotary motors, then it might not be that bad, but just at a glance, I can see why you're talking a 50k unit.
You really need to use an ampmeter to truly know.

coho · Mar 15, 2007

Rocky said:
To be sure, you need only do the following.
Turn everything on that you might ever run at the same time, and put an ampmeter to the lines, and double that amount.
In other words, if your draw on one line was 30 amps and 40 on the other, then you would need to supply 70 amps at 110v, 35 at 220v.
With the above example, you would need a 15K generator.
To be doubly sure that it is sufficient, you would turn absolutely everything on, including any water pumps that go on and off all the time, then measure again.
The max, should not exceed 85%.

HAHAHAHAHA.......FRICKIN HILLARIOUS......geez I hope you don't do your own accounting.....

cobraboy · Mar 15, 2007

coho said:
HAHAHAHAHA.......FRICKIN HILLARIOUS......geez I hope you don't do your own accounting.....

I dunno. I just went through the entire sizing/buying/installation process for a whole house generator in FL recently (in fact, ran it for the first time this morning), and Rocky pretty much describes the process.

I have a home with a 3 ton AC, fridge, freezer, lights, etc., and a hot water heater. I use around 10kw when all are running; I can run the AC and hot water at the same time, but cannot start the AC if the HW is on. I bought a 13kw unit. My intent is to use it for hurricane damage to the area-went 8 days without any power in '04. No mas. Not in FL.

Do some math and you'll see the OP's loads are quite large. 50kw would NOT be out of the question. I'll bet Hillbilly will have an authoritative answer soon. He knows that business well.

Ringo · Mar 16, 2007

With 4 apartments I would guess that you could have 8 or more people at the same time. Part of your power needs should involve looking at peek power usage times. 8 people getting up in the morning:

Turning on fans, AC, hot water and water pumps, toasters, coffee makers, microwaves, TV's, computors, pool pumps, refrigerator demands, curling irons, hair blowers, washer/dryers, water coolers, lights.

I would rather be slightly oversized then under. It is amazing how "power hungry", mostly Americans, are.

You should also consider your fuel storage and supplier access. IF you go to a 50kw you could use up to 4 gallons per hour. If the street power is off 8 hours per day, you use 32 gallons... X 30 days is 960 gallons. Consider that there have been times that the fuel deliveries into the Dominican Republic are delayed (no fuel).

Rocky · Mar 16, 2007

Ringo said:
I would rather be slightly oversized then under.

Absolutely.
It should have double the capacity of the high consumption times, and certainly 15% to 20% more than the absolute max.

Rocky · Mar 16, 2007

VirginianWishes said:
Not to hijack the thread but I see at Playero there is a 9.5kw diesel generator for sale with a bad head gasket. If we buy it does anyone know a really good person to fix it?

This is higly risky.
Even if you have a good mechanic, he is still at the mercy of the machine shop that shaves the head.
From my point of view, when you have a motor with a leaky head gasket, it's time to get rid of it.
Odds are you'll sink a fortune into it and frequently land up blowing the whole motor in the end.

Rocky · Mar 16, 2007

VirginianWishes said:
Anyone know the approximate cost of replacing the engine part then? We think we can get it cheap!! The generator that is

The part itself is no all that expensive, but it also involves shaving the head, and the problem is, that the odds are that the motor has overheated once or several times, if it's in this condition, in which case, the whole darn thing could be no good.
That's why it's being sold so cheap.

Andy B · Mar 16, 2007

The rule of thumb for generator size is figure the MAXIMUM draw (including a/c and reefer units in the START mode) and then at least DOUBLE it for continuous useage (anything over an hour). With your 4 units originally described I would go with your original estimate of 40 to 50kw. Those a/c units will suck up a lot of juice. And with a generator rated well over max load encountered, it will last a lot longer and use less fuel by not having to work as hard.

cobraboy · Mar 16, 2007

Rocky said:
The part itself is no all that expensive, but it also involves shaving the head, and the problem is, that the odds are that the motor has overheated once or several times, if it's in this condition, in which case, the whole darn thing could be no good.
That's why it's being sold so cheap.

When you machine/shave the head, you're increasing the compression ratio slightly, depending on how much needs to come off. Higher CR=more heat, requires more anti-detonation additivies (octane in a gas engine, cetane in a diesel). Additionally, if the head is warped-hence the need to shave the head-it means all the head internals are not necessarily lined up as designed, increasing friction in odd areas (valve guides, for instance). As Rocky said, you're looking at potential constant ongoing big maintenance items.

I'd pass, unless you can find a good head, and the cylinder(s) are proven to be true.

Soul Siesta · Mar 16, 2007

Generator size? Hillbilly please still respond

Thanks for all the great info.....REALLY HELPFUL. I think I'll go with a 47 kw generator. Hillbilly, I see that you haven't yet responded.... be sure to after you speak with your technician as I need all the solid info I can get.

Rocky · Mar 16, 2007

Soul Siesta said:
Thanks for all the great info.....REALLY HELPFUL. I think I'll go with a 47 kw generator. Hillbilly, I see that you haven't yet responded.... be sure to after you speak with your technician as I need all the solid info I can get.

Bear in mind that until you measure the amperage, you'll just be guessing.
Unless you have the specific consumption of each & every electric component, including their start up draw (for motors), you cannot judge the capacity of the generator unit needed.
It would just be a guesstimate.

Rocky · Mar 16, 2007

VirginianWishes said:
It appears none of you (who answered) know the answer to the question so far but thanks to all for the useless information. If there is anyone in the Bonao area (close to our house) or anywhere else, who can help, we would love to hear from you - the bar room quarterbacks can refrain. If we can buy this generator and make it like new for half the cost of a total replacement - WHY NOT? All we asked is : What is the cost ? if you know

It appears that you did not understand the answers.
When you have a blown head gasket, it's generally an indicator of an engine in big trouble, so you don't know how bad it's going to be until you get in there.
Maybe you need new valves.
Maybe you need new pistons and rings with a rebore.
So it's like asking how long a piece of string is.
It cannot be answered until you get inside.
Ask aa honest mechanic, and he will tell you the same thing.
Why do you think the vendor wants to sell it in that condition?
He knows that opening it up could spell disaster.

Rocky · Mar 16, 2007

Rocky said:
It appears that you did not understand the answers.
When you have a blown head gasket, it's generally an indicator of an engine in big trouble, so you don't know how bad it's going to be until you get in there.
Maybe you need new valves.
Maybe you need new pistons and rings with a rebore.
So it's like asking how long a piece of string is.
It cannot be answered until you get inside.
Ask aa honest mechanic, and he will tell you the same thing.
Why do you think the vendor wants to sell it in that condition?
He knows that opening it up could spell disaster.

PS: If you just want to know the price of the head gasket for that particular engine, phone the dealer.

laurapasinifan · Mar 30, 2007

VirginianWishes said:
Sorry my bad English. I meant anyone know the cost of replacing the whole engine - it is a Nissan 2 cylinder - not just the broken part

virginia I bet the cost of replacing the engine on a 9.5 KW generator could be more than the cost of a new COMPLETE generator....seriously....because parts cost more than the combined sum for sure....and a generator has to be 95 % engine!!!!!!!!

still a total rebuild of the engine, is still less than a new one if you dont get ripped off by the mechanic. My freined has a good buddy in La Vega who does mechincal work on BMW and saabs, and mercedes autos as a specialty. He is always very busy though....if you buy it and still cant find anyone.I could call him and get more info. I am sure he could rebuild that deisel motor..if he can get parts.

do you know how old the generator is????or how many hours on it?

Chris · Mar 30, 2007

coho said:
HAHAHAHAHA.......FRICKIN HILLARIOUS......geez I hope you don't do your own accounting.....

Uhm, I just came across this in a thread that I thought was progressing well. Care to explain your statement coho?

Chris · Mar 30, 2007

VirginianWishes said:
It appears none of you (who answered) know the answer to the question so far but thanks to all for the useless information. If there is anyone in the Bonao area (close to our house) or anywhere else, who can help, we would love to hear from you - the bar room quarterbacks can refrain. If we can buy this generator and make it like new for half the cost of a total replacement - WHY NOT? All we asked is : What is the cost ? if you know

You may not be able to make it like new for half the cost of a total replacement. I suggest you read through this thread again with a view towards accepting the information given, instead of rejecting what you don't want to hear. :cross-eye This generator that you're looking to buy is most probably a lemon, you'll be buying a cat in a bag .. (anyone know that saying?)

laurapasinifan · Mar 30, 2007

Chris said:
Uhm, I just came across this in a thread that I thought was progressing well. Care to explain your statement coho?

hey chris, I ll offer this...i think it was just a fun joke...at least thats the way i read it...

and it is in response to Rockys conglomeration of info with wishy washy percentages and a dash of this and a dash of that added in to make sure you are covered...

I doubt he hurt rockys feelings...

at least i hope it was the way i took it...

bob

Generator Question - What Size?

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