Well, I am not following eveyone's advice here, and I will probably regret it but here is what I am going to do:
The guy who rebuilds, installs, etc generators came down from Park Rapids with his Powertech 8kw genset. He was on another errand anyway. He looked at my Kohler/Perkins and we made a deal on a trade in of my 12Kw genset for his Powertech. This is the short version, we discussed several other options for repairing my Kohler as well. He quoted me a price of $500 to remove my Perkins/Kohler, remote radiator and install the Powertech. I hesitated for about 10 seconds before agreeing to that as I have looked at what a remove and replace might entail. Will be driving up to his place and leave the bus for about a week.
So going down in size, getting a Kubota engine with 264 hours, a brand new Marathon generator, quiet box etc.
Hopefully will be able to keep all 3 Cruisaires running, will let you know.
Chuck
I agree with you completely and I think it will work just fine.
Obviously, you must be sure that the air conditioners are off when you transfer to the generator and let them start one at a time. After that, it is very unlikely that more than one at a time will cycle on.
It would be easy enough to wire the hot water heater so that it will not come on when the least used air conditioner in running.
Easy enough to automate other load management such as turning off one A/C when the microwave operates, etc.
I have an 8kw Power Tech in my Eagle with 600 hours on it that I bought a few years ago new. I have never had any issues with it. It is much quieter than the 17.5 that we have in the coach we recently bought. I don't know about the issue of whether it will run all the things you want to do. Good luck.
Which 8kw Powertech do you have? The normal one with a blade radiator fan, or the partially laid to the side one with the hush cover and squirrel cage blower pulling through the radiator and exiting downward? Good Luck, TomC
8K doesnt tell you everything, what is its surge load? Some are able to provide up to 50% more than rated load for a short period.
The AC's take much more amperage to start than thier actual running current. The load rating on the AC unit should be its maximum draw on start up. Add up those ratings together with everything else and see if the Genny has a high enough surge rating to light everything up. While its doubful that would happen normally, its always a possibility if someone flips the main off and on. If there isnt enough power available, the motors wont get out of the start phase and the genny is going to trip/overheat. There are switches in some RV's that only allow you to run one AC or the other, but not both, and they are there because the genny simply doesnt have enough oomph. If you dont feel you would ever run all three at once, but perhaps have two that you could switch back and forth, one of those switches would give you a good safety that couldnt be overriden.
I understand the inductive loads imposed by air conditioners on start up, do not think it will be a problem.
Tom it is the partially laid over model in a hush kit. It brings in air from each side and exits under the unit.
The Kubota is 6 - 7 years old, according to the guy who will be doing the install, Cat owns, Perkins, and when they bought out Powertech, they now use Perkins diesels in the units, which has not helped the reliability. I know nothing about the relative reliability of Kubota vs Perkins.
So we will see what happens.
Chuckd
For anyone interested, I just saw that Powertech has a reconditioned 8KW generator with the quiet box listed for $3,500. It does have 3,800 hours, but if they went through and will warranty it might not be bad.
Before installing I would change the bearing in the power head the 8 and 10kw Powertech's are notorious for head bearing failure the 8kw and the 10kw use the same head.
My friends that use the 8 or 10 carry spare bearings for theirs
good luck
My 4104 has two 13.5K ACs, a refrigerator and a microwave which my Honda 6KW genset powers easily, never had any issues whatsoever, so 8KW should be plenty large.
I went with the 8 KW also and I have 3 rooftops, I'm not done with the system yet and don't have the info in front of me, but will get it if you want. I am having a temp sensor in each return and it will be set up so only two units run at one time, if one area starts to get warmer than the other two areas, it will shut the coldest unit down and then start the unit with the warmest return air, and keep the cycles going to keep the total bus at a constant temp. This way you have power for other things.
Ray D
He may can figure a way to start all 3 Cruisiair at one time but I have my doubts unless he can use a relay to delay the start of the evaporator fans inside the bus some have 2 fans for the evaporator, his units are totally different than roof tops you can not compare the 2 units he has 2 or more fans to start on each unit and a different compressor.
8kw is pushing to start 2 Cruisiair at one time Cruisiair just gives the info for the amp draw on the condenser unit outside the bus, the evaporator you add to it depending on which evaporator you have.
8 kw will never run all 3 Cruisiair units at one time here in AZ in Aug I know that for a fact
good luck
Who did you get the gen from?
ChuckD-don't worry to much about the reliability of the lay down 8kw. I had a truck driver friend that had that exact generator on his big sleeper (had all amenities in it). When he sold the truck the generator had 23,000 hours (that's like 920,000 miles!) on it and still running. The only thing he had to do was to rebuild the alternator end and I think a water pump and starter. With a bit of power management, I think the 8kw will work just fine for you. Good Luck, TomC
I got the from Northern Generator, (Mike Wells) he has several rebuilt units in stock. A good guy to deal with 218 556 7625.
TomC they have even put the starter almost on top of the engine, so it is not necessary to get under the engine for most anything. I am going to be moving the baggage door that is over the remote radiator to the gen set compartment so it will get enough air. (has louvers in it)
Chuckd