Diesel gensets, light loads, glazing

[Ignoramus21810]

So, they say that diesel gensets become somehow damaged by light loads. They become glazed or sooted or who knows what.

If and when I use my diesel generator to power up my house, it is going to be run at light loads for considerable periods of time.

Is there a simple cure for this? Would running it under full load for some time (easy for me), such as one hour per day of regular operation, remove "glazing" or whatever?

thanks

i

[SQLit]

I am confused, you say you have light loads for considerable amounts of time and then you say it is easy to put the engine under full load.

Better load the engine up for the long run > 70%. Light loading then heavy loading would not be my first choice. No sense in looking for the razors edge

[Ignoramus21810]

Well, to put the engine under full load, I would turn on a 4.5 kW water heater, dropped into a bucket of water. I did that to test my generator and I can make it a little more robust for everyday use.

So, yes it would be easy to use, and yes, I expect my house to be a light load for most of the time.

Thanks for your opinion. Perhaps I could devise something that would sense wattage and turn a load on and off depending on whether the house wattage is below some threshold.

I would have a device that would somehow sense average current going into the house, if it is too low, I would close a contactor that would turn on a water heater. The trick here is to make sure that water is added as it boils off and that it is safe from the fire standpoint.

In fact, I do have a 100A or so contactor, which I was planning on selling but might keep.

i

[Anthony Matonak]

Ignoramus21810 wrote: ...

...

Excuse me if this sounds like a wild, implausible idea, but perhaps it would work better if you had a smaller generator to handle the majority of the light loads most of the time?

You would only need to fire up the big generator for the occasional big loads. I know it would be additional expense but it would also give you a better chance of still having power even if one of the generators went down.

Anthony

[Ignoramus21810]

First, it is expensive, second, I do not like the idea of maintaining two generators, and third, loads are intermittent. Think about my refrigerators, range, etc, I cannot run out and switch from one genset to another every time someone wants to boil a teapot of water.

i

[nicksanspam]

This points to a need for a small demand management system for off-grid homes with limited instantaneous power capacity from generators and inverters. We might turn the fridge off while the range runs, turn the range off for a few seconds while the well pump runs, and so on, with Insteon/X10 hardware and a wireless controller to implement a priority scheme. If someone turns on a teapot with the switch on the handle, the AC receptacle senses that and signals the controller, which delays applying full teapot power until the controller turns off something else in the house. Small on-grid businesses with demand meters could also use boxes like this.

On a larger scale, a few years ago I met a negawatt trader who made money in New York State on-line power auctions by meeting predicted utility grid demands on peak summer days by turning off central AC systems in large apartment buildings for an hour or so in the afternoon. He got paid the same as an energy provider, and only bid when the instantaneous auction price got up to about $1/kWh, but he got more valuable credits, since reducing demand creates no pollution. The smallest practical load for him was

1 megawatt, and he seemed excited about the chance to control 1 kW loads automatically.

Nick

[Ignoramus30876]

I think that with my 7-7.5 kW output from my generator, I should be fine for most situations, sans use of central AC. There is no need, for me, to control power use except for the most common sense things (run hot tub for short time at night, do not use too many range burners at the same time, use electric heater sparsely).

Rather tham managing too high power requirements, which I do not expect to be a big issue, the bigger issue is managing too low power and its impact on a diesel generator. Here it is:

I am a little confused by your wording. (English is not my native language). Are you describing some existing setup, or are you referring to a potential application?

That's interesting.

What I have in mind for myself is some sort of a control box, that senses low power usage of the generator (should not be difficult), and if usage is indeed low, it would turn up some resistive loads like space heaters or water heaters.

i

[Takoma Park Volunteer Fire Dep]

Have you considered using a battery bank and inverter set to supply the lighter loads? Controllers are available that will start the generator only when the inverter capacity is exceeded or the batteries supplying it are running low. I worked as a remote power installer for a couple of years and batteries were almost always part of the engineering teams load shifting and buffering strategy.

-- Tom H

[Blah]

More toruble than it is worth. Just let it run!

Jameyu