Diesel or natural gas generators?

Mad Dog · November 2003

The folks that I did a big snowmelt job for, this summer want some backup power to keep the snowmelt system online in power outages. My first thought was diesel? But I do have gas nearby too, which could probably handle the generator and the boilers. Has anyone ever used a natural gas generator? Mad Dog

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Mark J Strawcutter · November 2003

natural gas

With NG you never run out of fuel and don't have to deal with regulations concerning tanks. All the backup/emergency generators here at work are NG - even in a couple of buildings where they had to add NG service just for the generator.

Mark

DIY Homeowner · November 2003

Also, depending on the size and the regulations in your state, diesel generators may require an air source permit from the state air quality agency.

JimGPE_3 · November 2003

Not enough info!

Generally, natural gas cannot be used for life safety power - egress lighting, fire alarms, smoke control, etc. But if this is a non-life safety load, natural gas is an option.

Next, you need to consider the size of the load. If it is a very small load, natural gas makes sense. Assuming all you are powering is a small pump and the controls on a gas boiler, natural gas makes sense. It is inexpensive and clean burning. Less maintainance than a diesel.

When the generators get big, or when large loads are imposed all at once and lots of torque is required, diesel starts to make more sense. But then you have all the local regulations regarding fuel oil storage to deal with. Dikes, double containment, spill alarms, etc. all need to be considered to keep the locals happy.

What is the load the generator will see?

Unknown · November 2003

Matt, do they use gas for something else?

If it's only the generator, find out if they mind the minimum charge every month, even if they don't use it....

Noel

Mark J Strawcutter · November 2003

curious

The primary purpose of the NG generators here at work is egress lighting.

Concerning load - you ought to see the NG generator they installed (for y2k) to power our server room, including A/C. 2.5in 2psi NG feed, V12 Beckwith engine, 4ft diameter radiator fan, muffler the size of 2 garbage cans.

Mark

JimGPE_3 · November 2003

Yeah

The requirements for egress lighting vary from city to city. Here in Pittsburgh and in Atlanta, the two cities in which I do most of my work, you may not use natural gas for life safety loads. They say the first thing the fire department does when they show up and the building is on fire is to shut off the gas, so bang goes your exit and egress lighting, and your elevator operation.

But then again, some municipalities have no problem with it. Go figure. Here, natural gas will kill someone. There, natural gas will save their life. Hmmmm.

They will sell you very large NG generators (Obviously!), but as they get bigger, oil starts to be a more financially sound selection, all other things being equal.

Uni R · November 2003

Standby Power

The simpler the better. Just remember that this machine is like a fielder. It'll be standing around most of the time scratching its nuts and bolts and only rarely will it have to make the big play. Whatever you use make it simple so that the users have no problems getting it started, keeping it running and more importantly so that it can be easily tested from time to time and make sure that is scheduled. Diesels tend to be simpler due to compression ignition.

How many watts?

Mad Dog · November 2003

Wow! what a fast response thanks......

all it would have to power is 2 Burnham 806bs (gas Hot water), 2, 007 tacos, and a large Taco 220 single phase pump. I'd have to look up all the watts and amps and load stuff. Anyone recommend any brands? MD

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J.C.A._3 · November 2003

Mad Dog.....

Don't foget the refigerators and freezers if there are any!
My parents lost a boiler about 8 years back after numerous power failures. Now, there's a plug hanging out of the firomatic (electrical) with a male end on it, so they can run the heat with a small gasoline generator. The other outlet on the gen. is for the refrigerator and/or freezer. Dad got pretty good at keeping everything going when the power problems were a lot more frequent than they are now.The old flip and switch between the 2 FOOD savers was a task. Chris

Mad Dog · November 2003

Thanks yall!!!

The ho just seems to be concerned with the snowmelt boilers although I will try to convince him to look beyond that. Mad dog

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jim lockard · November 2003

generators

Honda has a line of generators that would work for you MD.
along with WW Grainger. The generators I like MD are the ones you can get a service agreement with from a local company cause there is nothing worst then something that does not work when you really need it to.
Someone posted that you may want this for emergency red and white lites well they are most likly on battery back up so should not be an issue

John Lenhart · November 2003

Mad dog, I read a product reply on the generac site. Apparently the customer was not happy. They left out one little detail. This natural gas generator requires 11 to 14 inches of WC gas pressure. He had to install a separate gas line just for this appliamce. I have been researching home generators for about a month now. I didn't want one of the 3600 rpm generators with the throw away lawnmower engine. So I installed a diesel that idles at 1800. I think they have more longevity and durability. Hope this helps.

hr · November 2003

Diesels are

a tough start in cold weather. you would need a continous block heater, maybe a 1000 watts worth, depending on the generator size.

Natural gas, or LP fires much better in cold conditions, require less maintenance, and are probably a bit cheaper to purchase.

Is the snowmelt really thay critical during power outages? Where will they go once they get out the drive?

hot rod

hot rod

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Unknown · November 2003

Natural Gas Generators

Require a dedicated gas line with pressure of no less than 1/2 lb(14" W.C.) delivered to the unit. I recommend a pipe size no smaller than 1 1/2" to the unit. It requires a seperate meter for just the generator. Make sure you get a liscensed electrician to hook it up and make sure it has an automatic start every so often to insure it will work when needed. If it is going to be a whole house generator make sure it is large enough to handle the load. My experince with them is that they work great and a pretty much maintenance free unless they are frequently used then it is much like a lawn mower or snow blower for maintenance.

Shop around as pricing is all over the place on them. My sons unit was $3,000 for the unit. It is for an entire 12 room house with a lot of electrical demand. For the life of me I can not remember the make or the rating. I will check on it and post some info later.

If you are in an area with extreme cold weather diesel can be a problem.

David_5 · November 2003

trace

http://www.poweriseverything.com/product/T-pwrmods.html

Rather than a generator why not store power for that rainy day.

David

[Deleted User] · November 2003

None are Maintenance Free

I used to service the back-up generators for the National Weather Service in Alaska. They used NG, Onan generators with Ford engines. Any generator that you really want to use will require at least an annual maintenance. That means oil changes, to get rid of moisture that builds up in the crankcase. It also means you need to "exercise" it for at least 30 minutes once a week. This makes sure it starts, charges the battery, etc. Of course then you have all the air filters, and spark plugs, etc. The station officer explained to me, when I asked why all the work, for something that they never seemed to use, was, "You not only plan for an emergency, but you practice as well".

Floyd_5 · November 2003

here ya go MD...

http://www.norwall.com/generac2.htm

Check this out, I got a Generac unit on order through the local hardware, but this will give you an idea of what they are. Generac also has there own website, also. do a search, I'm sure it will pop up.

Floyd

Steve Ebels · November 2003

Standby Power

We have always used Onan generators Mark. Great factory support. Superb product. In smaller sizes (<10,000 watts) it's probably the only brand I would use on my own home. We recently had a 3 day power failure and I lost count of how many service calls I got because of the following statement, "I was running my furnace on the generator and now it won't work!!" Usually accompanied by a detectable trace of panic in the voice on the other end. The problem with most small generators is a lack of good voltage and frequency regulation. Usually the relays or transformers get smoked on heating equipment. Worse things happen to other electronics. My brother in law smoked his 371 Tekmar control even though the voltage output was OK. The issue with electronics is frequency...... 60 cycle current. All electronic stuff uses that 60 cycle alternation to "count" or process commands. When it's not right neither is the control........ I'm getting off the subject.

We've sold Honda's, (great engine but the generator part has no B---s. Coleman and Generac are good for skilsaws and drill type use but if you want good AC power get an Onan. My son-in-law has a 6500 watt contractor model that he ran his whole house with. Much to my dismay, I discovered on the second day of the outage, that my daughter was BAKING PIES!!!! all day long. Running the dishwasher, the electric water heater, frig, freezer and pump were all left to run as normal. GADZOOKS!!!!!!! all that from a 6,500 watt portable???????

As for nat gas vs diesel, it wouldn't be worth running gas to a house tht didn't already have it there as far as economy goes. If it's there it does have some pluses, the biggest of which is no stale fuel problems. This is a major item for typical homeowner gensets. They don't get used often enough to stay in good operating condition. We had a 200 KW nat gas for backup power at the store. We outgrew that and went to a 600 KW diesel. We had a little 6KW diesel that we rented out and sold with over 8,000 hours on it. Never touched the engine or the generator on it. A 45 KW diesel on a trailer was part of our fleet for over 4000 hours of run time and it ran with only basic maintenance also. All of these were Onan. Guess I'm starting to sound like a salesman for Onan gensets instead of a boiler mechanic, so I'll shut up now.

SeattleNick_3 · November 2003

I maintain over 30 Onan (Diesel) units for a Municipality here in the Northwest. I agree with what Steve says and assume his gensets were air cooled like most of ours. The problems we have are usually on the cooling system components on the water cooled units from sitting with a jacket water heater cooking the hoses year round and the circ pump is a '47 Studebaker design (alledgedly) and seems to weep within days of replacement.

These gensets are going to be replaced in the next few years with Deutz oil/air cooled diesels running Newage generators packaged by Stewart and Stevenson. The Viessmann of generators? We will see....

Emmisions shouldn't be a problem with the snowmelt system since the unit would be for standby use.....but who knows these days!
At my house I will opt for the best generator set ever made:
Fairbanks - Morse model 38 Opposed-Piston! The 12 cylinder puts out over 3megs, so I better hook up the neighbors house too....

Here is the five cylinder O-P.......

Steve Ebels · November 2003

Cooling

The little 6KW diesel had an air cooled engine, designed by Onan for military use during WWII. The only trouble we had with it was the air intake frezing off during severe snow and cold situations. The larger units were/are water cooled. The diesels have Allis-Chalmers industrial engines rated at 163 HP for the 45KW and 735hp for the 600KW. The larger one has a turbo the size of a wash tub on it and 8" diameter exhaust. The 200KW had a Ford 427 natural gas engine rated at 315hp. I NEED one of those locomotive engines to play with !!!!

tim smith_2 · November 2003

generators

Kohler is a good brand that I have hooked up before. Natural gas units are very reliable.

Jack, CVMS · November 2003

Diesel or gas generator

Since you're talking of a pretty small load, the NG generator will probably make more sense. The smaller diesel-powered gensets on the market are usually 3600 rpm and not really high quality, such as you'd want for a stationary installation.
The Onan units are time-proven, and service/parts are generally pretty widely available (especially after Cummins bought them 12-14 years ago). Several years ago I managed a shop that was the local service/warranty center for Generac gensets. Sorry, but I can't recommend them.
Anything with a Honda engine can usually be counted on as being pretty reliable, but in the past two years I've helped to change out nearly new Honda V-twins, running on LPG, at several remote cell repeater sites. They have some sort of problem with fuel delivery or ignition that causes them to start backfiring and then quit. Haven't been able to get hold of one to do a post mortem yet, so not sure of the cause.
Auto-start panels with automatic exercise option are the way to go. Once the engine is started, it has to be run under load to fully heat up, otherwise it does more harm than good, and electric block heaters are better.
The NG engine is considerably cheaper than a diesel, so that may tilt the scale in its favor.

Diesel or natural gas generators?

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