Boilers and generators.

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Old 11-01-12, 08:40 AM
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Boilers and generators.

Anyone have good solid advice on running a boiler off a generator? From what I understand the controls typically don't have good filters on them and generator electricity is quite noisy and may possibly damage the electronics.

I have a Burnham ES2 and I ebelive the controls are made by Honeywell.
 
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Old 11-01-12, 09:04 AM
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I would think that the generator couldn't be any more noisy then some grids.
I'm not sure about your aquastat, but mine is older (robust) components which I would suspect would handle any noise much better then most other items in the house.

I really think you'll be fine.
 
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Old 11-01-12, 09:20 AM
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My grid isn't noisy. My controls are new and fully electronic. The information that I have is that the boiler controls aren't built with the same protections that pc's have. I know that my UPS does not like the generator power and keeps kicking over to battery use. So that makes me wary. It would be nice to get the house warmed up especially with colder temps coming saturday night.

I'm hoping rbeck would be able to give me some good information about it if he comes around. Maybe I can call Burnham.
 
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Old 11-01-12, 10:25 AM
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What brand and or age is your generator?
I've have no issues with my Coleman 5000 throwing the UPS units.
 
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Old 11-01-12, 12:12 PM
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Some generators are worse than others in the electrical noise factor. Inverter generators generally put out very "clean" power and would be preferred. I have no problem whatsoever with my Lennox furnace and Yamaha inverter generator.

I asked the furnace technician about running on generator power and he said they didn't see control boards fried from "noisy" power as much as from low voltage. If your gennie is minimally sized for your load low voltage could be a problem. If the gennie's voltage regulation circuitry is less-than-optimal it could allow fairly wide ranging of voltage between high and low and THAT might be a problem for the furnace controls.

Also, frequency control, which is essentially engine speed in non-inverter generators, could be a problem. I think your UPS problem is more likely wide voltage variations or a frequency problem than it is electrical noise.
 
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Old 11-01-12, 12:19 PM
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Yeah, it is all about the noise. This generator does not publish their THD ratings. Burnham has said that they don't know how much noise the controls can handle. They said from what they have heard, they either work or they don't. Not good enough information for me so I will not take a chnace. The electronics are far too costly for me to blow them up now.
 
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Old 11-01-12, 07:03 PM
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The key to making sure you do not have burnouts with generators and boiler controls is use a continuous UPS not a standby UPS. Less expensive generators have a hard time holding the proper RPM/s and this is what gives dirty power.
You want to use an inverter type generator if not continuous UPS's on a standard generator.
Either way will keep clean power.

I have heard on standard generators that if you bring on a few items first and then the boiler you would probably be OK.
 
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Old 11-01-12, 08:58 PM
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Older boilers have no electronic/computer controls - they are all mechanical/electrical. Well, maybe the thermostat if it has been replaced with a programable type.
 
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Old 11-02-12, 05:32 AM
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The older style units probably would not have a problem.
 
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Old 11-02-12, 11:56 AM
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Running Buderus OK wtih Generac

Spoke to Buderus tech service and there is no problem with running the GC (non-condensing units) with a generator. It is the GB (condensing units) that use a sensitive UBA controller that doesn't like dirty sine waves. Buderus will send a new UBA to customer free of charge if they have a need to run with standby gens.
 
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Old 12-18-12, 03:58 PM
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Lawrosa had posted this link in another thread. I wanted to bring it here so it could be easily found in the boiler forum.

http://support.fluke.com/find-sales/...12_ENG_A_W.PDF
 
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Old 12-18-12, 07:18 PM
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Thanks guys... that's the kind of information I have been looking for! (admittedly half-heartedly...)
 
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Old 12-18-12, 08:23 PM
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Yes and I really want one....

I really liked that link too.

Is it biased? Dont know. Was the gen really 12% THD???? Or is it just a story to spend $3000 bucks on a instrument to test.

All gens UL listed fall under a certain criteria from what I read and must have less the 5% THD???? It was a manufacturing defect is all from what I think.

I tell you its all hokey.... My gen is spot on at 60 hz....

Its all a marketing ploy to some extent. The cheap inverter gens put out a modified wave from what I read and thats worse then a regular gen with no invertor...


Amazon.com: Fluke 43B Power Quality Analyzer: Home Improvement


Just my opinion
 
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Old 12-19-12, 11:20 AM
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I like/use/depend on Fluke but that literature is misleading at best.
The analyzer measured utility
power at 2.8 % THD under
normal loads…but measured the
generator power at 12.8 % THD
without any loads.
Probably a true statement--but why was the analyzer used to assess power quality under different load conditions? That's just comparing apples to oranges and it totally meaningless. My $300 portable generator also has noisy output with NO load, but smooths out nicely with any load on it. Many types of voltage regulators also NEED a load to work properly. Fluke of course knows this but in the end the marketing guys get to say whatever they think will sell product.
 
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Old 12-19-12, 02:56 PM
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Mike, it's more than just hz. You need to look at the wave form.

I think the whole point of looking at the power quality from the power grid was for a baseline read. If both power sources looked the same, they would know it wasn't the power quality.
 
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Old 12-19-12, 03:24 PM
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Mike, it's more than just hz. You need to look at the wave form.
Not really IMO its all connected. If the waveform is off the Hz will be off. The THD is the ability to maintain a steady Hz, No?

My $300 portable generator also has noisy output with NO load, but smooths out nicely with any load on it. Many types of voltage regulators also NEED a load to work properly. Fluke of course knows this but in the end the marketing guys get to say whatever they think will sell product.
Exactly what I was trying to say. I bet if they put a couple hundred watt load on that gen that they say was out of whack I bet it would of smoothed out and started that furnace.

But they based it on the fact that the manufacturer


Thats the first thing I do in a power outage is turn on some load, such as lights, refridge... My gen starts high at the 62 hz range. With load I am around 61 hz. My heavy load ,the well pump, will pull it down to the 60 hz range.

Its spot and and does not deviate.

With no load the hz jumps around some.

But if you read the last page, " what is distortion", you will see they say a good meter can test 51 points. Was this the reading they took for the gen in question? What is the standard? Of course you will get a higher % reading multiple peaks... 60, 120, 180,240...etc.

This means that the meter would
measure the sine wave at 51 evenly spaced points and report the
voltage (or amperage) deviation at each of the 51 harmonic frequencies.
Total Harmonic Distortion (THD) is derived from the sum of all of
the individual harmonic voltage (or amperage) deviations.



I am not sold.

And here is what the Briggs site says.... i will look up the listing and post back my findings.

Briggs & Stratton standby generators are UL (Underwriters Laboratories Inc.) listed and comply with the UL 2200 standard. UL 2200, Section 40, outlines Total Harmonic Distortion (THD) requirements to ensure that the THD of the generator will not damage other electrical equipment.

While specific THD levels are not published, adherence to the UL 2200 standard ensures the generator is safe.







 
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Old 12-19-12, 03:34 PM
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Last page.
http://www.ul.com/global/documents/c...ons/june10.pdf



Generator selection and sizing is only one of
the many factors that designer’s face. NFPA
20 and NEC Section 695.7 include
requirements that the voltage at
controller line terminals shall not
drop more than 15 percent below
normal (controller-rated voltage)
under motor-starting conditions,
and
the voltage at the motor terminals
shall not drop more than 5 percent
below the voltage rating of the
motor when it is operating at
115 percent of the full-load
current rating of the motor
 
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Old 12-19-12, 04:26 PM
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Not really IMO its all connected. If the waveform is off the Hz will be off. The THD is the ability to maintain a steady Hz, No?
I don't know for sure, but I don't think that is the case. Especially if they needed to see the sine wave to make a determination. Seeing the power cycle is easy to do with cheap tools.

But if you read the last page, " what is distortion", you will see they say a good meter can test 51 points. Was this the reading they took for the gen in question? What is the standard? Of course you will get a higher % reading multiple peaks... 60, 120, 180,240...etc.
I would agree that you would get a higher reading, but I would also call that more accurate. To be fair, I would say the number of readings would have to be similar to how the readings are taken by UL or whatever standard if they have one. I agree with you that the generator in question was defective. They advertised it as <5% THD. I don't think they lied about that.
 
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Old 12-19-12, 05:00 PM
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If the waveform is off the Hz will be off. The THD is the ability to maintain a steady Hz, No?
No, not correct.

THD is Total Harmonic Distortion.

You could have a 60 HZ SQUARE WAVE that would still be 60 HZ but absolutely the most distorted sine wave you could imagine.

Distortion has little to do with the frequency, other than the fact that the distortion products are always multiples of the fundamental frequency.

In other words, 120 HZ is the second harmonic of the fundamental, and 180 HZ is the third.

Harmonic distortion is the presence of these harmonics superimposed on the fundamental.

If your gen was running at say 58 HZ, then the second and third harmonics would be 116 HZ and 174 HZ respectively.
 
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Old 12-19-12, 05:07 PM
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When measuring THD, the more harmonics you measure, the more accurate the THD calculation becomes.

The fact is though that since the harmonics always are much lower as you go up in frequency that the amount of distortion the higher harmonics contribute is almost nil.

If one were to calculate THD of a sine wave using only the first say FIVE harmonics, your calculation would be so close as to make little difference if you went all the way up to 51 harmonics.

It's that 'point of diminishing returns' thing... I mean, how much 3060 HZ (51st harmonic) do you think really exists on a 60 HZ fundamental anyway? If you said almost not measurable, you would probably be correct. Look at the chart in the PDF showing the levels of the harmonics... can't even see anything up that high!

Mike, you like math, right?

Check this out!

Total harmonic distortion - Wikipedia, the free encyclopedia
 
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Old 12-19-12, 05:13 PM
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Gee troop....You always have to spoil my fun....
 
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Old 12-19-12, 05:22 PM
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Also note in that bar chart that the EVEN ORDER harmonics are nearly nil across the board. This is most often the case that it is the ODD ORDER, the 3rd, 5th, 7th, harmonics that are dominant.

The SQUARE WAVE I mentioned earlier is nothing but an EXTREMELY distorted Sine wave, and consists almost entirely of the ODD harmonics.



Still the same FREQUENCY, zero crossings occur at the same spacing.
 
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Old 12-19-12, 05:28 PM
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You always have to spoil my fun
Sorry Mikey! My bad! :bad poster:

I wish there were an easier way to explain THD...

Let's say it this way,

You have 120 VAC RMS of pure 60 HZ.

To that signal, you add 13 VAC RMS of the 3rd harmonic, and 5 VAC RMS of the 5th harmonic.

The resulting waveform would look distorted because it contains OTHER frequencies added to it.

Or, maybe we could say that a distorted 60 HZ SINE wave also contains OTHER frequencies riding on top of the fundamental, namely, the odd order harmonics.

The % THD is a mathematical calculation of how much of those other frequencies are riding on the fundamental in percentage of the fundamental.
 
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Old 01-03-13, 10:57 AM
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I have a Riello burner on my Buderus boiler that would cut out when running on the genny. I was using a 5kw(6.5kw start) Coleman Powermate. It would run the boiler fine until the well pump kicked on. The voltage would drop to under 100v for about a second while the pump kicked on, and the burner(and now my Tekmar 260) would shut off momentarily and then restart.

I'm pretty sure that's not good for either the pump, or the boiler controls, so I upgraded to an 8kw(10kw start) Generac. No problems since.....the Generac is supposed to supply decent power in terms of THD....don't know how true that is, but it's working fine.
 
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Old 01-03-13, 04:07 PM
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When we go onto gen power (5kw Honda), I turn off the water pump and water heater. The light loads remaining include the heating system and computer.. so far so good ! When we run out of water in the pressure tank, everything else goes off except the pump.. it's got a pretty high startup current and does trip the computer ups's from voltage sag.
 
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Old 01-03-13, 10:14 PM
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Voltage sag on a genset is almost always accompanied by a corresponding frequency sag because of the sudden load on the motor causing it to momentarily slow down while the governor works to speed it back up again.
 
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Old 01-04-13, 05:22 AM
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True.. and visa versa, when the heavy load drops off the gen overshoots some amount.

I gotta say, just because I havent had any issues with my boiler or other equip in the house on a small gen .. I realize with this thread that it could happen.
I have a large welder/ac gen that a bud left us when he moved out west, but it's been buried in the back of the garage for 10 yrs.. needs a carb rebuild and a fan shroud. But, it can put out 70a @ 240vac and if I recall it does have some features that the manuf claims makes it suitable for backup power.
Getting this running and connected is now further up on my priority list, thanks.
 
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Old 01-04-13, 07:25 AM
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When we go onto gen power (5kw Honda), I turn off the water pump and water heater. The light loads remaining include the heating system and computer.. so far so good ! When we run out of water in the pressure tank, everything else goes off except the pump.. it's got a pretty high startup current and does trip the computer ups's from voltage sag.


We used to do the same thing....shut off the pump until the house is warm etc....But it got to be a hassle cause I don't run the genny overnight unless it's bitter cold out. Then in the morning, when I get the genny going, the DHW demand gets to be satisfied on the boiler first(unless I turn off DHW priority). And usually somebody wants to shower too.

In the end, it was just easier to buy a bigger generator. I still have the 5kw as a back up. My wife often questions why we need three generators? (have a small 120v Honda too)

And yes, the freq would dip down down when the voltage went down too. I have checked both on the new set-up, and it's pretty stable. The voltage might drop a volt or two, and the freq remains pretty stable when the pump kicks on and off.
 
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