Steve H Show full post »
Ziller Tech
78buckshot;52537 wrote:
All of your appliances are good up to .5psi or 14" water column. So if you can get your neighbor to set up his manometer at an easy test plug anywhere in your gas system he can read what you currently have. Turn off all gas appliances, you can leave the pilot on if anything has a pilot. I would want to see 7.5" static pressure as a minimum, if you have that or more then test at the generator as close as possible to the internal demand regulator or at the regulator itself with your major gas appliances running, now start the genset and note the pressure drop, should be no more than 1" drop from not running to running and would like to see 6-8" while running as long as static pressure is not above 14". I have adjusted many natural gas and LP regulators to get what I need for HVAC work with no backlash or problems with equipment.


I would still check the nameplates... I have a commercial style range in my house that is max 7" and they spec a reg for anything over that. As mentioned though, most appliances are ok with the 11-14" range, but not all. :)
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Peddler
I have reread this post from the beginning and unless I have missed it we have not yet established from the owner if this is natural gas or LP.
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Steve H
Peddler;52542 wrote:
I have reread this post from the beginning and unless I have missed it we have not yet established from the owner if this is natural gas or LP.


NAT And yes it's set right and not leaking
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Steve H
78buckshot;52523 wrote:
Once the engine shuts down the intake manifold, throttle body, air filter and housing, rubber fuel hoses, and engine side of the demand regulator all revert back to atmospheric pressure and the fuel in them is free to dissipate. I doubt you have any air issue in the supply line to the demand regulator. I would go back through the valve lash adjustment and gap the plugs at .035-.040 and raise the incoming gas pressure enough to see 6.5" or higher at the machine as it's running.


I think we have a nerve.

As I recall, we were maintaining 6" water column with a load. It seems to me I was within spec. So! I took it upon myself to raise the gas pressure at the main regulator. I only did a 1/2 turn. Now I have to wait. But I did try it today and it seemed to start faster. Yeah Yeah I know. Jeans engineering. I've been tuning Mopars for years with my ear. And I'm a pretty good all around mechanic. Some of my Jeans engineering has been my best work. I've dealt more with LP engines on some fork lifts and an Old generator conversion.

What gets me more is the old 15KW was never a problem. This one is supposed to use less gas than that monster. (2900 running hours when retired) What I didn't take in consideration was this unit has a larger engine. They did make a lot of changes in 15 years. It may need more gas yet.

All that said, I will have to wait for a week before I test run it again. That will give the system more time to evacuate any residue vapors. If that works, I'll be happy.

I promise I'll tell you the outcome. Beers for everyone
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78buckshot
1/2 of a turn clockwise on the regulator will raise it about 1/4"w.c., you may not even see it on a dial gage, water tube manometer is more sensitive, accurate, won't go out of calibration and the price is right. Only drawback on the water tube is when your on a rooftop in zero degree weather with the wind howling-takes about 30 seconds to start freezing. I'm just giving info 'cause you didn't mention what type of equipment your neighbor has.
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Steve H
78buckshot;52555 wrote:
1/2 of a turn clockwise on the regulator will raise it about 1/4"w.c., you may not even see it on a dial gage, water tube manometer is more sensitive, accurate, won't go out of calibration and the price is right. Only drawback on the water tube is when your on a rooftop in zero degree weather with the wind howling-takes about 30 seconds to start freezing. I'm just giving info 'cause you didn't mention what type of equipment your neighbor has.


He works for the Gas Company. I'm sure he had a water gauge. He mentioned the freezing problem. Said he has to bring the kit in during the winter. I haven't caught up with him yet. What you said is the only thing that makes sense other than a pooter glitch.

Thanks man
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Steve H
It's been a while.  Sorry for the delayed update.  Lots of medical stuff going on.

I think we have this licked now.  The line pressure has been raised, the problem continued.  We decided to crack the line at the genset to see what may be going on.  Initially, we had no order of gas for about a second.  So we let it go for a week and tried it again.  Same thing.  Waited a week and cracked open the next union up the line.  Again, no immediate gas oder.  Obviously it came quicker.  I could have used a match, but I like my hair.  

Turns out, the 1" Tee is right after the meter.  It continues into the house for everything else.  As near as I can figure it out, the house siphoning the gas out of the Genset line.  I never saw anything like it.  This was kind of confirmed when the heat started to run.  There's no real way to prevent it.  It was never a problem with the old 15KW we had.  This started when I put the 22 in.

So!  The only solution I can come up with is to install a flapper check valve.  I hope it's not going to be restrictive.  It took a long time to find a high flow, low restriction valve.  We'll see
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BobS
For what it's worth, I had a similar issue 4 years ago right from the initial installation of my Model 6244 (20kW). Took a while to get it sorted out but finally was resolved by replacing the internal Regulator Assembly (which included the "reservoir"). I posted about the issue on this forum here: https://www.zillerstore.com/post/hard-start-on-new-20kw-9945621?&trail=15
  
I also posted videos of the hard start on YouTube here: 


and the resolved start here:


Not sure this will help but thought you might want to look at it anyway...
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78buckshot
SteveH, that does not add up, if the meter and main regulator are sized correctly and operating as designed then the entire line should maintain roughly 7.5"w.c no matter what is running. I think you need to start from square 1, add up the input BTU of all of your gas using equipment, you'll find it on the nameplate/specplate. An example would be, 100,000 BTU for the furnace, 40,000 BTU water heater, 20,000 - 30,000 BTU for the range/oven, etc. The generator alone wants 250 - 275 cu.ft./hour or 250,000 - 275,000 BTU, so all together in this example 410,000 - 445,000 BTU/hour. The gas meter, regulator, and piping have to be sized to carry the cubic feet per hour or you'll be starving for fuel. Most of our installs require a meter upgrade to handle the extra demand of a generator, I know that others will comment on how much a meter can flow but as a contractor we can't keep going back to a job for problems that we should have covered from the git-go. You could check the atmospheric vent on the regulator to make sure it's clear, insects and grass are prime causes of it being blocked and wont allow the diaphragm within to function.
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Gray
When I had our 16kw installed, here are the computations I used:

Generac, in the installation instructions, recommends using full appliance gas consumption of the house, and then adding full consumption of the generator for the required supply capacity.

At full load on a natural gas fuel source, continuous power capacity of 16,000 watts requires 312,000 btu/hr (312 cubic feet per hour) and a water column of 3.5-7 inches (7-13mm mercury). Generac also specifies 1-inch pipe from the meter for 15 - 17 KW generators.

Even operating at half power it consumes 193 cubic feet per hour (which is 193,000 BTU per hour).

My current appliance consumption is as follows:
Water Heater: 65,000 BTU
Furnace: 100,000
Dryer: 22,000
Fireplace: 35,000
Range: 45,000
_______________________
Sub total: 267,000 (267 CFH)
Generator: 312,000 (312 CFH)
Total: 579,000 BTU (579 CFH)

After advising my utility supplier of the above calculations, they installed a 630 C.F.H. supply meter.

IMG_0753.jpeg 
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Steve H
BobS wrote:
For what it's worth, I had a similar issue 4 years ago right from the initial installation of my Model 6244 (20kW). Took a while to get it sorted out but finally was resolved by replacing the internal Regulator Assembly (which included the "reservoir"). I posted about the issue on this forum here: https://www.zillerstore.com/post/hard-start-on-new-20kw-9945621?&trail=15
  
I also posted videos of the hard start on YouTube here: 
BobS wrote:


and the resolved start here:
BobS wrote:


Not sure this will help but thought you might want to look at it anyway...


Did that already.  I think it was your post that promoted that.  Only a slight improvement.  I really need a parts manual.  But that's what has been in the back of my head.  

  It acts like there is a void in the fuel flow during a cold start.   Even if there was a a small line feeding it, it should still start normally.  The pipe size issue should become a problem under a load.  The 15KW ran for years with no issues.  According to what I can determine, the newer units use less gas
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Geoff Z
Put your serial number in here and all documents for your generator will populate:   https://www.generac.com/service-support/product-support-lookup
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Peddler
It is impossible for the house to syphon the gas away from the generator, the other way around is possible.  The house has atmospheric burners which rely on the gas pressure to force through a nozzle for combustion.  The generator creates negative pressure in the line which is why it can operate fine on lower gas pressure.
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Steve H
Geoff  I'm just seeing this so I will do that in a few days.  I just figured out how to look at my history

Peddler
Yes I agree.  I installed a check valve in the gas line with no good results

Thank you
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