Natural Gas Generator Sizing Question --- any plumbers or Atmos techs on the forum?

[Sethmac]

My wife is wanting me to get a Tri Fuel Generator to connect to our natural gas line as an emergency backup. The generator I'm eyeing has 7600 peak watts and 6800 running watts on NG. I'm currently estimating the consumption at peak load to be 140,000 BTUs (but this is estimated based off of other units as this one doesn't publish the info).

My current meter is an AR-250 which I believe supplies 250,000 BTUs/H

Gas appliances in the house are as follows:
- Hotwater Heater 1 - 38,000 BTUs
- Hotwater Heater 2 - 38,000 BTUs
- Furnace 1 - 79,000 BTUs
- Furnace 2 - 79,000 BTUs
- Gas Range - 44,700 total across 4 burners
Total: 278,000 BTUs

Clearly we can throttle and manipulate what we use, but given another Snowmaggedon, I'm thinking we would be running the generator at half load (3500 watts) with my calculation, that means assuming the use of the furnaces and hotwater heaters with 2 burners running, I might need 330,000 BTUs of gas at peak.

I would plan to tee in a hookup between the meter and the house and probably have a line run of ~10ft from the tee to the generator in the driveway.


My question...I assume I need a meter with more flow for those peak times...will Atmos come install a higher flow meter, how much will it cost, and is there another bottle neck in the system I'm not thinking about...e.g. a high flow cut off switch if my gas spikes during an outage.

Thanks y'all!

[DallasCoon12]

In the Kerrville area, they will upgrade your meter at no charge.

[Sethmac]

Reaching out today..any other tried this?

[Tbar]

You know a plumber can spec and install all of that and I think its required in the city limits. They did this for me at the Farm where I had a Generac 24kw installed.

In town I just ran small gas generators to run the electric. During snowmageden I supported the 3500sqft house running two EU2000i generators. It ran lights in moderation, tv, internet, 2 of 3 hvac squirrel cages, two fridges, and the circuit board on the on demand water heater. Just no 220.

[PYBUCK]

If you're running an emergency generator you shouldn't be pulling as many BTU's as normal. Be sure you run a large enough supply line to not starve your generator for fuel

[DallasCoon12]

You may need get Atmos to install a 2psi meter and install a regulator before the house and another before the generator. We do this quite frequently with generator installs. Google Gas Split Systems

I recommend you hire a plumber!

[Sethmac]

Thanks folks..reaching out to plumber today. Any plumbers here in the DFW area near Keller? Would love to support a family-owned operation locally

[Sethmac]

Alright green screen plumbers..need help rationalizing something:

Plumber came out to the house. I already have a 2psi meter going into a 3/4" line. There is a regulator on the side going into the meter. There is also a regulator in my attic (Maxitrol 325-5AL regulator) feeding a manifold which I assume is stepping everything down to normal appliance levels.

I asked the plumber to quote teeing coming out of the meter (one side to house other side to another regulator for the generator) adding a regulator and a shutoff so I can connect the generator right there near the meter.

They quoted me $3,800 and they said its a flat rate..i.e. they wouldn't break it down. Another regulator seems to be obtainable for <$80 at the very max and adding on a tee and shutoff, caps, etc... it's not labor intensive, regulator, pipe dope, fittings, adjust pressure. What am I missing here?

[mavrick]

You will never run all those at the same time. That small generator will not use near as much as the heaters. I think your calculations are off. When you are using a generator you should be prepared to give up something. Shut down one heater and move everyone to a central location.

I think you will be fine with what you have.

[Txhunter3000]

Alright green screen plumbers..need help rationalizing something:

Plumber came out to the house. I already have a 2psi meter going into a 3/4" line. There is a regulator on the side going into the meter. There is also a regulator in my attic (Maxitrol 325-5AL regulator) feeding a manifold which I assume is stepping everything down to normal appliance levels.

I asked the plumber to quote teeing coming out of the meter (one side to house other side to another regulator for the generator) adding a regulator and a shutoff so I can connect the generator right there near the meter.

They quoted me $3,800 and they said its a flat rate..i.e. they wouldn't break it down. Another regulator seems to be obtainable for <$80 at the very max and adding on a tee and shutoff, caps, etc... it's not labor intensive, regulator, pipe dope, fittings, adjust pressure. What am I missing here?

I thought in the OP, the line after the tee would be less than 10'. In this post it seems you're having them run a line to the other side of the house, that may be the cost.

[DallasCoon12]

1000-1200$ job
250ish in materials
4hrs at 165=660$
permit 100ish

[Sethmac]

I thought in the OP, the line after the tee would be less than 10'. In this post it seems you're having them run a line to the other side of the house, that may be the cost.

No line to other side of house..was just trying to state there is already a regulator in the attic...the need is a tee, a regulator, a cut off and a quick connect

[TexasBob]

You got the I don’t want to do it, but it’s worth it at $x price. That’s absolutely insane. 3-4x multiplier on what it should cost which is still too much.

[Greenheadless]

I’m guessing there is more than one plumber in your area. I would ask for a 2nd and maybe 3rd opinion.

[Cookiemonster1]

Might check on how the gas line has to be run to the generator also. Discuss that with the company you purchase the generator from.