Natural Gas - Propane | Comparison

Most homes need a larger gas meter to support the added BTU load of a generator. However, it's possible that your meter can be upgraded to support a backup generator (There is currently a 1+ week delay on engineering done by National Grid). I handle all the paperwork for this on an installation.

If the existing gas relay to the street is too small to support a meter upgrade, then it will have to be replaced. Doesn't happen very often, but if it's required there is an 8 week lead time for this. Also, the costs involved (paid to National Grid) are generally around $1k+.

Some limitations to NG are listed below:

  • Limited to the total BTUH of the relay (line from the street to your house)
  • Limited to the total BTUH of the existing meter (this can be swapped out for larger by National Grid usually for no cost, providing the existing Relay can support it)
  • Limited to the size of the EFV (excess flow valve) that is installed inline on the street side as a safety measure on high pressure relays (these are usually rated at 800CFH and may not be a problem if the total BTUH load doesn't exceed this)
  • You may have to pay quite a bit for a relay to be installed to your house if it's not allready at the street (usually around $1k, for a normal relay installed by National Grid if it's located at the street).

Some advantages to NG are listed below:

  • Runtime not limited by tank size
  • No deliveries are required like with LP, there is a constant supply available
  • Safer than LP and disperses quicker since it's lighter than air.

Please follow the links below for more information regarding NG 



Some limitations to LP are listed below:

  • Runtime is limited to tank size (Minimum tank size required for 8kw is 250gal, approx 7days runtime at 1/2 load) 
  • You may need to go up to a 850gal tank to get the required BTUH in freezing conditions if you have a 16-22kw managed whole house generator (this would equate to almost 10 days at 1/2 load)
  • Tank must be buried or it will take up space in your yard (buried tanks also have more vaporization (BTU available) due to being insulated in the ground)
  • Tank must be sized larger if other appliances are using fuel from it
  • Pricing is not a constant value and changes with the seasons and demand
  • LP gas settles in low places making it very dangerous

Some advantages to LP are listed below:

  • Has more BTU output than NG (usually averages out to anywhere from 1kw-2kw) A typical genset will have an output 1kw higher running on LP than if it were on NG. So, if you had a Generac 9kW genset it would get its full rating of 9kW and not be derated to 8kW on NG.
  • Buy in bulk when the prices are low during warm months when demand isn't so high

Please follow the links below for more information regarding LP