propane for whole house generator?

[bcoke]

I am considering a whole house generator and need to know if I can tie into the gas line in my basement at the end where it goes to the gas cooktop out through the wall to the generator outside @20 feet or less? the point being @ 45 feet from the house enterance regulator which would make the total run @65 feet.....the supply is a 1000 gallon buried tank about 75 feet from the house enterance.....that being said the tank to generator distance @ 140 feet......is this doable? what concerns should I have and ask the installer? thanks for any and all input ......also any Generator recommendations good or bad ??????/ bcoke

 

[tyme2par4]

Ideally you would probably want to splice off the line before it enters the house I think.
Any distance is doable with the correct size pipe.
The best thing to do would be check what the manufacturer requires. Then check with your propane supplier, and they should be able to tell you exactly what you need.

 

[yeldogt]

You gas supplier can tell you in a second .... my 1k buried tank has 3/4 CU running to the house/ 20k generator/ my 1700 sf studio.

The 3/4 line is high pressure -- the regulators are located at buildings and the generator.

 

[rjkobbeman]

The concern is line size, distance, bends a pressure.

Tying in after the regulator would require a large enough regulator to handle the extra demand and much larger pipe for any given distance.

If you tie in before your regulator (high pressure) you can go farther distance with smaller pipe and add a regulator to handle the genny.

Pros and cons to each. Given your situation you will have to analyze each.


Sent from my iPhone using Tapatalk

 

[yeldogt]

FYI --- This is a new propane service. When I called the guy to ask about the pipe size and he said 3/4 -- thought .. sounds small. He told me 3/4 before the regulator will power anything a homeowner would want to put on it .. I guess it's a lot of pressure in those tanks.

 

[Highbeam]

All lpg tanks have the same pressure at rest. Somewhere around 120 psi.

 

[wyliesdiesels]

No way for us to know without the specs.

What is the BTU rating on the generator?

What is the BTU rating of all the appliances on that gas line?

You already provided length size and type of pipe so thats helpful...

Once you have the BTU ratings, you will need to calc the pipe flow... then convert BTUs to therms....

 

[yeldogt]

Mine is a couple hundred feet -- 20k generator -- my studio heater 38k -- huge stove w three ovens. Gas dryer - boiler for the house .. connection for the grill.

 

[theoldwizard1]

The concern is line size, distance, bends a pressure.

Size and any line restrictions are the big issues. Never heard of distance being an issue of gas/propane IF the line is sized correctly.

 

[wyliesdiesels]

Size and any line restrictions are the big issues. Never heard of distance being an issue of gas/propane IF the line is sized correctly.

Yup. the same goes for wire gauge.

On a job 10 years ago, I had to run a 2" line about 200' for a 200K BTU tankless water heater, wall heater and small gas range...

 

[Adk Mike]

A generator will not run off the low pressure from inside the house. For each KW is about 17,000 BTU's. They draw some fuel when running.
You run your gas line of the high pressure side of the system. If the system is twin staged most with the tank on the house are. You install a tee block and a first stage regulator. Then 1/2 copper to a 2d stage near the generator and pipe it in. You should have at least 2/420 tanks that hold a hundred gallons each. I do this every week did one today. Mike

 

[sberry]

3/4 hi line? 3/8 will carry 200K btu 66 ft from single stage. 1/2 a half a million. I agree, tap before the house reg with 1/2 line and screw another secondary on at the unit.
Ok, noticed a 20K genset.

 

[sberry]

Yup. the same goes for wire gauge.

On a job 10 years ago, I had to run a 2" line about 200' for a 200K BTU tankless water heater, wall heater and small gas range...

The run must have been in the building then?

 

[wyliesdiesels]

The run must have been in the building then?

Half was under the house in a crawl space, the rest was in a trench.

This was for feeding a detached granny unit.

NG gas meter was at front of property. Granny unit in the back.

 

[Bert_]

I don't know much about smaller home type backup generators. Do they usually take liquid and have a vaporizer or do they draw vapor from the tank?

Depending on which one it will require different line sizes. A half inch liquid line can supply several million BTU, I think the same line drawing vapor is good for maybe 200,000. (Those numbers are just a guess really but you get the idea)

Another consideration if it will draw vapor is if you tank is large enough to supply the generator without freezing up.

 

[bob15]

I don't know much about smaller home type backup generators. Do they usually take liquid and have a vaporizer or do they draw vapor from the tank?

Depending on which one it will require different line sizes. A half inch liquid line can supply several million BTU, I think the same line drawing vapor is good for maybe 200,000. (Those numbers are just a guess really but you get the idea)

Another consideration if it will draw vapor is if you tank is large enough to supply the generator without freezing up.

The OP has a 1,000 gallon tank which is more than enough for a single house sized generator. I have a 500 gallon tank that supplies both the house and the generator......with zero issues.

 

[ezover]

I has been several years since I did mine but I recall there is a size /distance chart. you can also buy a gas pressure gauge to check the pressure at the generator.

I had a install company come and inspect my install and line pressure. line size was correct but I had to change my regulator size and they adjusted the gas pressure. they also corrected a few minor mistakes I made. was 200 bucks well spent imho.

the only advice I can offer on size is, my preference was to buy a unit big enough that it would run my whole house and not have to use a second breaker panel.

the only downside to a large unit is, it burns more gas. if you have a long power outage that can be a concern in the winter time.

 

[soj]

You most likely have a two stage system. That just means you have two different regulators. First stage is a high pressure regulator at the tank. It will most likely be red. Don't let "high pressure" fool you, it is only 10 psi. Where the gas line goes in your basement you should find another regulator, about twice as large as the one at the tank, and most likely painted brown. This is your second stage and it reduces the pressure from 10 psi to 11" w.c. The btu capacity of this regulator will determine if it can supply your current inhouse loads + the generator. The common regulator used is rated at 935,000 btu. So add up the current loads in the house and add the expected generator load to see if you need to add a regulator or not.

Just for reference my loads are: Central heat, 90,000, tankless water heater, 157,000, kitchen stove (estimated) 40,000, generator, 203,000, 490,000 total. That would leave 445,000 btu on one regulator

Even if the regulator has the capacity, your existing basement pipe could be too small. You could get around that by supplying the generator with a new pipe from where it comes into the basement, instead of at the gas cooktop.

I attached a gas line size chart. I have a more detailed size chart, but it is too big to upload. It has info on calculating losses for 90* elbows. If you need it, pm me. Or just google for gas line size charts.

You can see from this chart, that at 65" and a 203,000 btu generator, you are close to maxing out 3/4" pipe. If you need many elbows, 1" pipe may be needed.
jp

 

[yeldogt]

NG in many parts of the country is very low pressure -- I need a 2" line to my 400k pool heater at my place with NG.

In PA with the same size heater -- longer run .. it's 3/4 with propane. Not sure if I have a regulator at the 1000g tank -- it's buried. I may under the hood -- it has some connections.

 

[wyliesdiesels]

Yeah my NG pool heater has a 150' 2" line going to it. Not sure of BTU rating as label is gone.