Whole Home Generator Advice

[gneimeth]

I have a 26kw generac arriving this week…so here’s my debate: I generally overthink things and started researching online and went down a rabbit hole.
My debate is that I rcvd two quotes from authorized Generac dealers to tie into my existing propane line that’s up in the attic (buried 500 gallon tank outside that feeds two hot water heaters and a cook top). I started reading and found many folks saying not to do it so started looking at options: place a new 250 gallon tank for $4500 or dig a trench and tie into main line off existing tank = about a 250ft run). After running through the scenarios and costs it seems that I have the 1” main line that goes into my attic and is tied to a manifold with lines T’d off to the devices mentioned above. Can’t I just add another T to the manifold (it needs to be the very first one and then run a 1” line (75ft) through my attic to where Geni will sit? Other points for clarity- the existing 500 gallon tank is on the opposite side of my house from the Geni and is about 100ft. I rcvd quotes because I wanted to see what turnkey costs would be and decided to do it myself and sub out the plumbing and running electrical from service to the transfer switch. I know that a meter to test the pressure will be needed to validate but overall is my thinking right here since both dealers were going to do that? I ultimately don’t want to starve my motor and burn it up…. Appreciate the resident GS advisors…

G.

[Sackett]

What does/did the installer/salesman recommend? I’m sure they’ve run into all sorts of scenarios so they should be your best source of information, especially if they’re going to warranty the work.

[Twist]

What does/did the installer/salesman recommend? I’m sure they’ve run into all sorts of scenarios so they should be your best source of information, especially if they’re going to warranty the work.

This.

You said you received two quotes so I would assume someone went and too a look, or you at least told them what you were wanting.

Did either contractor mention a different or better way? If not, and they feel the original plan is fine, I’d probably go with that.

[gneimeth]

I’m not using them, I’m going to sub out to another plumber individually (the dealers aren’t to willing to give advice since I’m not going to use them…). I’d like to have some perspective before I find a plumber (have experienced lots of folks over the years that act like they have experience or knowledge but really don’t…).

[Twist]

No idea then.

I do know my parent’s tank is a good bit behind their left back house corner and their Generac is about in line with the middle of the right side wall. It’s about a 100’ run to get the line to the generator.

They haven’t had any issues but it’s only be online service since around mid 2021, so definitely don’t take that as gospel.

[Txhunter3000]

2 tank water heaters or 2 tankless? Big difference! Any other appliances like an oven?

[gneimeth]

2 tank water heaters or 2 tankless? Big difference! Any other appliances like an oven?

Two regular water heaters and a gas cook top (there is a gas fireplace but we don’t use it so I’m not counting it)…

[Txhunter3000]

I'm not a plumber but from reading some Generac forums the 1" line should be ok from the tank. You should have a 10 psi regulator at the tank so your 1" gas pipe is adequate. You should have another regulator to drop the pressure before the manifold. So I'd say you can do what you're wanting to do. Get a plumber out to bid and look at what you have.

[TeamAmerica]

Maybe I'm missing something but why would tying into main Line differ in pressure from differ from tying into manifold?

i would spend the money to tee it from the attic and pressure test it first. First pressure test with no gas appliances running and one with all of them running to estimate how much pressure remains.

$4500 for a 250 gallon tank sounds high. Is that buried and/or a long run to the generator?

[RMW]

Think I paid 6500.00 for a 1000 gallon tank buried. I’d go separate tank

[WTucker]

If you end up going the separate tank route, I would really consider one larger than 250 gallons. You’re only going to get a few days of run time with the 250.

[gneimeth]

Maybe I'm missing something but why would tying into main Line differ in pressure from differ from tying into manifold?

i would spend the money to tee it from the attic and pressure test it first. First pressure test with no gas appliances running and one with all of them running to estimate how much pressure remains.

$4500 for a 250 gallon tank sounds high. Is that buried and/or a long run to the generator?

That’s where my head is at : tying into main line in attic avoids adding a dedicated tank or trenching a long way. I’m just trying to gauge from other’s experience if tying into my existing attic system with appliances is feasible AND I should be able to maintain the right pressure at the Geni… ultimately I understand I won’t know until I do the run and pressure test it.

[Txhunter3000]

What regulator do you have coming off the tank? From what I understand it should be around 10psi. so that a smaller gas line will be adequate since your line is 250'. You should have another regulator at the house to lower the pressure to what you need for the inside appliances. You would need to " T " into the 1" line before the second regulator. You will then need another regulator before the generator to lower the pressure to what it needs.

[jlinville]

"...through my attic to where Geni will sit?"

Are you planning on your generator sitting in your attic?

[Sackett]

If you end up going the separate tank route, I would really consider one larger than 250 gallons. You’re only going to get a few days of run time with the 250.

This is where I can’t wrap my head around “most” people buying large KW hour generators that run off a standing tank. You’re spending $10-20k after it’s all said and done to get maybe 2-5 days of run time on that generator. If we have a weather or other event that causes power disruption of 2 days or more, odds are very very slim that you’ll be able to refill the tank after running through all the propane. You’d be FAR better off simply buying a smaller, portable gas generator that’ll power your food storing essentials and a couple window units or portable room AC’s, especially in a situation like the Ops where you already have Hot Water AND a gas fireplace if power goes out during a freeze.

Op, it sounds like you’re trying to save money where you can for the complete installation? From your first couple sentences, I think you have “overthought” it and should consider having the company with experience in such installations handle the install.