Propane backup tank

[rmanrman]

I’ve got a 500 gallon in ground propane tank for heat ,hot water, shop heater. I’ve also got 4 -20lb bbq size tanks full after summer cookouts
Can I place a “T” fitting at the house where the propane enters the building. This will be after the regulator and the 20lb tank has a regulator also. Why? Bcuse I’m rural area and after last years snowstorms almost ran out.
Should I close valve to main in ground tank when empty? I would only use for heat boiler is high efficiency 99K btu. Any idea on how long 20lb tank would last?
Thanks

 

[toyotadriver]

I'm not certain I understand what you're asking but I'll take a try at it. I think you're asking can you run your house from a 20 lb tank.

If so, the answer is....sort of but it won't work for long if it works at all. I don't know where you live but the colder it is, the less likely it'll work at all.

Most likely you have a 1st stage regulator at the tank and a second stage regulator at the house. Your typical 20lb tank uses a single stage regulator so you have to feed it into the house AFTER the second stage regulator.

The biggest issue is the draw. 99k BTU is a heavy draw from a 20 lb tank. At that rate, if it was warm outside it'll still likely cause the 20 lb tank to freeze up. If it's very cold outside, it'll DEFINITELY cause the 20 lb tank to freeze up very quickly. The lower the propane level drops the quicker the 20 lb tank will freeze up. So, at that level of draw, you won't even be able to draw the full 20 lbs.

Basically, in my opinion, give the idea up. The smallest tank I think MIGHT work for you (and I don't know your climate) would be a 100lb tank.

A 20lb tank contains around 4 gallons of propane (depending on your supplier, it could be a little less or a little more. Propane has about 91k BTU per gallon so that's less than 4 hrs of run time....but since your 20lb tank will freeze up, you won't even be able to use all 4 gallons. You could potentially manifold all 4 tanks together but it's a lot of effort for the benefit.

Can you get a contract with a propane company and prepay for more propane? I don't like the contracts but if you need winter fills, a contract can save you some money.

 

[PoorUB]

What he said!

If you could get it to run you would get 4+ hours fo run time, but keep in mind your boiler never runs for 4 hours continously. You might get 8-10 hours depending on the weather, but again 99K BTU is probably too large of a draw if it were the summer. Even worse in cold weather. All four tanks manifolded together might do it, plus it would give you 4x the run time, so a day, maybe two with all four tanks.

 

[Walkers]

That is what I have, though I have a variety of tank sizes. If you want to use the BBQ tanks just manifold 2 tanks together. You can buy the gear at any RV place, or camping supply. I just put a tee in the line and a shut off valve, then a 3/8 flare fitting with a cap on it. Then if I need it connect a tank top reg with a pigtail on it, turn it on, bleed it out and then turn off the tank valve.

 

[Jackfre]

The issue off a 20 # tank and its regulator is that you may overdraw the tank and freeze the regulator up. As temps decrease your ability to deliver decreases as well. 20’s may not do it.

 

[finn]

Just use your bbq tanks to run an inexpensive propaysalimander. The smaller the better, probably.
It is less likely to freeze up, and should provide enough heat to prevent damage to the building contents for a day or two.

Watch out for CO though

 

[Adk Mike]

Won’t work. Save your energy. Propane techs can dump a small tank in an empty 500 with the correct tools. But with a modern 20 pound tank it has a back check installed and it slows the flow.
best to get your tank scheduled for a refill at 30 percent when it still has 150 gallons in it.

 

[gmcgeo]

That is what I have, though I have a variety of tank sizes. If you want to use the BBQ tanks just manifold 2 tanks together. You can buy the gear at any RV place, or camping supply. I just put a tee in the line and a shut off valve, then a 3/8 flare fitting with a cap on it. Then if I need it connect a tank top reg with a pigtail on it, turn it on, bleed it out and then turn off the tank valve.

Do not use Rv gear or camping gear on a house. most regulators that come from camping gear are single stage regs, meaning it has no protection if the regulator fails it sends tank pressure into the house. plus a 20# tank can only produce about 30,000 btu's at 30 deg outside. on top of all this if something bad happens like your house catches fire and they investigate it and see the 20#t tanks connected they tell you your insurance is not covered anymore. now you have to pay for your house out of pocket, in dept. and no where to live....... all to save $5..... just get it filled and save yourself a potential head ace

 

[Walkers]

The OPP from the house reg is still active and would readily cover any over pressure that a single stage regulator didn’t cover. Every LPG regulator I have ever used has a built in relief valve of some sort or another.

 

[gmcgeo]

The OPP from the house reg is still active and would readily cover any over pressure that a single stage regulator didn’t cover. Every LPG regulator I have ever used has a built in relief valve of some sort or another.

A large majority of applications use a relieving regulator. HOWEVER most rv and camping gear regulator use a non relieving regulator. meaning it relives into the line down stream. this is why you never use rv/ camping regs for house purposes. it is NOT NFPA approved.

but yes any over pressure should be stopped by the 2nd stage at the house.... hopefully .. it still would not be approved, in a bad situation they would say it should have never been installed

 

[Walkers]

It is for a back up in an emergency, not an every day situation. I have used mine exactly once in 20 years, and that just to take the tank out of service for recertification.
Probably the safest and surest would be to use a 2 stage regulator with the copper tube with the pol fittings on it.

 

[alwaysFlOoReD]

I lived in my non-winterized RV for a year and a half. Survived down to -47C. The trick I used to stop my 100lb tanks from freezing was using a battery blanket wrapped around the bottom of the tank.
PS: propane is liquid at -42 iirc.

 

[PoorUB]

I know guys that have started up some charcoal in the grill and then tossed it under the LP tank to warm up the propane.