Propane tank size

[natvtxn27]

We now have a dig date at the end of May. We decided to go with a propane heater (our neighborhood is all electric). I will very rarely heat the pool so it is really just to heat the spa. The propane heater should heat the spa much quicker than the heat pump alternative I had. We also plan to put in 3-4 propane tiki torches. My options for Propnae take are a 250 or 500 gallon buried tank or a 120 gallon vertical tank above ground due to room and HOA restrictions. We planned to go with the buried 250 but tank and install is almost $2000. I am considering the 120 since it is only about $700 for tank and install. Of course both prices do not include running the lines, tiki torches etc but will be equal cost regardless. I will be running a pentair Mastertemp 400,000 btu heater. Spa will be an '8x6 square, pool will be 14,300 gallon. Like I said I don't care to heat the pool here in S Florida. Any issues going with the 120? Will it freeze up due to too much propane flow for that size tank?

Thanks!

 

[jblizzle]

If you are willing to fill the tank more often, there should be no issues with going with the smaller tank.

I have not heard of a propane tank "freezing up" ... the flow out of the tank to supply the heater would be the same regardless of the size of the tank.

 

[crabboy]

Some rough number crunching...

My 400K natural gas heater consumes 1cf about every 14 seconds, so an hours worth is about 250 cf. (Your propane consumption will likely be different)

120 Gal of propane is roughly 4200 cubic feet (guessing by a chart I saw) you have about 16 hours worth of gas in the tank. With a guess of 1,000 gallons in your spa, it may take an hour to get the water from 80 to 105.

Someone correct me if I've gone wrong.

I think the tank freezing the OP is referring to is when you drain small propane tank rapidly, like for a torch or a mini gas grill. You shouldn't have that problem.

 

[tim5055]

Some rough number crunching...

My 400K natural gas heater consumes 1cf about every 14 seconds, so an hours worth is about 250 cf. (Your propane consumption will likely be different)

120 Gal of propane is roughly 4200 cubic feet (guessing by a chart I saw) you have about 16 hours worth of gas in the tank. With a guess of 1,000 gallons in your spa, it may take an hour to get the water from 80 to 105.

Someone correct me if I've gone wrong.

I think the tank freezing the OP is referring to is when you drain small propane tank rapidly, like for a torch or a mini gas grill. You shouldn't have that problem.

Remember to take into account the 80% rule. Largr LP tanks do not have "OPD" valves, so the companies will only fill them to 80% of their rated capacity. So, 120gal tank becomes 96 gallons - all of which is really not usable.

I have a 120 gallon tank buried at my house and the only thing it is really good for is gas logs and my grill. In this case, bigger is better.

 

[Patrick_B]

I agree. Bigger is way better, and Tim is right about the fill limit. I have a 250 for my pool, and if we used the heater much more than we do, I would want 500.

 

[natvtxn27]

Do you heat your entire pool? I assume that heating the spa alone would use significantly less fuel, based on less run time? Do you know what your fuel flow rate is for your heater?

 

[Patrick_B]

Yes we don't have a spa. When I do, it takes approximately 55 gallons to increase 12 F. I
I don't know the flow rate at all, and now I can't remember how long it took. For cost reasons, we just haven't heated that much. Of course your use will be far less.

 

[Sunbaby]

We are building our pool now - and installing a 250 gallon propane tank for the spa. It will have the ability to heat the pool - though I can't imagine paying for that. Unless I am gonna have a HUGE party or something. My PB suggested a 250 Gallon for my spa. I have no idea what the cost to heat the spa will be - but I want to be able to heat it fast and we don't have gas as an option out here in the sticks - so propane was my only real choice. Right now Propane is 2.25 a gallon - I have no idea if that is high or low. Never used propane other than for a grill. I can't wait to sit in my hot spa and complain about the cost!

 

[Patrick_B]

About the going rate here in Texas. Which is puzzling, considering it's made all over the place around here.

 

[hoosierrun]

Just for a very rough comparison, I live in the Tampa area and use a 120 gallon above ground tank to heat my 8 foot concrete spa. I'm thinking the heater is about 180,000 BTU. There is definitely no freeze-up problems with vaporization. The usage and costs can vary all over the place, but this time of the year I warm the spa to about 94 to 96 degrees about 3-4 times a week from about an ambient water temperature of 80 degrees. It usually takes about 15 to 20 minutes to reach the 95 degree setting. I probably won't need to get a refill until late Fall or early next winter (refilled at about 10%). I keep two layers of solar covers over the spa when I'm not using it.

Now if you plan to use the spa in the winter and want raise the temperature from say 60 degrees to 100 degrees a few days a week, you will go through 80 gallons of propane in 4 to 6 weeks (or sooner). It gets really pricey in today's world. That is why I say, usage can go all over the place.

Obviously a fiberglass smaller tub would be substantially more efficient (combined with a thick cover), but the typical Florida pool has the adjoining tub, usually about 8 feet, with a valve controlled spillover that allows heating the pool or periodically exchanging the water. When I first moved here, propane was 65 cents a gallon and we used the tub frequently and often raised the pool temperature in the Spring and up to early Winter. Now with propane at $4 to $5 a gallon, I would never consider doing such a thing. 95 degree water is reasonably comfortable and allows good muscle stretching and relaxation. 100 degrees will get you sweating after several minutes and is nice for short soaks but really adds a lot to the cost. I definitely use my tub more than the pool in the off season. I love sitting in the tub before heading off to work in the morning, drinking a cup of coffee, listening to the birds.

 

[natvtxn27]

Thanks everyone. I'm thinking the 120 gallon will be ok, just need to be filled more frequently (obviously). I think I can live with that. Eventually I plan to put a solar heating system in so the propane heater would be supplemental. Im still exploring the solar system but thinking it would be a year or so after completion of the pool to install it.

I hadn't considered that before I ran into a neighbor who has done just that. He mentioned he hardly ever uses the gas heater, even for the spa. I was unaware a spa could be heated to 100 degrees with solar. Is there any downside to solar heating with a gas supplemental? I did have one pool builder say it would void your roof warranty.

BTW Sunbaby, I just moved here from your neck of the woods. We were in Spring, but spent a lot of time up on the Lake.

 

[tim5055]

Thanks everyone. I'm thinking the 120 gallon will be ok, just need to be filled more frequently (obviously). I think I can live with that.

The only thing I would advise you to double check before making the final decision is the companies delevery fee on top of the gas cost. Some don't dcharge it but some do.

A smaller tank can get expensive when they charge gotcha fees

I have seendelivery charges, epa charges, hazmat charges and the like. They can add around $20 - $30 per delivery to your house on top of the LP Gas fee.

 

[hoosierrun]

The only thing I would advise you to double check before making the final decision is the companies delevery fee on top of the gas cost. Some don't dcharge it but some do.

A smaller tank can get expensive when they charge gotcha fees

I have seendelivery charges, epa charges, hazmat charges and the like. They can add around $20 - $30 per delivery to your house on top of the LP Gas fee.

That is a good point and it may depend how many other customers they can fill on the same day in the same area. When I call for delivery, I always tell them to come by when they are in the area since I know there is a stepped up cost for a request outside their normal route. When the gauge indicates 10% or less propane remaining, I call them. They still charge about $10 to $12 extra for each delivery for environmental and fuel surcharge fees. I also get charged about $52 yearly for tank rental.

 

[Sunbaby]

That is awesome! Lake Conroe is so nice and with all this rain - it will be better than it has been in YEARS! Would you believe that it was 50 last night? Rare late cold front came through. I actually have a hoodie on today! Im worried the weather has been so crazy this year - I hope that doesn't mean a super active hurricane season. I don't have a generator for the new house yet!