Propane tank size for radiant floor heat??

[mrtbolt64]

Just curious on what tank size to look for. Garage is 48x32x12 with 6 zones. Using a tankless propane water heater and the propane will only be used for the heating.

I would like to keep the temp around 55 to 60 as we are getting ready to go through winter. Northern Ohio is my location.

Woman from the local propane station stated I could get by with 120 gallon unit. I know I dont need anything in the 500 gallon area but the 120 gallon unit seems small. I have never used propane so I do not know.

Any help or ideas on what some of you are using?

Thanks in advance

 

[Fixin'Stuff]

What BTU rating? Tankless water heaters use massive amounts of gas while on. Far more than a tank heater does. If the tank will be above ground it needs to be physically large enough (surface area above the liquid inside the tank) to be able to supply enough vapor in really cold weather.

 

[mrtbolt64]

its a TAKAGI GT-240-PIH 160,000 BTU

 

[finn]

Radiant heat runs at very low delta T, and low flow rate, so your heater is going to be running just above idle most of the time (probably in an inefficient burn range). I doubt it will ever be running at a propane burn rate anywhere near 160k btu.

The 120 gallon tank should work, and, as a bonus, it can be located right next to the building.

A friend heats his old farmhouse with propane from one of the fat boy vertical tanks, which I assume is in the 120-150 gallon range.

 

[yeldogt]

wow -- why so big?

I heat my 1700 sf well insulated studio with an 80% 40k sealed combustion Empire cabinet heater. It has two (2) 100gal tanks ... I keep mine above 60. I was always told they were 100g ... unless they are 120g with 100g fill.

Tanks can only be filled to 80% and normally need to be refilled at 30% -- so you really only have about 1/2 the total for use .... although you can bring them down to 10%.

Unless you have a lot of heat loss the heater is going to be cycling a lot.

 

[Ed Devinney]

I assume you've had a heat loss calculation done? If so you know how many BTU will actually be consumed and your propane supplier should be able to model usage.

If you're renting tanks you could start with the single 120 and then see how often the truck comes.

Our well insulated house and garage, with 1700sf of radiant slab in the house, 1100sf in the garage, and propane hot water will probably use 400 gallons this year. We have 2 120s just so we're not dependent on a refill during a patch of bad weather

 

[finn]

wow -- why so big?

I heat my 1700 sf well insulated studio with an 80% 40k sealed combustion Empire cabinet heater. It has two (2) 100gal tanks ... I keep mine above 60. I was always told they were 100g ... unless they are 120g with 100g fill.

Tanks can only be filled to 80% and normally need to be refilled at 30% -- so you really only have about 1/2 the total for use .... although you can bring them down to 10%.

Unless you have a lot of heat loss the heater is going to be cycling a lot.

The issue isn’t the volume of lpg in the tanks, it’s the surface area on top of the liquid.

The liquid propane “boils off” the surface and flows as a gas to the regulator. That requires a substantial surface area, and the higher the btu release ( burn) rate, the more surface area you need in the tank. Low temperatures, thing outside storage in the winter, compound the problem.

Larger tanks have more surface area, so they facilitate higher energy release rates, ie bigger heaters.

 

[mrtbolt64]

Calc sheet was prepared by the radiantec co. I sourced all the parts through there aswell.
Estimate was 49920btus/hr for heat and 61440btus/hour produced by the floor. Sorry guys buts its all greek to me.

So it seems as if the the 120 gallon should suffice.

Thank you

 

[MEngineer]

in reality you could use anything from the bbq size tank all the way up to an in ground 1000gal tank. it all has to do with space constraints, fill schedule, cost, and availability.

I had a 120gal tank when I moved on to the property that was being serviced about once a month. I decided that I did not like paying the large inflated prices during the winter so I shopped around and found a 500gal tank and bought it. now I only have to fill once in the winter and I get it filled in the summer when the prices are lower.

I have saved over $1.20 per gallon by doing it this way. Also, if you purchase the tank, you can shop around and everyone offers you a lower propane price for an owner tank.

 

[Bretny]

In no way can you use a 20lb propane tank, nor a 30 or 40lb tank. For 61kbtu/hr you will need a 100lb tank minumuim and that could still freeze up. Your propane tank supplyer sounds about right on the take size.

 

[Voi]

So it seems as if the the 120 gallon should suffice.

There are propane tank vaporizations charts that account for outdoor temperatures and (I think) elevation. I recall looking them up am pretty sure the 120 gallon tanks weren't going to be good enough for the tank-less heater at our cabin.

 

[purplezr2]

Honestly. Why would you not just get a 500. You can fill it once a year and be done more than likely. No pre buy. Not added cost for winter fill etc.

 

[mike93lx]

In no way can you use a 20lb propane tank, nor a 30 or 40lb tank. For 61kbtu/hr you will need a 100lb tank minumuim and that could still freeze up. Your propane tank supplyer sounds about right on the take size.

My grill is at least that BTU draw and runs fine in the winter on a 20lb cylinder.

Sure it isn't ideal and it would need to be refilled frequently, but it does work.

 

[Randy in Maine]

If that is your only use of propane you will be OK. I burn through about 500 or 600 gallons a year @ $2.19 to heat my whole house and garage + provide hot water and the kitchen stove. I have 2 x 120 gallon tanks and they fill them about every month.

 

[4cyclic]

500g tank is what I had installed. Heating at 55 deg all winter. Used about 250g on 3000sq ft. last winter.

 

[jack stand]

Using a tankless propane water heater and the propane will only be used for the heating.
Thanks in advance

I'm curious if a tankless w/h is common for a radiant system? It would seem that you'll need some mixing valve and some storage to draw from to temper your w/h output temps as most radiant operates around 105*-115*. Can you set your on demand w/h that low?

 

[theoldwizard1]

The issue isn’t the volume of lpg in the tanks, it’s the surface area on top of the liquid.

The liquid propane “boils off” the surface and flows as a gas to the regulator. That requires a substantial surface area, and the higher the btu release ( burn) rate, the more surface area you need in the tank. Low temperatures, thing outside storage in the winter, compound the problem.

Larger tanks have more surface area, so they facilitate higher energy release rates, ie bigger heaters.

Very interesting ! I never knew this.

 

[theoldwizard1]

I'm curious if a tankless w/h is common for a radiant system? It would seem that you'll need some mixing valve and some storage to draw from to temper your w/h output temps as most radiant operates around 105*-115*. Can you set your on demand w/h that low?

There is a constant debate between water heat and boiler for radiant heat, irregardless if they have a storage tank or not.

About the only thing the 2 sides will agree on is that a water heater probably will have a shorter life than a real boiler.

 

[jack stand]

There is a constant debate between water heat and boiler for radiant heat, irregardless if they have a storage tank or not.

About the only thing the 2 sides will agree on is that a water heater probably will have a shorter life than a real boiler.

I actually have an oil fired w/h that I use in the "shoulder seasons" before I fire up the wood boiler for the serious heating demands. My radiant system is all I know about radiant but I had it professionally designed (and drawn) so that this "ol nail bender" could follow the drawings allowing me to install and understand it. The operating "design temp" for mine is 105* and I just wonder if the OP can throttle back his tankless back that far.

 

[jack stand]

The issue isn’t the volume of lpg in the tanks, it’s the surface area on top of the liquid.
Larger tanks have more surface area, so they facilitate higher energy release rates, ie bigger heaters.

This is an advantage of horizontal tanks.

 

[finn]

I actually have an oil fired w/h that I use in the "shoulder seasons" before I fire up the wood boiler for the serious heating demands. My radiant system is all I know about radiant but I had it professionally designed (and drawn) so that this "ol nail bender" could follow the drawings allowing me to install and understand it. The operating "design temp" for mine is 105* and I just wonder if the OP can throttle back his tankless back that far.

Tankless heaters typically are used with a tempering valve and primary / secondary loops in the piping layout.

 

[toyotadriver]

I'd do a 250 or 500. Yes you don't need that much but you'll only need to fill once per year and propane is cheapest in the summer....usually Aug or Sept.

 

[6768rogues]

Along with tank size, consider how often it will need to be filled. I had propane at an out of town building and, of course, the supplier would not deliver propane if the driveway was covered with snow. I had to go there, plow the driveway on the weekend, and then hope it did not snow again until the tank was filled. Not as much of a problem if it is at your home, but still a consideration. I put in natural gas last year so no more going there just to plow.
If natural gas had not been available, I would have bought a 1000 gallon tank so I could shop around for a low price in the summer, get it filled, and coast through the winter.

 

[Reflex]

Please forgive me if this has been covered, I didn't read every post carefully, but the key to your problem is below. The answer isn't too terribly tough, but it has nothing to do with what type of appliance you're using to heat your space. We can argue all day about tankless units for radiant purposes, but it doesn't answer your question. The key is:

Calc sheet was prepared by the radiantec co. I sourced all the parts through there aswell.
Estimate was 49920btus/hr for heat and 61440btus/hour produced by the floor. Sorry guys buts its all greek to me.

If you need roughly 50,000 BTU/h for heat and the floor is capable of producing 61,000 BTU/h all we really know is that the design of your radiant system is adequate for the load.

That being the case, we have to make some assumptions. Those assumptions are:

1) The design temp - If your heat loss is 50k, at what temp does that take place? (that's the design temp).
2) How often or how long will those outside temps last?
3) The radiant system is designed and installed properly.

If we know these items, then we can estimate the amount of propane to be used.

The calculation isn't tough. The are 91,000 BTUs in a gallon of propane. Assuming the appliance you're using to heat the water is roughly 95% efficient, you will get approximately 86,000 BTU's out of each gallon. So, at design temp, you will use .6 gallons per hour.

The the problem with this basic calculation is that you don't have any idea how long or how much you'll be at design temps. Depending on what the design temp is, you may at that temperature quite frequently or never.

The solution is:
1) Find out what the design temp is in the system
2) Go to nearly any weather site on the internet and find out how many "heating degree days" there are for your area. You can use that data to predict how much propane you'll use.
3) Decide how often you want to have the tank filled or see the propane truck show up.

Knowing this will also allow you to estimate the total cost of running your system. It isn't an exact science, but over a period of 3 - 5 years, your calculations will be ridiculously close if the heat loss was calculated properly.

 

[NWDeere]

Just curious on what tank size to look for. Garage is 48x32x12 with 6 zones. Using a tankless propane water heater and the propane will only be used for the heating.

I would like to keep the temp around 55 to 60 as we are getting ready to go through winter. Northern Ohio is my location.

Woman from the local propane station stated I could get by with 120 gallon unit. I know I dont need anything in the 500 gallon area but the 120 gallon unit seems small. I have never used propane so I do not know.

Any help or ideas on what some of you are using?

Thanks in advance

mrtbolt64,

I am finishing up my shop in western Washington, same dimensions as yours, except 16' walls. It has been couple years since this post. Curious if you have some data on your propane usage? I am getting ready to buy my tank and going through the same tank size decision. Any insight would be appreciated.
Thanks!

 

[PoorUB]

I would assume a building of that size will take about four gallons a day on the average. A 120 gallon tank will last somewhere around a month, more or less, lots of guessing going on. If you get and extremely cold month it might last a couple weeks.
Get a 500, fill it once a winter, refill it if you need too. The smallest I would get would be a 250. What it comes down to is how often do you want to fill it and do you want to watch it all the time, or check it once a month?

 

[gmcgeo]

in reality you could use anything from the bbq size tank all the way up to an in ground 1000gal tank. it all has to do with space constraints, fill schedule, cost, and availability.

I had a 120gal tank when I moved on to the property that was being serviced about once a month. I decided that I did not like paying the large inflated prices during the winter so I shopped around and found a 500gal tank and bought it. now I only have to fill once in the winter and I get it filled in the summer when the prices are lower.

I have saved over $1.20 per gallon by doing it this way. Also, if you purchase the tank, you can shop around and everyone offers you a lower propane price for an owner tank.

LOL, no.... no you can not

 

[gmcgeo]

To size your tank, here is a good Chart to go off of

 

[yeldogt]

The issue isn’t the volume of lpg in the tanks, it’s the surface area on top of the liquid.

The liquid propane “boils off” the surface and flows as a gas to the regulator. That requires a substantial surface area, and the higher the btu release ( burn) rate, the more surface area you need in the tank. Low temperatures, thing outside storage in the winter, compound the problem.

Larger tanks have more surface area, so they facilitate higher energy release rates, ie bigger heaters.

My comment was not about the propane tanks size .... it was the OP using 160k BTU water heater. My space was bigger and needed 32k.

Around me one may see a single 120g for hot water or cooking .... for heat they normally do 120g twins. This is when renting -- I did not pay any more for the twins. Having a bit more capacity allows for the possible saving of a summer fill vs get hit in the middle.

My new place really could have used twin 1k's --- that would have allowed me to go though the winter on one fill. The way it is now I need a fill in early Feb when propane is always the most expensive ... so my cheap summer fill is on the light side

 

[PoorUB]

My comment was not about the propane tanks size .... it was the OP using 160k BTU water heater. My space was bigger and needed 32k.

Sure the heater he has is large, but it will also modulate down to 13,000 BTU.

Personally I would have looked for a smaller heater. but the price point on many of these makes them attractive.

 

[mike93lx]

LOL, no.... no you can not

It's funny that people think propane tanks function like gasoline tanks.

My previous portable generator would freeze a 20lb cylinder solid in cold weather once it was around half full.

 

[kj_mustang]

My new place really could have used twin 1k's --- that would have allowed me to go though the winter on one fill. The way it is now I need a fill in early Feb when propane is always the most expensive ... so my cheap summer fill is on the light side

Wow, using over 800 gallons per year is a bunch but then my primary house heat is electric. I use about 500-600 per year, so only one tank fill for my detached and attached garage and house usage.

 

[gmcgeo]

Wow, using over 800 gallons per year is a bunch but then my primary house heat is electric. I use about 500-600 per year, so only one tank fill for my detached and attached garage and house usage.

everyone uses different amounts, size of house, insulation, ect. I use 350gallons a year. main heat, with fireplace, range, gas grill.
I have a 1,000 and fill once every 2 years

 

[yeldogt]

Wow, using over 800 gallons per year is a bunch but then my primary house heat is electric. I use about 500-600 per year, so only one tank fill for my detached and attached garage and house usage.

It's actually used about 1500g each of the past two years .... It's a big house and I'm not even living there. So that just keeping in mid 60's .. not a fan of propane. No NG at the property ...

 

[fitter30]

Gallon of lp 91500 btu's. lp doesn't go bad. Buy it in the summer its cheaper that the winter. Owning your own tank can buy from anyone. Buy a used tank it has to have a complete name tag for someone to fill it. Call a local. lp company find out what is the minimum purchase with no delivery charge.

 

[gmcgeo]

Gallon of lp 91500 btu's. lp doesn't go bad. Buy it in the summer its cheaper that the winter. Owning your own tank can buy from anyone. Buy a used tank it has to have a complete name tag for someone to fill it. Call a local. lp company find out what is the minimum purchase with no delivery charge.

I am confused about that statement.

Name plate? DOT tanks are stamped with s# and dates, ASME will have a Data plate

 

[fitter30]

The two tanks i own have a plate tank isn't stamped at all. Might be the age of the tanks both are 500 gallon and 50 years old. Know that the 20 to 100lb tanks are stamped and have to be tested. Larger tanks in Missouri don't have to be.

Propane Tank Installation - Mission Gas Co.

Propane tanks carried in our inventory include 250 gallon, 500 gallon, and 1000 gallon. Underground and above ground propane tanks are available in all sizes.

www.missiongas.com

Choosing the Right Propane Tank Size | Ferrellgas

Not sure what propane tank size you need? Explore small cylinders to large tanks and find the best fit for your home, business, or outdoor needs.

www.ferrellgas.com

 

[PoorUB]

Wow, using over 800 gallons per year is a bunch but then my primary house heat is electric. I use about 500-600 per year, so only one tank fill for my detached and attached garage and house usage.

A farmer I know runs a couple grain dryers most years, burns propane.

There is a natural gas line a couple miles from his place and he asked about tapping into it. The utility told him they would do the tap and set a meter but it was his responsibility to dig in the two mile run.
We did the math and he could save $70,000 a year going to NG. I don't know if he did it. The cost of knifing it in, and getting permission from other land owners for an easement would be a hassle!

 

[gmcgeo]

The two tanks i own have a plate tank isn't stamped at all. Might be the age of the tanks both are 500 gallon and 50 years old. Know that the 20 to 100lb tanks are stamped and have to be tested. Larger tanks in Missouri don't have to be.

Propane Tank Installation - Mission Gas Co.

Propane tanks carried in our inventory include 250 gallon, 500 gallon, and 1000 gallon. Underground and above ground propane tanks are available in all sizes.

www.missiongas.com

Choosing the Right Propane Tank Size | Ferrellgas

Not sure what propane tank size you need? Explore small cylinders to large tanks and find the best fit for your home, business, or outdoor needs.

www.ferrellgas.com

Correct ASME VS DOT tanks ASME tank do not need recertification unless moved to new location

 

[toyotadriver]

Correct ASME VS DOT tanks ASME tank do not need recertification unless moved to new location

In my area, no one certifies portable propane tanks. If the tank appears good, the local places will fill it. They will not fill the old non-OPD valve tanks but will fill everything else without issue.