What size LP tank for Modine HD75?

[LARSOFVT]

I picked up a used HD75 Propane unit. (no Natural gas here)

I did some searching on the forum and I am wondering what size tanks others are using for this size Modine.

My garage has R19 walls and R30 ceilings about 1100 sq. ft.

Heating will be for a few hours on evenings and weekends.

I don't want a huge tank because of cost but I want the gas production to be sufficient when the temps get around 10-20 F.

 

[dave67fd]

I think you will need at least a 100lb tank to satisfy the line pressure required. See what tank sizes are available from your supplier. They typically supply/install them free when you hook-up with a service agreement with them.

 

[mrobins297aaa]

they usually supply and install them for free but usually there is a min required useage, so many gallons of lp per year or they charge you a tank rental fee. also most of them don't want to come out to fill your tank unless your buying at least 200 gallons. so for that you would need at least a 250 gallon tank. They only fill them to 80%.
just some things to check before you commit to renting one of there tanks.

 

[csp]

See if you can buy a tank to keep from being strapped to one supplier. Our home is on propane and we own our 1000 gal tank and shop around when it's time to fill it.

 

[mrobins297aaa]

See if you can buy a tank to keep from being strapped to one supplier. Our home is on propane and we own our 1000 gal tank and shop around when it's time to fill it.

thats good advice we own our 500 gallon tank and you can save money like csp says

 

[787B]

they usually supply and install them for free but usually there is a min required useage, so many gallons of lp per year or they charge you a tank rental fee. also most of them don't want to come out to fill your tank unless your buying at least 200 gallons. so for that you would need at least a 250 gallon tank. They only fill them to 80%.

Not my experience. Propane is my primary heat source in my house. I have two 100-gallon tanks. I'm on contract and they almost never fill more than 100 gallons when they come out.

I agree Lars should buy his own tank(s). They can often be found on craigslist for a fraction of new. Propane companies will often move and install privately-owned tanks for free if you sign a contract for the gas. (Make sure you get a bill of sale when you buy the tanks!)

Note that you can store as many 100 gallons tanks as you want right up against the building, but as soon as you go over 100 gallons in a single tank it must be located a minimum distance from all buildings which means higher costs to run the buried gas pipe. (And a tank in the middle of your yard...)

Personally I would find two 100-gallon tanks if you have the room, or one 100 gallon if space is tight. I think that will be plenty.

 

[Camper]

I run a 45,000 Btu in my garage. I just have 2- 40 lb. propane tanks that I had from my camper. Cost about $25 to fill and will last between 2 to 3 weeks in my 16X24 running a few nights a week and from Friday night till Sunday night ( depending on the outside Temp of course) They are easier to lift into the truck and I have 2 tanks so I never run out. Not sure how they would work on a 75K btu heater though.

 

[toyotadriver]

I run a 45,000 Btu in my garage. I just have 2- 40 lb. propane tanks that I had from my camper. Cost about $25 to fill and will last between 2 to 3 weeks in my 16X24 running a few nights a week and from Friday night till Sunday night ( depending on the outside Temp of course) They are easier to lift into the truck and I have 2 tanks so I never run out. Not sure how they would work on a 75K btu heater though.

How well insulated is your shop and what temp do you keep it at?

 

[Camper]

3 1/2" in the walls....6" in the ceiling......Doors are junk...will be replacing them.

I keep it around 55 deg over night and around 65 to 68 deg during the day when I am working.

Now that is not running all week.....Like I said...1 maybe 2 nights a week and then weekends.
Garage never gets below freezing ( at least water does not freeze )....even during the week temp can be in the mid 30's and get to a decent working temp in a short time.

 

[LARSOFVT]

they usually supply and install them for free but usually there is a min required useage, so many gallons of lp per year or they charge you a tank rental fee. also most of them don't want to come out to fill your tank unless your buying at least 200 gallons. so for that you would need at least a 250 gallon tank. They only fill them to 80%.
just some things to check before you commit to renting one of there tanks.

True. My current LP source requires that I purchase one tanks worth of gas every year to avoid the additional charges. That is one reason why I don't want a huge tank. At this point I am really not sure how much I am going to use.

So far no one has chimed in specifically about the HD75.

 

[sawatch]

Be careful if you buy tanks. The Gas guys are always comming up with "regulations" on valves & such that cost a lot of extra $. They get you commin' & goin' with their rules.

 

[BigMike782]

My 32 x 32 x 10 is very well insulated and I keep it at 55.It takes two season to use 400(80% of 500 gallons)gallons.Lat winter I used a radiant construction heater for supplimental when I was working and a 30 lb would last about a month.
The installer for the first lp supplier I used said there was no way they would leave a 500 on my site but they never pushed the issue or charged me anything additional.

 

[Kevin54]

I have a 45,000 BTU in my 28'x36' garage (R13 walls and R32 ceiling) and run a 120 gallon tank. It will last me about a month and a half keeping it around 52* at night and up to 70* when I am out there. A 120 gallon has it's own regulator. If you go larger you may have to have a regulator put on the garage. I'm not sure whether a 250 gallon has it's own regulator or not. But one thing to remember is that even though a 120 may do the job, it has to be filled twice as much as a 250. Also a 120 gallon can set right next to a building. When you step up to a 250 gallon, at least what my company told me, it has to be at least 10' away from the building. This may vary from area to area though.

 

[mrobins297aaa]

Be careful if you buy tanks. The Gas guys are always comming up with "regulations" on valves & such that cost a lot of extra $. They get you commin' & goin' with their rules.

I found that when I was shopping around to buy my tank (500 gallon) most companies wouldn't sell me a tank and they also told me that once I own it no one would fill it for me.
now that i own it they all want to fill it............bunch of whores.......lol
its a real racket, Its the only business where the best customers get the worst price. (the ones that they have locked in with there tanks)

 

[fishheds]

If you own your cylinder/tank the lp companies are prolly gonna require it to have a "multi-valve" so the driver can easily fill it from the Bobtail(truck).
The driver may have a adaptor for filling ACME type valves but most don't like to use it because it requires unhooking the regulators pigtail to attach,is time consuming and the sale will prolly be a small one.
Propane has ~91K btu per gallon so dividing this into your heater rating will give you a good idea what size tank you'll need.
I'd recommend at least a 120 gallon,which will hold 100 @ 80%.If your demand increases you can manifold 2 together.And 787's right.Anything over 120 gallon capacity has to be 10 away from the building and source of ignition(breaker panel,heat pump,etc.)
Tanks over 500 must be 25' off.
The most aesthetically pleasing option is to buy your own AG/UG tank and bury it.In this scenario,you'd install a 10# regulator on the multivave,run copper or PE to the building and hang a low pressure regulator on the side,feeding the heater.
Owning your own tank allows you to price shop.LP companies sometimes waive your tank rental if you have it filled more than once a year.

 

[787B]

Owning your own tank allows you to price shop.

And that is crucial. I'm on auto-fill with Suburban. They fill my tank at the end of October and leave the bill. They were charging me $3.99 a gallon when everybody else was charging $2.30!

Two calls to the dirtbags with threats to cancel service before they reduced the bill. How's that for ethical -- they are counting on their best customers just paying the bill and not shopping each fill.

 

[BigMike782]

Around here right now board(list price) is 1.869 gallon.
I crapped myself when I saw they billed you at 3.99

 

[6768rogues]

I think you should have at least two 100 lb. tanks manifolded together so they both supply all the time. LP is a liquid in the tank and evaporates to a gas fuel. Evaporation is a cooling process. Too small a supply tank and you run the risk of freezing the tank, thus starving the furnace.

 

[dave67fd]

So far no one has chimed in specifically about the HD75.

This is because the actual heater is in sense not important. What is important is it's efficiency, the garage size, how well insulated it is, the average ambient temp during it's usage, how often it is on, what temp your comfortable with etc..etc..

 

[LARSOFVT]

This is because the actual heater is in sense not important. What is important is it's efficiency, the garage size, how well insulated it is, the average ambient temp during it's usage, how often it is on, what temp your comfortable with etc..etc..

I disagree. When the heater is firing it is pulling gas off the tank(s) at a certain rate. The rate corresponds to the heater size. If the heater pulls all the available gas off the tank it will shut down temporarily while the tank catches up. This HD75 is only a single stage burner. It does not care what the temperature of the room is.

You are talking about the average heat load of a space.

 

[csp]

Just about any tank is going to have enough "flow". The only thing that will stop flow is if the regulator freezes as the propane goes to a gas from a liquid. A friend of mine ran a 120k BTU unit heater on 20pound bottles while waiting for the propane company to run a line from his 500gal tank to his shop.

The biggest factor in tank sizing is BTU usage and how often you want to fill the tank based off of that BTU usage. Usage is going to be determined by the variables dave67fd mentioned.

 

[LARSOFVT]

The biggest factor in tank sizing is BTU usage and how often you want to fill the tank based off of that BTU usage. Usage is going to be determined by the variables dave67fd mentioned.

I had a 140k BTU running off a 100# cylinder and the heater kept shutting off because the tank could not keep up.
This is more of a concern to me than how often I have to fill up.

0 gas flow=0 heat!

 

[csp]

So you had one occurence which could have been a bad regulator or a freezing regulator and you're convinced that the vessel size has everything to do with the flow rate.

You might want to check with your local propane supplier and get their expert opinion then and good luck to ya.

 

[LARSOFVT]

For some reason you concluded that I had done all this on my own.
Not true. My gas company experts installed it.

Check the following link:

http://www.yamaha-propane-natural-gas-generators.com/fuel_consumption.htm

Go to the bottom where it says "Vaporization rates of cylinders"

Then maybe you will understand my question.

If the rate is exceeded the heater shuts down.
I can do the rate calculation based upon the BTU's of my HD75. I was merely looking for input from others with the same unit.

 

[dave67fd]

csp,
Just because your friends 20lb tank ran his heater doesn't mean it's correct and will work in every situation.

Vaporization is the process of a liquid being converted into a gas (or vapor). As propane boils, it is in the process of vaporizing. Water boils at 212°F at which point it converts to a vapor we know as steam. Propane works the same way but at a much lower boiling point. One might refer to propane vapor as "LP Gas steam". Vaporization is affected and influenced by the actual size of the propane tank.

Propane Vaporization Requirements:
In order for a propane appliance to work, vaporization must occur and the amount of vaporization rate must be ample enough to deliver the required amount of propane. A small propane tank such as a cylinder does not have the vaporization capacity to fuel a residential propane furnace. The furnace requires so much more propane than a cylinder can deliver. The propane in the cylinder can't vaporize fast enough to satisfy the demand of the furnace.

 

[csp]

csp,
Just because your friends 20lb tank ran his heater doesn't mean it's correct and will work in every situation.

Really? Is that what I actually said?

Any vaporization table for propane will show that a 20lb cylinder has the BTU capacity of the OP's unit heater, at well below freezing, at pressures much higher than the OP's unit heater requires.

That's not to say it's correct or will work in every situation. There, plainly stated what it isn't. Throw in a faulty or improperly sized regulator or other factors and then you have a problem. It should be fairly obvious that nobody in their right mind is going to use this as a permanent solution.

The point was, and still is, that vaporization, or flow, of the cylinder vs. volume required by the heater isn't the driving factor when selecting a tank size. A "reasonably" sized tank, lets use 100lb for example, is going to meet the needs of the OP's heater. After that consideration (a non-issue at that), other factors become predominant.

If the OP wants to base his choice of tank on the "flow" of the cylinder, so be it. No skin off my back.

 

[LARSOFVT]

Any vaporization table for propane will show that a 20lb cylinder has the BTU capacity of the OP's unit heater, at well below freezing, at pressures much higher than the OP's unit heater requires.

I guess I need help with the math on this one. Assuming the BTU/hr requirement of the HD75 is somewhere around 75000 BTU/hr, how do you figure a 20lb cylinder has the capacity?
The table in the link above states at 0 degrees F the 20 lb cylinder is only good for 7,500 BTU/hr.
Maybe I'm reading it wrong.

 

[Chetter]

I run a 45,000 Btu in my garage. I just have 2- 40 lb. propane tanks that I had from my camper. Cost about $25 to fill and will last between 2 to 3 weeks in my 16X24 running a few nights a week and from Friday night till Sunday night ( depending on the outside Temp of course) They are easier to lift into the truck and I have 2 tanks so I never run out. Not sure how they would work on a 75K btu heater though.

Just like you I also run a 45000 btu propane Big Maxx heater and use 2 40lb bottles with a auto switching regulator and have my garage temp set at about 45-50* when I am not out in the garage. I've been running this set up now for 3 years with no problems. My garage is pretty well insulated and tight around all the doors with no windows and is 24x32 with 10ft ceilings. I like being able to lift one of these tanks into my truck to have it filled.