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View Poll Results: Propane water heater or conventional heater?
Propane 7 38.89%
Conventional 11 61.11%
Voters: 18. You may not vote on this poll

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Old 28-05-2016, 05:55   #61
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Re: Propane Water Heater ?

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Originally Posted by sailorchic34 View Post
I would not assume that CNG is overall safer then propane. Both with a leak could cause the boat to go boom.
Possibility and probability are not thw same thing.

Natural gas (including CNG) is much safer than propane/butane. Both can go boom but natural gas is not as likely to go boom. Natural gas will only go boom if the air-gas mix is inside a fairly narrow range of explosive limits. The range for propane is much wider.






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Old 28-05-2016, 05:58   #62
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Re: Propane Water Heater ?

I put a small 5L per minute propane heater in my shower. Vents to overhead hatch. Of course I only need to heat the water about 20 deg typically so run it on the highest water flow and lowest flame. I have it connected to a 1 lb lpg bottle that hangs behind the bulkhead.

Certainly not ABYC compliant but there are no ignition sources in the area the bottle is in and it's a very small amount should there be a leak.
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Old 28-05-2016, 08:19   #63
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Re: Propane Water Heater ?

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Originally Posted by Paul L View Post
I installed the Zephyr model a couple of months ago and have been using it on diesel and electric since. That's how I know the 3 minutes. It does not rely on a hw tank.
If it doesn't rely on a tank why does it have an immersion element?

Oasis Zephyr HW | International Thermal Research
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Old 28-05-2016, 09:40   #64
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Re: Propane Water Heater ?

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Originally Posted by svlamorocha View Post
Possibility and probability are not thw same thing.

Natural gas (including CNG) is much safer than propane/butane. Both can go boom but natural gas is not as likely to go boom. Natural gas will only go boom if the air-gas mix is inside a fairly narrow range of explosive limits. The range for propane is much wider.
Hum....
Lets see, propane has a LEL (Lower Explosive Limit) of 2.1 and a UEL (Upper Explosive Limit) of 9.5. A range of 7.4

Natural gas which is 95% methane and generally contains 3-5% propane or butane, has a LEL of 5 and a UEL of 15. A range of 10.

Now to my eye, It seems that natural gas has a wider range of combustion. Though really its splitting hairs. Either will go boom in a closed cabin, such as in winter when the hatches are closed.

Natural gas has one advantage for boats in that it's lighter then air. But the disadvantage is it has 1/2 the btu's per CF of propane. So you need to refill far more often, or have larger tankage.

A CNG cylinder stores CNG at 3000 psig and requires a two stage regulator and a separate over pressure relief. More parts means more chance of failure.
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Old 28-05-2016, 10:31   #65
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Re: Propane Water Heater ?

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Originally Posted by sailorchic34 View Post
Lets see, propane has a LEL (Lower Explosive Limit) of 2.1 and a UEL (Upper Explosive Limit) of 9.5. A range of 7.4
Natural gas which is 95% methane and generally contains 3-5% propane or butane, has a LEL of 5 and a UEL of 15. A range of 10.
Now to my eye, It seems that natural gas has a wider range of combustion.
I will not get into the math of difussion of gases. Bottom line is that the "range" that matters is more about the ratio of UEL to LEL than the difference between the two. Think log scale.

Moreover, a natural gas leak that goes up and is more likely to vent to the atmosphere will diffuse (hence go across the UEL-LEL range) much fasterthan a propane/butane leak that will go down and is most likely to end up contained against a basement or the bottom of a boat. This means that a propane/butane leak is more likely to lead to a flammable concentration remains flammable over time, waiting for an ignition source to go boom.

When I was young and smart I worked for a utility that distributed both propane/butane and natural gas (which were progressively converted from the former to the latter) and we had real statistics about both. Those statistics match the story above.

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Originally Posted by sailorchic34 View Post
Hum....
Though really its splitting hairs. Either will go boom in a closed cabin, such as in winter when the hatches are closed.

Natural gas has one advantage for boats in that it's lighter then air. But the disadvantage is it has 1/2 the btu's per CF of propane. So you need to refill far more often, or have larger tankage.

A CNG cylinder stores CNG at 3000 psig and requires a two stage regulator and a separate over pressure relief. More parts means more chance of failure.
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Hum....
Though really its splitting hairs. Either will go boom in a closed cabin, such as in winter when the hatches are closed.
This is not splitting hairs.

Just a little bit of ventilation in any part (ideally two parts) of a boat will go a long way to stop a natural gas leak (which will quickly escape through any hatch) from going boom.

A lot of ventilation is required to prevent a propane leak from accumulating gas in the bilge that can go boom. Even with a lot of ventilation it will take a long time to get rid of flammable concentrations of propane because it accumulates in the bilge.

All that is abut probability. Now letīs talk about consequence. I have witnessed natural gas going boom and propane going boom with similar leak flows and could tell in practice that the theory was correct.
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Old 28-05-2016, 10:37   #66
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Re: Propane Water Heater ?

I doubt I can count on all fingers how many times the cook stove burner blew out on the boat. Nothing exploded, but the smell made us aware. We seldom cooked with the companionway closed. It's another good reason to have a dodger I guess.
Many houses have propane appliances (mine!) Hot water, dryer, cooking, home heating all propane. It's a very tight well sealed house... far less ventilation than a boat even when the boat is closed up. Propane pass thru heating water heaters are readily available for sealed houses.
Gas does explode now and then for sure. You just have to be diligent wherever you are.
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Old 28-05-2016, 11:01   #67
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Re: Propane Water Heater ?

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I doubt I can count on all fingers how many times the cook stove burner blew out on the boat. Nothing exploded, but the smell made us aware. .
No thermocouples on your stove ?

Our stove burners have blown out a couple of times with hatches open. The thermocouples shut down the system before we could smell anything.
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Old 28-05-2016, 11:05   #68
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Re: Propane Water Heater ?

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No thermocouples on your stove ?

Our stove burners have blown out a couple of times with hatches open. The thermocouples shut down the system before we could smell anything.
I don't think so, most of them older stoves.
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Old 28-05-2016, 11:10   #69
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Re: Propane Water Heater ?

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Originally Posted by svlamorocha View Post
I will not get into the math of difussion of gases. Bottom line is that the "range" that matters is more about the ratio of UEL to LEL than the difference between the two. Think log scale.

All that is abut probability. Now letīs talk about consequence. I have witnessed natural gas going boom and propane going boom with similar leak flows and could tell in practice that the theory was correct.

It's got nothing at all to do with a log scale: It's percent gas to air.

Both propane and natural gas are class 1A materials. Yes a propane leak would ignite first, but NG is not far behind and has a wider range supporting ignition.

Yes there are differences between the two gases, but either will cause problems. LOT's of building blow up with natural gas just as many blow up with propane. Both are inherently unsafe.

I would not assume that just because NG floats that it is safer in an enclosed area. Exploding buildings prove that. Dilution via ventilation would depend on the size of the leak.

One cool thing about propane is it quickly passes above the UEL threshold, so a large pool of propane in a bucket would not ignite. Of course one better have ignition proof bilge pumps and blowers. I know I do, plus a sniffer to alarm if there is a leak.
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Old 28-05-2016, 11:15   #70
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Re: Propane Water Heater ?

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Many houses have propane appliances (mine!) Hot water, dryer, cooking, home heating all propane. It's a very tight well sealed house... far less ventilation than a boat even when the boat is closed up..
Where is your house?

Most civilized places I know have very specific ventilation requirements for buildings that have natural gas or propane appliances that do not have a sealed (and vented to the outside) combustion chamber.
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Old 28-05-2016, 11:16   #71
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Re: Propane Water Heater ?

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Originally Posted by sailorchic34 View Post

One cool thing about propane is it quickly passes above the UEL threshold, so a large pool of propane in a bucket would not ignite.
That is a very cool experiment indeed!



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Old 28-05-2016, 11:19   #72
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Re: Propane Water Heater ?

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Where is your house?

Most civilized places I know have very specific ventilation requirements for buildings that have natural gas or propane appliances that do not have a sealed (and vented to the outside) combustion chamber.
And yet buildings will go boom. Weird....

My house floats and has sails.

I'm an engineer with well over 35 years designing propane and natural gas systems, and a whole bunch of other stuff, for buildings, including boiler plants, fueling stations, etc.
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Old 28-05-2016, 11:38   #73
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Re: Propane Water Heater ?

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And yet buildings will go boom. Weird....

My house floats and has sails.

I'm an engineer with well over 35 years designing propane and natural gas systems, and a whole bunch of other stuff, for buildings, including boiler plants, fueling stations, etc.
I give up in trying to persuade you that propane is more dangerous than natural gas, particularly on boats or houses with basements.

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Old 28-05-2016, 11:54   #74
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Re: Propane Water Heater ?

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I give up in trying to persuade you that propane is more dangerous than natural gas, particularly on boats or houses with basements.

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Cool.

Did I mention I have a PE in Fire protection too.

Thing is about codes and ABYC specifically, they assume that system as installed per "code" will always work. That is piping, valves, regulators will always operate perfectly. Alas that is so not the case.

Why I have a manual shutoff valve near (but not over) the stove, in addition to the electric solenoid. That manual valve does not meet ABYC. It does however, meet British gas codes (I'm not British BTW), which in this case, based on my experience, I think is smarter.

Submitted for your review, "homes with basements blown up by natural gas": https://www.google.com/search?q=home...utf-8&oe=utf-8

Not saying propane is safer, but that natural gas ain't safe either.
Have a great holiday and or great weekend.
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Old 28-05-2016, 12:15   #75
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Re: Propane Water Heater ?

What could possibly go wrong with Natural Gas? :>)
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