Custom trailer - low flow in propane line

[lightItUpTwice]

Propane experts, I need some advice and hope you'll bear with my not-quite-a-stove thread...

I've got a 6x12 trailer which I've converted into a travel trailer, and I ran propane hoses through the interior for my three outputs. One of the outputs works perfectly, the other two seem to have low pressure, and I'm at a loss as to why.

Here is the setup:

1. The exterior has two 20lb tanks with a Flame King automatic changeover regulator:

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2. I've got a 5' Camco hose running from the regulator, through the wall of the trailer via a waterproof fitting:

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. (I've checked the tightness of this fitting and ensured it's not pinching the hose and thus restricting supply.)

3. Inside the trailer, the same Camco hose comes up and into a Aupoco Y-splitter:

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4. The right-side of the splitter comes up into a Camplux water heater, which works just fine. This is the working output.

5. The left-side of the splitter connects directly into another, identical Y-splitter:

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6. The top (right) side of this (second) splitter comes up out of the countertop:

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, and here it terminates in a QCC1 Acme nut. The picture shows a manual, yellow valve before this nut - I've removed that since taking the photo. This QCC1 nut is basically the same thing you'd find on top of a 20lb propane cylinder. It has a built-in check valve that's activated (opened) by the male part of the propane accessory you screw on.

7. The left-side of the splitter goes into two, 12ft (each) Wadeo hoses.

8. The hose terminates exactly the same as the one going through the countertop, described in point #6:

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When I attach my Partner Steel stove to either the QCC1 nut in #6 or in #8, I hear a tiny trickle of propane coming out, but it's not enough to even light the stove.

I initially thought the issue was with the QCC1 connectors, and their valves being set too deep and thus not being opened by my stove's male counterpart, but that's not the case. I even took one of these connectors and completely drilled out the inside to have an unobstructed propane flow, and it made no difference. Best as I can tell, the problem seems to be low propane pressure. This is where I'm lost.

I've checked every single connection/component for leaks using both a handheld detector (which works, I've checked) and a permanently-installed and always-powered propane detector in the trailer itself. There are no leaks.

Could the problem be an obstruction in one of the hoses/splitters? Is the problem in my "design," or perhaps air trapped inside the hoses? Any ideas on what I can/should do?

For what it's worth, yes, I'm fully aware that the water heater should not be used in an enclosed space, propane lines would be best ran outside, etc. Please - I'm not interested in discussing that here.

 

[ABMax24]

You're trying to run 2 regulators in series. You need to remove the regulator on the stove in that configuration.

Actually your setup is wrong, you shouldn't be using the QCC1 connection on low pressure like that. Take a look at what RV's use for low pressure connectors. My fifth wheel has 2 low pressure connectors that can run a stove or BBQ. Again with those you need to remove the regulator from the stove or BBQ to get it to function correctly.

 

[lightItUpTwice]

You're trying to run 2 regulators. You need to remove the regulator on the stove in that configuration.

Actually your setup is wrong, you shouldn't be using the QCC1 connection on low pressure like that. Take a look at what RV's use for low pressure connectors. My fifth wheel has 2 low pressure connectors that can run a stove or BBQ. Again with those you need to remove the regulator from the stove or BBQ to get it to function correctly.

Thank you, I appreciate the quick reply!

I would have assumed that the second regulator would simply not decrease the already "regulated" pressure, and let it flow through as-is, but perhaps that's a wrong assumption. The stove I have is pretty "rare", uses a proprietary connection on the stove-end, and so it's a bit of an effort to get a regulator-free hose for it, but not impossible (I'll look into that).

I used the QCC1 connectors specifically so that any old camping stove could be hooked up. I'll do a search into what traditional RVs use. The one I had prior had a built-in Dometic stove and no hookups for anything else.

 

[lightItUpTwice]

I did some searching online and found more posts explaining that yes, running two regulators in series will not work. That's a bummer, but it's also a bit of a relief: I have the (likely!) problem identified, and I don't need to tear out half the trailer to mess with the hoses. Now to find a second hose for my stove and get a propane shop to remove the regulator from it...

Thank you again for the quick response and help!

If you find yourself ever passing through Vernon, shoot me a message, there's a cold six pack for you.

 

[ABMax24]

I did some searching online and found more posts explaining that yes, running two regulators in series will not work. That's a bummer, but it's also a bit of a relief: I have the (likely!) problem identified, and I don't need to tear out half the trailer to mess with the hoses. Now to find a second hose for my stove and get a propane shop to remove the regulator from it...

Thank you again for the quick response and help!

If you find yourself ever passing through Vernon, shoot me a message, there's a cold six pack for you.

Looking at the image I think you could just thread the regulator off the stove line and put a different connector on it.

Not a problem. I'll let you know if I do, although I don't get down that way much anymore, my brother went to College & University in Kelowna, but I haven't been back since he graduated and moved back to Alberta in 2019.

 

[lightItUpTwice]

Following up with a bit more learnings for anyone that may find this thread in the future:

RVs and travel trailers typically use low-pressure propane, and matching low-pressure appliances; this low pressure won't fly for most non-RV propane appliances, such as portable camping stoves. As it turns out, my stove requires 27 PSI of propane pressure, but the RV auto-changeover regulator I installed drops the pressure to 11 wc (water column), which is only 0.4 PSI. Even if I remove the regulator on the stove's hose, the pressure won't be anywhere near high enough to run my stove.

I'll be removing the auto-changeover regulator and running propane directly from the tank, with a separate regulator for each appliance. This will give "full" pressure in the lines, and allow each appliance to regulate its own pressure as needed.

 

[gthomas785]

11" WC is a very common pressure for household LP appliances as well. I bet your stove would work on that, and if not, fixing it would just be a matter of switching out some orifices. Running full tank pressure on those hoses inside the RV sounds like a recipe for blowing yourself up.

 

[lightItUpTwice]

11" WC is a very common pressure for household LP appliances as well. I bet your stove would work on that, and if not, fixing it would just be a matter of switching out some orifices. Running full tank pressure on those hoses inside the RV sounds like a recipe for blowing yourself up.

Stove manufacturer told me 27 PSI is required for the stove to work, and I'd rather not mess with the stove itself as I do want to retain the option of using it separately from the trailer.

Blowing myself up is not an immediate priority, so I'll give that some thought. Perhaps I'm getting a bit deep into territory I don't understand enough.

 

[ABMax24]

Stove manufacturer told me 27 PSI is required for the stove to work, and I'd rather not mess with the stove itself as I do want to retain the option of using it separately from the trailer.

Blowing myself up is not an immediate priority, so I'll give that some thought. Perhaps I'm getting a bit deep into territory I don't understand enough.

Does the stove regulator list an output pressure on it?

I can almost guarantee it's 11"WC or less. Maybe they are thinking 27psi of bottle pressure for the regulator?

Otherwise your local RV shop should be able to sell you a cheap 2 burner stove like for an outside kitchen that runs on low pressure propane.

 

[gthomas785]

Based on the pic it looks like you could just unthread the regulator and place a female-female union in its place. When you want to hook it directly to a tank, just put the regulator back on.

 

[lightItUpTwice]

Does the stove regulator list an output pressure on it?

I can almost guarantee it's 11"WC or less. Maybe they are thinking 27psi of bottle pressure for the regulator?

Otherwise your local RV shop should be able to sell you a cheap 2 burner stove like for an outside kitchen that runs on low pressure propane.

Honestly, I can't say either way. I've found a few other sources (https://ahappycamper.com/product/pa...-inch-2-burner-propane-stove-with-windscreen/, (broken link removed to https://rileystove.com/product/partner-steel-cook-partner-2-burner-22%E2%80%B3-propane-stove-with-windscreen/)) which also say this stove will not work with RV pressure, and claim the same 27 PSI, but the copy/pasted phrase with poor grammar doesn't inspire confidence.

The regulator itself does not have an output listed, but this is the unit: https://propanedepot.ca/product/megr130-series-marshall-excelsior-high-pressure-regulators/ . Seems that it has 3 versions with outputs ranging from 10 to 30psi, which sorta/kinda matches up the 27psi claim.

Based on the pic it looks like you could just unthread the regulator and place a female-female union in its place. When you want to hook it directly to a tank, just put the regulator back on.

Yes, that's possible, but honestly not something I want to mess with every time I use the stove. A dedicated hose would make life easier.

All in all, I think I'll simplify this setup to the extreme by removing the interior propane line, leaving it in place only for the current water heater. We cook outside 99% of the time, and I'll just disconnect and use one of the two propane tanks when we setup camp, cooking off of that. If I just have to cook in the interior I can always install an inverter and one of those 1500-2000W electrical hot plates. That, or I'll find a portable propane stove that can run off of low pressure; maybe one of the classic Coleman units?

 

[coaly]

As posted above, this is a high pressure appliance. Camp stoves for outdoor use use higher pressure than indoor appliances to prevent blowing out. The control is red, meaning it is a high pressure regulator.

That said, a low pressure stove installed on this line will not work either. The reason is the supplied low pressure requires the correct diameter tubing or pipe to supply the correct pressure. The POL fitting (cylinder connector nut) has a very small orifice designed for cylinder pressure. At high pressure, this supplies the regulator with plenty of volume of gas vapor.

Once pressure is reduced, line sizing becomes very important. 1/2 psi is less than your breath. Hence, tables are given for line sizing giving how many btu will flow through the diameter and distance. This is why Natural Gas at half the pressure of propane requires much larger line sizing.

Pressure will show on a gauge with no flow called “lock up” pressure. That is the pressure increase from the time it takes the regulator to respond, closing the orifice. This is not system working pressure. You then light water heater, and any other appliances on the system. The range is then pressure tested at the burner orifice. Correct line sizing prevents pressure drop. Regulator pressure is then set at full flow of the system.

The importance of the correct pressure at a unvented burner cannot be overstated. Correct pressure at orifice is needed for the correct amount of oxygen to enter mixing tube of burner creating the proper air/ fuel ratio. This provides complete combustion of the fuel and air mixture to prevent carbon monoxide from improper fuel and air ratio. You are breathing what this appliance produces.

Low pressure creates carbon on pan bottoms, and flame contact areas in water heaters or furnace. Propane is clean burning with blue flame at the correct pressure and orifice size, but burns extremely dirty with not enough air. It is the orifice size at correct pressure that allows atmospheric air pressure to fill the void in the burner mixing tube providing the correct air /fuel mixture.

The black soot created is like a large black fluffy wasp nest that becomes airborne when trying to remove. You absolutely need a low pressure gauge or manometer (very simple to make your own U tube or slack tube gauge) to test working LP pressure.

This is the reason for a larger diameter black iron manifold, and tubing with the required inside diameter supplying appliances. This short of a system should be 1/2 inch copper tube size minimum. The entire btu requirement for all appliances is added together and lines are sized for the btu required. Flexible connector hose must be exposed the entire length as well, it cannot penetrate a bulkhead, wall or floor. Copper tube can penetrate straight through the partition with protector sleeve, black iron is required within partition. This prevents pinching, reducing cross sectional diameter and allows inspection of entire length of flexible connectors.

 

[lightItUpTwice]

As posted above, this is a high pressure appliance. Camp stoves for outdoor use use higher pressure than indoor appliances to prevent blowing out. The control is red, meaning it is a high pressure regulator.

That said, a low pressure stove installed on this line will not work either. The reason is the supplied low pressure requires the correct diameter tubing or pipe to supply the correct pressure. The POL fitting (cylinder connector nut) has a very small orifice designed for cylinder pressure. At high pressure, this supplies the regulator with plenty of volume of gas vapor.

Once pressure is reduced, line sizing becomes very important. 1/2 psi is less than your breath. Hence, tables are given for line sizing giving how many btu will flow through the diameter and distance. This is why Natural Gas at half the pressure of propane requires much larger line sizing.

Pressure will show on a gauge with no flow called “lock up” pressure. That is the pressure increase from the time it takes the regulator to respond, closing the orifice. This is not system working pressure. You then light water heater, and any other appliances on the system. The range is then pressure tested at the burner orifice. Correct line sizing prevents pressure drop. Regulator pressure is then set at full flow of the system.

The importance of the correct pressure at a unvented burner cannot be overstated. Correct pressure at orifice is needed for the correct amount of oxygen to enter mixing tube of burner creating the proper air/ fuel ratio. This provides complete combustion of the fuel and air mixture to prevent carbon monoxide from improper fuel and air ratio. You are breathing what this appliance produces.

Low pressure creates carbon on pan bottoms, and flame contact areas in water heaters or furnace. Propane is clean burning with blue flame at the correct pressure and orifice size, but burns extremely dirty with not enough air. It is the orifice size at correct pressure that allows atmospheric air pressure to fill the void in the burner mixing tube providing the correct air /fuel mixture.

The black soot created is like a large black fluffy wasp nest that becomes airborne when trying to remove. You absolutely need a low pressure gauge or manometer (very simple to make your own U tube or slack tube gauge) to test working LP pressure.

This is the reason for a larger diameter black iron manifold, and tubing with the required inside diameter supplying appliances. This short of a system should be 1/2 inch copper tube size minimum. The entire btu requirement for all appliances is added together and lines are sized for the btu required. Flexible connector hose must be exposed the entire length as well, it cannot penetrate a bulkhead, wall or floor. Copper tube can penetrate straight through the partition with protector sleeve, black iron is required within partition. This prevents pinching, reducing cross sectional diameter and allows inspection of entire length of flexible connectors.

Fantastic insight, thank you! You've opened my eyes to just how little I know about propane, and how many of my assumptions were incorrect.

I'll be removing the interior propane lines.

 

[coaly]

Fantastic insight, thank you! You've opened my eyes to just how little I know about propane, and how many of my assumptions were incorrect.

I'll be removing the interior propane lines.

Another thing to be aware of is the pigtails (rubber high pressure hose from cylinder to regulator) should have excess flow valves in them for road use. This valve is in the POL nut and closes when excessive flow moves from cylinder valve to regulator. They have been required for quite a few years, so are probably in your pigtails. They are designed to shut off gas flow if a line ruptures. The problem is when opening the cylinder valve, open it very slowly to allow slow flow to pressurize system. If opened too fast, the excess flow valve closes stopping gas flow. Shutting valve off, and opening slow is the cure.

Another issue with flexible hoses is rodents chew them. A system with that many hoses, or any inside, should have a pressure gauge on the system at all times. Normally kitchen counter mounted on high dollar rigs. You turn the gas on at tank to pressurize system, and shut it off. Then open a stove valve slowly to bleed off pressure until you see the needle start to drop. Then close stove valve and it must hold this low pressure below 10 inches WC for 10 minutes. This is a legal leak down test.

The reason you bleed off the residual pressure, is because a slight leak may not show on the gauge in 10 minutes. The high pressure volume of vapor in hoses from tank to regulator supplies the pressure when valve is off, masking the leak. Bleeding it down releases this pressure in high pressure lines which is replenishing the vapor that leaks out on the low pressure side of regulator.

Also, the lower the pressure, the more you will see it on the gauge. Like draining a tub full of water, you can’t see the water level drop when there is a high volume of water in the tub. But the last gallon or quart you can see move fast. The needle of a gauge drops the same way as pressure runs out.

Retired from my own RV service business maintaining local campground customers all summer, and LP gas service winters by referal of local gas companies for 25 years.