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 > No gas to cook top

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Reisender

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Posted: 04/06/22 01:32pm Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Here's the regulator at issue. It's on a dometic D21 https://www.sevenuniverse.com.tw/en/products-1/lp-regulator-5


Yep. That’s ours. D21.

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Posted: 04/06/22 02:04pm Link  |  Quote  |  Print  |  Notify Moderator

I asked the mfg what the problem.. It is a company in Taiwan We'll see if I hear back. Used a translator and sent msg in Chinese.


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Posted: 04/06/22 02:12pm Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

I asked the mfg what the problem.. It is a company in Taiwan We'll see if I hear back. Used a translator and sent msg in Chinese.


Hope you get it worked out. Let us know how it goes.

Good luck.

John.

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Posted: 04/06/22 02:47pm Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Just to update my interaction with Dometic. While failing to find the regulator tube part on line, I went back to Dometic. They said that 50806 was no longer available. I said its a new unit! Then the person looked further and found that that part has been replaced by a new part 50817 which is a whole burner assembly that includes the regulator tube as an integral component! It's covered by warranty. But while I can buy it on line, I can't get it from Dometic because it's a gas part! The unit will have to go in to an authorized Dometic dealer! Remarkable. All this time to find that it is a defective part! As it had to be, given that the 4500 feet stuff was pure BS! BTW Ernie, what instrument did you use to reset the regulator?


Typical dealer lip service...schmucks!


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Posted: 04/06/22 09:45pm Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Many thanks John for all of your work on this. Yes, I saw the regulator in the manual diagram but dometic told me there was no regulator in the system! I don't think the CS rep actually knew. But the problem in all of this is that there is no gas flow at all at the stove at 5500 feet. None, not even a hint. Yet at the nearby outside camp stove fitting there is gas. Back at lower elevation it works fine. Why? The main regulator at the tank is not influenced by elevation. Not positive but fairly certain the "obstruction" is at the stove "regulator". But why. This will be checked more thoroughly. All other appliances work fine (though furnace now shows a sail switch issue on the board read out). Now, that original part that is called a "regulator pipe" has now been superseded by a new Dometic part that has the "regulator" integral to the entire burner assembly. With no help or sympathy from Dometic, I have one of these assemblies coming. Dometic would not supply it because it is a gas part. But I could buy it on line from an RV parts supplier! BTW, great pic of the R60 regulator. I was also told 4500 feet was the limit. Ill report any findings. the old regulator is going to be disassembled.


Hi enhas,

Let's compare notes on the Seven Universe R60 regulator. I went this afternoon to my pile of 6 of these regulators and took some pics for you.

This thread of mine here on RV.net from 2019 is where those 6 regulators started from as FYI. Atwood/Dometic Stove regulator 51062

My issue was, the new regulators would not regulate down to 10" WC. They would pass any upstream pressure to the stove. I called Dometic tech service and got 2 different techs with different answers. I suspect at that time, this was after Dometic bought Atwood and all the techs may not have been up to speed on the new product lines. The outcome of the calls did not help, they would not even want the new unopened regulators back to test.

Here are the pics. I suspect in my case, the diaphragm may have a hardness too high that the diaphragm will not flex under the low pressure or something is up with the spring. I tried adjusting the spring tension in one of them, but no change. I am still not sure why they will not work.

In case you have not found it, here is good cut away and explanation on how the simple regulator works. This is on natural gas, but the LPG version works the same but at different pressures. Back in 2019 I had a good cross section I found on the web, but could not find it now. This video has a good cross section where there is no lower spring pushing the poppet valve closed. Only gas pressure closes the valve.
https://controltrends.org/by-industry/co........s-is-how-a-gas-pressure-regulator-works/

In my case, the lower poppet valve would not close. The regulator is naturally a normally open valve allowing gas to pass through it and the pressure that builds, closes the valve.

In your case, I'm hearing or thought I did, you stated no gas was coming through. But the stove did work at lower elevations. I think I figured out the issue. Read on.

Here are the pics, see if yours looks the same when the time comes.

The pile of 6 regulators
[image]

Close up on part number and mfg dates
[image]

Top of the regulator. You will need a Torx T20 bit with the center hole for the security screws to take them out.
[image]

The cover off showing the diaphragm, spring and vent hole in the top cover.
[image]

There is an spring adjuster in the top cover, it is not user adjustable, or would you need to, but assuming the factory sets it. The adjuster is a threaded ring that hold the OD of the spring.
[image]

The valve poppet is peened (riveted) to the diaphragm. It was hard to see, but you can see the stem and the valve seat under the diaphragm. With the poppet stem being swedged to hold it in place, you cannot rewove the diaphragm completely. This is not a rebuildable regulator, you replace it.
[image]

Here is the poppet in the down position away from the valve seat looking in the discharge port.
[image]

The back side of the regulator body
[image]


This is what I think is going on in your case.

The upper cover is vented to atmosphere, so the top of the diaphragm is exposed to atmospheric pressure. If the regulator housing was in a vacuum, then I could see the spring in the regulator closing the poppet valve tight as the top of the diaphragm is at negative pressure compared the LP gas side at 11"WC on the inlet port.

My vacuum statement triggered me to dig into, that lower atmospheric pressure exists as the elevation gets higher.
https://www.nationalgeographic.org/encyclopedia/altitude/

https://en.wikipedia.org/wiki/Atmospheric_pressure

If I understand it right, gas regulators are set at sea level atmosphere pressure. Since the upper cap of the regulator above the diaphragm is vented to atmosphere, if the atmosphere pressure at 5,200 feet is low enough, it can affect the regulator to act like it was in a vacuum. The small difference in gas pressure of a stove regulator (11"WC stepped down to 10" WC) has week spring tension as they are only a regulating a difference of 1" WC.

This may be why Dometic states the stove only works up to an atmospheric pressure at 4,500 ft. As the elevation above 4,500 ft lowers the atmospheric pressure even further, the spring pressure that exists in the regulator is overcome with the vacuum so to speak going on above the diaphragm, and the diaphragm raise up closing the poppet valve and not allowing any gas to flow out of the regulator.

A possibly explanation on why the main tank regulator works, the main tank regulator has a different spring and diaphragm size. The 1st stage of the is stepped down from high tank pressure (~150 psi) to say 2 to 5 psi etc. Then the 2nd stage takes it from 2 to 5 psi down to 11" WC. low pressure. In this case, it works at 5,200 ft, but it might stop working at 10,000 feet or higher etc. or whenever the elevation gets high enough to lower the atmospheric pressure.

Maybe someone in the know can confirm this, but I can see it happening this way.

Hope this helps,

John


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enahs

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Posted: 04/06/22 10:29pm Link  |  Quote  |  Print  |  Notify Moderator

Oh my! Your post is simply outstanding. More than I ever hoped for. And I very much appreciate it! More than aa few have this issue, and you have provided the most thorough discussion anywhere on the web. I do understand in detail how a regulator works and understand and tend to agree with your conclusion. My only question is the insistence of others that the diaphragm is controlled solely by the spring tension; atmospheric pressure has no influence. But as you point out, with a very weak spring as the R60 has, I can easily see atmosphere having an influence. But, in the final analysis, is there a solution? I have that bit. BTW, one thing is beyond dispute: atmosphere is indeed having an influence, regardless of any spring.

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Posted: 04/07/22 08:28am Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Oh my! Your post is simply outstanding. More than I ever hoped for. And I very much appreciate it! More than aa few have this issue, and you have provided the most thorough discussion anywhere on the web. I do understand in detail how a regulator works and understand and tend to agree with your conclusion. My only question is the insistence of others that the diaphragm is controlled solely by the spring tension; atmospheric pressure has no influence. But as you point out, with a very weak spring as the R60 has, I can easily see atmosphere having an influence. But, in the final analysis, is there a solution? I have that bit. BTW, one thing is beyond dispute: atmosphere is indeed having an influence, regardless of any spring.


Hi again enahs,

You are very welcome, thankyou.

There are a few undisputed facts in all this if we stop and think the whole thing through. The atmospheric pressure in the upper chamber of the regulator "does" have an effect on the on the force holding the diaphragm open or closed. The effect may be very small, or not so small, but there is an effect.

The diameter of the diaphragm plays into this as well as the spring force. There is a formula, S=P/A where the units are: psi= lb force/inches squared. The larger the diaphragm, the more force can be exerted for the same pressure applied to the diaphragm. On a larger diameter diaphragm, a very small change in pressure can create a larger change in force exerted. And visa versa with smaller diameters.

Lets think of it this way, take the spring out of the stove regulator and for this example declare the weight of the poppet valve as 0 lb. Inside the regulator is 11"WC gas pressure pushing against the gas side of the regulator. At sea level, the atmospheric pressure in the upper chamber is 0.0 psi. It is undisputed that the poppet valve will close tight shutting off the gas flow as there is no spring, the 11"WC acting on the diaphragm is working against 0.0 psi at sea level.

Now insert the spring. The spring force and the diameter of the diaphragm now come into play along with the atmospheric pressure in the upper chamber. This is where the issues come. If the 11"WC gas pressure acting on the lower part of the diaphragm is stronger then the spring force combined with the force on the diaphragm exposed to pressure from atmosphere the system is at, the poppet valve will close and stay closed.

I do feel we understand the problem, now how to get out of the problem? There needs to be a way to compensate for the lower atmospheric pressure exerted onto the upper part of the diaphragm as this weakens the spring force applied. Granted, there may be a practical max elevation limit where the cost to overcome the issue becomes too much. But 4,500 ft is not much.

My first instinct is, the regulator needs a slightly larger diameter diaphragm, a slightly heavier poppet valve or a slightly less stronger spring in some combo to allow the lower atmospheric pressure to not be overpowered by the 11"WC constant pressure and still work with the 1" WC regulation need of stepping down to 10" WC.

I'm sure this has been solved as home stoves working on LPG I'm sure work at high elevation in the US. Say Denver etc? They should have the same need for a step down stove regulator. Us folks on the east coast never had to worry much about this.

Here is a post for RV.Net in 2014. They got closer to the issue, but they mixed up the low oxygen issue and the main tank regulator and never drilled down into just the stove regulator with it's very sensitive balance of trying to control 1" WC pressure. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27518594/print/true.cfm

I'm still thinking on this. I was hoping someone would jump in and explain what changes in the spring, poppet or diaphragm that makes the stove regulator work at higher attitudes.

Hope this helps

John

* This post was edited 04/07/22 08:41am by JBarca *

StirCrazy

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Posted: 04/07/22 09:01am Link  |  Quote  |  Print  |  Notify Moderator

JBarca wrote:



You are very welcome, thankyou.

There are a few undisputed facts in all this if we stop and think the whole thing through. The atmospheric pressure in the upper chamber of the regulator "does" have an effect on the on the force holding the diaphragm open or closed. The effect may be very small, or not so small, but there is an effect.

The diameter of the diaphragm plays into this as well as the spring force. There is a formula, S=P/A where the units are: psi= lb force/inches squared. The larger the diaphragm, the more force can be exerted for the same pressure applied to the diaphragm. On a larger diameter diaphragm, a very small change in pressure can create a larger change in force exerted. And visa versa with smaller diameters.

Lets think of it this way, take the spring out of the stove regulator and for this example declare the weight of the poppet valve as 0 lb. Inside the regulator is 11"WC gas pressure pushing against the gas side of the regulator. At sea level, the atmospheric pressure in the upper chamber is 0.0 psi. It is undisputed that the poppet valve will close tight shutting off the gas flow as there is no spring, the 11"WC acting on the diaphragm is working against 0.0 psi at sea level.

Now insert the spring. The spring force and the diameter of the diaphragm now come into play along with the atmospheric pressure in the upper chamber. This is where the issues come. If the 11"WC gas pressure acting on the lower part of the diaphragm is stronger then the spring force combined with the force on the diaphragm exposed to pressure from atmosphere the system is at, the poppet valve will close and stay closed.

I do feel we understand the problem, now how to get out of the problem? There needs to be a way to compensate for the lower atmospheric pressure exerted onto the upper part of the diaphragm as this weakens the spring force applied. Granted, there may be a practical max elevation limit where the cost to overcome the issue becomes too much. But 4,500 ft is not much.

My first instinct is, the regulator needs a slightly larger diameter diaphragm, a slightly heavier poppet valve or a slightly less stronger spring in some combo to allow the lower atmospheric pressure to not be overpowered by the 11"WC constant pressure and still work with the 1" WC regulation need of stepping down to 10" WC.

I'm sure this has been solved as home stoves working on LPG I'm sure work at high elevation in the US. Say Denver etc? They should have the same need for a step down stove regulator. Us folks on the east coast never had to worry much about this.

Here is a post for RV.Net in 2014. They got closer to the issue, but they mixed up the low oxygen issue and the main tank regulator and never drilled down into just the stove regulator with it's very sensitive balance of trying to control 1" WC pressure. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27518594/print/true.cfm

I'm still thinking on this. I was hoping someone would jump in and explain what changes in the spring, poppet or diaphragm that makes the stove regulator work at higher attitudes.

Hope this helps

John


your instincts are corect in that atmospheric pressure plays a part but non of your calculations will work if you us 0 as a atmospheric pressure. it is 14.7psia or 101kPa at sea level and at 4500 feet it is aproximatly 12.5psia or 85.7kPa and 10 to 11" of watter colume is 0.36 to 0.4psi so realy at 4500 feet there should still be plenty of differential for it to work, maybe a slight yellowing at the tips of the flames. the problem with atmospheric relief regulators is they do use atmospheric pressure to act on the diaphram, the intent is to prevent an air lock from forming above it and preventing it from closing and it has a neglagable effect, but it is also much cheeper than using a pressure ballanced regulator set up.

myself I would remove the regulator , make a fitting to bridge the gap and try the stove, if it works put a new regulator in. mind you this might be more than you want to do while camping. the other option is to change it out and see how it works next time your camping.

this thread has me wondering if mine is starting to get week, I changed out my main regulator and everthing got better but I do have a flame that is a little two yellow but I am under 1000 feet and even when I am at 4500-5000 feet it doesnt change realy, hmm something else to updte now I guess... thanks [emoticon]


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enahs

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Posted: 04/07/22 09:40am Link  |  Quote  |  Print  |  Notify Moderator

Perhaps I'v got my thinking bass awkward, but I believe that a stronger spring is necessary, at least in my case. Too, some have apparently resolved the problem by turning down the tank regulator making it easier for the stove regulator to open. Then there is the question as to whether other stoves or appliances use a regulator that works. In all my years of camping, often at high elevation with different RVs, I've never encountered this issue. There must be something that works.

Shane

* This post was edited 04/07/22 04:24pm by enahs *

StirCrazy

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Posted: 04/08/22 08:24am Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Perhaps I'v got my thinking bass awkward, but I believe that a stronger spring is necessary, at least in my case. Too, some have apparently resolved the problem by turning down the tank regulator making it easier for the stove regulator to open. Then there is the question as to whether other stoves or appliances use a regulator that works. In all my years of camping, often at high elevation with different RVs, I've never encountered this issue. There must be something that works.

Shane


no a stronger spring would help but then at sea level it wouldnt provide the function of keeping a back pressure on the system for the fridge and furnace when you are using the cook top. as for your last part thats why I suspect it has gone bad. I have camped for years up to 6000 feet with many different rv's which all had the stove regulator and they all worked. my new (used) camper was having some flame issues but it turned out the main propane two stage reducer had blown something and wasnt providing enough pressure when the furnace was running also, but it still worked just week flames.

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