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

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.

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 Then the person looked further and found that that part has been replaced by a new part 50817 which is a whole burner assembly that includes the regulator tube as an integral component!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?

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 Now, that original part that is called a "regulator pipe" has now been superseded by a new Dometic part that has the "regulator" integral to the entire burner assembly.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.

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.

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

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