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Open Roads Forum  >  Tech Issues

 > No gas to cook top

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Matt_Colie

Southeast Michigan

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Posted: 04/02/22 08:34am Link  |  Quote  |  Print  |  Notify Moderator

Enahs,

Before you get too much farther, inspect the unit and locate the regulator part. Then, with the gas on and a burner on, give it just a light tap with just about anything that is not hard. A plastic screwdriver handle will suffice. The regulator may just be stuck closed. It happens more often to new than used.

Matt


Matt & Mary Colie
A sailor, his bride and their black dog (one is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.


enahs

Washington

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Posted: 04/02/22 09:30am Link  |  Quote  |  Print  |  Notify Moderator

You may be right about debris. We'll see. But here's where I get lost. The regulator is set by the spring pressure and the ambient atmospheric pressure. More pressure on the spring pushes down on the valve and opens it making for more gas flow output and more pressure. But when the spring is set in the first place it is done in conjunction with ambient atmospheric pressure on the diaphragm. At higher elevation, that atmospheric pressure is less and the valve moves a tad toward closed — like turning the spring screw a bit counter clockwise (which will also decrease output pressure). The regulator itself is not closed to the atmosphere, though the tank is. What am I missing? I do grasp that the oxygen changes and that influences the flame efficiency. Urged kids to tap the stove regulator. Don't know if they did. We will work on this in the week ahead, but it is difficult/impossible to diagnose an altitude issue at now a lower elevation!

* This post was edited 04/02/22 10:56am by enahs *


'07 Chevy 3500 Dooley, CC, LT3, D/A

enahs

Washington

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Posted: 04/02/22 01:10pm Link  |  Quote  |  Print  |  Notify Moderator

OK, reviewing some of my physics, I see the source of my error. Spring tension in a regulator is a constant function of the length of the spring. It is not assisted or detracted by atmospheric pressure. Thus, the pressure on the diaphragm of the regulator is a constant at a constant spring length.

enahs

Washington

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Posted: 04/05/22 11:31am Link  |  Quote  |  Print  |  Notify Moderator

Finally was able to speak with a propane valve engineer. He surmises that what I havre taken for a regulator at the cook top is actually a flow shut off valve installed there for safety reasons. As he explains it, this is not mandatory but is sometimes used to shut off flow in the event of a line rupture. On the cook top at high elevation, when the stove valve is opened, the atmospheric pressure is not sufficient to push the ball/spring arrangement open against the flow supplied by the main tank regulator — which I believe is a constant at a given regulator setting. The flow control valve senses too much flow and closes, shutting off the gas entirely. He says that the flow valve is only there for safety reasons. Soooo, I am wondering if turning down the main regulator at the tank is a solution.

JBarca

Radnor, Ohio, USA

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Posted: 04/05/22 05:53pm Link  |  Quote  |  Print  |  Notify Moderator

Hi enhas,

I'm sure I'm going to learn something from your post, but I'll offer what have come to learn on your topic.

Many/most stoves that are part of a low pressure (11" WC) LP gas "system", (system meaning there are other appliances running on the same gas line feeding the stove,) use a stove mounted gas regulator. The stove regulator takes the incoming 11" WC gas pressure and steps it down to 10" WC. This step down regulator helps the stove burn more even when other appliances on the same gas line operate.

For example, you are cooking at 10" WC pressure on a stove top burner. You have the burner control knob (an adjustable orifice) set to the heat you want to cook at. Then, the furnace or water heater starts up. That large LP draw makes the main tank regulator droop and then open up. A slight dip and then a spike in the LP pressure can occur when the other appliance starts and the main system pressure may go slightly down and up from 11" WC to 12" WC or slightly more, until the main tank regulator has time to adjust. And some RV main regulators will not hold a constant 11" WC, they may drift up and stay up. They should not go higher then 14" WC. With all this gas pressure moving around, your stove top burner stays "closer" to the same as the stove regulator when it works right as it is running at a slightly lower pressure to help with the dip, and it helps tune out the spikes. Thus you do not burn up your meal.

I tried to find some info on your Dometic D21 cook top. Here is the manual I found https://www.manualslib.com/manual/1794703/Dometic-D21.html?page=7#manual Page 7 shows and states you are hooking up to a stove regulator. Not an excess flow device.

Here is a D21 for sale, and scroll through the pics to see the Seven Universe R60 stove regulator. That same R60 regulator is also used as a replacement part in the older Atwood stoves https://reparadise.co/great-products-for........versions/appliances/dometic-d21-cooktop/

I tried to download the install manual off the Dometic site, but I keep getting a 404 error, their link must be broke. https://www.dometic.com/en-us/outdoor/fo........-cooktops/dometic-drop-in-cooktop-138696


Unless Dometic changed something with the model you have, the D21 is shown to have a stove regulator to drop the 11"WC down to 10" WC.

Something is not adding up with this response from Dometic that they told you. This one, http://forums.trailerlife.com/index.cfm/........d/30325772/gotomsg/30326155.cfm#30326155

They never defined what "high elevation" was. 10,000 ft is often referred to as high in many instances and the air is thin that high which might mess with the LP/air mixture, but you would think the LP gas would light, but the flame be all yellow.

Searching around the web, this Dometic issue shows up, not only on your model.

A few I found
https://www.rvforum.net/threads/operating-on-propane-at-high-elevation.87986/

This one had a poster state Dometic told them 4,500 ft was the limit, yet that does not show up in the install instructions.
https://www.forestriverforums.com/forums........p-won-t-operate-above-4500-a-218875.html

I am not sure what the real issue is, I have had issues with that same R60 Seven Universe regulator before not regulating down to 10" WC on the Atwood range tops. In my case, it would not regulate at all. It passed what ever tank pressure was coming down the line. After 6 new regulators and 4 very upsetting calls to Dometic, I gave up on them and their tank regulators. I am at 500 ft elevation.

This sort of points to the stove regulator not working right for a reason I would really like to learn why. Suburban uses a different brand stove regulator and that may be why others have their stoves work in the range your kids camper is at, but yours does not. The Seven Universe regulator may be the issue.

Hope this helps and please report back.

John


John & Cindy

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enahs

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Posted: 04/06/22 09:52am Link  |  Quote  |  Print  |  Notify Moderator

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.

Reisender

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Posted: 04/06/22 11:25am Link  |  Quote  |  Print  |  Notify Moderator

For what it’s worth, this happens to us on our T@B400 trailer every time we turn the tank valve on too fast. To bleed the pressure, turn off the tank valve and let another appliance run till it quits. Then turn it on slowly and if you have to keep the stove burner valve open until the tank is fully open it will help.

Cheers.

enahs

Washington

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Posted: 04/06/22 11:41am Link  |  Quote  |  Print  |  Notify Moderator

Tried the slow turn on with no luck. BTW, I've learned that the main regulator hoses and some regulators have a flow control valve. Open too fast and it thinks there is a leak and shuts down. In this case, other appliances were getting gas. Only the stove shut down and only at 5500 feet.

Reisender

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Posted: 04/06/22 11:58am Link  |  Quote  |  Print  |  Notify Moderator

enahs wrote:

Tried the slow turn on with no luck. BTW, I've learned that the main regulator hoses and some regulators have a flow control valve. Open too fast and it thinks there is a leak and shuts down. In this case, other appliances were getting gas. Only the stove shut down and only at 5500 feet.


Yah. Our heat and hot water and fridge were fine. It’s only the stove that freaks out. And the only way to depressurize the line is to turn off the main tank, run another appliance until it quits and then start from scratch.

Good luck.

enahs

Washington

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Posted: 04/06/22 12:35pm Link  |  Quote  |  Print  |  Notify Moderator

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

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