I need a Mercury Shut off Safety Switch

[robatnorfolk]

It interrupts the gas the millivolt flow to the operater coil that opens the main gas flow through the burner. It senses that the pilot is active so that there can be little build up of gas in the combustion chamber with no flame present to ignite the gas. The standards that direct vent fireplaces fall under require that the gas flow if the pilot goes out shuts down very quickly (I believe 30 seconds is the maximum). Thermopile systems can take 3 times as long to shut down.
I'm sure it's just a question of economics to build a direct replacement for the mercury switch and have it tested and approved would cost a lot of money and I don't think most would pay the part for the price. Most fireplaces that used the Mercury Flame sensor can be fixed by replacing the pilot assembly and gas control with approved components.

[sbecksted]

I'm searching for a replacement mercury flame sensor for a Serenity model#5GN36HAP natgas firplace. Any help?

[robatnorfolk]

I don't recognize that fireplace model number. Do you know who manufactured it? Replacement kits are only available for certain makes andmodels.

[sbecksted]

I don't recognize that fireplace model number. Do you know who manufactured it? Replacement kits are only available for certain makes andmodels.

Serenity was the manufacturer, bought by Marquis Fireplaces. Also, the model number tag has Security Chimneys on it but perhaps that's just for the venting.

[robatnorfolk]

Thats avery old fireplace. I will try to find a manual but if they never certified that fireplace with a thermocouple system option then I dont think you can fix it.

[ckartson]

Makes no sense? You said your burner runs with that switch failed. Did someone play mechanic and provide an engineered bypass. Mercury is not used anymore in these products, just like mercury thermostats are gone, mercoid switches etc are done. That's why everyone is telling you that you probably won't find one unless someone has some old stock. But back to your issue, if I understood you correctly you now have no pilot safety but the burner operates? I would shut it down immediately and call an expert to provide a new ignition control for this unit. Burner on with this control broken IS NOT NORMAL and UNSAFE. Hopefully I misunderstood your post.

[ammoniadog]

I think he was saying that his pilot stays lit, but his burner will not come on, unless he jumpers out the mercury switch. This is probably normal for his unit.

As long as your fireplace works the way that I think it does, I don't see a huge safety problem with your plan to keep the flame safety jumpered out, as long as there is no thermostat or anything else that cycles the burner. If the burner control just consists of you turning a valve open or closed, I think you will be ok. The only scenario that I could see that would be a problem, would be if you lost gas pressure to your house while the fireplace was on, and then the flames went out, and then the gas pressure came back. In that case, you could fill up your house with gas and it could explode. That is a pretty unlikely scenario, though.

Legally, be aware that by removing the safety switch, you will void any fire coverage that you currently have on your homeowners insurance. For this reason, I would definitely keep looking for fix, or plan to get a new fireplace.

[robatnorfolk]

In ontario where I live it is against code to remove or render inoperative any safety device on a gas appliance. I would never operate any appliance with the safety disabled. It was put there fora reason.

[ckartson]

Ammoniadog, I think the mercury switch is the pilot safety. There were g100 switches at one time filled with mercury that were used for proving pilot. I don't think he is referring to a room stat. This is why I responded that way. If it is what I am thinking then it has no pilot safety. There is a huge safety problem.

[ammoniadog]

Yeah, I know it's the pilot safety. If the mercury switch doesn't detect the pilot, the main burner won't come on, but the pilot will still be allowed to spew all the gas it wants. That's how it is supposed to work.

The OP's point was, that if the pilot safety is jumpered out, he can still light the pilot and then turn on the main burner himself. Then when he wants the fireplace to go out, he can turn off the main burner, and the fire will safely go out. It will still pretty much work the same way with or without the safety switch. The only things that I could see that would cause a problem would be if the gas company ran out of gas for a short time, or there was a major flood or all of the oxygen was sucked out of the air to make the main burner go out.

Gas logs are still legal in most areas, and they operate pretty much the same way, without any safety devices.

By the way, if there is a room stat or a high limit switch any other type of control that can automatically turn the fire place on and off, DO NOT DO THIS.

[ckartson]

It's wrong and unsafe as it would be for any burner. There are fire places with remotes that you push a button and poof a fire in the fireplace is lit. If the pilot spews as old stoves or old furnaces it will not accumulate enough to cause damage, If a main burner spews it can be dangerous. I am assuming the have a switch or something to turn it on not a completely manual process. Pilot safety is called that to prevent main burner without proof of pilot.

[hearthman]

Most gas logs installed today are listed to ANSI Z21.60 meaning they have a safety pilot. The IRC does allow for match lit logs listed to ANSI Z21.84 but again you must check your local codes. In addition, gas logs installed into factory built fireplaces typically must be listed to Z21.60 only with a few approved for Z21.11.2 ventfree.

The primary functions of a safety pilot are twofold: flame proving and ignition of the main burner. On typical safety pilot systems, a pilot can dropout and the valve not close for 180 seconds. However, when it closes, it shuts off the entire gas train, otherwise known as a "100% safety valve". The Hg sensor is a substitute method of sensing flame rather than a thermocouple. Since the valve is matched to the thermocouple, pilot burner and bracket to ensure a certain dropout rate, you should never modify a pilot system such as by using non-OEM thermocouples or a non-OEM pilot assy. Direct vent fireplaces typically use a 30 second dropout. Electronic ignition systems vary but typically dropout btw 4-7 seconds up to 60 seconds with varying rates of re-trial ignition.

To replace an old Hg system with either a standing pilot or electronic ignition system should be done ONLY in cases where a mfr. has tested the drop-in replacement and gotten a letter of approval from their listing agency. Otherwise, advise the client it cannot be done safely or legally.

[GT1980]

It's wrong and unsafe as it would be for any burner.
methinks2

liability 101: actually I would be required to redtag and appropriately make inoperable

[theresadawn]

Napoleon gas fireplace gd1800n mercury flame switch needed!!!
Anyone still have one of these parts or a line on where I can get one. Selling the house it is in so I don't want to buy a new fireplace but I have to disclose that it's not working if I can't get the part. That will lower the offer by the cost of a new one and we need every penny for the next place. Any help would be welcome!

[robatnorfolk]

I have a customer with the same fireplace and same problem. I contacted Napoleon and they do not have an alternate for that model of fireplace. The only solution is to replace the fireplace. I believe the GD36 is the model that Napoleon replaced the GD1800 with.