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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I am putting together a fire pit system. The "Burner" is

Customer Question

I am putting together a fire pit system. The "Burner" is ideally 10 feet away from the gas control valve. I am proposing to us Honeywell SV9520H control valve because it us a hot surface igniter without a pilot. I do not think it is a good idea to run
a 10-12 pilot tube as it will drain out and there will be a long delay for a the gas to be ignited. The 120V igniter used is this system does not appear to have a wire for flame proving by rectification. Is the path of rectified current through the gas piping?
I would if so I will need to run a wire as the dope on the pipe joints may limit this conductive path. Any suggestions? The fire pit is above a occupied room, I don't want to but the valve in the ceiling under the pit. Gas leaks, and access panels. The valve
will be in almost open and ventilated mechanical closet. I think this is ideal from a safety and service perspective. 10 feet of interment low pressure gas out of the valve and 10 feet of wire to extended the leads on the 120v igniter. On the SV9520H the limits
switch circuit and air proving circuit will be shunted. Do you see any problems? If you don't like this at all what do you suggest?
Submitted: 1 year ago.
Category: HVAC
Expert:  BillyHvac replied 1 year ago.
hello,
is this assembly exterior of the home?
How do you plan on powering the SV952o
Why do you choose the smartvalve when there is no inducer motor?
The reason it is called a smart valve is because it controls exhaust fan, gets pressure switch signal, turns on a mini glow plug, and senses the flame..
Customer: replied 1 year ago.
Yes, the fire pit is in the open air on a roof surface. The induce air is not applicable to a fire pit. This valve was specifically selected as not having a pilot light if pilot tube.
It is a Direct ignition system which is ideal for a fire pit that is outdoors and in the rain and wind.
The question is very specific about the nature or the flame sensing system that typically uses a conductivity of a electrical path through the ionized gases in the flame. This is flame "rectification "
The other valves of this family have a sensor wire for this. The 120 hot surface igniter does not have this as all the hot surface igniter that are powered by 24 volts.
I don't think you can help if you have not had specific experience with this particular valve.
I have studied page 10 of the Honeywell manual on this valve.
The thing I don't get is how the flame is proven on this model without the flame rod. Is this a separate part from the igniter.
Maybe I have not found the right igniter as pictures I have seen of the 120v igniter do not show a flame rod. Maybe I need to be directed to the appropriate igniter?
Expert:  BillyHvac replied 1 year ago.
I have extensive experience with this valve.
Simply it will not work.
It must read an open pressure switch to start each cycle. Unless you want to unshunt/shunt everytime it is not prudent. so the exhaust fan question is not because I actually think a firepit has a draft fan..it is because it would need to be an open and close connection...if the inducer relay is closed it cannot start another cycle
Also the ignitor becomes the sensor after ignition and generates microamps...this useless unless we have a good ground.
Then you have a 3 second flame rectification period...but your valve is 10 ft away..you will not be proving flame in the 3 seconds. The valve must be close to the burner for a 3 second trial to work.
The 10 feet
The shunted inducer....makes this a poor design
Also the Honeywell Smartvalve has the highest failure rate of any valve ever made.
But I will opt out and see if you find someone you feel is has more experience with this valve. Mostly my experience has been getting rid of the smartvalve.
Customer: replied 1 year ago.
As I said before the pressure switch system or high limit control are not need or applicable to this fire pit system. Those input channels are simply shunted as being proved.
The Only thing that need to happen that the flame is lit with a switch and if the pit flame is blown out the gas is turn off as a safety precaution. The fame pit may attempt to relite after a blow out.
This valve can do this without having an to use a extended pilot tube that would not work when extended.
I believe my solution is to find and wire in an independent flame probe to the smart valve. This a smart valve I do not need all of its capabilities.
Just ignition and turning of gas.I am sorry but I do not think you have been helpful as this is a custom application the require a depth of understanding of how this valve can be use in a non traditional context.
Question what is the part number of the 120V ignitor that has a flame sensor as shown on page 10 of the tech manual for this valve?
That is a I need.
Customer: replied 1 year ago.
Bill now your talking and telling me something that I did not know I had to deal with. Thank you for your expertise and experience.
My next thought is to include a 24 time delay module to fake the power draft system. I thought this being a fast opening valve I could get the gas out the line in three seconds but I can see that is dicey.I really don't want to but a gas valve in a unventilated space in between rafters in a ceiling space. If the a leak the ceiling would explode downward.If you could recommend a control system to work with that would be great.
If all else fails the the valve could be places on top of the concrete deck surface and have a fire pan 6" above the deck. In that space I could put the valve and keep it outside.
This not ideal at best and desired look is have the flame as close to the ground as possible. I saw a Mercedes Benz commercial which the had a 5' diameter flame flush and next to a walk way. This for a very modern inner court yard in a house.
If you do not have a suggestion as how to bring gas to the flame burner 10 feet away I don't know any alternative. This is way I contacted your service. I do not have the hands on experience of the short comings of what I am proposing.If you have an idea as to how to continue in the direction I was going that would be appreciated.Otherwise this fire burner ring is getting off the ground it's doable but not desirable.