Possible direct spark ignitor alternative. Robertshaw 785-001

I stumbled across this the other day and I was wondering what the various experts out there had to say about the Robertshaw 785-001 as an alternative direct spark ignitor. Obviously it is less safe than a Honeywell ignition control module, but it seems like a good alternative for those who are willing to be less safe.

The big issue is that I can't find any specific information on what it does. IE does it just continuously spark or does it flame sense. Does anybody out there have specific personal knowledge on what this does and how it works?

rickyspeak said:

I stumbled across this the other day and I was wondering what the various experts out there had to say about the Robertshaw 785-001 as an alternative direct spark ignitor. Obviously it is less safe than a Honeywell ignition control module, but it seems like a good alternative for those who are willing to be less safe.

The big issue is that I can't find any specific information on what it does. IE does it just continuously spark or does it flame sense. Does anybody out there have specific personal knowledge on what this does and how it works?

Click to expand...

I am totally looking into the same thing as you and I have the same question...what I can find does lend itself to being flame sensitive..but doesn't directly say so....

I think it would be safe if it is wired inline with the gas valve...

I can't see dropping over $200 for a Honeywell system per burner...

I use a standing pilot now and have never had a problem...but then again I do watch it like a hawk....

Hopefully someone with experience can chime in...

It took some searching but I found the installation manual.

Basically, you apply power and turn on the gas to the pilot, the module then sparks until it senses the pilot flame. If the pilot goes out, it sparks again.

The downside is that there is no control of the gas flow in this. It is designed to be used with a gas valve that has its own sensors to shut off the gas.

This isn't what I would use to automate a gas burner.

reynolds5520 said:

It took some searching but I found the installation manual.

Basically, you apply power and turn on the gas to the pilot, the module then sparks until it senses the pilot flame. If the pilot goes out, it sparks again.

The downside is that there is no control of the gas flow in this. It is designed to be used with a gas valve that has its own sensors to shut off the gas.

This isn't what I would use to automate a gas burner.

Click to expand...

Thanks for the effort!

I am thinking this should be wired in series (or parallel) with the gas valve. I have a PID that energizes my gas valve open....

When the PID calls for gas, it will also energize the spark module at the same time causing the BG-14 burner to ignite...

When the PID senses temp is met it shuts off the gas valve and power to the spark control so it does not keep sparking...

My MLT and HLT are preset so the flame is always the same....

Great find reynolds5520. I couldn't find a manual anywhere. That answers all my questions. Basically this item has the same ignition functionality that the Blichmann Tower of Power provides (plus a solenoid valve of course). I'd say it's a little less safe than a standing/intermittent pilot light. All together it would be cheaper though. Which is good.

FYI Crimsonwine. You'd want to wire them in parallel. The voltage drop that putting it in series would cause might make it no longer work. Especially with a AC to high voltage DC converter that would be needed for the spark.

These units are traditionally installed in furnaces with pilots that have bi-metal switches in them, sometimes referred to as "3-wire pilots". Once these units light the pilot, the heat closes the bi-metal switch and sends power to the main valve terminal on the valve. Outdated technology and can get pretty pricey. You would not want to direct fire the burner with these. A light breeze could blow the gas mix off the spark and you could end up with a big flash and no eyebrows.

whatdyisit said:

You would not want to direct fire the burner with these.

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Agreed, in fact, it didn't even occur to me that anyone would be thinking to directly ignite a burner with these.

The only way I would use it, is to ignite a standing pilot. Just as a way to avoid having to reach in with a manual lighter at the start of the brew session. There are cheaper alternatives for that simple use, like the barbeque click button ignitors. The only advantage to this unit is that it relights the pilot automatically and that isn't enough to make for a safe unattended burner.

I wasn't trying to imply that it was entirely safe. Even manual ignition isn't safe. I know I've had more than one time where I was fumbling with a blown out lighter and gotten a small boom. It definitely would be a nice added feature to a standing pilot setup to protect from blowouts.

More I was looking for a DIY alternative to the tower of power ignition system for my own curiosity sake. There clearly is a commercial example of this sort of design. The guy clearly explains that if you don't get ignition it just continues to beep at you resulting in and the same "explosive" potential.

If my interpretation is wrong about what the blichmann product is doing, I'd love someone to open the guts and show us all what it's actually using for DIY cloning fun.

reynolds5520 said:

Agreed, in fact, it didn't even occur to me that anyone would be thinking to directly ignite a burner with these.

The only way I would use it, is to ignite a standing pilot. Just as a way to avoid having to reach in with a manual lighter at the start of the brew session. There are cheaper alternatives for that simple use, like the barbeque click button ignitors. The only advantage to this unit is that it relights the pilot automatically and that isn't enough to make for a safe unattended burner.

Click to expand...

Yeah the Blichmann is doing exactly what you are talking about, sounds like a different ignition module though. I had a 785-00A in the back of the shop and so I wired it up and shot a video real quick so you can see how it operates.

whatdyisit said:

These units are traditionally installed in furnaces with pilots that have bi-metal switches in them, sometimes referred to as "3-wire pilots". Once these units light the pilot, the heat closes the bi-metal switch and sends power to the main valve terminal on the valve. Outdated technology and can get pretty pricey. You would not want to direct fire the burner with these. A light breeze could blow the gas mix off the spark and you could end up with a big flash and no eyebrows.

Click to expand...

Ok, just stumbled across this thread as I currently use hot surface ignitors but want to switch to spark. This is primarily due to wanting to use true PID control not just on/ off temp control.

I am a bit confused at why you would not want to use this for the direct fire ignition? If I understand the above posts, this ignition system sparks until flame closes the bimetallic strip correct? My current setup is a bg 14 with timed relays and a hot surface ignitors. (see photo).






The other thought is this could potentially be a bit safer based on the automatically respark if the burner were to be blown out.

My safety concern is that there is no test for failed ignition in this setup. It is possible to have a situation where gas is pouring out of your burner and you're not getting ignition because of a strong wind. That would obviously be a very bad circumstance. It's my impression that HSI is much less likely to get into a gas buildup situation, while pilot lights are basically impossible to get a gas buildup. While direct spark can be pretty finicky.

If you are going to do direct spark ignition, I would recommend an appropriate ignition control system. Like: http://www.pexsupply.com/Robertshaw-780-504-Direct-Spark-Ignition-Control-w-7-sec-valve-trial.

I assume, you need an ignitor system like that for each valve? Do you use it's type of system too?

I don't use that type of system, but yes, you would need an ignition control for each valve.

Kyled93 said:

I assume, you need an ignitor system like that for each valve? Do you use it's type of system too?

Click to expand...

Don't mean to dig up an old thread, but here's my question about using this in my setup. I'm not interested in any sort of automation. Everything will be done manually. Would this work for the following:

1. I will use a PID to monitor temps.
2. When the temps drop too low, I'll flip a switch that will open a solenoid and turn on the propane.
3. I then flip another switch to send power to the spark ignitor.
4. Once spark lights the propane, turn off power to the spark ignitor.
5. Once temps are reached, turn off the propane.
6. Repeat as necessary.

I'm not going to use this in conjunction with a thermocouple, pilot light, or anything else. I'm going to use it to direct spark my Blichmann Burner like in the Tower of Power. Let me know your thoughts.

FYI I'm a gas inspection for our provincial utility here in Manitoba...

This module is for relighting a standing pilot that can get blown out accidentally... ie An overhead unit heater pilot gets blown out when the loading door opens. The sensor which is mounted on to the pilot detects no pilot light and continues to spark till either the pilot relights or the thermocouple de-energizes and shuts off main gas. Its not designed to ignite a burner directly.

You'd need a direct spark ignition (DSI) module which uses a flame rod to detect main burner ignition and has a limited trial for ignition period. There are different DSI modules with varying delays from 4-11 seconds which work for different applications. I'd personally go with one with a 4 second one over a 7 second trial for ignition... lots of gas flows out of your burner in 7 seconds.

Cheers!

OK let me ask it like this. If I hooked this up to a 110v signal would it spark?

I know I'm using it in a way that it wasn't designed to work. But rather than relying on a separate valve or sensor...I'm the sensor. I'll look at the gas to see if it is lit. If it is I won't let this keep sparking.

So, setting "safety" aside will this spark if it's hooked up to a 110v signal?

With this module you'll require both 120v and 24vac for it to spark. The 120v side supplies the spark and the 24vac notifies the module to spark until it senses flame at the pilot head.

If there isn't a 24vac supplied the module, the module thinks there isn't a need to spark since the thermostat isn't calling for heat (completing 24vac circuit for burner control) or else it would spark indefinitely till the module would burn out.

Also the flow of gas from your burner may be too powerful for this little sparker to ignite... Like I mentioned in the previous post its design is to relite a small pilot not a main burner.

Hockeyman said:

With this module you'll require both 120v and 24vac for it to spark. The 120v side supplies the spark and the 24vac notifies the module to spark until it senses flame at the pilot head.

If there isn't a 24vac supplied the module, the module thinks there isn't a need to spark since the thermostat isn't calling for heat (completing 24vac circuit for burner control) or else it would spark indefinitely till the module would burn out.

Also the flow of gas from your burner may be too powerful for this little sparker to ignite... Like I mentioned in the previous post its design is to relite a small pilot not a main burner.

Click to expand...

You are helping me understand now. So what about this...

If I had a switch on the 110v supply for the spark and a 24v signal to tell the module to spark. I'm planning on using a terminal strip to split the incoming supply out to the PID, solenoid and spark unit. I'd run a 110v line to the spark unit and a separate line to a transformer to take the 110v down to 24v.

Could I get away with having the module always being "told" to supply a spark but controlling when it actually "can" by putting a switch on the 110v spark side?

Its typically always supplied the 120v and the 24vac starts/interrupts the spark on call for heat. Also keep in mind that the spark gap is only 1/8" and where the start of ignition of your burner flame is more than likely higher than this off the burner when lit. So you may have to MacGyver a grounding location for the sparker above the burner.

It may work, but if the spark isn't in the right location to ignite your main burner your work is all for nothing...

Why not just install an HSI? 41-311 or a 41-403 are both universal 120v hot surface ignitors which you can mount an 1" or so above the burner. Flip your 120v switch wait for it to illuminate and then power your solenoid to supply gas... no module, no 24vac, just a simple hsi.

It might be worth looking at Benni Technologies Maxliter direct spark ignition system. I haven't personally used them, but I have a few friends who have used there products and have been quite pleased with them.
http://www.bennitechnologies.com/DSI.html

Also, a dual electrode setup will let you move your spark where you want it, since one side will be the high voltage side, and the other electrode will be the ground, just wire it up with silicone high voltage wire and you should be good to go. Crown engineering makes a wide array of electrodes with ceramic insulators, which are great for direct spark ignition, but require a separate flame sensor. What I would like to find is a direct spark ignition system which verifies that the spark is running before it allows the main valve to be opened. Yes, I could verify the spark to exist with a U.V. sensor, but sunlight, or other U.V. sources could lead to a false verification, but that is for a completely different, more of a "hold ma beer and watch this" kind of project.

Hockeyman said:

Why not just install an HSI? 41-311 or a 41-403 are both universal 120v hot surface ignitors which you can mount an 1" or so above the burner. Flip your 120v switch wait for it to illuminate and then power your solenoid to supply gas... no module, no 24vac, just a simple hsi.

Click to expand...

That sounds like a perfect solution. I have never heard of an HSI before. So, I could wire this with a standard 110V source with a switch to open and close the circuit. When I need power, flip the switch to the HSI. Let it heat up until it's glowing and then flip the switch for the propane. Then turn the HSI off. Is that right?

Would this one work as well:
http://www.pexsupply.com/Honeywell-Q3200U1004-Glowfly-Universal-Hot-Surface-Igniter-Single-Kit

How about these:
http://www.pexsupply.com/Robertshaw-41-604-Norton-Hot-Surface-Mini-Ignitor-41-604-12366000-p
http://www.pexsupply.com/Robertshaw...itor-w-Harness-and-Brackets-41-605-12367000-p

The two above have only 3 second heat times. Very good in my opinion. Others can take upwards of 15+ seconds.

Any 120v HSI will work provided you can make/buy a bracket to mount it in the gas stream to ignite the gas... I just know that the 41-311 comes with a bracket kit as I've installed many of them in gas furnaces over the years.

I wanna' hear about the "Hold ma' beer and watch this" project!

Although the Robertshaw 785 has a flame outage detector (if the attached spark electrode supplies the signal), I've encountered it being used in outdoor automated gas Tiki Torches, where the igniter sparks continuously for hours on end. In that application, it sparks about 2 times per second, reigniting the torch flame whenever it gets blown out.
The installation I saw had 5 torches lit for 5 years, for several hours every night. The Robertshaw modules were fine after all that time, although the electrodes were failing mechanically at their mounting points due to outdoor moisture corrosion.
The Tiki torch igniter sparks continuously because it's driving an electrode with no flame sensor in it.