Seeking advice, new to boilers, boiler broke over winter

it is doable but probably not worth what you'd save in gas on the pilots.

you'd either need to find an ignition control with 2 flame rod inputs or wire 2 ignition controls in series.

or use a self resetting baso switch in series with an ignition control

it would be easy if you could still get mercury flame sensors, youd just wire them in series.

I do not believe that kit is directly compatible with two pilots. Since it can only monitor one pilot. So far I have not found an intermittent pilot system that supports two pilots.

It really all depends on what direction you want to go in.

If it was me and I wanted to revive that boiler and wanted both pilots the way the boiler's manufacture basically intended, I would go with this BASO L62GB-3C or L62GB-1 or something similar for the second pilot. That way if the second pilot goes out it can be wired to lockout the intermittent pilot system. The wiring obviously would be different than the example below.

I suppose you could use two intermittent pilot modules, one for each pilot, but the wiring would get more complicated and may require relays to make it work correctly. It may be a bit of a kluge since there is only one gas valve.

Personally I like standing pilots since the maintenance is usually very low cost.

you'd have to find out how it was designed initially. it may have been designed with 1 pilot and the pilot at the left was added to try to fix the issues from the failing chimney or it may have been designed with 2 pilots. Typically to allow a boiler that large to work with 1 pilot there are crossover tubes between the burners that help the flame spread faster and maybe a slow opening gas valve to keep the firing rate lower until all of the burner sections are lit.

There certainly are ways to control 2 intermittent pilots with one control but it wouldn't be with an off the shelf kit, you'd have to know how to put the separate parts together.

If you have a constant flame monitored by a thermocouple AND a flame sensor in that flame you have created the Error that a flame is present when there should not be scenario.

No point in having two spark gaps when only one flame needs lighting. Think it through better.

you are lighting both.
they are controlled off the pilot valve in the intermittent pilot gas valve
the spark from the intermittent pilot ignition control is y cabled and lights both pilots like in a bbq grill or on a cooktop
the flame rod for the ignition control proves one pilot
the self resetting baso switch and thermocouple prove the other pilot
the self resetting baso switch sits between the mv terminal of the ignition control and the mv terminal of the gas valve so both the ignition control and the self resetting baso switch prove one pilot each

it would be relatively economical to set it up as standing pilot but if you insist on intermittent ignition it migt be better to replace it with a mod con that matches the system.

@triode Any obvious reason they converted a steam system to hot water ?

Did it heat the house OK on the coldest days ?

If I was tasked with building a dual intermittent pilot system, I would do it this way. Since I believe it retains all the functionality of a single Intermittent Pilot Module. Two Intermittent Pilot Modules, both modules 1 & 2 have to be active at the same time for the appropriate gas valve to operate. It requires 2 relays. Module 1 supplies the power for the gas valve. Module 2 powers the relays which have to be active for the gas valve to receive power. The call for heat would be applied to both modules at the same time.

Again this assumes the gas valve pilot gas circuit can support two pilots from the single gas valve. I would make the tubing to each pilot the same length from the Tee.

my guess is that someone that didn't understand the vapor system couldn't get it working right so they converted it.

" What I am reading from the comments:

A single pilot is bad and could cause real problems.

Hook up the system as it was "before" with two pilots, but both would be standing pilots.

If I do not like standing pilots, get a new boiler instead of risking running only one ignition pilot.

No other solutions are "good" (e.g. reduce the number of burners since it is grossly oversized, and then use only one pilot, or two pilot systems cost more than a new boiler). Again one of the issues with the standing pilot is now I have a blower system and it only pulls air when it is running. "

So @triode you did not like the Dual Intermittent Pilot wiring I posted ? No standing pilot. From a wiring point of view it is actually easier than I originally envisioned.

Seems like it is the second least expensive alternative, just need two relays and a second module of the same model. The least expensive is probably down sizing the boiler. I not sure I'm good with a significant burner reduction.

I don't think you need relays here, I think you can trigger the second ignition control with the MV terminal of the first control. Since you a using the PV to control the gas to both pilots the spark for both pilots should come from the first control.

You could also do something similar with HSI I think, those might be easier to parallel than the spark ignition assuming you don't draw too much current with 2.

Note that after you replace the gas valve you need to find someone that knows how to check/adjust the combustion to make sure the new valve is firing it at whatever rate it wants to fire at. That might not be whatever it fires at if you set it to the manifold pressure on the ratings plate.

I would suggest that it can be underfired some in that endeavor but given the mass of the system it is going to have enough trouble getting hot enough to not condense within a reasonable time frame so with the way it is set up now underfiring it probably isn't a good idea.

the 1 and 2 refer to 2 separate but identical ignition controls. the 1 suffix is the terminal on control 1 and the 2 suffix is the terminal on control 2.

The terminals;

MV-1, PV-1, MV/PV-1 are MV, PV, MV/PV on Intermittent Pilot Module 1

MV-1, PV-2, MV/PV-2 are MV, PV, MV/PV on Intermittent Pilot Module 2

The setup I suggest both modules do the same thing at the same time, basically independently except for the pilot gas source. If either module locks out either can shut the gas valve down.

With @mattmia2 version (just sequencing), I think sequencing the modules with violate the flame proving logic of the second module. Since a flame will exist before it is expected.

With @Steamhead 's extra pilot gas valve version I would sequence the modules.

I just think the relays are less expensive than a pilot gas valve.

With the relays if either module fails to prove the gas valve is closed. It is a logical AND circuit for both the PV and the MV.

If the module (say #1) that supplies the gas valve power fails to prove there is simply no power to the gas valve. If module #2 fails to prove neither relay remains energized so the gas valve power is shut off. Which would then fail the proof of Module #1 since the pilot would go out.

A bigger picture showing the connections to the two Intermittent Pilot modules. The relays provide a logical AND circuit for both the PV and the MV. If either module does not prove the pilot it will cause the the gas valve to close PV & MV.

As @Steamhead suggested you could add a second Pilot only Gas Valve wired in parallel with the PV valve shown. Creating an independent gas path for the other pilot. Or see the configuration below for sequential module / pilot operation.