is there a 2-stage 3/4" gas valve with standing pilot?

Inliner311

is there a 2-stage 3/4" gas valve with standing pilot on the market? I want to add in a 2-stage gas valve to my boiler but would like to keep the standing pilot. I've went thru and can't seem to find one that doesn't need direct ignition, HSI, or an intermittent pilot.

Alan (California Radiant) Forbes

Call Honeywell. I'm sure they have one.

(800)328-5111

Inliner311

I've had two bad experiences with Honeywell customer service in the past couple weeks. They were really no help both times. Rather not go thru the trouble of sitting on hold for 20-30 minutes to have them direct me somewhere else for help. Both times they told me to go to my local supply house and ask for help.

EzzyT

Robertshaw 700 is both standing pilot and spark ignition

Inliner311

> @EzzyT said:
> Robertshaw 700 is both standing pilot and spark ignition

Thanks. I researched the robertshaw 700 series and found that it seems like they discontinued the standing pilot models. The order sheet doesn't list any standing pilot models. I might be able to find some old stock model but it seems like the robertshaw 700 are not dual automatic valve and need to an energy cut-off. What do you hook a energy cut-off to in a steam system?

I've also started to research adding an intermittent pilot system just so I have more options and will be able to get a replacement gas valve in the future if needed. What is the preferred spark system of this forum? HSI, Direct spark, or intermittent? Would still prefer to keep a standing pilot if someone still makes a model.

ratio

You could add a two stage gas valve downstream of the standing pilot valve. Commercial burners use a version of this, substituting a modulating gas valve for a two stage valve. &, well, the lead valve isn't standing pilot either, but inline gas valves is a real thing.

JUGHNE

Would you then have two regulators in line doing a tug of war back and forth on pressure regulation?

Inliner311

> @ratio said:
> You could add a two stage gas valve downstream of the standing pilot valve. Commercial burners use a version of this, substituting a modulating gas valve for a two stage valve. &, well, the lead valve isn't standing pilot either, but inline gas valves is a real thing.

This seems interesting but how would I control the modulating gas valve? It seems people control 2-stage gas valve with a vaporstat since it's basically on or off for the hi/low settings.

Could I run two different valves in parallel basically simulating a two stage? would there be an issue with backflow pressure on the closed valve?

Ideally I would just like a single 2-stage valve with a standing pilot just to keep the amount of devices to a mininium. Also with a dual automatic valve so I don't have to figure out how to wire in a energy cut off.

mikeg2015

JUGHNE said:

Would you then have two regulators in line doing a tug of war back and forth on pressure regulation?

The upstream valve would need the regulator set wide open. It’s only function is the pilot. You would set the regulator on the downstream 2 stage valve. I think you’d jumper out the pilot like it was DSI.

Problem with HSI is they seem to burn out faster than spark fails. DSI seem to be the direction most furnace mfg’s have gone.

ratio

Inliner311 said:

> @ratio said:

> You could add a two stage gas valve downstream of the standing pilot valve. Commercial burners use a version of this, substituting a modulating gas valve for a two stage valve. &, well, the lead valve isn't standing pilot either, but inline gas valves is a real thing.



This seems interesting but how would I control the modulating gas valve? It seems people control 2-stage gas valve with a vaporstat since it's basically on or off for the hi/low settings.



Could I run two different valves in parallel basically simulating a two stage? would there be an issue with backflow pressure on the closed valve?



Ideally I would just like a single 2-stage valve with a standing pilot just to keep the amount of devices to a mininium. Also with a dual automatic valve so I don't have to figure out how to wire in a energy cut off.

With the modulating valve, they're either 2-10 volt or Maxitrol style, which I believe is current loop (possibly 0/4-20 mA), you'd need an analog signal. But the practice still holds true with a simple two-stage valve on the outlet of a standing pilot valve. I'm not sure you'd gain anything more than complexity by going modulating in any case.

Two valves in parallel doesn't seem like a good idea to me. Series-connected works just fine.

As @mikeg2015 noted above you set your pressures on the last valve, the initial valve will be set high enough that you can overcome all the pressure drop in the second valve, typically wide open. When I set up a modulating series valve train, I typically run the modulating valve open 100% & set the high flow via the first valve to give maximum control to the modulating valve.

gerry gill

Maxitrol in series with whatever gas valve you want.

Inliner311

> @gerry gill said:
> Maxitrol in series with whatever gas valve you want.

I went and looked up the maxitrol 2 stage regulator. It seems like a good solution. I also looked up some old thread that people here discussed it to wire it to a vaporstat.

The one question I have is the fact sheet for the valve has a list of different size valves and the corresponding model numbers. There is a list of spring options. Do I have to special order the valve with the spring options I want? The model numbers have additional numbers behind them that the I can't figure out what they correspond to. I also can't seem to find the springs for sale on their own. I assumed you ordered one and were able to sort thru this.

mikeg2015

I’m installing a regular Honeywell 2 stage 1.7/3.5” on my boiler tomorrow. I’ll post the results. For Now I’m keeping the 2 outside burners plugged and see how the combustion tests looks. Should be about 70% firing onnlow stage.

It will give me 300/210 input and about a 240/165 output. Nameplate is 375. EDR is about 700 but after TRV and downsizing one radiator it’s 620.

I’m going to use a 140f snap disc to drop out hi stage once the header is hot.

Steamhead

mikeg2015 said:

I’m installing a regular Honeywell 2 stage 1.7/3.5” on my boiler tomorrow. I’ll post the results. For Now I’m keeping the 2 outside burners plugged and see how the combustion tests looks. Should be about 70% firing onnlow stage.



It will give me 300/210 input and about a 240/165 output. Nameplate is 375. EDR is about 700 but after TRV and downsizing one radiator it’s 620.



I’m going to use a 140f snap disc to drop out hi stage once the header is hot.

@mikeg2015 , what model Honeywell 2-stage?

mikeg2015

VR8345Q4563

Wil have a high pressure drop at 375k input if I remove the 2 plugged orifices. But fine for 300k.

mikeg2015

Gas valve installed. Haven’t wired up high stage yet. Honestly, I don’t think I need it, but would be nice for cold starts I guess.

Pressure spot out right out of the box on lo fire. I ran a quick combustion check. Might need ot make some adjustments. Could also be the section have a lot of crap from 36 years and need cleaned. But I’m seeing 478F, 12.6% O2, 4.3% CO2 but good news is only 20ppm CO. I could be getting some air mixing where I inserted the probe just past the hood.

Efficiency only calculates out ot about 70%. Excess air is too high, over 2x. Having 2 tubes plugged is probably driving most of that and it will be hard to make any adjustments because of that. Might pull the burner and put them back in.

So far no balance issues. SO I think undersizing an eventual replacement boiler will be a non issue since it’s a vapor system. It never builds any pressure os it doesn’t rely on pressure for distribution. Rather it relies more on back pressure from the presences of air in the radiators resisting stem progression.

gerry gill

Inliner311 said:

> @gerry gill said:

> Maxitrol in series with whatever gas valve you want.



I went and looked up the maxitrol 2 stage regulator. It seems like a good solution. I also looked up some old thread that people here discussed it to wire it to a vaporstat.



The one question I have is the fact sheet for the valve has a list of different size valves and the corresponding model numbers. There is a list of spring options. Do I have to special order the valve with the spring options I want? The model numbers have additional numbers behind them that the I can't figure out what they correspond to. I also can't seem to find the springs for sale on their own. I assumed you ordered one and were able to sort thru this.

Been awhile since i used one but here goes from memory
I think 3/4'' was SR-500-1 or SR-500-2 depending on desired range. I think 1'' was SR-600-1 or Sr-600-2 again dependent on range desired. I did that blindly from memory so double check that on their spec sheet.

Inliner311

> @gerry gill said:

> Been awhile since i used one but here goes from memory
> I think 3/4'' was SR-500-1 or SR-500-2 depending on desired range. I think 1'' was SR-600-1 or Sr-600-2 again dependent on range desired. I did that blindly from memory so double check that on their spec sheet.

Thanks. I looked at the spec sheet more and found their full catalog which gave the 4 configurations. The sr600-2 and sr500-2 seems to be for LP. The rest of the model numbers don't seem to correspond to the models on the plumbing supply sites. I figure I'll have to speak to Maxitrol direct to figure which ones are which if I go that direction.

Right now I'm debating between adding an intermittent pilot and going the Honeywell route or go the Maxitrol route.

mikeg2015

Intermittent pilot isn’t that hard ot add. S8610U universal Controller is I think around $115. Then you just need a pilot and igniter/flame rod assembly and igniter cable. Another $80 I think.

That VR8345Q works great. Independent hi and lo fire pressure adjustment. It includes the LP conversion kit. But you’ll need a manometer to set the regulator if you do a conversion. Honestly, you could make one out of clear aquarium tubing. And some water and just buy a 1/8” NPT barb fitting.

Inliner311

@mikeg2015 I've warming up to the idea of using an intermittent pilot. Still debating though. I looked up how to wire an intermittent pilot and I didn't realize it was so easy especially if I got one of the Honeywell kits.

SuperTech

> @mikeg2015 said:
> Gas valve installed. Haven’t wired up high stage yet. Honestly, I don’t think I need it, but would be nice for cold starts I guess.
>
> Pressure spot out right out of the box on lo fire. I ran a quick combustion check. Might need ot make some adjustments. Could also be the section have a lot of crap from 36 years and need cleaned. But I’m seeing 478F, 12.6% O2, 4.3% CO2 but good news is only 20ppm CO. I could be getting some air mixing where I inserted the probe just past the hood.
>
> Efficiency only calculates out ot about 70%. Excess air is too high, over 2x. Having 2 tubes plugged is probably driving most of that and it will be hard to make any adjustments because of that. Might pull the burner and put them back in.




Combustion analysis is supposed to be checked BELOW the draft hood. You are measuring a diluted sample and no adjustments should be made based on those results. Try again, this time drill a hole in the flue pipe as close to the boiler as possible.

mikeg2015

I described it wrong. It has an external hoodmlime a WM. I measured before the hood just inside the collector box.... flue. I know the gassed are diluted in the hood.

But I might get a little better results drilling a hole from the top of the boiler. Still could be some mixing only 1” inside the flue.

Inliner311

@mikeg2015 so I've been looking more into putting a vr8345q4563 on my boiler. Does it default to low fire and the high fire needs to be energized to come on? I'm trying to figure out what vaporstat I need.

From what I understand about the maxitrol sr500, that is default to high fire and low fire is when it is energized. So with that one I think I would need a vaporstat that breaks on pressure rise and makes on pressure fall.

mikeg2015

Yes default is low fire. You need to supply 24VAC from the same circuit as lo fire to the hi terminal. So you could just split spade connector on MV and wire it in series with the vaporstat to the hi terminal. Make sense. MV/PV is the shared common for all 3 coils (pilot, main valve with low regulator setting and hi regulator setting)

Inliner311

@gerry gill I have been looking at the maxitrol sr-500-1 and been reading some old posts about 2-stage gas valve. The maxitrol info I've found says that when energize it is in low fire and when deenergized it is on high fire. You have comment that you need a vaporstat that makes on rise for the maxitrol, which would be the opposite of that. I trust that you are right on this but wanted to make sure. It also possible I could have vaporstat make and break mixed up.

mikeg2015

Vaporstat or pressure trol should open when it reaches the pressure setting. Although I’m thinking some make have two taps.

Inliner311

@mikeg2015 I read the Honeywell literature on vaporstats and I think I had it mixed up. @gerry gill had it right that the maxitrol needs a vaporstat that makes on rise.

Honeywell makes two different types of vaporstats now. The ones that make on rise with two connections. Then they make ones that can both make on rise and break on rise, which have 3 connections. They seem to stop selling the ones that only break on rise.

gerry gill

if it has 3 terminal screws it should make or break on rise depending on which terminals you use.

Inliner311

So I decided to go with the maxitrol but the one I bought on eBay ended up being a 1/2" npt instead of a 3/4" that would match my boiler and gas valve. If my boiler is 186,000 BTUs will there be any problems putting the 1/2" maxitrol on it?

gerry gill

Difficult to say.

Inliner311

I'm returning the maxitrol and will look for a 3/4" one. I might just go with @mikeg2015 suggestion of taking a direct ignition two stage valve and run it in series with my current valve. The Honeywell valves seem to have the widest range of low fire with .9-3.0wc. White Rodgers also makes a two stage valve but it says the mininium high/low differential must be 1.5wc so if my high fire is at 3.5wc the max low fire I could use is 2.0wc.

I never got a response from Maxitrol on which model numbers correspond to the spring options. They keep referring me to their PDFs which has a completely different set of model numbers that none of the retailers use.