fluid actuated gas safety shutoff (e.g. honeywell V5055A). look ma no wires?

archibald tuttle

in the something new everyday category. or what you get for not taking the off the shelf solution. just getting ready to pipe the two stage solution for a burnham atmospheric boiler discussed once upon a time (last winter) here.

hatterasguy kindly recommended the valve he has used many times and although that is literally a plug and play replacement (with the exception of two stage control) for the robertshaw valve that is on the boiler, I selected a honeywell which allows regulation of the stages while the Robertshaw is factory set at 1.3" low and 3/5" high.

I admit this gets me into a realm of industrial valves that I haven't plumbed before. It has no pilot provision so a separate needed a separate pilot valve and regulator. not a big problem. the pilot safety is already a 24V intermittent so just a little extra piping. But making the quintessential mistake of reading the instructions I see that the honeywell typical installation for this valve shows a "safety shutoff valve". So I looked up what honeywell was talking about and this V5055A line is what i found.

So this isn't 24V opened or closed. It has no capillary or apparent actuator. In fact I don't see any trigger at all. I can only assume it is designed to give an extra clamp to any minor flow of gas by the main valve when the main valve is off. Maybe it is actuated by monitoring inlet pressure and when it sees greatly reduced pressure at the inlet then it actuates itself? Honeywell tells you how to put it in and test it, but not how it works. I kinda like to know what kind of black boxes i'm adding. Maybe your typical spec gas valve for res or small commercial boiler simply has this function built in which is why you don't see them on all the standard small boiler/furnace setups?

I'm kind of beginning to wish I had just gone with the Robertshaw. It would be in already. But now that i'm halfway pregnant. . . . And there is some space in the piping where I had planned a 1" x1/4" tee downstream of the valve 5 pipe diameters or so where I could test the outlet pressure while the boiler was operating in order to facilitate adjustment. This SSOV will more or less fit right in there and it has quarter inch tappings so I don't need another place to stuff the Tee.. Anyway, any education on these safety shut offs appreciated.

brian

SWEI

archibald tuttle said:

I see that the honeywell typical installation for this valve shows a "safety shutoff valve". So I looked up what honeywell was talking about and this V5055A line is what i found.

So this isn't 24V opened or closed. It has no capillary or apparent actuator. In fact I don't see any trigger at all.

The V5055 requires an actuator, shown in the drawings on p. 6 & 7 of the instructions. From p. 8:

A V5055 Industrial Gas Valve is operated by a V4055, V4062,
or V9055 Fluid Power Gas Valve Actuator. The valve opens
when the actuator is energized, and closes when power is
removed. When closed, the valve seals off against the
rated close-off pressure with no power applied. For further
information, refer to the Instructions for the actuator.

JUGHNE

I changed out one these on a 80 HP Kewanee with power burner. It was a 2" IPS. Just a note that this one took 13 seconds to fully open and max of 1 sec to close. Don't know if you want that much slow opening on an atmospheric burner. It seems to be a lot of hardware for a resi boiler IMO.

archibald tuttle

swei,
in tje duh dept. just keep reading fine print.

junghe,
yes, it seemed like overkill in my applucation. maybe the diagram showing it was just typical. can't believe that the V8944B1019 cant quench that robust quarter pound of pressure in our residential supply piping -if its a good day at the gas company, otherwise its lower. i would assume these SSOVs are intended for systems with higher delivery pressures and those might be typically encountered where this gas valve is normally used. as i said, i went outside the residential catalogue not because this was an industrial setting, but because i wanted to be able to adjust the outlet pressure, esp. of the low stage.

JUGHNE

I believe depending upon the size of the burner (BTUH) some AHJ require redundant shut offs. This 80 HP in in a hospital it is the MGV, the next valve is the throttling valve linked to the air inlet shutter, it is a hi-lo burner. I can't believe the throttling valve is 100% shut off. I have a school with a 800,000 max power burner that has 2 shut offs. A CI 500,000 + boiler in a church with only the single gas valve, it has a separate pilot solenoid valve. Another school with 1,080,000 boiler with only the single gas valve . All of these are under the Hartford Inspection Agency, though I don't they look at the gas train much. The only thing said was that the regulator vents needed vented to the outside or in one case a vent limiter on the reg.

SWEI

CSD-1 requires a lot of redundancy, and for good reason. Large burners can burn pretty much anything if they happen to run amok.

My experience with two stage fired appliances has convinced me that it should really be a standard feature on just about all appliances. The manufacturers and wholesalers don't appear to have seen the memo, but I've been following two stage conversions here for years. From what I've seen, the Robertshaw 700-053 and -064 are about the easiest. Some of the White-Rodgers 3H65 series look similar.

archibald tuttle

SWEI

so as a tinkerer, I wanted the ability to adjust the stages, esp. the low stage. the more i think about it, maybe the simply way to keep OEM shutoff capability since neither the Honeywell nor the Robertshaws actually say in their literature what ANSI or UL standard they are manufactured to comply with, i could just leave the OEM valve inline since it must have qualified as the safety shutoff under a combination standard at least maybe as tested with the specific boiler.

from what I can see, this would be the CSD-1, CF-180 standard 400,000-2.5 mil btus and I assume it is covered by the manufacturer's testing and certification of the unit to begin with even though the OEM setup has no separate Safety Shutoff Valve:

(a) Each main burner supply line shall be equipped
with a safety shutoff valve(s) that shall comply with the
applicable provisions of ANSI Z21.21/CSA 6.5, Auto-
matic Valves for Gas Appliances, ANSI Z21.78/CSA
6.20, Combination Gas Controls for Gas Appliances, or
UL 429, Standard for Electrically Operated Valves.

The Robertshaw 700-064 is an exact plug and play replacement for the OEM supplied valve with the exception of the two stage feature, but there are no ANSI or UL specs in the product literature from Robertsahw that i can find with regard to either their single or double stage valves. I can only assume that is because these certifications are per application rather than to the valve generically.

So technically speaking I'm in the same boat with either swap because, as you point out, the boiler manufaturers have simply not gotten the memo about dual stage operation. Maybe I'm off the hook because Burnham does specify a minimum BTU input so maybe they actually did test the boiler running and starting at lower btus than the delivered setup.

Still, abundance of regulatory caution I can leave the OEM gas valve in line now serving the redundant shutoff feature (i've got to get the number to cross check what i have got, but one interesting distinction is that all the single stage valves have integral factory set regulator for 4", but the high stage on the 2 stage valves is 3.5". Minor discrepancy but makes one think, WUWT)

Then the only thing I'm not 100% sure about is whether the boiler is tested for lighting at the lower stage in accordance with the minimum btu input rating. I can check with Burnham on that, or maybe i'll stop by and see them in Orlando.

But, in the meantime I think I could probably come up with a control scenario that would prevent starting on low stage. I just have to wrap my mind around it. Probably take an extra relay-yet one more complication in the chain of control.

In almost all circumstances the boiler would not be called to start in low-fire anyway, because the steam pressure in this large system diminishes so quickly when the burner is shutoff that you aren't likely to get a thermostat call in the 30 to 45 seconds I've seen it remain above 6" of steam (that is the cutin for the high stage - cutout is 12". Still, it isn't inconceivable since this single zone system having several thermostats in parallel that when the coldest apartment is satisfied someone in that or one of the other apartments could around that instant decide they wanted it warmer than usual and turn up their thermostat causing a restart that normally would be avoided by the deadband of a single thermostat system.

I've actually spent some time monitoring low fire operation by significantly closing the gas shutoff adjacent to the boiler to reduce gas flow simulating a low fire and clocked the gas valve to estimate btu's to compare combustion results and check lighting behavior. The boiler lights fine every time, but me doing it a hundred times isn't the same as doing it thousands to satisfy UL, so i gotta finish checking with Burnham on their low fire figure and control against low fire start until I know that's OK by somebody besides myself.

Sorry about the novel, just using this medium to think things through. This would be so much easier if the boiler makers had gotten your memo, but i appreciate it, if they don't.

brian