Slow or delayed closing gas valves...

[amd]

Out of curiousity do they exist?

[super_tech_1]

Can't say I've ever heard of it. Atleast not if it was working right. My question would be why would you want one. The gas should shut off before the blower does so it can cool down the exchanger.

[skippedover]

Yup. Every one I've ever worked on. As long as the electricity is present at the valve coil, the valve stays open. When the electricity stops, the valve closes. How else would you want it to work? Want a longer delay? Keep the electricty on the coil. Shorter delay? Remove the electricity sooner.

[amd]

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[amd]

Can't say I've ever heard of it. Atleast not if it was working right. My question would be why would you want one. The gas should shut off before the blower does so it can cool down the exchanger.

I was doing someone a favour (filter/humidifier cleaning) and noticed that the gas valve takes several seconds to close after the power is cut during a call for heat (it's being dealt with, taking no risks) - I was just wondering if valves were designed to do that. (Why someone would design a valve like that, I have no idea :confused: )

[the dangling wrangler]

Out of curiousity do they exist?

I've seen 'em before. On some of the older units. Can't really remember which one now. Not that long of a delay, less than fifteen-twenty seconds, on or off. I'm sure of that.

[superfittertech]

honey well used to make an adjustable slow opening/closing gas valve used on natural draft boilers. it had an adjustment screw on the vent that slowed down both opening & closing times. i haven't seen one in at least 10-15 years though.

[ar_hvac_man]

Ive run across a couple myself. Seems like they were all on old a$$ equipment.

[Wirenut]

I have seen them on some very old equipment, Essex valve with brown cover , they had a bimetal actuator with heater coil. They were slow opening and closing.

[amd]

Ive run across a couple myself. Seems like they were all on old a$$ equipment.

This was on a 1980 Lennox G8* - defect or design?

(*Canadian plants made that model until '92)

[the dangling wrangler]

This was on a 1980 Lennox G8* - defect or design?


That might depend on who you ask. I couldn't tell you, with any certainty.

[Wirenut]

If the valve on your old lennox had pilot button on the left side and a separate pilot on and off valve on the top, it is a slow open and closing valve. The G8 and 12 furnaces may encounter pilot outage problems if the correct valve isn't used.

[amd]

If the valve on your old lennox had pilot button on the left side and a separate pilot on and off valve on the top, it is a slow open and closing valve. The G8 and 12 furnaces may encounter pilot outage problems if the correct valve isn't used.

This one had a standard valve - single unit, can't visualize it. (not mine BTW)

Thanks.

[BaldLoonie]

The "Old Blue" Bryants had a valve that would stay open for several seconds after power was removed. I think they were an Essex.

[Tom R]

We use to see the slow opening valves on the old natural draft, standing pilot units with ribbon burners especially on the units with more than 3 burners where the crossover channel got pretty long..

I can't say that I ever remember seeing one on a unit with inshot burners.