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Any unit ventilators have manual fresh air damper?

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Considering a unit ventilator with a fresh air damper. I assume that in some locations, these would be set to a certain opening to match the design number of people for the space and then left in that setting.

Is this correct or are they all variable past that point with pneumatics or electrically operated controls?

Thanks guys![:-wiltel]

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Hi,

Out here there are ordinary full-opening actuators connected to timers on our systems. The timer orders up fresh air and the actuator opens the intake all the way. With your humidity, setup might be different.

ONE TEAM - ONE FIGHT!!!

Mike

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Considering a unit ventilator with a fresh air damper. I assume that in some locations, these would be set to a certain opening to match the design number of people for the space and then left in that setting.

Is this correct or are they all variable past that point with pneumatics or electrically operated controls?

Thanks guys![:-wiltel]

What application is the UV for?

While you might be able to get away with putting the O/A damper to a fixed position down there it wouldn't work up here - we were at 2 degrees a few days ago.

If you're looking at fresh air for something, like a school, control companies make a CO detector that will proportion O/A dampers based on levels. Again, if you're trying to do something like that up North then you'll need to interlock freeze controls if the heat will be hydronic.

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Terry,

Do the CO detectors go inside the univent or remote mount (typically)? This is for a school - and yes the coils can freeze.

Ok. So manual dampers were likely never used because of outside air freezing issues. This makes sense.

So typically it would seem that my 1967 typical school univent up north with currently abandoned pneumatics, was originally probably controlled with a timer on the building pneumatics working in conjunction with boiler...

Does that sound correct to you guys.

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Terry,

Do the CO detectors go inside the univent or remote mount (typically)?

No, they go in any general area of greater occupancy/classroom. It all depends on how much money is in the kitty.

This is for a school - and yes the coils can freeze.

Ok. So manual dampers were likely never used because of outside air freezing issues. This makes sense.

No, they were always used and the coils always froze. That's why the custodians always blocked off the fresh air intake with plywood.

So typically it would seem that my 1967 typical school univent up north with currently abandoned pneumatics, was originally probably controlled with a timer on the building pneumatics working in conjunction with boiler...

Does that sound correct to you guys.

Your system is a very typical school HVAC system. Hot water heat, maybe steam but in '67 it would be doubtful, unit ventilators with hot water/steam coils. Doubtful if there was any a/c back then. I doubt there was any timer as the schools were typically staffed with boiler operators/stationary engineers.

Are you teaming up with any control companies, Barber Coleman, Johnson Controls et al?

Thanks guys![:-wiltel]

My bark is worse than my bite.

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Thanks Terry,

I am trying to get a general gameplan together for "Direction" for many schools. I cannot determine direction until I figure out what they had to begin with - and how it was "supposed" to work back then.

Then I can try to figure out what to do now.

I like to hope that the original designers had designed a system that worked back then. Many times, they did know what they were doing (more so than many today) and designers today throw it away. Of course, I do realize that fresh air requirements weren't quite as stringent.

I am very familiar with demand control ventilation (CO sensor) and it is definitely the way to go - I was just "fishin" to see if you knew of a successful way to put it in the unit. I have heard of it being done but I am not too sold on it working properly. I have heard bad reports.

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I am very familiar with demand control ventilation (CO sensor) and it is definitely the way to go - I was just "fishin" to see if you knew of a successful way to put it in the unit. I have heard of it being done but I am not too sold on it working properly. I have heard bad reports.

You can put the detector anywhere, return air etc but where is the right place to install it? It needs to be planned out as a zoned system. You can't go about, willy-nilly, slapping controls in. You need to walk the property to determine where to place things like thermostats, CO detectors etc.

Have you teamed up with any control companies? I'm happy to help but am not in a position to design/build over a home inspector forum. You need to partner with the necessary contractors. I'm sure you understand.

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Thanks Terry,

I am trying to get a general gameplan together for "Direction" for many schools. I cannot determine direction until I figure out what they had to begin with - and how it was "supposed" to work back then.

Typically blueprints can be had by determining the control manufacture and contacting them. The custodian may have prints as well as the administration building for the school system. Have you checked these sources?

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I have. Thanks Terry. I am more on the "pre-funding" side right now so I am just pointing in the right directions right now. Not planning actual installation solutions.

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