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Unit Ventilator Thermostat


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Unit Ventilator Thermostat

I am looking at many old classroom unit ventilators.

These are basically a cabinet style fan/coil with outside air vent - usually pneumatic with a single water coil used for heating in the summer and cooling in the winter. At least half the pneumatics don't work.

Most of the fan motors are controlled from the breaker or from a toggle switch if lucky.

The units are typically 1970.

Is there some reason that I am completely overlooking why they cannot:

1) replace the pneumatic with electrical to control outside air vent

2) replace the pneumatic with electrical to water flow

3) Add Setback thermostat (that will also close outside air at night)

I know that they should just replace everything - but that hasn't happened since 1970. That will be recommended.

I am aware that any thermostat is problematic around students. I am talking about basic mechanical problems.

Any idea what it would cost to replace the pneumatics on the unit with electrical (assuming they completed about 40 at a time)?

Thank you all again and Merry Christmas.

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You can retrofit the UV with electric/electronic controls however by the time a tradesman is done farting around trying to fit a square peg in a round hole it would be wiser to replace the whole unit. One problem with these units is that the o/a damper would stick open and would cause the coil to freeze. The custodian most likely went around and disconnected them and/or boarded it up. The damper bushings also wear out so you would have to look at rebuilding the damper as well. You may still be able to find the blower motors but maybe not given the age.

To me is akin to rebuilding a window air conditioner.

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I realize that it should be replaced.

My reasoning (which I am trying to ferret out) is that the unit will never be replaced and the best bet is to get some stimulus funds to retrofit it.

My thought is to request funds for thermostat & retrofit in one line (that may get funded) and ask for a new unit in a separate line (that has not been funded in 40 years) - so hopefully they will at least do something.

It is definitely like rebuilding a window unit.

I have been looking all over for pricing on a good new unit ventilator with very little success. I assume that I can get one for about $1k + install, controls, etc - is that correct?

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I realize that it should be replaced.

My reasoning (which I am trying to ferret out) is that the unit will never be replaced and the best bet is to get some stimulus funds to retrofit it.

My thought is to request funds for thermostat & retrofit in one line (that may get funded) and ask for a new unit in a separate line (that has not been funded in 40 years) - so hopefully they will at least do something.

It is definitely like rebuilding a window unit.

I have been looking all over for pricing on a good new unit ventilator with very little success. I assume that I can get one for about $1k + install, controls, etc - is that correct?

There was/is a HB (House Bill - HB283??) that has funding for just the type of thing you're speaking of. It also can go toward, new HVAC, new windows or other energy saving devices in schools. There was a lot of activity in this, back when I got out of the business, in 2001. The big guns like Johnson Controls were going after this market. Anyway you should check into this as well. Also, control companies make transducers and digital interfaces for existing pneumatic controls - you keep the pneumatic valve or pneumatic damper operator but now control them digitally. I would think that any stimulus funding would be weighted on energy savings, not in putting a new carburetor on a 30 year old engine.

Trane and Carrier would be your best bet for new UVs (although McQuay might be an option as well).

Good luck.

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