Dryer intakes: leave open or close at night?

[sloassmac]

I'm opening an existing mat in a cold climate and I'm really concerned about the two gaping 3x3 holes in the back of the building. This system is designed to draw air across the uninsulated dropped ceiling down to behind the dryer area. It seems as if in the winter the mat is operating like an door is constantly wide open. I know from reading previous boards that this isn't ideal, and having the dryers isolated with intake in that area is ideal, but that's not a option in my case. I've read on posts that some of you install motorized louvers that operate by dryer exhaust temp or linking to machines. Do any of ya'll have first hand experience on how to do this? What about the old fashioned method of opening in the morning, closing at night? Any ideas better than a piece of hinged sheet metal? What about a gigantic duct to get the fresh air a little closer to the source? Just trying to make this place a little more efficient. Thanks ahead of time!

[MrMachine]

Well, I can't see your layout, but I like the idea of running intake ductwork closer to the dryers.
You can't escape the importance of makeup air for a laundromat.

I operate in NYC. We can get as cold as 15 degrees on occasion.
My stores have a similar setup as yours with the makeup air traveling between the roof and the ceiling, towards the dryers. That space between the roof and my drop ceiling IS my giant duct, lol.
Works fine for me. One store is open 24/7 so the supplemental heater is always on.
When the temperature drops below 20 degrees we leave the heat on in the store that closes at midnight and opens at 6am for fear of freezing the sprinkler system (which has never happened).

I guess you could close the air duct openings when you close, but you risk someone forgetting to open them in the morning.

[Adamski]

Mac,

The motorized louvers, which you mentioned, are generally controlled by a relay in each dryer. When the dryer turns on, the relay closes and that turns on the motor for the louver. In your case, you might have 4 powered louvers - 2 for each opening. Each louver would be operated by 1/4 of your dryers.

Getting a little deeper into it now ... let's say you have 20 dryers so 5 dryers will operate each louver. The 5 dryers will each have a new relay installed inside the control section. The coil of each relay is wired into the dryer so that it is energized when the dryer turns on. The Line (supply power) to the relay comes from a new circuit breaker (1 breaker supplies all 5 dryer relays). The Load from the relay (all 5 relays) goes to 1 louver motor. The louver motor also gets a neutral from the circuit breaker panel. This is repeated for the other 3 sets of dryers and the other 3 louvers.

The theory is that if 1-5 dryers are running, at least 1 louver will be open (depending on which dryers are running). If at least 6 dryers are running, at least 2 louvers will be open. Obvoiusly, this system can work pretty well but it takes time to install it and it does require some additional maintenance. I've seen it done but I'd be reluctant to do it just to tighten up the building.

[mjwalsh]

I've read on posts that some of you install motorized louvers that operate by dryer exhaust temp or linking to machines. Do any of ya'll have first hand experience on how to do this? What about the old fashioned method of opening in the morning, closing at night? Any ideas better than a piece of hinged sheet metal? What about a gigantic duct to get the fresh air a little closer to the source? Just trying to make this place a little more efficient. Thanks ahead of time!

Mac, Paul, Larry, Case, Kim? & others,

When we revised our makeup air intake 2 years ago, we installed a device that measures the differential of normal outdoor air pressure & with even slight negative air pressures inside the laundromat. It has a 0-10 VDC analog output. There are milliamp versions too. We have another device that uses that output analog signal that opens & closes a Belimo Proportioning Damper in proportion to the negative air pressure. For us, it made sense to use an analog module & an output within a PLC that we needed anyway for our new self service dog wash. There are other devices besides a PLC that can accomplish the same proportioning output --- we used a PID loop to tweak it. In a cold climate the air pressure approach seems to make way more sense than the other approaches especially if you have a sprinkler system or other freeze potential. The proportioning appears to help with energy efficiency, dryer performance & even in some cases --- comfort. Our unique summertime "fresh air" air conditioning is way different than most with our doors & vents open but it seems like the proportioning could help with "doors & windows closed" type of air conditioning situations too.

Ideally, others of you have at least checked into the proportioning approach --- if not using it or tried it or whatever --- any comments --- we need some engineers & almost engineers to come out of the woodwork instead of just those silly bugs!!! In my humble & bashful opinion --- this approach should not be categorized as "rocket science".

MJ

[Laundry_Mike]

That give me an idea for a new window sign: Fresh Air Conditioned! :)

[mjwalsh]

That give me an idea for a new window sign: Fresh Air Conditioned! :)

Laundry_Mike & others,

We need to keep this thread focused on "ways to solve make up air issues" Air conditioning is relevant to the type of facility cooling --- if the make up air area for the dryer is not completely sealed ---- like it sounds like most of you have accomplished????

Just so I do not mislead anyone on the no humidity added cool air fan exchanger units --- the operator would have to have his water inlet temperature stay very cold during the summer months like we get from the Missouri being this far north in north dakota. Also the laundry & the car wash needs to have a steady flow of customers so the water flows enough!

I consider myself a pretty healthy person but if I am dressed for warm outdoor temps --- light clothing --- I don't feel comfortable in air conditioning --- set too low --- I think most people would agree. I remember needing to leave early at one of the largest presentations (workshops) at Clean Show 2007 because that exact situation.

MJ

[KJ]

My back room (make up air room) was always cold. It had motorized louvers on 24" X 24" openings that opened at 6 am and closed at 10pm.
They were open all the time the store was open and were never hooked to the dryers to open and close. It was always frigid to work back there.

I switched them out to these mechanical ones, although I do not use the weight in the arm to keep them closed. They just open one way when the dryers need air and close when not needed. The residual heat off the back of the dryers now heat the back room.


http://www.pexsupply.com/Honeywell-SPRD20X12-20-x-12-Rectangular-Static-Pressure-Regulating-Damper-13615000-p

[mjwalsh]

My back room (make up air room) was always cold. It had motorized louvers on 24" X 24" openings that opened at 6 am and closed at 10pm.
They were open all the time the store was open and were never hooked to the dryers to open and close. It was always frigid to work back there.

I switched them out to these mechanical ones, although I do not use the weight in the arm to keep them closed. They just open one way when the dryers need air and close when not needed. The residual heat off the back of the dryers now heat the back room.


http://www.pexsupply.com/Honeywell-SPRD20X12-20-x-12-Rectangular-Static-Pressure-Regulating-Damper-13615000-p

KJ,

If I read that right ---- it sounds like you took the balancing weight off the arm & the change in air pressure still opens your mechanical vent louvers reliably & in proportion to the need???

MJ

[KJ]

KJ,

If I read that right ---- it sounds like you took the balancing weight off the arm & the change in air pressure still opens your mechanical vent louvers reliably & in proportion to the need???

MJ

In my application I saw no need for the weight.
The weight is adjustable to keep them from opening till a certain pressure.
Don't want to starve the dryers at all.

[mjwalsh]

In my application I saw no need for the weight.
The weight is adjustable to keep them from opening till a certain pressure.
Don't want to starve the dryers at all.

KJ,

Sounds like that makes sense for your facility. In a colder climate like ours though --- where pipes could be frozen etc. ---then sometimes partial opening of the vent according to the amount of pressure could be of value. The amount of pressure should be tweaked so like you say we want to avoid starving the dryers --- even a tiny amount!

MJ