Motorized fresh air louvers

Andy Morgan_2

I have an engineer spec'd job that has 2 120v powered open, spring closed louvers that are supposed to be wired to four seperate oil burners. (480 WM, and 3 51E Bocks).
Without getting crazy, what are some suggestions on wiring this. Obviously, when any one of the burners come on, the louvers open. I have been racking my brain with this but am to the point where I think I am missing something simple.

Thanks


Andy Morgan

R. Morgan Mechanical, LLC

Mike T., Swampeast MO

One way...

You need four SPST NO relays. Coil voltage same as oil pump. Contacts rated to COMBINED load of both louvers. (You may have to use SPDT or DPDP relays but just use the appropriate contacts). Make sure you use the inductive contact rating for the relays--it's usually well below the resistive rating and with inductive loads it doesn't hurt to give a good amount of headroom...

Wire relay coil in parallel with the oil pump. One contact (or common if using DP) to 120v; other contact to louvers--also connected in parallel. Repeat for all four boilers. (It doesn't matter how many relays are giving a path to power--just that if any one is on the louvers are powered.)

If you need to either ensure that the louvers stay open for a given amount of time ALWAYS or that they stay open for some period after the boiler stops firing, use an electronic "delay on break" relay. You would then use the oil pump relays to power the electronic relay "coil" and the contacts of the electronic relay to power the louvers themselves.

p.s. You can get electonic relays with selectable mode of operationg but the single-mode models are significantly less expensive.

hr

Actually, if these are combustion air louvers

just the opposite. Only when the louver opens should the boiler fire. Some powered shutters have "end switches" to provide this function.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

Bill Nye

Didn't think............

this one all the way through yet, .... but what about a 4 zone hydronic pump relay? The xx terminal could make line voltage to your damper motor every time a burner had to run.

You wouldn't have to run any power through C1C2 part of the relay, just the low voltage call would work.

Do you need an end switch on the damper to prove before the burners run? Somebody probably makes a relay for this purpose.

Mike T., Swampeast MO

THANKS HOTROD!!!! PROVING!!!! PROVING!!! PROVING!!!

FAIL SAFE!!! FAIL SAFE!!! FAIL SAFE!!!

I should keep my keyboard quiet sometimes!!!!

Call for heat--any heat--first opens louvers? Relays required if multiple "calls" possible?

End "proving" switch on louvers powers relay coil(s) for four contacts (in this case) that allow power to go to the any/all oil pumps as dictacted by initial and subsequent call(s) for heat?

Andy Morgan_2

Yea

I thought of that ,too. The problem is I have no low voltage controls on the Water heaters to pull the relay in, other wise, a simple RA89 would work. I almost need the opposite of a circ relay.(sorta, kinda!)


Andy Morgan

R. Morgan Mechanical, LLC

Andy Morgan_2

Oil pumps

on these Bock's do not have solonoid valves on them. They are almost "old fashioned", considering the burners on today's boilers.

Andy Morgan

R. Morgan Mechanical, LLC

Andy Morgan_2

J.C.A._3

Have you looked at.....

> I thought of that ,too. The problem is I have no

> low voltage controls on the Water heaters to pull

> the relay in, other wise, a simple RA89 would

> work. I almost need the opposite of a circ

> relay.(sorta, kinda!)

>

> Andy Morgan

>

> R.

> Morgan Mechanical, LLC

Andy Morgan_2

A thought

Back to the RA89 idea. Why could'nt I make the aquastats on the WH's low voltage, wiring them to TT on the cad cell relay, and put 120v directly to the burner. Take a wire from all four aquastats to a zone valve relay(for isolation purposes), dry contact to TT on a RA89 relay and power the louvers through c1 and c2. Sounds like a long way around, but it might work.Is there a zone valve panel with a pump circuit built into it? I never use them so I am not sure.

I am also trying to make it as easy as possible to troubleshoot later.


Andy Morgan

R. Morgan Mechanical, LLC

J.C.A._3

Have you looked at.....

The Tjerlund UC1 control? I believe there is a way to get this to operate the louvered vents and switch multiple units on . I think there does have to be some kind of proving switch on the vent for the boilers to get the call for heat.

I've used them for power venters and fan in a can installs with multiple boilers. If I'm not mistaken , we did use a Taco 504 with this multi boiler install.(my brain is mush from all the freeze ups in the last few days) Chris

Eric

Combustion air damper?

Even in alaska with cold weather We Do Not Design combustion air dampers. Too much trouble and dont fix the problem of cold infiltration.

We do a "engineered combustion air opening" for stioc. combustion and then put in a boiler room ventilation fan for cooling/mixing air in room. The combustion opening then normaly becomes a relief louver for boiler room cooling supply fan.

Andy Morgan_2

You oughta know

you can't argue with what engineers want!!! You can only try to reason with them, and with this guy, it's his way or the highway! They don't know any better.


Andy Morgan

R. Morgan Mechanical, LLC

Eric

Engineer

Must have sounded like an engineer huh.

BTW.

Check your IMC (Internation mechanical code) section 709.2. Dampers shall be electrically interlocked with firing cycle.....

Art Pittaway

It always interests me

that these engineers can write a "hard spec", (120v?) but couldn't wire it to save there soul. The damper manufacturer will supply an actuator as spec'd with an end switch and in almost any voltage you want. This damper should have been spec'd for size (clear opening) and some damper manufacturers by name. They (Greenheck, Ruskin, etc.) may have wiring suggestions. We make the Invensys DuraDrive line of actuators here in northern Illinois and have made actuators since the '40's. (www.invensysibs.com) Layout your wiring on paper first and watch where the 120v and 24 volt wire is going. Most code won't allow 24v (burner) and 120v (damper) in the same conduit so make sure the actuator meets code for your area BEFORE you order it. Some don't come with separate conduit connections for different voltage, or it's an accessory $$$. We probably don't have a wiring diagram for your specific app. either, so get a good tech from your company and lay it out. I hope this helps. Art