Bypass damper & DATS installed incorrectly?

[richmod]

I noticed that the bypass damper on our new system (2 zone) is installed downstream of the zone dampers (only a foot or so after, but still after). The instructions say to install it upstream of the zone dampers. Is that a problem?

Also, the DATS is installed directly in the silver box that the ducts connect to (don't know the name of that box!), which means in the line-of-sight of the air handler. The instructions say not to do that. Is that a problem? It's also installed in the same box mentione above, before the bypass damper (which is correct) but after the zone dampers. Is that correct?

Shouldn't the correct set-up be:

Air Handler> DATS > Bypass damper > Zone Dampers

[airworx]

bypass damper should be installed in the supply plenum just like the zone dampers.
Also discharge air sensor also should be mounted in the supply plenum.

[beenthere]

You are correct.
Some times you can't install the DATS out of line of sight.
So a sheild can be installed between the DATS and HX, to block the radiant heat.

[beenthere]

Was the zoning an add on after the install began.

[richmod]

Supply plenum - that's the silver box, correct?

If so, then yes - both the bypass damper and the dtas, as well as the zone dampers, are all installed in the supply plenum. On the plenum, the install order is: zone dampers>DTAS>bypass damper. Everything was installed all at once.

So it's okay that way, even with the DATS in the line of sight of the AHU? Is the shield you mentioned a necessity?

Also, since they're all in the supply plenum, does that mean they're basically all at the same point of airflow, even though the DTAS and bypass damper are farther downstream within the supply plenum?

[beenthere]

Yep, no problem.
If they didn't install a shield. The DATS will heat up a little quicker, and the panel will shut the heat off to protect the HX.

[razorwit]

Honeywell zoning instructions call for the bypass damper to be installed upstream of the zone dampers.
The DATS should be located in the supply trunk between the evaporator coil or heat exchanger and the first zone damper. If this is not possible, it is permissible to mount the DATS in the bypass duct.
http://customer.honeywell.com/techli...0s/70-2321.pdf

[beenthere]

They consider, the plenum part of the supply trunk.

[richmod]

What is the plenum?

From razorwit's reply, it sounds like it hasn't been installed properly. What's the general consensus - is it an acceptable install or something I should insist be changed?

[beenthere]

Instead of lots of speculation on something we can't see.
Take pics of it, and post them.

[Airmechanical]

Honeywell zoning instructions call for the bypass damper to be installed upstream of the zone dampers.
The DATS should be located in the supply trunk between the evaporator coil or heat exchanger and the first zone damper. If this is not possible, it is permissible to mount the DATS in the bypass duct.http://customer.honeywell.com/techli...0s/70-2321.pdf

never seen a dats installed in the bypass duct!

and if i did i would move it!



.

[richmod]

I'm out of town this week - will post pics upon return.

The manual for the dtas shows it installed in the bypass duct: will post manual link later.

Why would you move it? Where is it normally installed - in the supply trunk? Isn't that always in the LOS of the AHU?

[beenthere]

It some times is, sometimes isn't.
If its more then 3" away from teh HX, it can be in line of site.

[richmod]

Here's the link to the dtas manual: http://www.bayareaservice.com/Manuals/dats.pdf. I believe Fig. 2 shows the dtas installed in the bypass duct.

The HX is actually in the AHU, correct? If so, then the dtas is at least 3 feet or more from it.

Basically, the AHU is outside, the supply trunk starts out there, goes through the foundation and into the crawl space. Total length is about 6 feet - 3 feet outside, 3 feet in crawl space. (Rough estimates). On the crawl space portion of the trunk, the first thing installed into the top of the trunk (closest to the crawl space wall) are three ducts with zone dampers (I assume one is a shared zone since we only have two zones?)
Next in line is the dtas, which is installed on the side of the trunk. Then the bypass duct is installed in the same side of the trunk, about 1 foot from the dtas.

I know that's not a picture, but hope it helps visualize things. I will say that there doesn't appear to be any room before the zone ducts on the trunk to put the bypass duct, so it almost has to be after the zone ducts. My main concern there is whether that's acceptable or if it somehow reduce the efficacy of the bypass damper.

My next concern is that the dtas is both in LOS of the HX (although about 3 feet from it) and also installed AFTER the zone ducts. Again, does that reduce the efficacy of the dtas? If it's better to keep it after the zone ducts rather than before (since moving it before would move it at least a foot closer to the HX), should it stay where it is or would installing it in the bypass duct just before the damper be better since it would be out of the LOS?

[beenthere]

Your find that set up.

[richmod]

I assume that means that I'm fine with that set-up?

[beenthere]

Yes.

Your find with that set up.

[richmod]

oops - double post.