A/E Clarification

[dragan2u]

I work for a ATC company as a controls engineer, and am wondering what the general consensus is on the role an A/E plays in the mechanical control design process.

My question is, are the specification's, mechanical drawings, and sequences simply guidelines that need to be altered by the contractors associated with the project to fit the equipment being provided, or are they "blue prints" that are to be followed through completion?

When I see something that may be done better or are in need of a clarification, I usually issue an RFI, but I have been typically given the same answer over and over again, and it goes like this:

"A-E review comments provided are self-explanatory as A-E provides general comments and not exhaustive reviews or guidance to
perform the work. This is a matter of coordination between the Contractor, sub-contractors, suppliers, and Controls Subcontractor. Contractor shall provide and submit means, method or configuration acceptable to meet the functional intent for approval."

Can anyone shed some light on the responsibilities of the A/E, and their role during a project? I ask because specifications are not clear, and the sequences for the equipment have been copied from another job, as I see it. They state that the sequences they, the A/E, wrote are wrong. Something doesn't seem to jive with all this.

 

[KiwiMace]

Many A/E engineers use standard details, and in my experience, controls is a much weaker subject area for your average mechanical HVAC consultant engineer. There are a few other factors though:

1. The consultant may not know or be engaged at a sufficient fee to examine the details of existing controls or systems.
2. The equipment may be subject to contractor bid offer, and the consultant may not know what exactly is being controlled.

The answer above is consultant speak for "Yes please, send me something that works." However, read the comments and specifications as notes are often added to the drawings and specs to push in the general direction intended, if there is one.

You have the right to expect more encompassing drawings and specifications with larger and more complex projects.

 

[cvg]

you also have the right to have someone answer your RFI's with something other than boilerplate BS. Yes, they are indeed blueprints. But no you are working design build which means the design is not usually considered 100%. I have never seen a set of plans or specs yet that were perfect and couldn't use a little tweaking to work better.

 

[cdxx139]

Control Sequences - I write them so they follow an intent. When this happens, that should happen. I dont know the details in how you can make that happen, I just know you can make it happen, and that I feel is your "means and method" that I wont tell you how to do.

Submittal time is when you should add your two cents in. There is nothing I hate more than when the contractor copies our sequence word for word. That tells me it better do everything word for word.

As for specification. That is where I tell you I want a 1% accurate temperature sensor, and not 3%.

And truthfully, there are portions of the specification that talk about System Architecture, that I feel I need to be a computer major to understand, but I trust the senior engineers at my firm wrote it correctly.

Knowing I dont know everything, I am always open to suggestions. Maybe provide the suggetsion as part of the RFI, so the engineer can give a simple "Approval"

Great question.

knowledge is power

 

[KiwiMace]

Much of this process is a result of all parties protecting themselves under the contract. In the construction stage, the process should be to pick up the phone and talk about what you are both trying to achieve before issuing an RFI on the subject.

 

[dragan2u]

Thanks to everyone for the great discussion.


cdxx139, I am fairly new to the industry, so please excuse my ignorance, but your comment that "There is nothing I hate more than when the contractor copies our sequence word for word. That tells me it better do everything word for word." If a sequence is made to be followed, considering that all bases are covered for feasibility and the technology available, why is it wrong to follow the spec word for word? Are the specs quickly compiled, using only general information that "mostly" covers the scope and intent? The way I observe it, if I give plans/blueprints to build something, I expect it to be followed word for word, to get "exact" design intent, not what they think it means. When I tell someone how to change the oil on their car, I don't expect the procedure to be interpreted, like the laws of the land, but followed. I may be missing something about the process, and what it takes to put together the best submittal package. An example of this, I am working on a project where the sequences found in the spec will not work at all with the energy recovery units. The first time the submittal was sent, it had the sequence copied, the second time, I supplied a new sequence that covers the units operation, but still kicked back with the engineer stating that spec is not followed. I cannot read his mind, and I am not the brain behind the design of the mechanical system. I can only read what he has written as how the unit will operate. If it is wrong when he wrote it, then he needs to make the corrections, and pass that through the chain to us. Only then, after he has made his corrections, should we proceed. His job is not finished till the project is over as far as I am concerned. If I wire a bunch of relays in a drawing that may confuse a installer or tech, I don't them that it is not the job of the engineer to provide "exhaustive reviews or guidance to perform the work." I am sorry, but that would make me an a**.

That being said, I would like to start a thread to see what everyone thinks an ATC submittal should contain to make it the best package. Also, what everyone has seen time and again missing from said submittal's. I appreciate everyone's input to my question. Like NBC used to say, the more you know the more you grow.

 

[dragan2u]

Also, to add to my previous comment, I receive sequence's and points lists from MEP's that do not match almost 95% of the time. Am I to incorporate that which is missing in both, add them, and change the sequence so that both are the same? I don't see why these drawings go out as construction documents if they are not complete or there are conflicting items all over the spec. I understand that the document is large to compile, so there may be some inconsistencies, but not that many. Are there crazy time constraints on deliverable as an MEP? I know for us, we get jobs that are fast track all the time.

 

[cdxx139]

dragan, I am also fairly new to thei industry, so maybe well both learn something.

Lets start with a clarification. We do sequences are part of the drawings packages with a controls flow diagram. The specification provides the system and component requirements, such as the accuracy of the sensor. Specifications should be mathched word for word. Sequences should not (in my opinion).

My experience has shown, when the sequence is matched word for word, then the controls contractor did a copy paste, without confirming the sequence can be done. Should that have been confirmed by the engineer? yes, but should is also be confirmed by the contractor? definately!

As far as lousy sequences...there are lousy engineers and lousy contractors out there. I have seen both. Controls submittals always get rejected the first time around, so dotn take it to heart. Its too complicated of a system. My suggestion, is to get on the phone after the rejection and talk it through.

Not sure how to do it, and didnt want to steal your thread, but is we can continue this thread in the HVAC/R Engineering forum, we would get a lot more help and advice from a lot smarter people.

This is a test

http://www.eng-tips.com/viewthread.cfm?qid=297687&page=1

knowledge is power