setting up a vfd on a pump

[coolright]

I inherited this control and piping mess.

Building size is 120,000 sq.ft. build 8 years ago.

1) 200 hp boiler running a exchanger then feeding 2 RTUs with 100% OAT.
7) lochinvar boilers 2,070,000btu each. On common header. Running the
hot water of the pumps I want to control better, these feed 2 RTUs that
are 260 tons each. With preheat and heating coil in each, again 100%
OAT. and 30 reheats.
1) Trane intellpak 160ton with gas feeding 24 FPT boxes with electric
reheats.
1) McQuay 160 ton with gas.
1) McQuay 100 ton with gas 100% OAT.
1) York 160 air cooled chiller.feeding 14 chilled water coils. (talk about over
kill)
6) 50 hp exhaust fans 24/7 365.

200 hp boiler in shut off in summer. Lochinvars sit there and just cook all summer.(that's why I shut 3 of them down, not needed in summer) No OAT reset on anything. 10 pumps above 15 hp only 2 on VFDs. 3 of the RTUs have VFDs all others are full on.

ALC for control. Every day I find more points that were never hooked up, or have been disconnected.

Just took over this plant about 4 months ago. Slowly getting things working right. Last engineer was there from the being to about 6 months ago. He didn't fix anything. Would just call in his friends that hacked the systems.

[coolright]

Thank you chesehd that is a good point. I will check that out in morning.

[bob_scheel]

Just a thought but I didn't see it mentioned earlier.

Make sure your motors are inverter rated. I have a customer that (somehow) ended up with VFD's on motors not rated for inverter duty.

He's gone through bearings like Grant went through Richmond until they got that figured out.

Not necessairly what you were looking for but my .02

Regards!

Slow inverter speeds are what kills bearings. They put a lighter grease that stays fluid without much heat in an inverter rated motor. The slow inverter speeds and resulting cool running of the bearing can cause heavy grease to not circulate and lube the bearing adequately.

[kontrolthis]

A little more on the VFD front. We install and do warranty work for Danfoss out here on the Left Coast. The dual output single drive selection with electronic by-pass is a great option if you need to keep the costs down. I personally like dual that way you get 100% backup.

In regards to the motors, you can get away without inverter duty but you must be cautious. #1 do not turn down the non inv. duty motor more than a 3:1 speed. Otherwise like already mentioned, bearings will be the death of you before overheating will. #2 Keep the drive to motor leads shorter than 100ft if possible. This will keep the amplification of the DC down. Less amplification=less motor winding breakdown. Then for whatever reason the motor finally does die, replace with inverter rated.

Just a few things that might help either way

[hotrod53]

CoolRight, I'd like to say that this is the first time that I ever heard of your situation, but unfortunately it's not. It sounds like you will have somewhat of a journey to get things straightened out, especially if your system is hacked and neglected. I have experienced Facilities Managers such as you have, it's never good. Did they at least keep your ALC system up to date? What are you running Supervision, InterOp Supervision, or WebCtrl version ___? Whatever version, you'll at least have the flexability of making changes to correct the problems.

Are you talking about the Lockinvar instantanious type in a common header? I have a customer who has 8 of those in a common header and you have to be sure that your staging is right, otherwise you just suck in hot water from the previous boiler and they short-cycle. Even if they aren't the instantanious type, that is always a concideration with a common header since there are no lockout/isolation valves.

[bob_scheel]

CoolRight, I'd like to say that this is the first time that I ever heard of your situation, but unfortunately it's not. It sounds like you will have somewhat of a journey to get things straightened out, especially if your system is hacked and neglected. I have experienced Facilities Managers such as you have, it's never good. Did they at least keep your ALC system up to date? What are you running Supervision, InterOp Supervision, or WebCtrl version ___? Whatever version, you'll at least have the flexability of making changes to correct the problems.

Are you talking about the Lockinvar instantanious type in a common header? I have a customer who has 8 of those in a common header and you have to be sure that your staging is right, otherwise you just suck in hot water from the previous boiler and they short-cycle. Even if they aren't the instantanious type, that is always a concideration with a common header since there are no lockout/isolation valves.

I once encountered an installation where there was a honeywell automation system for running the HVAC, but the maintenance crew had removed valve motors etc and were regulating chilled water flow through a valve w a coat hanger wired to pull down on the valve stem. ( because they didn't know how to adjust setpoints and didn't want to pay to bring in someone who did )

A classic case of reducing the system to their level of understanding.

[coolright]

Hotrod53 yes the lochinars are on common header. Common return header each boiler has it's own pump, then boiler and back to a common supply header. First day that we were really calling for heat, and did notice that the boilers did seam to be short cycling.

Might be why each boiler has had it's burner tubes replace. Have 3 right now that need new burner tubes again. The service company that does the work here (will not be for much longer) said it's the way these boilers work about ever 2 years you new new burners.

Thank you for that info I will be keep more of an eye on them to see if they are short cycling.

Yes the controls are all still here and, working as far as I can see just not all hooked up. Just found out about a month ago that the company that install system and has been servicing the system is no longer a ALC dealer. Found the dealer in my area and starting to work with them. But any info from you guys is always a big help.

hotrod53 anyway that you can work on the program and maybe parts? Or am I of your area of sales?

[simsd]

Is this and apartment building or something?

[coolright]

No it's a pharmaceutical company. We do a lot of RD for other companys and also make the APIs for other companys.

[simsd]

That answers a lot of questions. Pharmaceutical companies usually consider HVAC as part of their R & D or manufacturing costs. So therefore if your energy costs are $ 10,000 a week, but their production costs are $2,000,000 the energy represents only 1/2% of their overall operating costs. To them it's negligible relative to the overall cost pf running the place. So if a few extra boilers are running and the cost is an extra $1,000 per month, what's the big deal?

That's probably what you're up against.

API's? Application Programming Interface's?

[joey791]

Not to hijack but theres some good discussion going on here so I'll throw this out

I have never set up a pump on a vfd, ever(controls wise). Depending on the size of the pump what is the actual value(monetarily) of doing this, is there some kind of formula for it? The reason I ask this is that we have several of these systems that we work on and I have yet to see one that was designed correctly yet.

I take that back I have seen one working correctly for the most part

[simsd]

I believe Danfoss Graham or Bell and Gossett can run the equation for you. I'm sure at this point in time you can find something online that will help you calculate the savings. It's very important that if you use one of these programs that the data input you use is accurate. All too often I see callously over estimated savings used. Case in point - I constantly see people calculate savings on a two-speed cooling tower fan based on a single speed fan. When I explain to the customer that a two-speed fan generally runs on low speed 85 to 90% of the time, they realize that they are not really saving anything. I had Danfoss run a simulation on one of these once for me on a 25HP Tower fan, and all we ended up with was a few hundred dollars a year.

Garbage in - garbage out. So just make sure your measurements make sense.

Here's an article I found that might help you.

http://www.plantservices.com/article...91.html?page=2

[kontrolthis]

^^^^^^What he said 100%^^^^^^^^

The information is extremely important. And to complicate things its not just info taken off the pump or motor. Cooling towers need true design wetbulb, pumps need true design head and calculated % there of. We install and commission a lot of drives but have to admit it is about 50/50 for the application. Just the benefit of soft starting is enough for a lot of people. It's not always energy savings pushing the drive sales.