ReplyLet me get this straight, the two schematics you've posted were drawn by engineers with little to no field experience. And the customers got the engineering they paid for? Right?
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Yeah, again RFI came back make that chiller primary. Only thing is it turns out these chillers do NOT like to sit unused for a couple months, multiple faults (I think oil related) if you try to switch to one after that. Trane tech said rotate weekly so that's what we did, no problems with the chillers after that. Just don't get the DHW preheat benefit but a third of the time now.
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Let me get this straight, the two schematics you've posted were drawn by engineers with little to no field experience. And the customers got the engineering they paid for? Right?
I do a triple evac with nitro to remove non condensables.
Professional Member*
So, the auxiliary condenser isn't a condenser at all? Just a heat exchanger, but no change of state? LOL
I do a triple evac with nitro to remove non condensables.
Professional Member
No idea on their experience level. But it gets better. There was one other large mess up on this job but I have no diagrams for it.
The new plant is a primary variable plant, only three huge building CHW pumps are supposed to be in the entire CHW system. Except for the pumps that got forgotten about on the back wing in what was originally part of the secondary loop. The original plant was a primary-secondary system and these just got overlooked. That means there was a bypass pipe for the "primary" loop past that secondary loop. The whole primary variable plant did NOT like having a huge bypass out in the field. We could not build pressure even with multiple pumps in the new plant running flat out. Air handlers at the end of other wings weren't getting water and lost control. Took us a while to figure that out but the engineer had the drawings for the original plant and building so I'm thinking no excuse.
That was a huge change order because shutting the hospital down wasn't going to happen. They had to come in, liquid nitrogen freeze the bypass pipe in two places and cut in a valve to shut that bypass off. It's just impressive that can be done.
In the end they are still constructing a large bed tower which should add a big heat load. Hopefully that will mitigate some of the rotation troubles as total load will require two and sometimes all three chillers.
Still more: none of the air handlers have energy valves. Not even pressure independent valves. We can't push these hard enough because frankly the delta temperature in the plant sucks. Unfortunately the customer is not interested in spending that money, even if the payback would be under five years (a guess). But hey, while you are here can you tune this air handlers CHW valve PID, it's hunting all over the place and we are concerned it's going to prematurely wear out this actuator.
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I think it's just a heat exchanger inside the condenser, the water is separated from the tower water. It isn't required to run the chiller. What I don't get is why there is another heat exchanger outside of the chiller? Next fun thing on that loop is there is no expansion tank, all hard pipe and two heat exchangers basically. Don't know what type of pressures happen in there but nothings exploded yet so maybe I don't know what I'm talking about there.Originally Posted by BBeerme
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The way it is drawn, the auxiliary condenser is a separate component. What I think you explained, is that is actually built into the Chiller/Tower (?).
The devil is in the details. For example, does CWR mean cooling water return, or chilled water return. Either way, the schematic is not clear what that auxiliary condenser is doing. Other details on the prints may give the full picture. Remember, you're only giving us a small snapshot of the big picture.
I do a triple evac with nitro to remove non condensables.
Professional Member
The aux heat exchanger is to heat the domestic hot water and is probably an integral part of the chiller. Heating the water using the refrigerant is not unheard of. It offers energy savings if you have a continuous domestic hot water demand.
No man can be both ignorant and free.
Thomas Jefferson
Professional Member
Please explain your post #24 further. As a rule an oversized bypass between the primary/secondary should not be a problem because the primary just circulates the water and the secondary pumps take what they want.
No man can be both ignorant and free.
Thomas Jefferson
Professional Member*
Since there is more than one way to skin the cat, we really know very little without seeing the scope of work.
We used to get prints like this all the time. Cannot put in a change order until you have the job; everyone needs to bid the same thing. After you are awarded the job, then you put in the change orders. If they are not accepted or approved, then the customer gets an inferior product but the contractor is not at fault. So long as the system is built to spec, and the contractor did not design the project.
I do a triple evac with nitro to remove non condensables.
Professional Member
The plant was designed as primary variable. The loop in the back wing was designed as a primary secondary system, these two systems are pretty different and don't mix well.
Professional Member
If they tried to mix a variable primary with primary/secondary that is not likely to work very well.0
No man can be both ignorant and free.
Thomas Jefferson
Professional Member
I saw one of these domestic water heating systems on a elementary school. It didn't work worth a dang because in an elementary school the domestic hot water demand is too low. That one was designed to preheat the water only. I was ask how to make it work and my advice was to not use it.
No man can be both ignorant and free.
Thomas Jefferson
Professional Member*
But they got a Gold LEED rating and a pretty plaque, right?
I do a triple evac with nitro to remove non condensables.
Professional Member
As a matter of fact BBeerme they did. Funny thing I work with the engineer a lot and he ask me about how feasible I thought doing it was and I told him it wasn't. He agreed but was over ruled.
No man can be both ignorant and free.
Thomas Jefferson
Professional Member*
How did I guess that?
I do a triple evac with nitro to remove non condensables.
Professional Member
You guessed it because like me you have seen these liberal morons make themselves look good no matter how ridiculous. I got so sick of hearing "sustainable".
No man can be both ignorant and free.
Thomas Jefferson
Professional Member*
LOL
I do a triple evac with nitro to remove non condensables.
Professional Member
The equalizing pipe in my picture was an after thought installed the 1st summer of operation after issues arose with flooding basins. Then nobody thought about winter operation until it froze 3 years later. It was never insulated and now has been replaced with a stainless steel trough between tower cells that is level with the tower basins, no low point for static water to freeze.
Below is how we typically see tower bypass installed in multiple tower systems. Single valve means less potential problems in my opinion.
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RE: the first post.....I've never seen a bypass to a tower basin. in a single tower scenario, I suppose it would work ok if your machines could tolerate 30* (or less) water at a cold start.....but in that instance, it should be piped in before the towers.
secondary condensers can be designed to be used while the chiller is running, to make use of the heat, rather than dump it outside......Or they can be used while the chiller is OFF, and just allow the refrigerant in the chiller to naturally circulate through the machine, and move heat without mechanical assistance.
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Yes, I either wanted to tack it on the end like this one or just move it all the way back into the plant.
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