Power or controls

JohnW2 · 15 Aug 2019

SimonH2 said:
Well as I pointed out, while we may assume that they "forgot to add it", we have to work with what they actually wrote, not what we think they probably meant to write. When what they actually wrote doesn't make sense, then that's a problem

Well, if they didn't 'forgot to add it', then the section (with lower required CSAs) for flexible cables is over-ridden by the initiual section (since "flexible cables" are undeniably "cables") - in which case the higher minimum CSAs specified in the first section would be required for all cables, including flexible ones.

SimonH2 said:
Ah, so the answer is to wire everything in flexible cables

See above. if they didn't 'forgot to add it', then minimum CSA for flexible cables would be the same as for any other cable.

SimonH2 said:
But a serious point, if it's OK for the exposed flexible cable to be 0.75mm², it's hard to imagine why the same size of wire shouldn't logically be acceptable (subject to ratings, OPD rating etc) when nice and snug in a protective conduit or trunking.

Quite so. As they say, "go figure"!

Of course, the CCCs for a flexible cables are considertably lower than for non-flexible cable of the same CSA, perhaps because the cable may be subjected to a lot of flexing (hence potential strand fracture) - but that's a different matter.

Kind Regards, John

SUNRAY · 16 Aug 2019

JohnW2 said:
It did. It seemed to be saying that a 230V single-phase pump was connected between two phases of a 3-phase supply - but (per the questions I asked), I would not have thought that it would ever have lasted very long like that.

As I also said, I also couldn't understand what the story had to do with the point being made (about control circuits and control engineers).

I'm sure we'll get clarification.

Kind Regards, John

My whole point is the eectrician:
A) made a change in the panel and destroyed a component by his lack of experience.
B) couldn't be arsed to even bother trying to fault find.

OK I accept the heating guy(s) ballsed up in the first place but it really shouldn't have taken 6 visits to sort it out.

I have another example where I was recommended by a gas fitter for a domestic swimming pool.
I was asked to attend site for a survey to replace the control panel as they had several breakdowns and each time the various electricians had charged for repairs which 'got it working' but incorrectly. It is a small panel with a timeswitch, 3 switches, 1 contactor and 3 or 4 relays. 2 of the 3 switches had been replaced at some time and wired incorrectly (I suspect due to the switches being a different layout).
In order to establish the functionality of the system I reverse engineered (worked out the circuit diagram) of what was there and the 2 inconsistancies were obvious.
I made the changes (moved the wires) and got the customer to demonstrate the oporation to me (Rather than me to him) including the reverse flush process.
I gave him a price for the repair with the promise of knocking it off the price of a replacement panel if he still wanted to go down that route.
I also asked him to contact me in a few weeks to let me know if what I had done was was correct or not. It was many months later on Boxing day that a friend at a pool party asked him if he'd got it sorted which reminded him to ring me to let me know it was working well.

JohnW2 · 16 Aug 2019

SUNRAY said:
My whole point is the eectrician:
A) made a change in the panel and destroyed a component by his lack of experience.
B) couldn't be arsed to even bother trying to fault find.

All true, but you're just talking about an incompetent electrician (or a usually competent one having a very bad day) - but I still don't understand it as an argument that, as a generalisation (when one assumes that people are competent to practise their trades) a pump should be replaced by a (hopefully competent) 'control engineer'.

Kind Regards, John

SUNRAY · 16 Aug 2019

JohnW2 said:
but I still don't understand it as an argument that, as a generalisation (when one assumes that people are competent to practise their trades) a pump should be replaced by a (hopefully competent) 'control engineer'.
Kind Regards, John

I'm not advocating the mechanica/plumbing work should be done by a controls engineer but having said that I have changed a number of pumps, filters, strainers, dosing pots etc. and fitted sensor pockets and flow switches etc. in the time I've been doing controls works.
My big gripe is is people who do not know what they're doing tampering within the controls environment. Especially inexperienced electricians inside the complex enclosures where time and time again I have to correct their mistakes which are sometimes very costly.

The motor overloads are there for a reason and willy nilly resetting the current adjustment or even worse bypassing their functionality is irresponsible and again these are common things I end up going in to clear up the mess.
Making a mistake with the ratings of a pump replacement is actually fairly common (along with other devices such as drive belts, valve actuators, fans etc.) but making the same mistake 3 times on the same device is out of order.

I worked on a pair of chiller units which each had 4 compressors rated at about 30A, each was wired star-delta with pneumatic timers which had all died and never pulled into the 'star' position (another common problem) which meant the motors were starting DOL and the 40A mcb's kept tripping and sometimes the overloads. By the time I was called in, on a different problem, the MCB's had been replaced with 80A fuses and the overloads were all in the tripped state and their control contact bypassed. The problem then was the drive belts and compressor seals were failing prematurely. The system log book read like a fairy tale with repairs most weeks. Replacing the pneumatic timers with electronic versions and reinstating the overloads and 40A MCB's cost a lot less than keep repairing the bearings and belts.
EDIT: It also means the chillers did not have to be taken out of service on a regular basis

Such tales are endless and all attributable to incompetance

(or a usually competent one having a very bad day)

does come into it but not very often.

A relevant bit you didn't notice in my post:

SUNRAY said:
OK I accept the heating guy(s) ballsed up in the first place.

JohnW2 · 16 Aug 2019

SUNRAY said:
I'm not advocating the mechanica/plumbing work should be done by a controls engineer but having said that I have changed a number of pumps, filters, strainers, dosing pots etc. and fitted sensor pockets and flow switches etc. in the time I've been doing controls works. My big gripe is is people who do not know what they're doing tampering within the controls environment.

Yes, I understand that, but I'm still a bit confused ....

SUNRAY - in a thread now locked said:
.... even then it would still come under the jurisdiction of the controls engineer. Everything within the control panel is quite deliberately kept locked away from untrained personel including 'qualified electricians'...

.... and then ....

SUNRAY said:
.... In real life the control panel and all the associated peripherals are classed as control. .... Another example and this time a simple one, a heating company were called in to look at a heating problem and found a pump had failed. ... [and we know the rest of that 'example' story].....

Maybe I've misunderstood, but you appeared to be quoting this ('another') example story to support the view that a control engineer (not an electrician, or plumber) should have been changing the pump.

SUNRAY said:
A relevant bit you didn't notice in my post:

I did notice it, but you were merely acknowledging that someone ["the heating guy(s)] "ballsed up in the first place". That was clearly the problem, but the same presumably could have happened if the job had been done by a control engineer who was as incompetent at control engineering as were the heating engineer at heating engineering and the electrician was at electrics?

Kind Regards, John

SUNRAY · 17 Aug 2019

JohnW2 said:
Yes, I understand that, but I'm still a bit confused ....

.... and then .... Maybe I've misunderstood, but you appeared to be quoting this ('another') example story to support the view that a control engineer (not an electrician, or plumber) should have been changing the pump.

It seems you didn't understand as this

SUNRAY said:
I'm not advocating the mechanica/plumbing work should be done by a controls engineer

was there.

I did notice it, but you were merely acknowledging that someone ["the heating guy(s)] "ballsed up in the first place". That was clearly the problem, but the same presumably could have happened if the job had been done by a control engineer who was as incompetent at control engineering as were the heating engineer at heating engineering and the electrician was at electrics?

Kind Regards, John

Indeed there are incompidants in all spheres but in the respectable controls companies they seem to be rooted out very quickly, much quicker than some other trades (my opinion) and the non-respectable companies don't seem to last long. I have worked in controls for 18 years or so and been a SE subby for 15 working for maybe 10 controls companies. In that time I have come across only one controls guy who couldn't and he didn't make it to anywhere near the 3 months of the probation period.

I fully accept that mistakes happen, we are only human after all and yes I have made mistakes, In the example being quoted the heating company got it wrong 4 times, at least 2 of those were totally unacceptable and adjusting the overload was incompetent. The electrician made a horrible mess of his botch which was anything but a mistake (I provided detailed photos to the customer and they refered them back the his company for a full refund). The original overload had been dumped in the bottom of the panel and i suspect it was still perfectly serviceable but he had inflicted so much damage on the contactor there was no way I would leave it in service.

SimonH2 · 17 Aug 2019

I'm not so sure about incompetent controls guys getting rooted out quickly. But then the "poor" ones I've come across have been those working for companies where controls is either an incidental thing to their main business, or the in-house maintenance.
Worst one was a customer at my last job whete the guy really had zero idea of basic networking - yet was programming IP linked panels. In our case, he was connecting it to the client's existing network - and picked the IP address of their phone system for one of his panels. Best of it was, they'd asked for an address - but didn't tell us they were using three

This was a case of controls being almost incidental to the supplier's core business of water turbines, and networked panels being new to them.
It was only when I went to site to figure out why they couldn't co-exist that it was obvious. I had to change the IP address on the phone system - no chance of getting them to change theirs

And there's the fan cooler with expensive inverter with the PID set so it basically did on-off modulation of the fans . And the 3 pump set with completely unsuitable controls - and the attempts to make them work. And I could go on and on with examples from all trades of complete ignorance and incompetence ...

SUNRAY · 17 Aug 2019

SimonH2 said:
I'm not so sure about incompetent controls guys getting rooted out quickly. But then the "poor" ones I've come across have been those working for companies where controls is either an incidental thing to their main business, or the in-house maintenance.
Worst one was a customer at my last job whete the guy really had zero idea of basic networking - yet was programming IP linked panels. In our case, he was connecting it to the client's existing network - and picked the IP address of their phone system for one of his panels. Best of it was, they'd asked for an address - but didn't tell us they were using three This was a case of controls being almost incidental to the supplier's core business of water turbines, and networked panels being new to them.
It was only when I went to site to figure out why they couldn't co-exist that it was obvious. I had to change the IP address on the phone system - no chance of getting them to change theirs

Hence my use of the term 'respectable controls company'
Now my confession... I don't do the software, or programming. I made a conscious decision to stay with the hard stuff and many of the companies I've worked for are the same as in many cases the contract to supply is with the 'Engineer' (sometines a consultant) who specs the system, then when (s)he gets the job farms out the hardware to their selected range of panel companies to build, install, commission (in conjuction with the programmer) and quite often design. These panel install (as opposes to panel assembly) companies include qualified electricians for the installation requirements and they may truthfully have a demarkation within their staff of controls experience.

And there's the fan cooler with expensive inverter with the PID set so it basically did on-off modulation of the fans .Anddifficult the 3 pump set with completely unsuitable controls - and the attempts to make them work. And I could go on and on with examples from all trades of complete ignorance and incompetence ...

These are not dissimilar to the the sorts of things that I can quote and again I'd repeat the term 'respectable'.
If you are refering to the '3 pump cold water booster set with a pale blue control panel with 6 position switch', I understand your criticism, the company had managed sell loads of them, then go into liquidation when the poo hit the air pump. I came across them on a very regular basis and the control PLC and its associated devices and minifolds were simply wrong. The first one, I was working on site for a controls company and closely with the EM guys installing some new kit and the job included investigating the set and quoting for repair/replacement, between us we'd tested the fairly young skid and found the pumps to be good quality and in good health (and in a location making it difficult to remove/replace). we concluded the problem was the crazy range of one way valves (way more than 6) and the position of the multitude of pressure and flow transducers and we came up with an alternative arrangement for them, the EM guys made the new lengths of pipe required and I sat there for a night shift with their apprentice stripping down and rebuilding the manifolds and replacing the PLC with a Trend IQ3 & sensors, which had been programmed off site, to match the rest of the network. After that I and the EM company had a price for the repair which we did quite often together, and on more than one occassion I did all of the 'on site' work on my own.
One of the chiller manufacturers supplied a floppy disk with the Trend software for their chillers although they were supplied working and tested with a Telemeque PLC they even made the space and wiring for the PLC suitable for a simple change to Trend. I'm sure it was simply for interface purposes rather than functionality.

SimonH2 · 17 Aug 2019

SUNRAY said:
Now my confession... I don't do the software, or programming. I made a conscious decision to stay with the hard stuff ...

Can't say I blame you. But being from an IT background I'd be interested in doing both - if the opportunity arose (which I don't think it will). At a previous job I got the opportunity to do a little bit - they still have panels designed and programmed by yours truly running moulding machines and the water system pumps. Nothing complex, just small panels with a Siemens Logo (original version, digital I/O only, no communications) - IIRC something like 8 or 12 inputs and 4 or 8 outputs, with a limit of something like 7 functions between any input and an output, and only 53 function blocks total (funny how numbers like that stick in your mind and pop out a couple of decades later !) Choice of programming on-device (painful) or on computer with ladder or function block styles.

If you are refering to the '3 pump cold water booster set with a pale blue control panel with 6 position switch'

No, I don't think it was - it certainly doesn't fit your description of the plumbing side.
This one was an off the shelf 3 pump set for use as a booster in blocks of flats etc, controlled by a number of pressure switches and a "box of something". It was probably fine for the job it was designed for - making sure that everyone in the block gets water pressure. Thing is, IIRC in our system that wasn't the requirement - it just had to take water from a big tank, pump it through a large fin&tube cooler, and up into a header tank with a variable draw off rate. I have a vague recollection that there was a 'kin big ballcock up there. So the controls were the opposite of what we needed.
In fairness, the guy did say that the reason for buying that was that it was a cheap way to get the three pumps (Grundfoss things 2 or 3 foot high IIRC). I think it got setup so that one pump ran continuously and the got manually switched every now and then.
In a later development, the pumps got controlled by an ABB inverter drive in it's "run on up, when it's getting up to full speed, drop the speed and fire up another using it's DOL starter" mode - using an ultrasonic level sensor. It really needed a flow sensor and nested control loops as what we had was exceedingly non-linear - but that wasn't something I was allowed to add to it during the time I was there. The sharp changes in flow rate played havoc with the controls on the fan cooler, causing rapid changes in fan speed needed, but which we couldn't do because a fast PID loop was unstable at low flow rates with a long lag time between fan speed changes and sensor feedback. The fan cooler also had an ABB inverter drive, running 6 fans all variable speed - but controlled by another panel controlling how many fans running.

Mind you, if you really want a laugh, some of the stuff we had was designed by the chief engineer of our US based owners - who had some interesting ideas. One large machine came with no guarding because he designed it to their safety standards, not ours. He also designed it for their power supplies, so we had to add a 'kin big transformer to power it. It would have been trivial to have had it built for 415V - heaters in star instead of delta, pick a different model of inverter drives for the motors - but he didn't.
But the thing I think you'll laugh at was he came up with a composite mould as a cheaper alternative to the tin ones we used - we made candles. Basic principle for many of them was "big cast iron chest, lots of moulds mounted vertically, heat everything up with hot water, pour in wax, cool it down with cold water, crank the pistons up to push the candles out. We used tin for it's thermal conductivity ...
Our US friends came up with the idea of composite (glass filled resin) which were a lot cheaper to buy (our tin ones suffered from wear and needed frequent replacement). No amount of "discussion" would have their engineer accept that the thermal conductivity was lower and would significantly affect cycle times and water usage

Our guy setup a demonstration, plugged the bottom of one each of the two moulds and put the kettle on. I suspect you're ahead of me here.
Our US friend holds a mould in each hand, our guy pours hot water into their composite mould, asks how it is, is told "it's getting warm". Our guy then pours hot water into the tin mould, US guy immediately utters an expletive and lets go of it

But he then explains that it doesn't count because the hot water was inside the mould rather than outside of it

This was the same guy that proposed a water system that would have blown the seals out on the moulding machines in the event of a power or pump failure. We installed a system using gravity, open vented, and impossible to pressurise the machines and blow the seals

But we're going further OT here (no MODs, that's not an invitation to lock the thread

), even though it is fun to exchange tales like this

JohnW2 · 17 Aug 2019

SUNRAY said:
It seems you didn't understand as this [I'm not advocating the mechanica/plumbing work should be done by a controls engineer] was there.

Yes, I know that statement was there, and it was the apparent contradiction it represented in relation to what you had previously written (seemingly quoting the story as an example of why problems had arisen because the person replacing the pump was not a control engineer) which is what confused me. However, you seem now to be confirming that you didn't think the problem was due to the people involved not be control engineers - so that's fine.

SUNRAY said:
Indeed there are incompidants in all spheres but in the respectable controls companies they seem to be rooted out very quickly, much quicker than some other trades (my opinion) and the non-respectable companies don't seem to last long.

As Simon has said, I suspect that might be wishful thinking!

Kind Regards, John

SUNRAY · 17 Aug 2019

SimonH2 said:
Can't say I blame you. But being from an IT background I'd be interested in doing both - if the opportunity arose (which I don't think it will). At a previous job I got the opportunity to do a little bit - they still have panels designed and programmed by yours truly running moulding machines and the water system pumps. Nothing complex, just small panels with a Siemens Logo (original version, digital I/O only, no communications) - IIRC something like 8 or 12 inputs and 4 or 8 outputs, with a limit of something like 7 functions between any input and an output, and only 53 function blocks total (funny how numbers like that stick in your mind and pop out a couple of decades later !) Choice of programming on-device (painful) or on computer with ladder or function block styles.

No, I don't think it was - it certainly doesn't fit your description of the plumbing side.
This one was an off the shelf 3 pump set for use as a booster in blocks of flats etc, controlled by a number of pressure switches and a "box of something". It was probably fine for the job it was designed for - making sure that everyone in the block gets water pressure. Thing is, IIRC in our system that wasn't the requirement - it just had to take water from a big tank, pump it through a large fin&tube cooler, and up into a header tank with a variable draw off rate. I have a vague recollection that there was a 'kin big ballcock up there. So the controls were the opposite of what we needed.
In fairness, the guy did say that the reason for buying that was that it was a cheap way to get the three pumps (Grundfoss things 2 or 3 foot high IIRC). I think it got setup so that one pump ran continuously and the got manually switched every now and then.
In a later development, the pumps got controlled by an ABB inverter drive in it's "run on up, when it's getting up to full speed, drop the speed and fire up another using it's DOL starter" mode - using an ultrasonic level sensor. It really needed a flow sensor and nested control loops as what we had was exceedingly non-linear - but that wasn't something I was allowed to add to it during the time I was there. The sharp changes in flow rate played havoc with the controls on the fan cooler, causing rapid changes in fan speed needed, but which we couldn't do because a fast PID loop was unstable at low flow rates with a long lag time between fan speed changes and sensor feedback. The fan cooler also had an ABB inverter drive, running 6 fans all variable speed - but controlled by another panel controlling how many fans running.

Mind you, if you really want a laugh, some of the stuff we had was designed by the chief engineer of our US based owners - who had some interesting ideas. One large machine came with no guarding because he designed it to their safety standards, not ours. He also designed it for their power supplies, so we had to add a 'kin big transformer to power it. It would have been trivial to have had it built for 415V - heaters in star instead of delta, pick a different model of inverter drives for the motors - but he didn't.
But the thing I think you'll laugh at was he came up with a composite mould as a cheaper alternative to the tin ones we used - we made candles. Basic principle for many of them was "big cast iron chest, lots of moulds mounted vertically, heat everything up with hot water, pour in wax, cool it down with cold water, crank the pistons up to push the candles out. We used tin for it's thermal conductivity ...
Our US friends came up with the idea of composite (glass filled resin) which were a lot cheaper to buy (our tin ones suffered from wear and needed frequent replacement). No amount of "discussion" would have their engineer accept that the thermal conductivity was lower and would significantly affect cycle times and water usage Our guy setup a demonstration, plugged the bottom of one each of the two moulds and put the kettle on. I suspect you're ahead of me here.
Our US friend holds a mould in each hand, our guy pours hot water into their composite mould, asks how it is, is told "it's getting warm". Our guy then pours hot water into the tin mould, US guy immediately utters an expletive and lets go of it But he then explains that it doesn't count because the hot water was inside the mould rather than outside of it
This was the same guy that proposed a water system that would have blown the seals out on the moulding machines in the event of a power or pump failure. We installed a system using gravity, open vented, and impossible to pressurise the machines and blow the seals

But we're going further OT here (no MODs, that's not an invitation to lock the thread ), even though it is fun to exchange tales like this

Brilliant... It's fine to chinwag, I think the OP topic is satisfied and a tangent is fine with me, especially without a particular former member slagging us off.

We had one where an a/c unit condense pump above a suspended ceiling in an apparatus room discharged into a 32mm waste pipe via an air gap and water trap followed by about a metre of near horizontal pipe, this ran down 2 or 3 floors to finish above an internal drain in the toilet on a high floor (about 10th to 12th floor).

A consultant designed a new gym facility with several toilets and shower cubicals and a maserator into the 32mm pipe at the junction where it changed from horizontal to vertical.

The design flaw was pointed out to the consultant by email but after the proposal was nearly completed and he was on holiday so it went unacknowledged.

The first few days seemed fine but that was because nobody had a reason to to go to the apparatus room or the adjacent cable riser.

A colleague were trying to find out why there were repeated temerature variations in the aps room and became the first to find the disolved apps room ceiling tiles floating in a brown slurry which just happened to find the wall temp sensor as it ran down the wall on its journey twixt waste pipe and floor puddle, unfortunately the floor was a raised floor and the 150mm or so below was also full and it had been running down the cable riser.

The lower floor with the original toilet had been refurbished and awaiting new tenants to move in so therefore unused, all of the brand new carpets had been laid and the very long corridor ran very slightly downhill from the toilet.

I love consultants

SUNRAY · 17 Aug 2019

We were asked to quote for a rear projection system by on of our regular (finance) international customers in Canary Wharf, we discussed the spec in detail at an internal meeting and I stated I'd not be prepared to commission the system, promptly followed by the engineer refusing to have any involvement. The proposed system had a video projector using one mirror and a pair of slide projectors using the mirror plus a second. The problem we had on the similar job we'd done a year or so before was the image reflected off the back of the glass screen and round the mirrors several times until it was too dim to show.
We declined to quote and explained the problem. This came as a bit of a shock to them that one of their main prefered contractors declined.

Half a year or more later I was at the the customer on another job and got chatting about the problematic new system and asked if we'd be interested in having a look. It was a struggle but we managed to rip out the ridiculous arrangement and shoehorn something diffent in the limited space.

What I didn't understand was the consultant constantly tried to argue that his design works and it had been installed wrong even though it was millimetre perfect to his drawings. Hopefully the contra charge went someway towards convincing him.

SimonH2 · 17 Aug 2019

SUNRAY said:
We had one where an a/c unit ...

Brilliant. Did the consultant get the bill for the specialised cleanup ?

But you've reminded me of a fairly recent one ...
Customer had a small computer room, about 2kVA worth of stuff. I'd suggested while they were still at the "building is flexible" stage that they look at air only cooling (fan for fresh air in, fan for warm air out) but various factors (including planning conditions) precluded that. So the A/C people who were doing the offices were asked to put a unit in the computer room.
I made a point of checking that the proposed unitvwas suitable (not all comfort systems can handle the dry air in computer rooms), but needless to say, they ignored my suggestion as to location (but it still worked "well enough").
All worked fine for a couple of years, then the unit started tripping out. Reset it, runs for a couple of minutes without blowing cold, then trips. A/C people called in, engineer sent, he declares that it's the room at fault because it doesn't have enough insulation. Client has been out and bought insulation to lay on top of already insulated ceiling, and been cooling room with a desk fan stood in the doorway for several days, before they get frustrated and call me for advice. I speak to engineer on ohone, but he's not for accepting that the system was ever suitable even though it had been working fine for a couple of years.
In the end I phone the engineer's boss and (remarkably tactfully for me) suggest thst the engineer is "mistaken". A couple of hours later a faulty reversing valve has been diagnosed and fixed

SUNRAY · 17 Aug 2019

SimonH2 said:
IIRC something like 8 or 12 inputs and 4 or 8 outputs, with a limit of something like 7 functions between any input and an output, and only 53 function blocks total (funny how numbers like that stick in your mind and pop out a couple of decades later !) Choice of programming on-device (painful) or on computer with ladder or function block styles.

I have programmed a couple of PLC using ladder but they were both stupidly simple to move a lighting rig, basically a button to a DI, one or maybe two interlocks (DI from a proximity sensor) operate DO, some O/P's didn't even have an interlock.

No, I don't think it was - it certainly doesn't fit your description of the plumbing side.
This one was an off the shelf 3 pump set for use as a booster in blocks of flats etc, controlled by a number of pressure switches and a "box of something". It was probably fine for the job it was designed for - making sure that everyone in the block gets water pressure. Thing is, IIRC in our system that wasn't the requirement - it just had to take water from a big tank, pump it through a large fin&tube cooler, and up into a header tank with a variable draw off rate. I have a vague recollection that there was a 'kin big ballcock up there. So the controls were the opposite of what we needed.

That is pretty much the description of the units I'm talking about, basically they were available in a big range of pump sizes, anything from a domestic central heating size up to... Largest version I saw used 4" pipe the minimum pipe size they used was 2" even if only 1/2" was required. Over that sizewould have been far too cumbersome.

In fairness, the guy did say that the reason for buying that was that it was a cheap way to get the three pumps (Grundfoss things 2 or 3 foot high IIRC).

A very common reason and I've seen skids purchased with the intention, at the design stage, of rebuilding.

But we're going further OT here (no MODs, that's not an invitation to lock the thread

), even though it is fun to exchange tales like this

SUNRAY · 18 Aug 2019

SimonH2 said:
Brilliant. Did the consultant get the bill for the specialised cleanup ?

But you've reminded me of a fairly recent one ...
Customer had a small computer room, about 2kVA worth of stuff. I'd suggested while they were still at the "building is flexible" stage that they look at air only cooling (fan for fresh air in, fan for warm air out) but various factors (including planning conditions) precluded that. So the A/C people who were doing the offices were asked to put a unit in the computer room.
I made a point of checking that the proposed unitvwas suitable (not all comfort systems can handle the dry air in computer rooms), but needless to say, they ignored my suggestion as to location (but it still worked "well enough").
All worked fine for a couple of years, then the unit started tripping out. Reset it, runs for a couple of minutes without blowing cold, then trips. A/C people called in, engineer sent, he declares that it's the room at fault because it doesn't have enough insulation. Client has been out and bought insulation to lay on top of already insulated ceiling, and been cooling room with a desk fan stood in the doorway for several days, before they get frustrated and call me for advice. I speak to engineer on ohone, but he's not for accepting that the system was ever suitable even though it had been working fine for a couple of years.
In the end I phone the engineer's boss and (remarkably tactfully for me) suggest thst the engineer is "mistaken". A couple of hours later a faulty reversing valve has been diagnosed and fixed

Funny that isn't it?

I've done jobs for a couple of a/c companies (which reminds me of the hard work involved in getting into the departure lounge of Gatwick to do a night shift...) and too much of their work is replacing unsuitable kit. One server room currently has 3 pairs of a/c units where each successive company said not suitable and added their own ideas

I will say it's always cold in there with the latest system, more so than the middle system but the customer has always said leave them in for emergency standby.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Power or controls

Similar threads