Previous in Forum: Trends in Trainings on Engineering Standards   Next in Forum: Using the Pressure of Water and Rising Bubbles to Produce Energy
Close
Close
Close
21 comments
Participant

Join Date: Oct 2019
Posts: 3

Cracked Heat Exchanger

10/30/2019 12:07 PM

I am a heating contractor looking for someone who makes residential aluminized heat exchangers, or is an engineer, to comment on the following queston. I have a customer who is saying we drove a screwdriver into their aluminized heat exchanger and damaged it. I pointed out to them that if a screwdriver is driven into an aluminized heat exchanger it will not cause radiating crakes to appear as is the case. Can anyone please comment to me as to your thoughts if this is possible to drive a screwdriver into an aluminized heat exchanger and product radiating cracks? I have worked hard to be known as an ethical company, and to have someone think we caused this damage is hurtful. Thank you for your time.

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
2
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33231
Good Answers: 1807
#1

Re: Cracked Heat Exchanger

10/30/2019 12:22 PM

I sympathize with your predicament....How old is the unit? If it is past the design life he has no case to begin with....19 years....If it has failed prematurely, then I would appeal to the manufacturer....If on the other hand the customer has some proof of either intentional or unintentional damage to his unit, then I'd like to hear that....seems to me that it would be easy to tell the difference between a naturally occurring crack and a hole intentionally punched in a heat exchanger....the question is who and when...some pics would be helpful....

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply Good Answer (Score 2)
2
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33231
Good Answers: 1807
#2
In reply to #1

Re: Cracked Heat Exchanger

10/30/2019 12:42 PM
__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply Good Answer (Score 2)
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32044
Good Answers: 838
#3

Re: Cracked Heat Exchanger

10/30/2019 12:56 PM

One option is to rock-up with a scrap <...residential aluminized heat exchanger...> from elsewhere and a <...screwdriver...>, and to invite the <...customer...> to damage it by way of a demonstration.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply Score 1 for Good Answer
Guru
Fans of Old Computers - ZX-81 - New Member

Join Date: Feb 2011
Location: 18N 65W o
Posts: 989
Good Answers: 27
#5
In reply to #3

Re: Cracked Heat Exchanger

10/31/2019 7:40 AM

While this is a great idea if you were a crash investigator for the NTSB, the O.P. is dealing with someone whose mind is already made up. He is in a lose-lose situation. Best to cut his losses and follow S.E.'s advice below

Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32044
Good Answers: 838
#7
In reply to #5

Re: Cracked Heat Exchanger

10/31/2019 8:31 AM

Therefore any further comment would be superfluous.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 3990
Good Answers: 144
#9
In reply to #7

Re: Cracked Heat Exchanger

10/31/2019 10:05 AM

Your suggestion has had merit.

__________________
High Tolerance is Beautiful
Register to Reply
4
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33231
Good Answers: 1807
#4

Re: Cracked Heat Exchanger

10/30/2019 1:50 PM

As anyone in the business knows, it is best to take a compromising approach to situations like this.....What exactly does the customer want? Does he expect you to replace the exchanger for free?...this is out of the question....so what can you do to arrive at an agreement, offer a reduced price, don't admit any wrongdoing or liability, but try to help them in this unfortunate circumstance...It's always best to come to a solution that is satisfactory for both parties....unless the guy is just crazy....then just walk away...it happens...

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply Good Answer (Score 4)
Commentator

Join Date: Nov 2007
Location: Western NC
Posts: 92
Good Answers: 3
#6

Re: Cracked Heat Exchanger

10/31/2019 7:51 AM

Has anyone worked on it before you? If so, how long ago? I'm not saying what he states is impossible but the likelihood of it is very slim indeed. Does he say why he thinks you caused this? Does he offer any proof? What is his level of knowledge? I'd tell him if he's so smart to fix it himself. Everyone in life has to realize you cannot please all of the people all of the time.

Register to Reply
Active Contributor

Join Date: Oct 2014
Posts: 14
Good Answers: 2
#8

Re: Cracked Heat Exchanger

10/31/2019 9:02 AM

I am a Master Level Tech in HVACR of 30 years. The quality of gas fired HX's has been steadily going down for the same amount of time. This is because everything has been monetized and everything is literally evaporating because of this negative mindset that dominates the production of machinery which one worked much better. I would be curious to know what the Delta T of that box was when it was running right. The other thing is to check out failure reports from the OEM on the same type HX. There is often times known issues on particularly lame designs. I worked on some very sorry package HX's made by Carrier-Bryant in the early 90s that were actually 2 piece affairs with a flange that was gasketed and screwed on at the burner face. These were very dangerous. What I determined way back in 1990 is that residential service is a very unsavory line of work. People seem to think Heat and Air are some kind of inalienable rights that they should not have to pay for.You are an enemy from the minute you walk in the door.....

Also the trend in install quality has been mostly going straight down since those days as well. Much of the gear has undergone numerous redesigns that have made it dependent on very unreliable solid state " Tech " which in most cases are just bad reinventions of the wheel. Its mostly all very temperamental, unstable, cheap, mickey mouse gear. Eveyrthing has become volume driven and all the equipment is very short lived and throw away Technology. Only in the industrial end where things have to work better is quality still sometimes seen.

Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 3990
Good Answers: 144
#10
In reply to #8

Re: Cracked Heat Exchanger

10/31/2019 10:16 AM

Funny you should say that.

A couple weeks ago I went to a neighbors to get their "Whisper Air" heater up and running.

It looks like some 90's junk.

I never worked on a unit without a thermocouple. What's that about?

A bend of the heat sensor into the weak pilot flame did the trick.. for now.

The unit felt like it was made from tinfoil.

__________________
High Tolerance is Beautiful
Register to Reply
Guru

Join Date: Jul 2016
Posts: 1243
Good Answers: 89
#11

Re: Cracked Heat Exchanger

10/31/2019 3:59 PM

If the metal is so brittle to crack on impact, there may be no bending inward at the edges, indicating a blow from the outside. My guess would be an inclusion in the steel that was missed before treatment, the aluminizing holding it together for a decade perhaps, the expansion & contraction of heating cycles finally working loose the inclusion that was mechanically welded in place by the force of the stamping mechanism at build time. And not really a ‘weld’, more like a press fit.

Register to Reply
Guru

Join Date: Jul 2016
Posts: 1243
Good Answers: 89
#19
In reply to #11

Re: Cracked Heat Exchanger

11/01/2019 6:02 PM

Not an inclusion...

Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32044
Good Answers: 838
#12

Re: Cracked Heat Exchanger

11/01/2019 9:27 AM

The pressure rating of <...aluminized heat exchangers...> if of interest in the discussion, as is the pressure test record of the <...damaged...> one and the date it was carried out, as well as the date that it is alleged that the <...screwdriver...damaged it...>, as well as the date(s) that the <...we...> were on site adjacent to the <...damaged...aluminized heat exchanger...>. If it can be shown that there is incompatibility in the dates, then the <...we...> is in the clear.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Participant

Join Date: Oct 2019
Posts: 3
#13

Re: Cracked Heat Exchanger

11/01/2019 11:07 AM

Thanks to all who have responded. Attached is the picture we took of the cracked heat exchanger. Would you consider this a cracked heat exchanger, failed from normal wear and tear? Thanks to all who have commented.

Register to Reply Score 1 for Good Answer
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33231
Good Answers: 1807
#14
In reply to #13

Re: Cracked Heat Exchanger

11/01/2019 11:19 AM

Looks like a manufacturing defect to me, but would need a closer look to confirm...

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21024
Good Answers: 793
#16
In reply to #14

Re: Cracked Heat Exchanger

11/01/2019 3:37 PM

I disagree. To me, it looks like impact from a fairly sharp object. That still leaves open the question of whodunit.

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Participant

Join Date: Oct 2019
Posts: 3
#18
In reply to #16

Re: Cracked Heat Exchanger

11/01/2019 5:26 PM

Thanks for your response. I did indeed take an aluminized heat exchanger and put a hole in it with a screwdriver and hammer. I did not have any radiating cracks appear around the hole. This is the picture of the hole as we found it, and the next day or so the customer accused us of damaging her heat exchanger. Have you seen cracks appear immediately when an aluminum heat exchanger is damaged? Thanks for your response.

Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 3990
Good Answers: 144
#15
In reply to #13

Re: Cracked Heat Exchanger

11/01/2019 1:34 PM

Looks like porosity, temperature, and time did that.

Whack other areas with a screwdriver while filming it with your phone.

__________________
High Tolerance is Beautiful
Register to Reply Score 1 for Off Topic
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21024
Good Answers: 793
#17
In reply to #15

Re: Cracked Heat Exchanger

11/01/2019 3:41 PM

I disagree.

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33231
Good Answers: 1807
#20
In reply to #13

Re: Cracked Heat Exchanger

11/02/2019 6:00 PM

It's hard to tell from the picture....So is the surface dented where the hole is, as if pressure was applied, or is it uniform in shape and contour..?

I would say if the surface is dented, there was some pressure applied, if it is undented and the contour of the exchanger looks uniform then it is a manufacturing defect of some sort....

What is the age of the unit?

__________________
All living things seek to control their own destiny....this is the purpose of life
Register to Reply
Guru

Join Date: Mar 2007
Location: City of Light
Posts: 3943
Good Answers: 182
#21
In reply to #13

Re: Cracked Heat Exchanger

11/27/2019 10:21 AM

It is a pity not to have a picture from the side.

Cracks started at edges which means either that the wall is made of a brittle material ( and it is not) or that a high stress was generated and the strain concentration went over the fracture limit. But for this a load should be applied and according to the cracks several times.

If I understand the picture part of the wall was bend toward OUTSIDE. If a screwdriver was pushed on the wall from OUTSIDE then the wall should be deformed toward INSIDE and no part of it could be bend outside.

It is a contradiction some where and without more pictures it is difficult to come to a result but the counsel to find a compromise solution is the best.

Register to Reply
Register to Reply 21 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

JE in Chicago (3); JWthetech (1); nick name (1); PWSlack (3); rickmoore69 (1); rwilliams (2); SolarEagle (5); stanley johnson (2); StarCat (1); Tornado (2)

Previous in Forum: Trends in Trainings on Engineering Standards   Next in Forum: Using the Pressure of Water and Rising Bubbles to Produce Energy

Advertisement