That is a good question. My thoughts are, if you were speaking practically, in real world operation, the exact bulb location does not make too much of a difference. Provided it is securely fastened and at least marginally insulated. (I believe air conditioning and refrigeration is not an exact science and what works on one job, may not work on another, experience and experimentation on start up and maintenance check ups are what works)
Originally Posted by keviekev70
My father says he has seen an instance (a large capacity valve) on a particular installation, where the bulb capillary was pointed downward, above the txv power element, and the valve sort of "hung open" and over fed. Rotating the bulb 180 degrees fixed the problem.
From memory, a Carrier recommendation was to install the bulb a minimum of two piping turns (if possible) from the evaporator outlet to ensure good refrigerant mixture before the sensing element. Also, to locate the bulb on a vertical section of piping (if possible) and if horizontal, to locate the bulb 45 degrees from the bottom of pipe to protect against oil insulation from true temp and possible liquid flowing along the bottom of pipe.
I decided to dig out some books and review. I don't have any links because I prefer books. But anyway, the old Trane Reciprocating Air Conditioning Manual suggested placing the txv sensing bulb upstream of the equalizer line as keviekev70 suggested. Reason being from a possible liquid leak-thru from the high side to the low side via the equalizer line, influencing and falsely throttling down the valve. I myself have not experienced this, possibly due to modern expansion valves being manufactered with better and more precise designs. The Carrier system design piping manual had no real details on the exact location of the sensing element, however the IOM for the Carrier 38AE condensing units suggested via an evaporator piping layout diagram the appropriate location for the txv bulb as upstream of the external equalizer line. The McQuay refrigerant piping manual also depicted the txv bulb upstream of the external equalizer line.
To summarize, technically it is correct to install the piping in that manner.
Having plenty of hands on time with this installation however, I can say that it performed well.
Last edited by AiResearch; 01-04-2013 at 06:30 PM.
These days its seems it more about cheap and fast...
Your are correct ,,,,caplilary up if vertical. If down you will have issues!
Cheap and fast..
We were just talking about that today. Contractors doing installations for peanuts, spending little time on the job and exhibiting no workmanship, making the other contractors who do work right, look like crooks, overcharging people because all a/c jobs are the same right.
What they are doing is de-rating the trade and industry as a whole, while hurting others and themselves in the long run, preventing businesses and trades people from making a decent living and profit. Decent and fair.
The consumers are at fault for looking at none other than the price, and contractors are at fault for complying. If every contractor charged a fair amount, people would be forced to pay a solid price for a solid job.
Doctors work miracles, and Air Conditioning was miraculous when it was in infancy, but now it is granted and entitled. But it is not that simple.
Funny thing is.. Certain organizations realize the complexity and necessity of quality air conditioning, and they pay dearly for it. They are proud of their systems and I can see them almost enjoying writing the check. Google and their obscene data centers for example.
But then again, they depend on HVAC, so it does boil back down to the dollar.
There is always room for workmanship in even the most budget jobs. It is the only way for me.
If it gets much worse friends of mine may see my face at the counter of Joe Smith's non-corporate hardware store.
With a very sore heart.
Very well put. I too am a third generation in the trade, having learned it from my granddad and dad. I strive to be as good as they were, but will never make it. Yeah, maybe I am a more accomplished troubleshooter with the tools that we have available these days, but they could troubleshoot with a thermometer, smoke tester, and an analog set of refer gauges. And they weren't wrong very often. We as a society have sacrificed quality for price. Shame on us.
Originally Posted by AiResearch
Techs who try to become contractors are de-rating the trade on many levels, most can't even pay a decent wage to keep tech's with a stable job.
Originally Posted by AiResearch
Most tech's are jumping around doing fly by nite jobs, doing the jobs companies should be hire to do.
Big Property owners, general contractors are hiring their own hvac tech's and putting them payroll to cut-back from using a hvac company.
All this with technician's shortage I've been hearing all these years is all BS IMO.
Technicians are available, hvac companies just aren't keeping these techs stable, the techs would go out and flood the market with the lowest prices just to get the jobs and to make more than they would normally make as an employee.
IMO most of these one man show popping up shouldn't be operating killing a profitable market.
I'm my experience, it has been the opposite. The mom n pop shops are doing better work than the big guys with many workers. (exception being large mechanical contractors who have a standard of excellence and get plenty of money for their large installation and service jobs)
Originally Posted by keviekev70
I think the reasons for this are several. First, the chances are greater with a small company to have a multi-generation work force, where teachings are passed down and around. Second, the small shops generally can't afford to mess up, lots of times the company principles are on the job and working, or will at least visit the job to make sure everything is right. Their name and livelihood is on the line. (with bigger companies, the customer may not know who they are going to get, and that guy just gets paid by the hour and could not care less, with lots of room to hide things among the muck)
And finally, the big shops have lots of hands to keep busy, and that means lots of jobs, which leads to underbidding, buying jobs, and rushing through just to keep the books turning.
It takes much less to make a big difference with a small business.
The flunkies who somehow get a license dont make it very long and are not much of a concern as far as competition.
Just my opinion and reflections on the area where I work.
So true. The last job we just did the customer was so impressed with our installation they said it was all the detail we payed attention too. They were also saying they were so glad they did not go with Costco. That is how they think of it, it is not the company that is working the Costco store it is known as Costco. If I was doing all the marketing they do I would be thinking what a joke to be doing all this for Costco and to not be building up the contractor company name. So no mater what kind of job Costco does it is no reflection on that contractor. And if he does great work it does that contractor no good as he is not building up the name of his own business he is building up the Costco name. I would never sell out to a big box store, but then I have built up our company and our company name for 40 years.
That's some quality work there, buddy! Commercial DX piping can be a poor proposition because the contractors out there have so few pipefitters who know WTF they are doing when it comes to DX. I have seen way more jobs that were butchered than not.
I saw one recently where the customer had (4) dual circuit 30 ton splits. Each circuit had (4) 30 ton TXVs. 120 tons of TXV for 30 tons capacity. Flooding and hunting like crazy. Overcharged by at least 60# each
"There is no greater inequality than the equal treatment of unequals."
One of those fancy-ass guys huh? Probably a navy man.
I would say one with a level of sophistication.
Originally Posted by deerwhistle
Nice tidy work!
Heres a vid i took of a txv leaking down the equalising line, think this is about the second one i've seen do it in 20+ years, other one was a Danfoss valve.