Wellll, what about safety???
Do the welds meet safe operation standards?
Is the coil static tested to at least a 4:1 safety factor over working pressure?
Are there flame control devices in place?
Who do you blame if it does not work? What about warranty?
What about emmissions? CO, CO2, NOx.
Efficiency? Fuel flow, nozzle size, pattern? Our oil fired coils use from 94.5' to 157.5' and gas fired coils from 136.5' to 183.75' depending on Btu. input and heat rise.
Which insulation to use? Do you need insulation at all? Many coils are now made with a cold wrap design to eliminate the insulation blanket.
Noise? Tight coils with high Btu input can roar like a jet engine.
Smoke on start up, run and shut down?
How and what do you adjust for each?
How green or black are you willing to let the smoke be?
Increased smoke leads to increased soot which will cause a coil to become inefficient and eventually could lead to a fire much like a chimney full of creosote.
Can you buy the components as well as someone who buys thousands of the same thing?
We buy Honda engines by the container load (500+) each month, we get containers of guns/wands/pumps direct from Italy each month.
Daimler-Chrysler/Ford/GM are extremely willing to sell you the parts to build your own car because they make a lot more money selling it to you that way.
You can buy a car at $20,000 or build your own for $60,000; your choice.
What is your time worth?
Do you do this every day and have experienced all of the potential pitfalls so you are prepared for them?
And so on.
IMHO, safe operation of any machine is equally dependent on the operator and the manufacturer. If the manufacturer has taken all reasonable efforts to comply with set safety standards and provide operator's manuals with directions for the safe operation and maintenance of the unit, then it is incumbent on the operator to use it in a safe manner.
Given a little ingenuity and knowledge, anyone can build anything they want. Unless they are exceptionally gifted and skilled it will most likely not meet the fit, finish, quality and safety standards of a product manufactured by someone whose business it is to do so. In other words, building your own is false econmics.
Many years ago I sold Mack trucks. A local municipality had a tender out and mine were $65,000 (Cdn). I was told by them that is a good price because "the Mack is good for 10 years".
The other tenders were at $40,000 so they decided they would buy them because they were saving $25,000.
But, they also said that the truck they are buying is only good for 4 years, they fix it for 2 then sell and replace it.
So lets do the math: Mack @ $65,000/10 years = $6,500/year.
Other @ ($40,000/ 4 years = $10,000/year) + (repair for 2 years @ $10,00 then sell for cost of repairs = $0 net) + (new vehicle at year 6 for no price increase or $40,000/4 years = $10,000/year).
So long winded example later my "expensive" Mack truck cost $6,500 per year based on what the customer told me.
The "cheaper" truck cost, on average $8,000 per year. ($40,000 for 4 years + $0 for 2 years + $40,000 for 4 years = $80,000/10 years)
Or $1,500 more per year for the "cheaper" truck. Like I said false economics.
A previous post lists the fact that his downdraft burners lasted two years and he is replacing them at $2,000 total or $1,000 per year for heat exchange coils. Is this economical, when a coil from Landa, Hotsy, Epps et al are warranted for at least 3 years and may cost $2,000 or ~$667 per year.
"The road to failure is paved with good intentions" Anonymous
Merely my $0.02. Hope this helps? Cheers.
