I suspect the contractors if nothing else are using different design temps. I think some do lead calculations, but beleive that the "Design temp" should be the highest temp you'll expect to see. So because once ever 3 year you get a 95F heat wave... you should design for that.
I hate to say it but personally I do believe 86 is low for our area, we have been 88 for the past two days and hit over 100 on average 3 days a year and we will be at 90+ for a week or two. Even still the difference in size between 86 and 95 in our area is still fairly minimal. I would guess the "load calculation" was not a true load calc. I have customers tell me all the time the other guy did one and then procedes to tell me how many registers he has so I can do mine Nope, time to measure windows and they look at me funny like, nobody else did that.
Originally Posted by motoguy128
The sad truth is that MOST hvac contractors don't understand simple thermodynamics. The AC is effectively a black box that puts out a certain amount of cold air. Each register will use a certain amount of air. The only math needed is add up the registers, and that is how big of a unit you need. It's horrible, and the number one reason the trade has such a bad reputation in the residential sector.
The sad truth is that SOME hvac contractors don't properly identify the cooling and heating losses. Their view: AC is effectively a black box that that can be properly sized using rules of thumb. Each register will deliver a certain amount of air (cooling capacity). The only math needed for a corner cutter is adding up the registers, pad the numbers, and that determines your capacity. It's not accurate. It may lead to comfort and efficiency problems,and is a short cut that needs to be avoided.
Originally Posted by CraziFuzzy
There, now that I've got the inflammatory post that throws MOST of the trade under the bus fixed, teg is still no closer to a solution.
The internet has limits to its usefulness. To get down to the truth and have a professional outcome, you need a detail oriented pro, using the most advanced technology, and a track record of results. Call Sky...He might offer the same capacity system as one of the others, but his attention to detail will prove why.
was throwing noone under the bus, and I'm pretty sure most HERE agree with what I said. You can't take the population of this forum as a representation of the trade as a whole, as just by going though the effort of joining this forum, you have already shown a higher level of care for the trade. Most in the field got there because they heard it paid well, and didn't need college, and there was no other reason for them. They have no interest in providing a great end user experience, only getting the invoice signed and on to the next pay check. They will gladly oversize a system because it will eliminate the risk call backs - few people will call a contractor back due to poor comfort levels or system efficiency, as long as the system is cooling the space good enough. They will then complain about the electric company charging them too much, instead of the hack hvac contractor that is throwing their money away. As I said, I am not talking about - well, anyone on this forum - this is the good part of the industry here... but it is NOT the majority, or even remotely representative of it. What are the odds that any of those three quotes came from a contractor that even knows this forum exists?
This thread is not atypical of the common residential hvac experience.
Once again, thanks for not helping the op get closer to his solution or offering a flattering view of the industry in an open forum.
Some members here are business owners and don't need their credibility eroded with reckless remarks that could be read by anyone.
Concentrate on the thread objectives and be a professional representative of the industry( that's why you were given an AOP button).
Twilly says call Sky, he's a real pro.
No Heat No Cool You need Action Fast
The OP was asking why he had 3 different people give him 3 completely different recommendations - which I believe I answered accurately. HVAC, like all other purchases, are a buyer beware situation. He obviously already knows this as that is the reason he came here - I don't feel anything I said was detrimental to anyone worthy of his business, and he will likely, because of my comments, greater appreciate what a GOOD tech can do for him (in short, call SkyHeating). Are you saying i should have instead flattered the guys who just rattled off some numbers they were guessing at and lying to the OP about doing a load calculation? Would that have been better for 'the industry'?
Who is going to steal a simple motto ....
... Not harder !
that goes for both the Installer AND the Equipment.
It's Not Rocket Science, But It is SCIENCE
with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE
Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities
I stopped by the house on Saturday and was surprised by the load calc, the house has quite a few windows on both the east and west walls(over 100 sq feet of glazing) and actually came out to 34,500 BTU cooling load and 25,000 BTU heating load(exact figures not used for discussion sake) We are now looking at heat pump options, I expect about a $300 a year savings based on our electric rates and current natural gas rates/usage at the home. The homeowner said the people who guessed the 2 ton, the 2.5 ton and the 3 ton all did exactly that, guessed, two didn't even look at the windows just said a size, which i am surprised they undersized so much, usually they oversize.
We are currently looking at the XB or XR series heat pumps and Ruud 15 SEER Achiever heat pump.
I began doing HVAC/R service work back in 1974 & CraziFuzzy is telling it like it is; consumer's of our industry 'need to get educated' as do a ton of so-called service techs.
I started to tell the things I witnessed & then deleted it...
I will say that unless we require better educated & trained service personnel that truly want to do their trade justice, we are not going to have a highly respected trade.
In this Energy Efficiency age until we include the EE of the home & the duct system & airflow there will be insufficient utility savings for our consumer customers.
The customer needs to be educated & provided with the transparent realities essential to achieving optimal energy efficiency savings...
Print some hand-outs; include some vital info in your various print, radio & TV ADS. Potential customers will respect you for being honest & upfront with them before they lay their money on the line.
Every PRO on this forum could walk into nearly any home & show them a host of things to be done to achieve optimal heat & air performance. Some of those gross things that need correcting will be beyond belief.
We also need to quit citing the SEER Savings figures as though they are absolute in every situation, because the SEER that is actually achieved is predicated on many factors that have to be correct to achieve that potential SEER Savings.
Consumers will respect you for providing some reality based transparency in these core matters to them & their investment. It can help build customer/consumer TRUST.
If you're doing your best to do what is right regarding "Best Practices," there is no reason to consider these factual realities as something to hide or conceal from your potential consumers.