Why is the installation the most important part of choosing a furnace?

Page 1 of 2  
I've been doing some research in preparation for next year when I will be replacing my gas furnace and a lot of people seem to mention that the make of the furnace doesn't matter as much as the quality of the installation ... but what exactly does that mean?
The furnance comes preassembled from the factory more or less so it's not like the contractor is building the thing. How can a poor installation ruin a good furnace? What makes it a poor installation? Are we talking about the preparation part of the installation, like getting the correct size (BTUs), proper chimney size, correct vent sizes, etc. ... or are those persons refering specifically to the installation part ... what can go wrong during that part?
Thanks, Harry
P.S. The more technical the information you provide the better ... thanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Well I have seen plenty of systems the wrong size (too cold/hot).
And I have seen plenty of systems where one or more rooms are colder or more hot than the others.
And then plenty of systems where it may be very cold around the outside walls, and the problem with this is that the return ducts are located on inside walls in each room (to save money on duct work I suppose).
*But* I have seen most modern commercial high-rise buildings which have very good systems all around. Every room perfect temp.!
"Harry Muscle" wrote in message

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
However, since this is a remove and replace situation, will any of the points you mention really apply? The house is prefectly comfortable as is right now, it's just that the existing furnace is 35 years old.
The reason why I posted this question is that the comments I've read about the installation being most important are usually part of answers to persons just like me ... replacing a furnace, not a brand new installation. I can understand a brand new installation where all the duct work needs to be run, etc. That's a lot more planning and more chance of things going wrong like you mention. But what can go wrong when you're basically swapping in a newer furnace.
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have seen situations where the air flow was more than the old unit and the duct work was not modified - caused problems. If same BTU, same air flow, then this will reduce a lot of potential problems.
Then could be problems with a newer high efficiency unit. Old venting for exhaust gases might not be right. Also venting for fresh air might need to be modified.
Then new code regulations may apply and modifications may need to be made to bring everything up to code.
Old thermostat may have problems with new unit.
And of course do they know what they are doing? Know codes, wiring, etc...
"Harry Muscle" wrote in message

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

not as critical...however it never pays to have a hasher do the work.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Not going to get techincal, but I will go to the extreme. Not trying to be funny, but think about it:
Do you have a neighbor that has a 14 year old kid. Good! Tell him you will pay him $100 to hook up your furnace.
There! You're all set....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What about the electrical, sheet metal and other plumbing connections?
I assume you did your manual calculations, for capacity and for air flow. You know how to calculate the volume that your duct work can handle right?
What makes it a poor installation? Your kidding! What can go wrong,,,,, gee the list is almost endless.
If your changing exact model numbers and the same manufacture then you MAY have an easy go of it.
Lastly a qualified,licensed installer warranties the installation and equipment. Most of the mechanical manufactures I know do not sell to homeowners and will not warranty anything directly to an home owner.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Endless list...... Can you offer at least the first few entries to give us a flavor.
In the OPs situation perhaps installation and features/efficiency are more balanced in importance.
In a furnace replacement, at least some sheet metal will need to be bent/formed to interface the new furnace to the old ducts. Naturally, here is a place where workmanship can matter. Lead time can be effected too if they need to go to a third party shop for sheet metal or can do it on site in the back of the truck.
Furthermore, you may have chosen a furnace with different features which must be accounted for. Building codes may have changed over the years so what was done then may not be acceptable now. A good installer will know this as second nature but a green guy might just swap things over 1 for 1 not knowing an upgrade was required.
Newer model furnaces have complicated control systems and sensors not found on older models. It may not be obvious to a new owner or green installer if something is set marginally wrong and the procedures for adjusting those things may not be obvious. Reading the manual and calling tech support can help but you need to know when you need to do that.
IMO the make, features and efficiency are most important while you choose a model but the installation is most important when choosing a dealer/installer. Since most dealers sell limited models and brands, You will need to find the optimal point between these two factors. I would say that if a dealer can answer your question satisfactorally, then use him.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

Absolutely right. They are both important. I would just add that reliability/longevity is also important for brand choice.
We did this about a year ago, and had about six or seven companies quote the job (I know conventional wisdom is 3, but we just kept going until we felt we had the right combination). You want a good installer, sure. But if the equipment fails in 5 years the quality of the response you get will have more to do with the manufacturer than the installer. And of course, a reliable brand will be less likely to fail in the first place. The installer we chose spoke authoritatively about the reliability/quality of the equipment he was recommending, which gave us confidence in both.
Good luck.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There were some other responses and I'm going to add mine.
You hire a gent to install the furnace. It is 'preassembled', but does he really know the right way? Does he know the local codes? Does he know that brand A has a certian quirk the brand B dosen't? Does he service it and know how to work on it if and when it goes bad?

That's it....

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Installation generally means two or three guys more interested in getting off work than anything else. This means they'll take whatever shortcuts they can and not really care about what they might do to your house, either cosmetically or functionally.
We replaced our furnace and A/C a couple of years ago with similar units and if I wasn't home and asking questions I would have had some pretty ugly hackery done to my house, including fresh air vents where I didn't want them, wiring where I didn't want it and a water heater moved(!) where I didn't want it. All of what they would have done was for their convenience in getting in and out as fast as possible.
As far as the specific equipment goes, generally that's decided pretty easily by the sales guy who checks what you have and how well it works vs. what he wants to replace it with. I agree that it's pretty largely a drop-in replacement, but *how* its dropped in is what matters.
I'm sure there are some installers that are good as gold, but based on what other homeowners in my area have complained about, I think they're rare. Business, as usual, relies on volume and speed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Harry how bout this - pay somebody to develop the specs, including pipe layout, sizes and locations for intake and vent - then use your "Muscle" and install the sucker yourself. I got a quote on a new HVAC system installed with high efficiency air for around $7K for a 2,400 sf 1 story structure. Some parts of the country have really pricey HVAC contractors - lots of demand now. At least get a quote from a good installer/dealer and get an idea of about how much you could save - you might find out your time is more valuable than your savings on a hourly rate.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ever see a chimney vented down hill? Ever see PVC venting that did not drain condensation properly? Ever see improper materials used for supply air duct? Wrong gas pressure, or improper gas line size? Ever see condesate drain from the AC coil improperly and ruin a perfectly good furnace? Ever see some one replace a furnace where the old duct work as inadequate for the new unit, but it was fine for the old unit? I have seen so much hacked up, shit installs I wish I could do something myself to keep the crooks from ever doing business again! There is so many points as to the difference to a good install compared to a great install it would be impossible to list them all. USUALLY experience will lend itself to a better install, assuming the installer gives a shit what his work looks like! One of the worst installers I have ever seen worked for the same company I work for! ( No longer!) He knew it all, but in reality know very little. He would do something wrong and you could show him in the install manual proving he was wrong, but no, he knew more than the manufacturer!
When I do an install I take a few minutes to go through the manual, even if I have installed the same equipment before, things change! I check my gas supply to make sure it is adequate, even on a change out of similar equipment. I measure duct work to make sure the duct is of reasonable size, too big or too small is bad. I lay cardboard on the floor in the working area to catch drips of pipe dope and PVC solvents. I use a level to get pipes straight and neat. On start up I check amps, gas pressure, temp rise, blower speed, AC pressures, super heat/sub cooling, and more depending on what is required. When it is all done, I get a broom and dust pan from my truck and sweep up the area, perhaps even wash the floor if needed. I have seen installs where they set the furnace in place, hooked up the gas, duct, and vent then start it up and run. . Not one test was made to ensure it was running properly and the install manual is still sealed shut, rolled up in the furnace. Greg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
(snip)

(snip)
He
if
size,
rise,
gas,
rolled
Hope I can find somebody like you in my town, when I break down and contract for the furnace upgrade I need, sometime in the next year. Even though I grew up in the construction business, and basically know what is and isn't good workmanlike practice for mechnical installations, I dread the prospect of having to play roulette with the local tradesmen, and walking that fine line between micro-managing and pissing off a good guy, and staying away on install day, thereby rolling over for a possible quack. As an installer, how did you feel about the owner standing there and watching, as long as they kept their mouth shut and didn't get in the way? (Still getting over a bad experience with a plumber that came highly recommended, but made stupid mistakes, and had to be called back twice for followups. I wasn't in the house for his work, but probably should have been.)
aem sends....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm assuming the installation manual comes with the furnace (ie: not something bought seperately) ... so if I were to read it from cover to cover would it explain things enough for someone good at handy man work to understand it and be able to double check that the HVAC contractor did most of his work correctly? Or in other words does the installation manual outline the correct gas pressure, gas line size, how to properly drain the AC coil condensation, how to know if the existing duct work is adequate, etc.?
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The manual will have wiring diagrams, utility requirements, space requirements.
It will have nothing about good plumbing practice, local codes, duct requirements, etc. That varies for each situation so the installer must know how to do that and do any calculations for sizing and the like. You won't know if the proper procedure was followed for hooking up the line set to avoid contamination.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The reason why the installer is so important is because most houses have crappy installed HVAC, even new ones. A good installer will be able to properly size, fix ductwork problems, etc. Now if your existing system is working perfectly and you can buy one the exact same size and install it yourself, and pay the pros do the startup and fill freon I say go for it, but that is probably the rere freak exception. As another example, my house probably now has an oversized furnace bacause it had no insulation when I bought it, and I insulated it Even if my system was working perfectly before (it wasn't) I certainly will want to make sure that any new system is properly sized and can get proper air flow to every room, etc.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm curious, where do HVAC contractors get the formulas, etc. for doing all these calculations? I'd be quite interested in getting my hands on it just to see how it's done ...
Thanks, Harry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Several years ago we suffered a nightmare of a poor installation of a furnace. The new oil furnace needed better flow through the chimney which we found later was partially blocked and we had to have it cleared and lined. Furnace also backfired and poor installation of a simple thing like changing the filter replacement around left an unsealed vent and smoke went from furnace room throughout house. We had to have the house cleaned 3 times from the original cracked plenum and the chimney and backfire problems of the poor installation. Took about a month to straighten out the mess and insurance which installer had to pay.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Both matter ... if the install is bad though the brand of furnace wont matter. So install quality is first. also a good installer will not be selling junk.

Too small or leaky air ducts.. leaks will cost you a fortune, too small will not provide sufficient heat to rooms farthest from the furnace..and if you want to add cooling later small ducts will be a problem.
What makes it a poor installation?

Bad venting can fill the house with carbon monoxide.. thats fatal, the wrong vent pipe material can cause a fire.
Improperly secured and sealed duct can come apart later.
Phil Scott HVAC contractor/ mech engr since 1741

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.