A nice anecdotal story with very few facts.

Is this same company that installed the system in question?

What are size and model numbers of existing equipment? Size area that this system serves? Any operational issues with this system?

Going down your list.

Cracks and leakages around plenum at furnace can either be repaired or replaced. Shouldn't be a big deal. Who installed the original plenum?

How many returns do you have and what are their sizes? Seems odd if this was not pointed out when this system was installed.

New ductwork. Why? How was this determined? How old is your ductwork?Insulation quality? Moisture issues? What moisture issues? Be specific.

I am highly suspicious of your story. Sometimes a good company can morph into a bad company when they get too big for their britches.

You need another dealer to take a look at your situation. And don't tell this dealer what the other company advised.

Just on the surface, you have not said anything that indicates your existing 10 yr old system should be replaced.

I can't really comment about the venting issue without seeing the job.

Something smells here even on the Internet.

IMO

This post was edited by tigerdunes on Sat, Nov 15, 14 at 12:20

agreed.

what, if any issues have you had with the system
in the time you've lived in the house?

why couldn't cracks at plenum (supply? return?)
be mastic sealed.

why remove ducts & replace with flex?
what are ducts now? hard pipe?
if they leak///why not just mastic seal them?

you need more options from another company.

we need more info, pics would help.

best of luck.

How are your heating and cooling bills?

TD

I will undertake to get more information and report. I'll get a picture of the vent. But, I don't think it will tell you a lot. I've gotten two other referrals that I will be calling on Monday.

This system was existing when we bought the house 10 years ago. The company we are dealing with installed the Trane heatpump 10 years ago. The furnace and ductwork were existing installations.

Let me vent for a moment (No pun intended), I pay for twice yearly service on three units. No one was going to tell me about this problem(s) until I brought it up. Why is it suddenly a crisis? That pisses me off. I'm not one of the homeowners that come on here and want a Cadillac for Yugo prices. I'm willing to pay what is necessary for an efficient and reliable system. The hard part is determining what is necessary. I've got Trane and we are talking about Carrier replacements. It's not like I'm buying ACME brand. Rant over.

We only have one return in a 2,000 sq. ft. conditioned space. More returns seems prudent. Our heating and cooling bills are not out of sight and we haven't seen any changes in billing that are concerning.

We only noticed the situation and made the phone call after a landscaper hit our gas line during a project. The gas company had to relight the furnace and commented on the plenum leaks. We had moisture problems in the crawl years ago, but landscaping changes took care of those issues. The crawl is only partially covered in plastic.

I'll keep you posted.

How old is furnace? It has a pilot light, no electronic ignition?

One return even if sized correctly which is doubtful is not enough. You should add at least 2 more for improved comfort and airflow. Do you have a filter cabinet for this system?

Again it would be helpful to know models and sizes of existing system's components. I assume a new matching evap coil was installed at same time as new HP 10 yrs ago. Correct?

The gas company noticed the plenum leaks? Makes you wonder about the effectiveness of those regular service contracts doesn't it?

TD

This post was edited by tigerdunes on Sun, Nov 16, 14 at 8:26

It seems that you have few problems, each of which may not be that difficult to solve without a total system replacement:
- Add more cold air returns. This is a good idea, but certainly not a crisis. Have it done at a convenient time.
- Seal leaks in the plenum. Installers like the convenience of flexible ducting, but that does not mean the older site-built or metal ducts are bad. Unless they have been damaged in large areas, it should not be that hard to seal leaks, or replace any bad sections. Flexible ducting is okay, but certainly not an upgrade compared to good quality metal ducting with good air flow. However, for convenience you can use flex duct for the new returns you add.
- Replace the exhaust vent. I have seen double wall ducting used for the exhaust, but I'm not sure there is code that would require immediate replacement as long as its kept out of contact with flammable building materials. I don't consider switching to all electric as a good choice unless you are very far south and seldom need the backup heat.
My last two houses used single wall ducting for the exhaust and nobody mentioned it as a problem. Even if you have to tear open an interior wall to replace the exhaust, that should not be expensive. It will be messy to open up drywall for access and patch it all back correctly, but nothing compared to the cost of installing an entire new system.

Companies often like to install new instead of fixing the old (and yours is only 10 years old). However, its your money and it does not sound like a total replacement is required.

Bruce

I took the advice of the group. I found a qualified professional. He took a look at the issues.

Normally, this guy does mostly commercial. He has a small group of referral only residential customers. He said that there was no need to replace either the 10 year-old Trane heat pump or the slightly older 80% efficiency backup natural gas furnace. They had more years of satisfactory service.

He did warn me that coolants would be changing in a year or so. The old stuff will start to get scarce. That's not a problem until the heat pump springs a leak.

He suggested for immediate attention he would remove all the stopgap tape and mastic. He would properly align the plenum and clean the coil while he had access to it. Then he would button it all up.

He agreed that the vent pipe was fine as is. I told him we would be doing a renovation in the near future and would undertake to address the situation when the wall was opened. He said that a new double insulated pipe could be inserted through the roof, if necessary. But, as things currently stood it was okay.

He said to develop a phased plan. We will think about adding more returns replacing duct work in the future. I like how he addressed things.

We felt like we were dealing with a used car salesman when we were dealing with the first guy. I called and cancelled the replacement appointment. This company has lost my business.

I know I didn't provide all of the system details, but I appreciate the second opinions. If it doesn't feel right, it probably isn't. You've saved me some money and a lot of wasted effort.

Just curious, the age of existing furnace bothers me. What is size and efficiency. And pls advise, it has a pilot light? If so, I would give serious consideration to replacing.

IMO

I was incorrect in my first description. The gas furnace pre-dates our ownership of the house. But, it's not that old. It does not have a continuous pilot. Rather, it's electric ignition. It is marked 80% efficiency. As a back up unit, it should be fine. Natural gas is not that expensive in this area.

The salesman engineer just called me. He wanted to know why I had cancelled the installation appointment. I told him that I never spent that kind of money without a second opinion. I would get back with my decision.

I've already decided to do a phased project. We'll repair the leaks. Then, we will think about new flex ducting and adding some more returns.

I found a neighbor who had dealings with the new salesman. He threw him out. Apparently the salesman always suggests complete replacement rather than service. This will come back to bite this company in the end.

Thanks everyone for your help. I'm glad I asked for your opinions.

Flex is OK for runs but not for trunk lines. I prefer metal. R8 insulation at a minimum.

I would start on the plenum repair. Have you actually seen it?

I think you have made a wise decision. A perfect example of a salesman looking after himself not his customer.

I also would reconsider these service contracts. Once a year is plenty. You should change dealers altogether. On the system in question, how do you filter your return air? 1" throwaways? If and when adding additional returns and you don't already have one, I would consider a filter media cabinet assuming good access.

On your DF system setup, you have an outdoor sensor that cuts off HP at certain temperature?

IMO

This post was edited by tigerdunes on Tue, Nov 18, 14 at 9:20

Thanks Tigerdunes.

The DF system has an outdoor sensor that automatically performs the switch over. Today, all of the backup systems are running hard. It's 20 degrees Fahrenheit. Sunday it will be 70. Go figure. Can you imagine that the salesman wanted to do the new system this week? Crazy.

We cancelled our maintenance contract, too. You bring up a good question. What is the appropriate maintenance schedule? Every six months, once a year. Don't the filters need cleaning or changing twice a year. I have long hair pets. Please advise.

What size filters? Where are they located? This is something you should change rather than relying on a service contract whether once a yr or twice a year.

IMO

Personally, I would do filters myself. They are not that difficult and usually readily available. I use the 1" kind and replace every 3 months or so, depending on usage. My thermostat tracks hours used and suggests change times.

I like media filters myself. they've worked well when
I had a long haired dog, and with current short haired dog.
changing the return air filter grill to one that fits
4" media filter is less costly than filters with 1" lip
that retrofits into existing return air filter grill.

what is your location?
size of system, model numbers & size of house?

I like the idea of doing upgrades in phases, its how
I stage many of my jobs.
but while in planning stages, evaluate existing
ductwork/plenums. size the ducts & plan for
new system by using manuals J, S & D.

use this time to get it right, and the upgrades/changes
will be long term.

best of luck