You plan on keeping and using your existing furnace on new AC condenser?

IMO

By furnace, what do you mean? I always thought of a furnace as the thing in the basement that makes heat. Our furnace in this house is a boiler. And yes we are keeping that since it works very well and isn't integrated with the AC at all. If a "Furnace" is something else in the AC world, fill me in! Haha. I'm clueless

Oh and for clarity, we plan on replacing everything but ducts.

What is the total living space in the house? Is it 2850 + 450 for a total of 3300 sq. feet? What will be the R value of the new insulation in the attic? What was the cause of the attic mold issue?

My first thought is 5 tons is too big for a house of your size and climate. Plus you live in a humid climate so you don't want to over size the unit. Has any contractor done a load calculation? I think a 4 ton condenser would be the proper size, but I would like to see a load calculation for confirmation.

You quotes need to include the model numbers of all the equipment (air handler, coil, and condenser). The quote is incomplete without this information. In addition the filter and thermostat should also be specified. Once you have those details you get opinions whether the price is reasonable or not.

Prices vary across the country. The best way to determine a fair price is to get 3 quotes on similar equipment and installation.

Post back when you have more quote information.

nat gas fired boiler?

IMO

Sorry for not being clear, Mike. The TOTAL square footage is 2850 (ish). Without the bonus room, it's around 2400 sq ft. He told me you need to calculate 400-500 sq ft /ton.

Trane XR13

"install trance 5 ton condenser with trane 5 ton TAM7 variable speed air handler"

Yes ours is natural gas

Oh and he walked around with a little laser pointer thing and measured things but I don't think he did a load test with the "J manual" or whatever it's called (sorry I've been reading the Internet too much)

Trane XR13 is not a 2 stage condenser. It is a Sgl stage model. I thought the XR13 had been phased out and discontinued. The XR17 is the lowest level Trane 2 stage condenser usually 16-17 SEER. Of course comes with a price. If staying single stage condenser, I suggest the XR14 model with best matching var speed air handler. Same available from sister company Am Standard.

IMO

THank you. That's very helpful. I thought he was beating around the bush a little when I directly questioned whether it was single stage or 2 stage. He was a salesman through and through and I felt like I was getting the "stupid woman" sell. Of course I am ignorant on these matters but that's why I'm here.

You are doing a good thing by doing your research and challenging the "salesman" with your questions. All questions are good, don't be afraid to ask. I was a little suspicious when you said a 2-stage condenser only had a SEER 13 rating. That didn't sound right.

"He told me you need to calculate 400-500 sq ft /ton."

This is a rule of thumb that leads to over sized equipment. Contractors who don't want to do a load calculation use numbers like this to calculate the size. Let's see, if you take his 400-500 sq ft/ton rule and divide it into 2850 you get 5.7 - 7.1 tons, but the biggest residential condenser is 5 tons. I guess he used this information to try to sell you the mini-split to cover the short fall. On top of this he is being evasive in his answers. I think you should eliminate this contractor from your list.

I think your biggest challenge is correct sizing-4 ton or staying with 5 ton. Can you tell me about your runtimes and cycles/hr this summer?

IMO

I wish I could tell you how long the cycles are. Unfortunately, I probably wasn't observant enough. I did have a repairman who told me I had great air flow through the ducts (which I don't know if is related at all)

I would say on average the system would run for 20-30 minutes then shut off for 10-20 minutes and then return. The cycles would be longer like 30-35 minutes when the bonus room vents were open. Of course that varied due to outside temperature changes. We live in the Northeast and most days are high 70s-mid 80s with a ton of humidity. Now on 90+ days it would run almost continuously with it set at 73. The system was 20 years old so I imagine a newer system could probably handle that load better. These are just my guesses. Like I said, reading everything now tells me I probably should have paid more attention. The system hasn't been working for 2 weeks now and my memory is already fading. :)

Oh and the other complication is that I haven't had any insulation in the attic for over 2 months due to the mold. We've been waiting for the MASS SAVE program to do it because we get labor for free and just pay for materials but of course that has led to a long wait and bureaucracy. They are coming Monday though. So that has also affected the run times and could have been the reason the whole thing broke anyway.

Most homes don't have duct work large enough to handle the air flow of a 5 ton AC. You need to find at least one contractor who will do a proper load calculation. The correct size and installation is very important.

Well the A/C and it's ductwork is original to the house. And the airflow was always fantastic so I am not sure that's a problem. But I think you're right that we need a calculation done. I think I might ask the mass save people who did our energy audit to do that once the insulation goes in. I also have 2 more people coming this week.

2400sf total? So your foundation is about 1200sf? Is it a 2 story? Multilevel?

2 story farmhouse (side entry) with mud room and garage with rooms above. Second story is bigger than first because of garage. 2400 without room over garage but includes laundry above mud room. Foundation is probably more like 1000

Well, with the new attic insulation, and your concern about humidity, I wouldn't oversize the equipment. A thorough heat load calculation must be done to ensure you get a properly sized system that will run long enough to dehumidify the air in the summer. I suspect 4 tons will be optimal which, with sealed ducts, should prove a very comfortable system. 2 stage is nice but adds cost, of course. Make sure you get the matching Trane thermostat for your variable speed air handler so that the dehumidification features of the system can be fully exploited.

Thank you for your thoughts, sktn77a.

Honestly, if the playroom (bonus room) can run on a 5 ton unit as is wouldn't it be best to maybe keep the 5 ton? Now that I have new insulation, maybe that room can be left open without any inefficiencies in the system like before. I know I'm paying to cool a room I don't necessarily use all the time but it seems silly to go through the trouble of window units and all that for a short season cost savings. Then I'd have to keep remembering to shut the door to that room (kids) and all that annoyance that goes with keeping that room closed off from the rest of the system.

Sorry for the rambling just thinking things through via this forum...

Husband doesn't want to spend any extra money on extras because we got hammered this year with this house financially. So I'm not sure if the variable speed thing will go in but we'll see what the next few quotes say.

whether 4 ton or 5 ton, sgl stage or 2 stage, you definitely want condenser to be paired with a var speed air handler.

IMO

Ok that's helpful. I have no idea what a *sgl* stage is but I can probably google it. From what I've read the 2 stage is harder to repair and I don't want that especially if the new systems don't last as long as the old freon ones. The var speed handler does sound nice. I'll push for that. I had always thought that you need the 2 stage for that effect but I guess just the handler can accomplish some itself?

I have been reading this thread and what I don' see any effort to get more estimates or a load calculation. A 5 ton unit will cost more than a 4 ton. It is time to stop gathering information and start shopping. Are there more installers in your vicinity? Look in the yellow pages and get recommendations from friends. Try some. This forum has given you good advice, but unless you start shopping you will be stuck with the installer that won't do a manual J

Have you been reading? Because I said I have another estimate today and one tomorrow. I also have the energy audit company coming Monday and I said I'd ask them. So I don't know what else I have to do to constitute effort in your book. I'm just gathering information and I greatly appreciate all the time and help people have given me here. They've been amazing and really kind.

single stage means only one speed of delivery of conditioned air....2 stage means there are 2 speeds of conditioned air, a high speed and a low speed. It can vary between brands/models but typically low stage or speed is about 66-70% of high speed or stage. Hope this helps. Of course the 2 stage condensers come with a price.

IMO

Thank you, tiger. It does help I just didn't know if sgl was another variation between 1-2 stage. It does help. Hopefully the guy that comes today leaves me with a better vibe. He was recommended to me by someone else and this company primarily does commercial not residential. I'm not sure whether that's better for me or worse but I'll find out. The local one-man operation guy came out but has never given me his estimate in the last two days. I'm not sure if he doesn't want the business or if he's backed up. So now it's down to the last 2 estimates this week unless I pursue another company for a new estimate next week. Honestly, I just want to get something scheduled so I can stop sweating.

You have to be a little patient trying to get the attention of HVAC contractors in the middle of the summer. They are typically tired and over worked. You are better off buying an inexpensive window unit for the bedroom to hold you over until you find a good contractor.

The bonus room is the hottest since it is getting the heat trapped in the garage below. You should look into improving the insulation of the garage ceiling. This is an ideal place for foam insulation.

I am also thinking you have a some duct problems. You stated that if you close the vents to the bonus room, the AC is able to cool the house. When you close off the bonus room you are cooling a 2400 sq. foot area with a 5 ton AC. With those sizes you should be able to bring the temperature below 70 degrees when it is 100 outside.

Let's see what the next contractors have to say about the situation.

Thanks again Mike. Yeah the old system was able to keep the house cooled to 72 even on our hottest days. Some days the vents would be open too (forget to close them or left them open because it's too hot outside to play) and it wasn't really an issue. I think you're right about the garage being the hottest room though. It is insulated but the ceiling of the garage is all plastered so it would be an expensive process to replace that.

I will post back when I hear more. Thanks again! You rock!

So we have had two more guys out. One guy agrees with you all that we could probably get away with the 4 ton and offered to do the manual J to figure out heat loss. He also agreed that would likely work best if the playroom was sealed and if we were the type of people to keep the house continually cool and not try to cool it off from 85 to 70 all the time. The difference is only $400 and my husband is very reluctant to go that route. He's really concerned that the system won't work how it used to and doesn't want to risk it. His estimate for the 5 ton system is $5450 which seems more in line with what I was originally expecting. I mean the labor should be minimal. We're keeping the lines and the attic is a walk up with tons of space for the newer, larger units. He plans on using Ruud sp? equipment with a 10 year warranty.

The other one hasn't given us the written quote yet. He did say that he recommends the 2-stage unit and was going to keep us at 5 tons. He's typically a commercial guy but came out as a favor to a friend. He says the job is as easy as it comes so it's no big deal to do for us. I'm expecting the quote to come in between 6-7. Oh and he wants to use York equipment with a 5 year warranty.

I'm leaning toward the first guy but the second guy seemed really thorough. He didn't like how our ducts were long and kinked in one spot. He says you see "all sorts of stuff in the world of residential." We'll have to see what his quote says.

I'm so confused :( All I know is first guy is out. Too shady.

Don't understand why York equipment would only have a 5 year warranty. That doesn't seem right. I would be concerned about using someone who doesn't do residential work.

Let's see what the load calculation says. The second guy appears to know what he is doing.

The biggest concern with commercial guys is that they rarely do residential type systems (split systems).

Split systems come in parts and are assembled on the job site. While commercial can have split systems it might be as low as 10-20% of overall equipment. Many times commercial equipment is 'packaged' equipment.

Packaged means 1 piece. They come pre-charged and all ready to go. All you have to do is place it properly on a curb on the roof, hook up electrical, (gas connection if necessary), drain lines and start it up. In some cases in the event of a side discharge air supply / return it may be required to construct and hook up duct work.

The other animal in commercial is chillers which is completely different from anything else.

The commercial guy is likely looking at this as a 'side job' with no intent to service the equipment after the fact. If something goes wrong, you may be in big trouble.