Newbie needs help..builder installing only a single unit for a 3250 sq ft house?

[lithnights]

First off, great site. I have learned a lot here, and am appreciative of any help.

I am working with a builder and am at the HVAC stage. The new home is 2 story colonial, 3250 sq ft finished, plus basement (will finish in the future). I am in the Philadelphia, PA area. 2x6 walls. Andersen 200 series windows. I would like to spray foam 2 inches but that depends on cost. I plan to be in this home 20+ years. Basic floorplan attached if that helps at all.

The contract simply stated, "Heating: Gas heat with central air. Performance 85% single stage by York" so it was very vague. In verbal discussions before construction, I let him know that I wanted a heat pump with propane backup and he said that was fine. I asked if the house would need 1 or 2 units, and he said they wouldn't know that until later when the manual J was completed. But if it needed a 2 unit system, that is what they would provide. They said usually anything over 3K sq ft, they do 2 units.

Well today, I met the HVAC guy and builder on site, and they are telling me they are installing a single unit, 5 ton 13 SEER. I asked why just 1 unit and they said that is what was specd out by York. I asked to see the manual J and the HVAC guy said he would have York call me. The builder said I could do a 2 unit system but that extra cost (they guessed $ or so) would be on me. They also said, which they suggested over 2 units, I could do an electronic programmable zoned setup.. but that could run $+. Again at my expense. OR I could simply manually control the dampers each season to try to even out the temps. Not ideal. The builder actually said, after I expressed my concern to them, "you're not going to get a 2nd unit for free".

Bottomline, I think we are getting screwed a bit here. I would think a 3250 sq ft house would come with something better than a single unit system that even they admit could have a 4,5,6 degree difference between the 1st and 2nd floor. I really think the builder is cheaping out on the HVAC system but I'm not sure what I can do about it. Perhaps I should have demanded a 2 unit or zoned system when signing the contract, but we didn't think about it.

I know it's tough to reply without a manual J but based on what I describe, should I be concerned with just a single unit? I actually have read that that may be OK, as long as there is a zoning system, but should I have to pay extra for that? It seems what they're putting in (as is) will not adequately heat/cool my home, even though they say it will. I believe in trust but verify. Is the builder cheaping out here? They've already started running ductwork so time is tight if I want to have them change anything. Do I trust the manual J..assuming I ever get it? Don't I have a right to see it? Or can I pay someone else to do one if I want a 2nd opinion? Thoughts? We're really stressing about this since I hear so often about how you need to get the HVAC right in a new build.

Thanks in advance,

[beenthere]

Manual J doesn't actually determine if you need 1 or 2 systems. Only determines what capacity your home needs.

Zoned would work fine.

[jtrammel]

You need to get it done right. Pay
The extra to
Get two systems. I've redone way too many houses that were built with one system and the homeowners were miserable until finally biting the bullet and tearing up the house to convert from one system to two. I would also demand to see a manual J and D before any ductwork is installed.

[hvac hero]

I'd just pay the extra money for a second system. I know it's not really fair to you to have to do that, but you'll be happier if you chalk this up to a bad experience than if your miserable through every summer for the next 20 years.

[lithnights]

So if manual J only determines what capacity, what determines 2 systems vs. 2/3/4 zones?

And how do they take into account that my wife likes the thermostat super high in the winter and super low in the summer? I'd think that would affect capacity, no? Since our house furnace and A/C would likely be running a lot more than another house the same size?

So at what point, would zoned NOT work fine? Is there a sq footage cutoff, or some other measurement? Or is it all subjective?

Thanks!

Manual J doesn't actually determine if you need 1 or 2 systems. Only determines what capacity your home needs.

Zoned would work fine.

[lithnights]

So 2 systems and not 2/3/4 zones? What's the advantage?
And back to my other question, if you're saying it should have 2 units, shouldn't the builder install that as part of the house build, if that is what SHOULD be done?

You need to get it done right. Pay
The extra to
Get two systems. I've redone way too many houses that were built with one system and the homeowners were miserable until finally biting the bullet and tearing up the house to convert from one system to two. I would also demand to see a manual J and D before any ductwork is installed.

[lithnights]

So what is it about 2 units that is advantageous over multiple zones using 1 unit? You're right, it's not fair, and unfortunately, it just may not be affordable to shell out 6K. We are already so over budget doing things I thought would be cost effective.. upgraded windows, spray foam, better front door, better insulated slider etc.

And when you say I'd be miserable for the next 20 summers, why is that? Are you basing that on just doing manual dampers or doing programmable dampers (separate thermostat on 1st floor and 2nd floor). i.e. what is it about those options that make it miserable? Just not enough cool air getting to that 2nd floor?

I'd just pay the extra money for a second system. I know it's not really fair to you to have to do that, but you'll be happier if you chalk this up to a bad experience than if your miserable through every summer for the next 20 years.

[jtrammel]

Zone systems have to be ducted near perfect to get up/down temps within 2-3 degrees. With new construction hvac subs I see out there on average they don't do very good duct jobs. With 2 systems you can set each thermostat and the seperate units will maintain that set point granted they're sized correctly.

[lithnights]

I see. Makes sense.
So it comes down to how much faith I have in the HVAC sub. I will say that this builder has a great reputation, and they've been using their subs for years, so if nothing else, that gives me confidence.

But it sure doesn't help the wallet.

And regarding the manual J, which I intend to obtain ASAP, will that not discuss at all the options of 1 unit vs. 2 unit vs. 1 unit with zoning etc.? If not on the manual J, who/what makes that call?

Zone systems have to be ducted near perfect to get up/down temps within 2-3 degrees. With new construction hvac subs I see out there on average they don't do very good duct jobs. With 2 systems you can set each thermostat and the seperate units will maintain that set point granted they're sized correctly.

[vstech]

what part of the country are you in? 3200sqft 2 story is a small house for 5 tons... even if you factor in the basement.
NOW is the time to verify the duct is sized properly, the returns are sized properly, and the equipment is sized properly for your structure. ESPECIALLY if you are foam sealing your home!!!
VERY FEW CONTRACTORS understand how to size equipment for a foam sealed house!!!
get your OWN HVAC contractor if you are uncomfortable with the builder's YOU need to be comfortable. the system needs to be sized and installed properly. filtration is KEY to comfort on a multilevel house with a single system. manual dampers are not code in most states... temps need to be within 2 degrees to pass code usually.

VISUALLY inspect the Load Calculation yourself.

[lithnights]

Philadelphia PA.
So you're saying the 5 tons is enough. At least that makes me feel better.

I will ask him if/how he treats the job different knowing it's to be spray foamed. IF I end up doing that.. again, depends on cost.

You're saying temps need to be within 2 degrees to pass code.. you mean between 1st and 2nd floor?

Do you know if manual dampers are allowed in PA? I googled it but can't find an answer. I'd assume yes, if he gave that as an option. If not, I just lost some confidence in him.

Thanks!

what part of the country are you in? 3200sqft 2 story is a small house for 5 tons... even if you factor in the basement.
NOW is the time to verify the duct is sized properly, the returns are sized properly, and the equipment is sized properly for your structure. ESPECIALLY if you are foam sealing your home!!!
VERY FEW CONTRACTORS understand how to size equipment for a foam sealed house!!!
get your OWN HVAC contractor if you are uncomfortable with the builder's YOU need to be comfortable. the system needs to be sized and installed properly. filtration is KEY to comfort on a multilevel house with a single system. manual dampers are not code in most states... temps need to be within 2 degrees to pass code usually.

VISUALLY inspect the Load Calculation yourself.

[BaldLoonie]

Around here, a house only gets 2 systems if it needs more than 5 ton. Result: hot upstairs and in many cases, even the rare homes that are zoned aren't much better. If it were mine, I'd want 2 systems, 1 per floor. Not zoning either. Also fishy is the 85% furnace, no such thing. And York doesn't spec systems.

Foam sure is nice if you can afford it. Long term it can pay in energy savings.

[lithnights]

Your "result" is my concern I guess from what I've read.. a hot upstairs. Part of the reason we moved into a newer home was that we wouldn't have that 75 degree downstairs but 81 degrees upstairs in mid July. I'm afraid we'll have that again.

What do you think of their estimated price of $6K for running an additional system? In line? And why not a zoned system for what could be thousands less, and not have to replace twice the equipment eventually? Worried about them setting it up correctly?


The 85% was what was on the builder's spec sheet for the house. Not sure about that.

When I say "spec" i mean put together the Manual J. Are you saying they don't do that? If so, who does? Is it possible that the HVAC guy doesn't even have a manual J for my house?

Thanks!

Around here, a house only gets 2 systems if it needs more than 5 ton. Result: hot upstairs and in many cases, even the rare homes that are zoned aren't much better. If it were mine, I'd want 2 systems, 1 per floor. Not zoning either. Also fishy is the 85% furnace, no such thing. And York doesn't spec systems.

Foam sure is nice if you can afford it. Long term it can pay in energy savings.

[vstech]

what he's saying is they make 80% or 90 - 96%, nobody makes an 85% furnace.

[motoguy128]

If you go with Spray foam, you shoudl be able to cool that whole place with 3 tons easy. maybe even 2 tons in your climate. When you get that small, a single system still makes a lot of sense. Every home is different, but I can cool the same size house with just 3 tons in hotter temps than Philly sees on average.

That being said, 5 tons is common, because you'd need 5 tons to cool off a home that large by 3F in 1 hour. That' unfortunately is what people expect. That's not how systems are intended ot work. In a home that size, it should take 1 hour just to cool the house by 1F even if its' 50F outside and there's no heat gain.

A properly sized systme matches ot heat loss and gain. A oversized systme attempts ot match the the perception of how quickly most ignorrant homeowner think their home should heat up and cool down. The trouble is, once is reaches temperature, it will not control humidty well and cycle on and off even in how weather which uses a LOT more energy.


What's more efficient a car with a big V8 that you lay rubber at every stop light, or a 4 cyclinder that is adequate to keep up with traffic? The first is sure a lot of fun, but that's not the purpose of HVAC... to see how fast you can cool off a home.

[vstech]

If you go with Spray foam, you shoudl be able to cool that whole place with 3 tons easy. maybe even 2 tons in your climate. When you get that small, a single system still makes a lot of sense.

That being said, 5 tons is common, because you'd need 5 tons to cool off a home that large by 3F in 1 hour. That' unfortunately is what people expect. That's not how systems are intended ot work. In a home that size, it should take 1 hour just to cool the house by 1F even if its' 50F outside and there's no heat gain.

A properly sized systme matches ot heat loss and gain. A oversized systme attempts ot match the the perception of how quickly most ignorrant homeowner think their home should heat up and cool down. The trouble is, once is reaches temperature, it will not control humidty well and cycle on and off even in how weather which uses a LOT more energy.


What's more efficient a car with a big V8 that you lay rubber at every stop light, or a 4 cyclinder that is adequate to keep up with traffic? The first is sure a lot of fun, but that's not the purpose of HVAC... to see how fast you cna cool off a home.

wonderfully put.

[teddy bear]

Being able to balance the conditioned air supply to the different parts of the home is a critical issue. The new modern VS blows also help balancing out the temps in the spaces are the solar gain and heat/losses move around a home throughout the day help alot. Keep solar gain to a minimum also important.
All of this scrambling makes me wonder if you have considered fresh air ventilation as part of your design. You need a fresh air change in 4-5 hours as a critical part of the desigh for purging indoor pollutants and renewing oxygen.
I assume there is a basement in this home. Will it be developed?
Philly is a humid green grass climate. How are you going to keep all of the space ,50% RH during cool wet weather?
If you none of these issues concern you, disregard my post.
Regards TB

[lithnights]

So you're saying, IF I do the 2" of sprayfoam, I'd be able to cool it with 3, maybe 2 tons.. BUT I wonder would I still have the issue with e.g. the kitchen being 75 and bedrooms at 80?

And you're insinuating, if sprayfoam, that 5 ton could be overkill? I guess that is part of my concern, that as part of the load spec or manual J or whatever analysis was done, I don't think they assumed that I was doing sprayfoam (I told the builder I'd like to but we never finalized since he didn't have pricing). So wouldn't that change the calculations?

Maybe I'm not the typical homeowner, but I don't really care how fast or slow it takes to cool/heat my home..just that it can be a certain reasonable temperature and be fairly consistent throughout the home.

I completely see your point with the V8 and V4 but does that mean the 5 ton is oversized or isn't, for me?

Even with all these replies, and perusing this site, I'm still not sure what to do. What I do know is I am trying to get in a 2nd HVAC company (good reputation, good Angieslist reviews, met with them years ago on my old home) to get a 2nd opinion and see if they can take a look at the manual J, or maybe do their own, and tell me what THEY would do.

Thanks!

If you go with Spray foam, you shoudl be able to cool that whole place with 3 tons easy. maybe even 2 tons in your climate. When you get that small, a single system still makes a lot of sense. Every home is different, but I can cool the same size house with just 3 tons in hotter temps than Philly sees on average.

That being said, 5 tons is common, because you'd need 5 tons to cool off a home that large by 3F in 1 hour. That' unfortunately is what people expect. That's not how systems are intended ot work. In a home that size, it should take 1 hour just to cool the house by 1F even if its' 50F outside and there's no heat gain.

A properly sized systme matches ot heat loss and gain. A oversized systme attempts ot match the the perception of how quickly most ignorrant homeowner think their home should heat up and cool down. The trouble is, once is reaches temperature, it will not control humidty well and cycle on and off even in how weather which uses a LOT more energy.


What's more efficient a car with a big V8 that you lay rubber at every stop light, or a 4 cyclinder that is adequate to keep up with traffic? The first is sure a lot of fun, but that's not the purpose of HVAC... to see how fast you can cool off a home.

[lithnights]

Yes I had thought of air circulation, since my many many hours of research taught me a home can sometimes be too tight. So I was looking into doing an ERV.
I asked the HVAC guy yesterday about an ERV and he looked confused. I then had to explain what I meant, and then he caught on. I hate to judge, but not knowing immediately what I was talking about when I said an ERV, concerned me. Maybe it goes by a different name to different folks. Or maybe he knows it as HRV. Or maybe he's never installed one in his life! Who knows. This is what stinks about having to use the builder's HVAC guy.

Yes there is a basement, and I plan to finish it in the near future. When you ask about keeping it 50% RH, are you talking about the 1st and 2nd floor or the basement? I'd assume with the AC going, the 1st and 2nd wouldn't be an issue. I could see the basement humidity could be a concern, and figured I'd run the 70 pt. dehumidifier I used to run in my old house basement..it ran pretty darn often unfortunately.

Thanks!

Being able to balance the conditioned air supply to the different parts of the home is a critical issue. The new modern VS blows also help balancing out the temps in the spaces are the solar gain and heat/losses move around a home throughout the day help alot. Keep solar gain to a minimum also important.
All of this scrambling makes me wonder if you have considered fresh air ventilation as part of your design. You need a fresh air change in 4-5 hours as a critical part of the desigh for purging indoor pollutants and renewing oxygen.
I assume there is a basement in this home. Will it be developed?
Philly is a humid green grass climate. How are you going to keep all of the space ,50% RH during cool wet weather?
If you none of these issues concern you, disregard my post.
Regards TB

[motoguy128]

I would do at least 3 zones. 1 for upstairs (bedrooms) and divide the downstairs into the kitchen dining room and the livingroom/family room areas.

IF you sprayfoam, 5 ton is definitely overkill, 4 ton is probably big as well. I'd expect to see you closer to 3 tons, but depdning on other factors like shading and windows, building orientation, it could be lower, but with just 2" not 3 or 4" probably closer to 3 tons. But you'll need a Manual J and room by room load calculation doen and a Manual D to size the ductwork. Then a contractor that understands zoning. Typcially you oversize ductwork by about 25% for zoning applications, but it depends on the size of your smallest zone.


The beauty of zoning, is that if your entertaining or cooking in summer for example, if you size the ductwork right, you could send 3 tons of capacity to the kitchen and dining room. Then still cool off the upstairs later that evening when you sleep. But at night, it only needs to cool just the upstairs.

Personally I prefer the Infinity Zone cotnrols because it's modulating and can proportionally send capacity to the zones as needed.