Damper system or heat pump advice

[cgol]

Hi all,
I’m looking for some guidance on my HVAC options w/ finishing my basement. Before I start getting quotes, I would like to be more educated on my options.

When we purchased the our home, the basement was completely framed so I believe the HVAC system we have was intended to be zoned for the basement and the first floor. We got the house via a short sale so the builder ran out of money and didn’t complete the basement finish job.

I had a HVAC sales consultant out to the house and he said we could do, what he called a damper system, but it would cut the life of the compressor and the furnace in half. He suggested we get a third unit in form of a heat pump.

Can the downstairs furnace/compressor (details below) handle the basement load to if I were to have the system zoned? If it can handle it, would it really cut the life of the units in half? My wife really doesn't want a third unit outside and the addition of a heat pump would require extensive work outside. We'd have to rearrange of the compressors to maintain the proper distance from the gas and it's on a steep grade so would have to do some potential grading/ground work.

House details:
1st floor (1700 sq ft) has a 2.5 ton Trane XB furnace (in basement) w/ 3 ton Trane XB 13 compressor.
2nd floor has its own furnace in the attic and its own compressor. I’m not sure of the details but the compressor is half the physical size of the other.
Basement has 1130 sq ft.

Thanks for helping me get educated!

[George2]

Zoning is the right way to go. It will not cut the life of the equipment.

3 ton (for 1700 sq. ft.) is too much, but nothing you can do about that now.

With zoning, depending on the 1st fl. layout, you could do 3 or 4 thermostats.

I have a 2,250 sq. ft. 2 story with 3 thermostats. It's great.

[pwg11386]

hmmm, do you mean to say that your furnace blower is only producing 1000 cfms? (2.5 tons) on a 3 ton ac? whats the furnace model #?

how many square feet is the basement?

[George2]

hmmm, do you mean to say that your furnace blower is only producing 1000 cfms? (2.5 tons) on a 3 ton ac? whats the furnace model #?

how many square feet is the basement?

I missed that. But they don't make a 2.5 ton blower (normally). The smallest Is a 2 (small furnaces) and most have 3 ton blowers if the furnace is of any size.

[cgol]

Thanks for the info guys.

Sorry if I calculated the tonnage incorrectly on the furnace. I used the same divide the 7th and 8th digit of the model number by 12 as recommended for the compressor on the Trane site faq.

The furnace model number is: 2TXCB031BC3HCAA (my guess based on your all's comments is now 2ton)

The total sq footage for the basement (1130) and 1st floor (1700) is roughly 2830.

Should I still go with the zones? I really like this idea as the half of the downstairs, farthest from the furnace, doesn't get much push from the registers.

[George2]

Thanks for the info guys.

Sorry if I calculated the tonnage incorrectly on the furnace. I used the same divide the 7th and 8th digit of the model number by 12 as recommended for the compressor on the Trane site faq.

The furnace model number is: 2TXCB031BC3HCAA (my guess based on your all's comments is now 2ton)

The total sq footage for the basement (1130) and 1st floor (1700) is roughly 2830.

Should I still go with the zones? I really like this idea as the half of the downstairs, farthest from the furnace, doesn't get much push from the registers.


Sure. Zoning will work with no problem. Like I said, you can put the thermostats were you need them most.
What is an extra with zoning is you'll also increase the airflow were you are having none now.

[seatonheating]

Thanks for the info guys.

Sorry if I calculated the tonnage incorrectly on the furnace. I used the same divide the 7th and 8th digit of the model number by 12 as recommended for the compressor on the Trane site faq.

The furnace model number is: 2TXCB031BC3HCAA (my guess based on your all's comments is now 2ton)

The total sq footage for the basement (1130) and 1st floor (1700) is roughly 2830.

Should I still go with the zones? I really like this idea as the half of the downstairs, farthest from the furnace, doesn't get much push from the registers.


What area are you in? Might want to think about higher efficiency.

[George2]

What area are you in? Might want to think about higher efficiency.

I'm not fimiliar with Trane numbers. Is that an 80% builders special?

[seatonheating]

I'm not fimiliar with Trane numbers. Is that an 80% builders special?



Yep, XB is as cheap as it gets. Not saying it is a bad furnace but if he is in a northern climate he is wasting gas. And if that XB13 is a heat pump then he really has a baseline system.

[cgol]

Again, many thanks for the information.

We're in Charlotte, NC. Can you please elaborate on what you mean by higher efficiency?

[seatonheating]

Again, many thanks for the information.

We're in Charlotte, NC. Can you please elaborate on what you mean by higher efficiency?


Furnaces have efficiencies up to 98% these days, yours is 80%. That means that for every unit of heat(BTU) you furnace puts out you are wasting 20% of it. With a 98% you are only wasting 2%.

Heat pumps are a little more complex with their efficiencies. They are rated by HSPF, you can google it. Higher the better.

Since you are in NC I would focus on SEER of the AC mostly, which means you need a furnace that has a variable speed fan. Others will chime in with better information for you.

[George2]

Furnaces have efficiencies up to 98% these days, yours is 80%. That means that for every unit of heat(BTU) you furnace puts out you are wasting 20% of it. With a 98% you are only wasting 2%.

Heat pumps are a little more complex with their efficiencies. They are rated by HSPF, you can google it. Higher the better.

Since you are in NC I would focus on SEER of the AC mostly, which means you need a furnace that has a variable speed fan. Others will chime in with better information for you.

If he doesn't need much heat in N.C. then he can get a zone system with a retrofit Dc, hi-eff. motor which will help the SEER of the H.P. plus it's nice for the zoning.

[George2]

S.H.

What is the btus of his Trane furnace?

[seatonheating]

S.H.

What is the btus of his Trane furnace?


He doesn't give the model number of it, but I would guess probably 80K input based on the other pieces matched to it. I could be wrong though.

[George2]

He doesn't give the model number of it, but I would guess probably 80K input based on the other pieces matched to it. I could be wrong though.

Thanks, that would make sense in N.C. It has a 3 ton drive, so zoning would be no problem (with too much air) even with a small zone.

I try to size the zones so I can get away with not using a by-pass damper.

[seatonheating]

Thanks, that would make sense in N.C. It has a 3 ton drive, so zoning would be no problem (with too much air) even with a small zone.

I try to size the zones so I can get away with not using a by-pass damper.


The only thing I don't like with zoning in his application is that we are dealing with a lot of existing ductwork. Chances are he could get set up with a real noisy system.

Remember, zoned systems need to be designed so that the smallest zone can handle airflow at the system's minimum CFM output. If it were me, the most practical solution would be to include a "dump" zone into the basement hallway as it is still accessible.

[George2]

The only thing I don't like with zoning in his application is that we are dealing with a lot of existing ductwork. Chances are he could get set up with a real noisy system.

Remember, zoned systems need to be designed so that the smallest zone can handle airflow at the system's minimum CFM output. If it were me, the most practical solution would be to include a "dump" zone into the basement hallway as it is still accessible.

S.H.

Right. I'll leave a "wild" supply to one area that's not being used, if need be.

Also, like you said, a "wild" or "dump" in the basement hallway sound fine.

We're on the same page. We need to know how many supplies (and size of said supplies) on the smallest zone.

I installed a 2 zone system that had a 3.5 ton A/C. It was a 1.5 story home.

5 supplies upstairs, one "wild" supply in the foyer, no by-pass and no problems. She loves it.

[seatonheating]

S.H.

Right. I'll leave a "wild" supply to one area that's not being used, if need be.

Also, like you said, a "wild" or "dump" in the basement hallway sound fine.

We're on the same page. We need to know how many supplies (and size of said supplies) on the smallest zone.

I installed a 2 zone system that had a 3.5 ton A/C. It was a 1.5 story home.

5 supplies upstairs, one "wild" supply in the foyer, no by-pass and no problems. She loves it.


The problem with "wild", dump or bypass zones is that they can be an energy wasters and are poor practice in general.

I absolutely will not sell zone systems without addressing the entire duct system. If I absolutely have to do a bypass of some sort it will always be a modulating zone based on static. Anyone who uses a barometric bypass is a hack in my eyes.

I signed up for Bryant just for their zone systems. I got some real cool ones coming up this spring that I am building from scratch.

[George2]

The problem with "wild", dump or bypass zones is that they can be an energy wasters and are poor practice in general.

I absolutely will not sell zone systems without addressing the entire duct system. If I absolutely have to do a bypass of some sort it will always be a modulating zone based on static. Anyone who uses a barometric bypass is a hack in my eyes.

I signed up for Bryant just for their zone systems. I got some real cool ones coming up this spring that I am building from scratch.

S.H.

You can use a barometric by-pass with a A.C. blower motor. It'll work. But I try to sell a V.S. motor type system or retrofit a D.C motor to a newer, decent furnace.

I agree that a modulating by-pass is necessary with a V.S. blower, if the smallest zone won't handle the cfm.

I've also sold the (deluxe) Carrier/Bryant zoning were the dampers modulate to compensate for the smaller zone. It's a sweet system.

[cgol]

Thanks again for all the info guys!

I've had two pros out to the house and one recommended exactly what you all suggested with zoning. I also found from him that the downstairs has a 3ton compressor with a 2.5 ton coil and 3 ton furnace. We went on to check the upstairs unit and it has the 3 ton coil w/ the 2.5 ton compressor on it. I guess the original installers mixed them up. Anyway, thanks again for the knowledge and helping me not be completely lost on the topic.