dual, quad, or what? Mini split....floor plan inside

dablack · 10-01-14, 10:39 AM

I'm currently building my own house. My brother in law is saying he is going to give me the hook up on a normal HVAC system, but I'm not sure I want to go that way. He was saying he could do a full house traditional HVAC system for about $6k.

Down stairs, I have a large open room that 26'x39' (except for a pantry in the corner that is about 8x16 (each grid box is 2'). I think one large minisplit would work great downstairs. It could be mounted above the cabinets in the kitchen (that is the north wall/back yard).

Upstairs is where I start having problems. Up there we have the two bathrooms, laundry, and four bedrooms. I was looking at a 30,000 BTU 18 SEER Quad Zone Heat Pump System 6+6+6+12. I would put the 12k btu in the master, and the three 6k BTUs in the 3 bedrooms. The problem is the 2nd bathroom and laundry room. Won't they get hot? I just so used to having a vent in every little room.

We are in east TX and it does get hot here. I'm not so worried about the cold. We sometimes get freezing temps. Sometimes.

NiHaoMike · 10-01-14, 11:06 AM

Leave the doors open most of the time and airflow will take care of it.

gtojohn · 10-01-14, 09:22 PM

I recently saw an HVR used to duct and circulate the air through out a house. Instead of outdoor air it moved conditioned air to the less conditioned spaces. This one was just on a timer switch, but there could be more eloquent ways to control. Personally I think on a large house central is better, and made to last longer and be repaired. If I were to go mini split, I think Its a better deal to go multiple single zones. You can get higher seer ratings and extra redundancy for less money on the single zones. Compare EER ratings on all your hvac options. I installed a 2 zone 24kbtu (12kbtu each) 22 seer mini on Monday and was surprised it drew 15 amps @ 240v, twice what my 24kbtu 14 seer central draws. Look at the Gree Terra line, 12k at 25 seer and 9k at 27 seer.

dablack · 10-02-14, 07:27 AM

John,

So you are saying that downstairs, you think a single large minisplit would be fine but I might be better off with either multiple single upstairs minisplits or central air?

I'm shocked that your 2 zone mini draws more power than a central unit! That is crazy. Would there have been a way to know that before hand? Is that was the EER tells you?

thanks
Austin

gtojohn · 10-03-14, 08:07 AM

I was surprised as well. SEER is very subjective but EER is straight forward apples to apples. EER = btu/watts. The higher the eer the better and if you double the eer you cut power usage in half. The larger the btu the harder it is to get a higher seer and eer. A couple things about mini splits, supposedly they get a higher seer because the duct heat gain, air leakage and airflow resistance has been eliminated. I think the last manual J I did the losses accounted for 3kbtu on a 1200 sqft home, so the 24000 btu unit only netted 21000. I'm not sure how they calculate those losses for hvac certifications but thats one way you can get differing seer ratings with similiar eer. Additionally many minisplits modulate the cooling load so a 9kbtu unit might slow down and cool at 3.5kbtu and this could be the point they get the super high seer that skews the rating super high. The mini split route should save you money in the long run b/c you will have multiple zones and the ability to not cool unoccupied zones. If you're unconditioned rooms are on the north side you might be fine without hvac unless your wife uses that restroom!

dablack · 10-06-14, 07:18 AM

Yep, both bathrooms are on the north wall but we have four kids. I think it would get a little warm up there. I'm still not sure what to do. I think I would really like one large minisplit downstairs. I'm not sure about what I'm going to do upstairs.

10-01-14, 10:39 AM	#1
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	dual, quad, or what? Mini split....floor plan inside I'm currently building my own house. My brother in law is saying he is going to give me the hook up on a normal HVAC system, but I'm not sure I want to go that way. He was saying he could do a full house traditional HVAC system for about $6k. Down stairs, I have a large open room that 26'x39' (except for a pantry in the corner that is about 8x16 (each grid box is 2'). I think one large minisplit would work great downstairs. It could be mounted above the cabinets in the kitchen (that is the north wall/back yard). Upstairs is where I start having problems. Up there we have the two bathrooms, laundry, and four bedrooms. I was looking at a 30,000 BTU 18 SEER Quad Zone Heat Pump System 6+6+6+12. I would put the 12k btu in the master, and the three 6k BTUs in the 3 bedrooms. The problem is the 2nd bathroom and laundry room. Won't they get hot? I just so used to having a vent in every little room. We are in east TX and it does get hot here. I'm not so worried about the cold. We sometimes get freezing temps. Sometimes. Attached Thumbnails

10-01-14, 11:06 AM	#2
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	Leave the doors open most of the time and airflow will take care of it. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

10-01-14, 09:22 PM	#3
gtojohn Journeyman EcoRenovator Join Date: Jul 2014 Location: Austin, TX Posts: 314 Thanks: 39 Thanked 50 Times in 45 Posts	I recently saw an HVR used to duct and circulate the air through out a house. Instead of outdoor air it moved conditioned air to the less conditioned spaces. This one was just on a timer switch, but there could be more eloquent ways to control. Personally I think on a large house central is better, and made to last longer and be repaired. If I were to go mini split, I think Its a better deal to go multiple single zones. You can get higher seer ratings and extra redundancy for less money on the single zones. Compare EER ratings on all your hvac options. I installed a 2 zone 24kbtu (12kbtu each) 22 seer mini on Monday and was surprised it drew 15 amps @ 240v, twice what my 24kbtu 14 seer central draws. Look at the Gree Terra line, 12k at 25 seer and 9k at 27 seer.

10-02-14, 07:27 AM	#4
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	John, So you are saying that downstairs, you think a single large minisplit would be fine but I might be better off with either multiple single upstairs minisplits or central air? I'm shocked that your 2 zone mini draws more power than a central unit! That is crazy. Would there have been a way to know that before hand? Is that was the EER tells you? thanks Austin

10-03-14, 08:07 AM	#5
gtojohn Journeyman EcoRenovator Join Date: Jul 2014 Location: Austin, TX Posts: 314 Thanks: 39 Thanked 50 Times in 45 Posts	I was surprised as well. SEER is very subjective but EER is straight forward apples to apples. EER = btu/watts. The higher the eer the better and if you double the eer you cut power usage in half. The larger the btu the harder it is to get a higher seer and eer. A couple things about mini splits, supposedly they get a higher seer because the duct heat gain, air leakage and airflow resistance has been eliminated. I think the last manual J I did the losses accounted for 3kbtu on a 1200 sqft home, so the 24000 btu unit only netted 21000. I'm not sure how they calculate those losses for hvac certifications but thats one way you can get differing seer ratings with similiar eer. Additionally many minisplits modulate the cooling load so a 9kbtu unit might slow down and cool at 3.5kbtu and this could be the point they get the super high seer that skews the rating super high. The mini split route should save you money in the long run b/c you will have multiple zones and the ability to not cool unoccupied zones. If you're unconditioned rooms are on the north side you might be fine without hvac unless your wife uses that restroom!

10-06-14, 07:18 AM	#6
dablack Helper EcoRenovator Join Date: Jan 2010 Posts: 65 Thanks: 0 Thanked 13 Times in 6 Posts	Yep, both bathrooms are on the north wall but we have four kids. I think it would get a little warm up there. I'm still not sure what to do. I think I would really like one large minisplit downstairs. I'm not sure about what I'm going to do upstairs.