Heating and cooling a condo with interior rooms and lack of options! Help!

[Cotler Jen]

Hi, I hope someone can help! I have a condo that is heated and cooled with a ptac unit. We are taking the existing one bedroom and carving it into three. As a result, the Ptac will be in one bedroom, but the other two are interior and don’t have access to an exterior wall. In addition(and annoyingly) the condo association does not allow anything on the balcony so a split is out of the question.
So my question is, is there a way to duct the ptac to the other bedrooms? I know you can use a diverter for the room right next to it, but I don’t think diverter can go as far as I’d need to for the third room. I heard that something like this was in the works at Mitsubishi but who knows! my only connection to outside air is the grill for the ptac- I can put something different there as long as the outside looks the same, but I’m not sure that’s enough space for fresh air to go in and hot air to go out.
HELP!

 

[Reach4]

For those who forgot, as I did, a PTAC is a Packaged Terminal Air Conditioning, as is fairly common in motel rooms.

 

[Sponsor]

 

[wwhitney]

Apparently there is at least one manufacturer of through wall split system heat pumps. The "outdoor" unit would sit in the place of your current PTAC, and then you could have a traditional indoor unit, air handler, and ductwork, which you'd have to allocate space for. So you can look into whether any of those products are available with a wall unit that would fit in the space you are allowed and with sufficient capacity for your HVAC load.

Cheers, Wayne

 

[Fitter30]

Do you pay for water?

 

[Cotler Jen]

Apparently there is at least one manufacturer of through wall split system heat pumps. The "outdoor" unit would sit in the place of your current PTAC, and then you could have a traditional indoor unit, air handler, and ductwork, which you'd have to allocate space for. So you can look into whether any of those products are available with a wall unit that would fit in the space you are allowed and with sufficient capacity for your HVAC load.

Cheers, Wayne

Thanks for your response! What manufacturer is making through the wall split systems? That sounds like what I’d need although I don’t have space for a traditional “inside” unit- my pipe dream is a split where the condenser portion is Th rough the wall and then I could hang the handlers on the ceiling (like a mini split but through the wall). Who makes this??

 

[Cotler Jen]

Do you pay for water?

Included in HOA

 

[wwhitney]

Thanks for your response! What manufacturer is making through the wall split systems?

Well, when I google "through wall split system heat pump" the first hit is for "National Comfort Products". Maybe there are others. Not sure about through wall mini splits.

Cheers, Wayne

 

[Cotler Jen]

Well, when I google "through wall split system heat pump" the first hit is for "National Comfort Products". Maybe there are others. Not sure about through wall mini splits.

Cheers, Wayne

Thanks! I had looked at this before, it’s a smaller VTAC but the problem is that the outside grill has to be horizontal like the ptac (I have to be uniform with the hoa rules on what the balcony looks like) and this is vertical.

 

[wwhitney]

OK, let me see if I have the terminology right, a VTAC is a ducted PTAC with a duct out the top on the indoor side?

The National Comfort Products I were looking at said they were split systems, so they wouldn't be VTACs, they'd work with a conventional air handler.

What are the exact HOA restrictions? Height and width of the opening? Or also something about how the grill looks?

Sounds like what you really want is a multi-head mini split system where the outdoor unit has its air intake and exhaust on the same side, or has the provision for some ducting to achieve that effect. Obviously possible in theory, the question is figuring out what's available commercially. Which so far I haven't been able to assist with.

Cheers, Wayne

 

[Cotler Jen]

Exactly! My opening is 40 wide by 14 tall. This unit would be perfect if not for the outside grill is taller than my opening. If I could find that exact unit but 14 inches tall, it would be perfect

 

[wwhitney]

One approach, not sure how well it would work, would be simply to leave the PTAC as is. The heat loss/gain in the interior rooms should be low, as they have no exterior surfaces. The PTAC would handle the heat loss/gain of the room with all the exterior surface.

I assume the interior rooms won't be bedrooms? I believe any bedroom requires an emergency opening that opens outside:

https://up.codes/viewer/pennsylvania/irc-2015/chapter/3/building-planning#R310

Cheers, Wayne

 

[Cotler Jen]

One approach, not sure how well it would work, would be simply to leave the PTAC as is. The heat loss/gain in the interior rooms should be low, as they have no exterior surfaces. The PTAC would handle the heat loss/gain of the room with all the exterior surface.

I assume the interior rooms won't be bedrooms? I believe any bedroom requires an emergency opening that opens outside:

https://up.codes/viewer/pennsylvania/irc-2015/chapter/3/building-planning#R310

Cheers, Wayne

Im not sure that’ll work because the interior rooms will be walled off

 

[wwhitney]

If you're referring to the HVAC, it will work to a large extent but you may get some temperature imbalances.

If you're referring to the interior rooms being bedrooms, bedrooms are not allowed to be walled off. They must have an exterior emergency opening, so rethink your plans.

Cheers, Wayne

 

[Dana]

Getting to the "right" heating & cooling solutions always calls for reasonably careful room by room load calculations. If you're aggressive enough on the input information (when in doubt, guess aggressively on insulation values, air tightness and window performance) using online Manual-J-ish tools such as LoadCalc or CoolCalc can be reasonable. They tend to overshoot reality (by quite a bit if you're not aggressive enough), but it'll give you a better idea of what to expect from rooms that are doored off from the heater.

Heat pump versions of PTACs are usually called PTHPs, and most manufacturers have PTHPs that fit the same wall sleeves as PTACs of the same cooling capacity. I'm not aware of any PTHPs that are designed to be duct-extendable.

But there are many ducted mini-split heat pump options, if the condo association allows for bracket mounted or ground mounted compressors.

With the low heating loads of rooms multi-unit buildings the individual room loads can be tiny, tiny enough that heating them with an appropriately sized hydronic baseboard or radiator running off the water heater. That approach can't deliver on the air conditioning though.