HVAC Decision help... Trane?

7 years ago

So we live in a rather non-typical house. Two stories... it's essentially a log cabin on top of a walkout cement block basement cut into a hillside. It's a fixer upper in liveable state. We've got mostly single pane glass windows... minimal insulation downstairs, but some. The one wall I've exposed to the blocks had 2x2 framing, with thin insulation. No insulation on the back wall (the one underground).

My HVAC is dead. We are in the Charlotte, NC area so winters are temperate and we're not dying off while we sort this out. We had a 3 ton TRANE heat pump that developed a leak and lost all refrigerant. It was 22 years old, so impressed by that.

We've been getting Trane quotes... I definitely want at least a two-stage heat pump. We've been looking at the XR17+TAM9 air handler, XLi18+TAM9, or XV18+TAM9.

Do you guys have any advice? I read about how we should focus on sealing the house and insulation, but I simply don't have the time or funds to prioritize that at the moment (dealing with a leaking roof, septic tank issues, etc). But I recognize this is a substantial investment.

We originally had a 3 Ton system for the 2400 square feet. We had one rep who said we should have a 3.5 T system, which led to us looking at a 4T dual speed heat pump. Any thoughts as to sizing? Down the line, I'll get the windows replaced and do a better job insulating and sealing the place up.

Also curious what you all think of the Clean Effects air filter? I definitely want a better air filtration system then the usual as we do get a lot of dust.

Thoughts?

Featured Answer

mike_home

7 years ago

You should try to find a contractor who will do a proper Manual J load calculation. That is the best way to properly size a HVAC system. The problem is very few contractors do the calculation. If the current size worked well and did not short cycle, then that is a good data point for sizing.

Ideally you upgrade the insulation first and then do the calculation based on the new insulation values. Heat pumps are sized for cooling and not heating. Hopefully you find a contractor who can take all these parameters into consideration on selecting the size and equipment.

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Comments (9)

HU-608441623
Original Author
7 years ago
I should also note that we are planning to have all of the existing flex runs replaced.
mike_home
7 years ago
When the current system was working was it able to keep the house cool (75 degrees) during a hot summer day? If it did then 3 tons is the right size even with your poor insulation and windows. If you increase the size to 4 tons and upgrade the insulation and windows you will likely be over sized and experience poor humidity control.
HU-608441623 thanked mike_home
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weedmeister
7 years ago
Like Mike said, if you're going to insulate and put in new windows I would not recommend going bigger.
HU-608441623 thanked weedmeister
HU-608441623
Original Author
7 years ago
We bought the house in October and the system failed before we really got into June, so I can't say whether it handled things well or not. I can see in October we still had some warm days and it was comfortable in the house. We can't insulate upstairs (main living space), well, won't, beyond the log walls, because that's part of the appeal. But downstairs in the walkout basement, I do plan to insulate down the road.

If we get down to the vendor we're going to go with, would a manual J calc be the right request then to truly determine whether to go with a 3 or 4 Ton? I've also heard of a manual D but I'm not sure what that is.

Any advice on Trane longevity and two speed versus variable speed pumps?
tigerdunes
7 years ago
I don't believe there is enough data on the inverter type VS heat pumps yet to make a comparison to the 2 stage models as far as longevity. Keep in mind you get a 10 yr warranty on the parts for both type models.

TD
HU-608441623 thanked tigerdunes
sktn77a
7 years ago
Basements are not large sources of heat gain/loss. Insulate it by all means - it will help some, but not a lot. Definitely change out the windows for more efficient units as soon as possible. If you have supplementary heating (eg wood burning stove), a 3 ton two stage may well be enough. Heat pumps are sized for cooling, not heating - any additional heating needs are made up with auxilliary resistance strip heat in the air handler.

A manual D is a duct size and design calculator. This ensures correct air (heat) delivery to the various areas in your home.
HU-608441623 thanked sktn77a
HU-608441623
Original Author
7 years ago
Thanks guys, I really appreciate the help!
Lashari Khan
7 years ago
Good suggestion have been given by guys... i think you should contact some HVAC design company....

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