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MEASURE ONCE, CUT TWICE
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Discussion Starter · #1 ·
Was discussing my house project in the showcase forum and HVAC zoning came up.

I thought I should start a new thread for it here.
I have an HVAC company lined up for the project but that won't be required for at least 2-1/2 months. Still have time to talk about this with them.

The house will be 2288 square feet. 1144 for each 1st and second floors. Basement not included in this.

I have a Luxaire model # TM9V080C16MP11

Thoughts, recommendations?
 

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MEASURE ONCE, CUT TWICE
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Discussion Starter · #2 ·
How this thread came about:

Make sure you allow room for large sized ducts and plenty of return air and supplies to the upstairs. 2 stories are always a problem with AC and sometimes heat as the furnace is so far away from the rooms and the air slows down by the time it gets there.

If you want specific advice visit the HVAC forum.:)

Not trying to sell you stuff but there are reasonable priced Honeywell zoning systems available now. You are going to need a bigger furnace and AC. Don't know what you plan to use, just trying to help before you get too far and cannot undo or get at the ducts etc. Most architects know squat about HVAC.

Yuri, you hit it dead on about the architects.
I'm the one pretending to be an architect. I designed the house. Learned how to use Autocad on you tube and I'm a regular George Costanza now, ha.

Does this system you refer to control dampers automatically using several thermostats?
I already have a 3.5 ton condensing unit which I hope won't be over sized. It was in the bungalow and couldn't run long enough to pull the humidity out of the air.

My existing furnace is 80 K BTU's and according to my HVAC engineer, using 2015's calculations he said 60K would be enough. This is a new (3 years) Luxaire unit. I believe its a DC motor? Not sure if it's dual whatever? (architect talk again)

HVAC issue

First let me ask a few questions:

How many sq feet are you going to have above grade?

Are you going with triple pane argon windows and 2x6 walls? I have them and you get no drafts by the windows even in Winnipeg.

Luxaire is York so post the model # and I can look it up along with Beenthere.

Maybe get a mod to move this into it's own thread on the HVAC forum as it will get long. PM Beenthere or one of the others can do it if they read this.

I will give you a Honeywell link so you can start reading.

Basically it is a generic zoning system and any dealer can access it unlike a Lennox or Carrier proprietary system. It uses motorised dampers and I would zone your house main and 2nd floor and use 2 thermostats. It has a air pressure operated bypass damper so when 1 zone closes it bypasses air and lets the unit keep running. PERFECT if you have a DC ECM variable speed motor.

You would need to find a contractor willing to do it. Watched some videos on their site and it looks fairly straightforward.

If you have a skilled contractor and use 6" pipe for your upstairs supply runs and good return then you can balance the system and your DC ECM fan can compensate. Zoning is nice but you need to research it.

https://www.forwardthinking.honeywell.com/products/zoning/zoning_products.html
 

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What problem are you trying to mask or solve by zoning?

Zoning shouldn't be needed in a 2-story home with properly designed ductwork. For zoning properly sized, if not oversized ductwork becomes even more critical to have. If your ducts are undersized now, the furnace will have a hell of a time maintaining proper airflow when one zone is calling for heating/cooling. A bypass damper and duct may be needed for zoning to work.

At least for heating, temps should be even. For cooling, it's necessary to damper down some supply vents a bit and force more air to the second floor. The variable speed blower in your furnace can help with that, with its ability to comepensate for duct pressure and speed up when u close vents.
 

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He is not trying to solve or mask anything. He is adding a 2nd story to a Bungalow and doing a big remodel. If he wants better climate control then zoning may help. Heat rises and zoning helps get the AC upstairs better.

Go to the Project Showcase forum and see what it is about.
 

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The V in the furnace model is Variable speed ECM. It is a 2 stage ( heat ) furnace. Even if it is a bit big it will work most of the time on low fire. That may work to your advantage with that Honeywell zoning system also.

For that amount of square feet it sounds like the 3.5 tons is fine and I would not worry about the furnace size. Having big enough ducts and enough return air is my concern. If your HVAC guy can work with the zoning and you want it then it will be more comfortable. With a big house like that I would. Under 1500 sq ft I may not bother. Go to that link I gave you and they have references and good training videos which will give you a idea what it does or can do.
 

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I see.

With additions a complete assessment and re-design of the duct system is needed - hopefully that's being done.

------------/quote]I have an HVAC company lined up for the project but that won't be required for at least 2-1/2 months[/quote]

This stuff shouldn't be an afterthought; hvac needs to be considered in the planning process before any construction even starts.

You need a design oriented contractor who will do a accurate room by room load calculation and re-size all the ducts correctly. This is far more important than zoning. I'm betting that the original ducts were only sized for 600-800 cfm of airflow, if the system was put in a long time ago for 1000 sq ft. 2200 sq ft is medium sized as far as i'm concerned that you shouldn't need zoning for heating. For zoned cooling you would need a 2-stage a/c to do it right, otherwise a lot of air will be cycled back into the return (or dumped somewhere), reducing efficiency and causing other issues.

I already have a 3.5 ton condensing unit which I hope won't be over sized.
Grossly oversized unless your walls are all glass.

Your profile says markham ontario - if the you bring the insulation up to modern standards and put in low-e windows during the re-model, a typical house of that size in your climate should cool with 2-2.5 tons maximum and heat with 60-70k btu input. 3.5 is crazy and it's exceedingly unlikely that it's getting anywhere near proper airflow right now.

Again, a load calculation must be done.

Zoning should be the least of your concerns now.
 

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Ignore parts of the original post - didn't look at the thread.

The tmv9 80k furnace can be saved if it hasn't been damaged by low airflow. Being two stage - it will run on low all the time except for when raising the temp a few degrees at a time. A two-stage thermostat should be used, which will hold it on low fire and prevent it from up-cycling + shutting down prematurely.

The 3.5 ton a/c must be replaced if you want decent dehumidification and long cycles. I hate rules of thumb, but in general a re-done well insulated house should actually cool and dehumidify very well with 900-1100 sq ft per ton depending on shape, glass area, and sun exposure. (a heat gain calculation will prove this)

The duct system will have to be designed to handle 1400 cfm for that furnace to get proper airflow on high (it will jump to high if you set back your t-stat); if your budget allows, consider downsizing the furnace as well - a 60k and 2.5 ton a/c only needs around 1100 cfm at most, ---> means smaller ducts and bulk heads, longer cycles & more even heating/cooling.
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Going back to the original topic:

I really have to disagree with yuri with due respect. My bias is against zoning due to the extra cost, complexity of controls and having to dump air back into the return when only one zone is calling for heating/cooling. Zoning is great for 3-4 story houses or multi-unit rentals, but I don't see a need for it in a single family 2-story house. Worry more about getting enough return/supply air to the second floor and properly sizing the a/c.
 

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1100 sq ft /ton? I am not going to get into a great argument but I have a 2 ton in a 1365 sq ft house. I have 2x6 walls, R38 attic, 3 pane low-e argon windows, vapor barrior all glued and sealed tight. The 2 ton is not oversized. Not sure where you got that info. I could go up to 1500 sq ft. NO way I was going 1.5 ton. A proper heat load calc shoud be done and you need to factor in whether you have large West facing windows etc. If you do and don't close the drapes etc your load will be high. Even with drapes and a blind my unit runs steady from 4 pm - 10 pm when the Sun goes down. No tribe of kids just 2 people. If you cook a lot or have a big family and they go in/out a lot your AC load goes up. Load calcs are fine but real world usage can be higher.

Zoning is an option you may be interested in. It is not totally necessary but people like higher end climate control nowadays. That is why we have communicating thermostats and ECM fans. Everything has a price but I can easily sell $12,000 AC and furnace pkgs as there are rich people who want the best climate control.

Do some research and talk to your contractor about zoning. Honeywell is a major player in the market and obviously there is a market for those panels etc.

3.5 tons may be a bit large but I doubt you want to throw it away. 3 tons is my choice.
 

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As you go up in square footage, the capacity needed per square foot goes down. Exterior aurface area is what counts.

In southern ontario (where i am) newer/larger post 1980 houses which cool with 1000 sq ft per ton or sometimes even less if well over 3000 sq ft, probably more (600-800 sq ft per ton) if poorly insulated, single story, and/or smaller.

Really I shouldn't have mentioned sq ft per ton; floor area based rules and thumb are garbage and a heat gain calc should always be done.
 

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A Honeywell HZ322 zone panel should work well for you. You can set it not to bring on the second stage of heat unless both zones are calling. Plus, it will keep the blower slow during a cooling call unless both zones are calling.
 

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isn't there a risk of freezing the coil or getting liquid back to the compressor like that? slowing the fan kills efficiency anyhow. better to have a 2-stage a/c if zoning is used.
 

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He has a ECM motor so it does not care about the zoning and will maintain its cfm. It will bypass if 1 zone closes and still maintain its cfm/static pressure/ flow across the coil automatically. With a PSC you need to be more careful.

We are trying to give the OP good advice on how to use his existing units not throw them away and buy new stuff because of HVAC theory. Not bashing you. Watch the videos on that Honeywell site as they are very good about explaining those zoning panels. Thery also have very good wiring diagrams so I would study the different types of panels. There are 3 types with multiple combos for 1-2 stage furnaces with or w/o 2 stage ACs. I have done full blown Lennox Harmony zoning systems and know quite a bit about zoning.

Honeywell is the big Cahuna and spent millions of $$ on [email protected] before releasing them so they do work well. Zoning is very pouplar in the US and with rich people and very big houses in Canada.

A 2 stage AC is better if you have a proprietary full blown system like the Lennox Harmony or the Carrier if you have a ECM and communicating tstat as they all talk to each other and it can adjust the ECM. The Honeywell is generic and works for everyone else. With the Harmony you can have 8-32 zones but we are almost talking a BAS Building automation system level of control.

https://www.forwardthinking.honeywell.com/products/zoning/zoning_products.html
 

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isn't there a risk of freezing the coil or getting liquid back to the compressor like that? slowing the fan kills efficiency anyhow. better to have a 2-stage a/c if zoning is used.
The panel uses a DATS(all good panel do). Which will shut down the condenser if the air temp gets too cold.

While it does lower the efficiency, it also keeps air noise down, and removes a lot more moisture from the air. Plus aids in protecting the VS blower motor.
 
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I am very impressed with the Honeywell. The vids are good and they even have some showing contractors how to set them up and troubleshooting etc.

Google: Honeywell zoning system > Videos and there are UTubes galore
 

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MEASURE ONCE, CUT TWICE
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Discussion Starter · #15 ·
What problem are you trying to mask or solve by zoning?

Zoning shouldn't be needed in a 2-story home with properly designed ductwork. For zoning properly sized, if not oversized ductwork becomes even more critical to have. If your ducts are undersized now, the furnace will have a hell of a time maintaining proper airflow when one zone is calling for heating/cooling. A bypass damper and duct may be needed for zoning to work.

At least for heating, temps should be even. For cooling, it's necessary to damper down some supply vents a bit and force more air to the second floor. The variable speed blower in your furnace can help with that, with its ability to comepensate for duct pressure and speed up when u close vents.
Thanks.
As mentioned, no problems yet as the house has not been built.
This was brought up and is very interesting as every house I've been in, the basement is always so much cooler than the rest of the house.
 

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Zoning on a 2 story home enables both floors to be at thermostat set temp. And to set back the floor not being used. Can make the house both more comfortable, and use a little less energy.
 

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Thanks.
As mentioned, no problems yet as the house has not been built.
This was brought up and is very interesting as every house I've been in, the basement is always so much cooler than the rest of the house.
You could have 3 zones. One for basement. Need a contractor who knows how to install the dampers and ducts properly.
 

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Ya, that's pretty typical especially in the summer. The basement foundation is in contact with the ground and has heat loss almost all the time.

This can be mitigated by insulating the walls very well with closed cell foam boards, as well as having return air in the basement and carefully sealing the ducts. (edit: forgot to add, putting the vents near the floor helps with heating)

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When it comes to deciding to keep vs replace equipment, here's what comes to mind:

The capital cost of the equipment is a small portion of the total cost of an hvac system. You'll be getting new ducts and most likely relocating the equipment.

When you buy a 3000-4000 furnace, only 1/3 of the cost is materials - the rest is markup and installation. You'll be paying for an installation whether you re-use the equipment or not.

Keeping the existing equipment will completely alter how the duct system is designed, and you'll be paying more for 30%+ larger ducts needed to support a larger furnace and ac. When it comes to replacement, if you downsize the furnace; lets say put in a 60k two-stage model, there could be distribution problems on low fire. (pushing 600-700 cfm through a duct system made for 1400)

I don't like throwing stuff away in general; check out habitat restore-> http://www.habitat.ca/findarestorep4235.php

I've seen furnaces there. They also take more typical stuff like cabinets, light fixtures, toilets, etc.
 
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