4 Zone HVAC

[joethompson]

Hello All,

I'm building a new house in Minnesota. The house is about 3,300 sf. We have a basement, main floor, second floor, and master bedroom above the garage. We'd like to have a 4 zone HVAC system. One for each area I just described.

Most of the contracters we've spoken with have said 4 zone would be fine, but one of them said a 3 zone would work better because otherwise the ductwork gets so small that the furnace could overheat.

I've read that you're just supposed to oversize the ductwork, and we're also going to get a variable speed furnace. I would just like your thoughts on a 3 zone versus a 4 zone for our sized house. Also, would there be any issues with A/C?

Thanks,
Joe

[seatonheating]

I would go 3 zone with one system and have a separate system for one of the remaining zones(basement?). Tis true that 4 zones, may be too small of duct, although at 3,300 sq ft you may be ok. If you could break down the sq ft. of each zone we could better assist you.
Josh

[mark beiser]

4 zone is fine with the correct equipment and controls. Be sure you find a contractor that is experienced with zoning, and absolutely use 2 stage heating and cooling equipment. You don't want to the guine pig for a contractors first 4 zone job, especially not with a mulitstory house.
Kick anyone out the door that wants to do a 4 zone system with single stage equipment.

A Trane XL19i system with the Trane Integrated Zone system, or a Carrier Infinity with the Carrier zoning system would be the only 2 options I would even considder for a 4 zone forced air heating and cooling system.

[Freezeking2000]

I would look into hydro-air systems (boiler) and use at least 2 airhandlers 2 zones each for some redundancy in your heating system. Also the boiler could do the hot water for you oversized tub which has to have alot of capacity to meet the needs of a large home.

[mark beiser]

Just noticed you are in Minnesota. Freezeking has a good recommendation on the boiler.
Since it gets cold and stays cold there, you sould probably look into a boiler and radiant heating, wich can be give you individual temperature control of every room in the winter.

The options are limited only by your budget. ;)

[joethompson]

Thanks for the responses. I originally looked into doing a geothermal system, but the 2 bids I got were for almost 40k and almost 50k. Which is WAY more than I want to spend. Since I'm doing my own general contracting, I'd rather not get a system that is too complicated. A forced-air system seems fairly simple, while still getting the options that I want.

For square footage, the house will be about 1600 in the basement, 1600 on the main floor, 1000 on the second floor, and 600 above the garage. I forgot to include the basement square footage in the 3300...I'm not finishing the basement right away. So, when it's all finished, it will be around 4500 sf.

Thanks for the recommendation Mark, I'll look into those 2 systems.

Thanks!
Joe

[bluetooth751]

Originally posted by mark beiser
4 zone is fine with the correct equipment and controls. Be sure you find a contractor that is experienced with zoning, and absolutely use 2 stage heating and cooling equipment. You don't want to the guine pig for a contractors first 4 zone job, especially not with a mulitstory house.
Kick anyone out the door that wants to do a 4 zone system with single stage equipment.

A Trane XL19i system with the Trane Integrated Zone system, or a Carrier Infinity with the Carrier zoning system would be the only 2 options I would even considder for a 4 zone forced air heating and cooling system.
I second

Also pay attention to the length of the duct runs as they may exceed the external static pressure rating of the furnace. Duct sizing will be critical and zoning with dampers may not be the best answer.

Make sure you get a seasoned pro.

[Freezeking2000]

With hydro-air system you do not need to run ducts all over the home from the basement. Install a seperate zone for MBR on its own airhandler and split a second airhandler up and down. Then add baseboard hot water as needed when you finish the basement. A nice oil boiler in Minn is the way to go. Also if wanted you can install in-floor heat......nice!

Absolutely the most reliable way to go is with a boiler.

[tinknocker service tech]

i would think with a house that size it would be better to install three systems this way if you are not using one it can be shut down or set to a differant temp. i cant see one unit handling that much load if all zones call at the same time or if there is a real cold front or hot spell

[Christheheatingdude]

Hydro air would be a excellent way to go. And you could do radiant in the basement, then air handler and zoning for the rest. This would be my first option. You could go with a 90+ condensing gas boiler, and take advantage of its enery savings. Plus heat your domestic hot water as well.
There are just so many options with hot water. Makes it hard to beat.

Second choice would be the Carrier Infinity System. 2 Stage Variable Speed furnace and zoning. Possibly two units, depending on the load calc. One for the basement, and then the rest of the house.

Just my opinion, but that is what I recommend for my customers, and I live and work in northern michigan. So weather is comparable.

[AllTemp]

Zoning 3 zones, 4 zones, 5 zones... what ever the system needs should not be a problem to an experienced knowledgable contractor familar with zone controls....

With the use of capacity controllers, by-pass dampers this is all accomplsihed quite nicely...

Take a look at this site they have some useful consumer information and videos to look at...

Goodluck

http://www.hvaccomfort.com
http://www.zonexsystems.com/images/diag_2.gif

[brian in mass]

I'll tell ya what, almost every system I do seems to be zoned. And these guys are giving some good advise. I LOVE the idea of hydro air, in fact, that is mostly what I seem to do. It would be what I would put in my own home nomatter what.
As far as zoning is concerned, there are two schools of thought on the subject....the right way and the wrong way. This is where you come in, you'll need to watch out who you have do this for you. I read your post and the thing that popped out at me was someone's advise to you to just over size the ducting.

What you need to do, is find the right guy for the job. Someone who just agrees with everything you say, and says ok i can do it.....is probably not the right guy. Someone who looks over your prints and comes back with a load calc and realistic ideas of what can be done and what is going to work right....is more on the line of what your looking for.

With a zoned system it is much more important to have it done right, not that it shouldn't any other way. But if your guy isn't familiar with the right way of doing it, then find someone who is.

And again, as far as the boiler is concerned......there is no better way in my eyes to heat your home than with radiant hot water, and hydro air as a backup. Even doing straight hydo-air in the house still leaves many options in the future, such as a radiant bathroom or maybe towell warmers.

[dash]

Originally posted by AllTemp
Zoning 3 zones, 4 zones, 5 zones... what ever the system needs should not be a problem to an experienced knowledgable contractor familar with zone controls....

With the use of capacity controllers, by-pass dampers this is all accomplsihed quite nicely...

Take a look at this site they have some useful consumer information and videos to look at...

Goodluck

http://www.hvaccomfort.com
http://www.zonexsystems.com/images/diag_2.gif


Zoning with NO bypass damper is superior.

[brian in mass]

how is that superior ?

I am not sure i understand.

[dash]

On a zoning system that can operate without a bypass,the dampers modulate ,so hen one zone calls,others get some air if they can use it,instead of air going thru the bypass,and likely shutting down the equipment on leaving air temperature.

This would also have two stage heating and cooling ,so when one or two zones are calling,it can run in low,and of course a VS blower,with cfms controled by the zoning system.

[brian in mass]

I see what your saying, and i like the idea of the zoning system controling the VS blower. But I don't know if I like the idea of the zone dampers "modulating". To me that sounds like a fancy way of saying..by-pass air. A trick alot of guys use when then not so good at zoning to get rid of the extra air by letting it blow by the damper.
I use bypass dampers on almost all my zone systems and have yet to have any problems. On my jobs, if there was a trickle of air coming out of the registers when the t-stat wasn't calling.....rest assured my phone would be ringing !

But I do find it quite interesting how some guys set up there zones. We should put up some sort of post and see what others are doing. For example, I know a guy who thinks that the proper way to go about it is to size each zone to handle the entire unit. I asked him some questions about it, 'cuz I just had to, and he didn't seem to know what to say.