Question on zoning choices
I am looking for the best options or suggestions for zoning a 2 ton HP. Does it have to be 2 stage? Does it need to be Greenspeed?
I would like 3 zones, Main living area is priority and is 780 sq ft of an open concept area with cathedral ceilings that are 21ft from the floor. There are 3 ceiling fans for air circulation .
2nd zone is 2 bedrooms 240 sq ft and bathroom of 80 sq ft. This is on one level. There is a loft above that is open to below that no ductwork will be needed.
Using HVAC Calc m The heat loss for the main floor living area is 11800 at 7F and if I heat the whole floor it is 15500( this includes 2 bedrooms and the bathroom.) The whole house heat loss is 21258 and heat load 23110 and 21315 sensible total.
The other zone is a 1130 sq ft basement seperated into one room 580 sq ft a 120 sq ft spare bedorom and the utility room.
This will have a 4300 heat loss, and would not be used on very cold days anyway.
I have propane fireplaces in the basement and main floor if I need extra heat.
With correct zoning I think I can get my balance point down to < 10F using the York Affinity YHZ 2 ton.
I wonder what size heat strips I would need for aux heat.
A 2 speed unit would be nice but not necessary. I do like a variable-speed blower for zoning, however. If your system is newer but has a PSC motor, an upgrade to a variable-speed is very affordable. The heat strip will be limited by the size of the blower.
I don't have a system installed yet. I am planning on putting one in with zoning and would like to know which would be suitable.
With such a low heat loss and gain, a Greenspeed would be a waste of money IMO. Plus you might as well get a 3 ton greenspeed and restrict max motor RPM's as needed to suit the ductwork restrictions. The 2 ton version is basically just a 3 ton restricted... as is the 4 ton model. I'm not quite sure why carrier bothered making the 2 and 4 ton sizes. Actually with you low heat gain an Infinity 19 would be MORE efficient than a Greenspeed because you don't need the capacity. The Greenspeed and most inverter unit trade low temp COP for capacity. So a convenitonal unit has higher effciency but would normally need heat strips a lot. For you home, I would get the smallest heat strips available, just to temper the air during defrost.
Infinity zoning is still arguably the best system on the market since it's fully . I would still go 2 stage just for comfort. This sounds like a luury home, why go cheap on comfort. IT will also be a LOT quieter when a single zone is calling... about 400CFM vs. 650CFM with Infinity. More efficeint from longer run times when a small zone is calling.
Since this home is well insulated and probably tight. You'll also need a HRV, or you might want a whole house ventilating dehumidfier. A large protion of hte time this will manage you humidity (latent) load and you won't need to run the AC to dehumidify.
Congrats on building a very well cosntructed and insulated home. Don't stop short os a well balanced, installed and designed HVAC system. Asking quiestoin on here at least shows your concerned and interested in comfort.
FWIM, Carrier has quite a few rebates right now. The Infinity 19 is only a little more than an Infinity 16 heat pump. THe 19 is also a little quieter. I'm having a Infinity 19 installed in my home this week.
Thanks for your imput. What do you mean by the statement.
(Infinity zoning is still arguably the best system on the market since it's fully) Fully what.
I want to put in a good system.
The dampers (fully) modulate..........no by-pass needed.
Originally Posted by JimmyP
Carrier wasn't the first to introduce a zoning system with modulating dampers, and it isn't exclusive technology. However, Carrier's is arguably the most user and tech friendly and does work very well when installed and set up properly. The Trane ComfortLink II zoning system is still pretty new (although the original ComfortLink had been around for years), so I'd imagine most aren't familiar with it and there aren't many out there compared to the Infinity. I do like what I'm reading about it; it has the same functionality as the Infinity system in many ways.
Last edited by RyanHughes; 04-08-2013 at 12:11 PM.
sorry, forgot the word "modulating". Any modulating system that is based on a controller, will be superior to a discrete system that just opens and closes dampers and thermostats that "call" for heating or cooling. Modulating system more closely mimick commerical systems that run continously and modulate to send air flow proportionally based on heating, cooling or minimum ventilation requirements.
Agreed, modulating zoning is really the best solution for efficiently controlling zone spaces. It'll be more prevalent when more true variable capacity systems are introduced, such as the Greenspeed.
Originally Posted by motoguy128
Originally Posted by RyanHughes
Very true. With multistage equipment while modulating distributes the capacity proportionally, you still must cycle the equipment for the overall heat loss and gain. With modulating equipment, the equipment capacity and airflow always matches the load precisely. Although there are still limitations. The optimum way to manage load is with chilled water. You can vary both airflow and water flow to get exactly the capacity you need.
Me? I keep it simple... simple peice of equipment.... motorized dampers and a by-pass.
Thanks everyone for your imput.
I had a guy drop by today from a HVAC company and he suggested just 2 zones one for basement (1130 sq ft and heat loss of 4190 btu's/hr) and one for main floor and loft ( 1400 sq ft and a heat loss of 16686 btus/hr).
Those numbers I came up with using HVAC Calc.
He said I had a heat loss of ~ 38000 btu's /hr so I needed a 3 ton 2 stage and duct work to handle over 1200CFM. He needed that air flow to run 2 supplys to a loft that that is open to below, for AC purposes not heat. The loft is less than 500sq ft and has a vaulted ceiling with a ceiling fan. From the posotion of the AH the two runs would be 6" lines and one almost straight up so 9 to 10 feet. The other would be about 30ft long.
I don't know how he got the 38000btu number bet he measured floor, wall and and window areas. He did say it would be more difficult to heat this main area where the vaulted ceiling is 21 ft from the floor. There are 3 ceiling fans to move the air.
Would my calculation be off by that much?
Last edited by JimmyP; 04-09-2013 at 03:52 AM.