\"Holy Grail\" of air handlers

Jack_23

One of the great advantages of hydronic is that when you have a leak...you know it. Certainly not so on sheet metal. These are compact, multiposition AH's and while they make them in capacities up to 5 ton, I'd always prefer to do smaller systems, keep the duct work small and short and zone that way. Too, I've never liked zone dampers, such as Trol a Temp and EWC, on single stage systems. On a VS unit they make more sense to me.

Steve Ebels

\"Holy Grail\" of air handlers

I've been asking different suppliers around here for a variable speed air handler that ramps fan speed up and down based on room air temp. Specifically, this would be the difference between set point temp and actual room air temp. The more the temp difference the higher the fan speed and the less.......... you get the idea. None of them say that they have a system or air handler available that does that. To my wet headed brain this would seem to be a match made in heaven for a modulating type boiler. Trouble is I get the proverbial blank stare whenever I pose this question to the salesmen. Like I've just asked them to walk out on the street buck naked while carrying a dead chicken. Something like this has to be made by someone. If it's not, some company should do so IMHO.

Anyone know of a product that fits this description??

Jack_23

Ecologix

Ecologix, a small company in Canada has the best AH on the market. Will fully modulate fan speed on cooling and is three stage on heat. Operation is not based upon dip switches. Operation on H/C is fully automatic for the fan speeds. In heat mode, the unit maintains a 25F delta t. It is available as conventional sized duct as well as a moderate hi-velocity system using 3" duct. That is nice because the hi-v's use about 225cfm at about 1.5" of static vs Ecologix 320cfm at about .8". Neat, neat product.

Joe_13

AC makers

All have them but why pay for an A coil if your only gonna do heat. If you are planning AC, it would make sense to get one of their AH with a hot water coil option.

Jack_23

Available Heat only

These AH's are available heat only. Your statement that everyone has one however is incorrect. There are "variable" speed AH's from the majors but none of them has "true" modulating cooling fan speed nor do they have the 3sp automatic operation on heat. With most you get what they call variable speed but in fact you must make decisions on what speed is best and set the dip switches to reflect that. Other companies are trying to follow, but right now Ecologix has the only true variable speed unit which responds to conditions in the space.

Steve Ebels

Exactly

To call the air handlers that I see on the market variable spped is a farce. All they are is a selectable single speed blower unit with a fancy motor. They are not delivering the true potential that is there.

Mike T., Swampeast MO

Here's the link to Ecologix air handler

http://www.ecologix.ca/Frameset/frameset.taf?_UserReference=B05EDB264333058D3F96A2BA

Technical info provided certainly says it fully modulates the blower for heat (while providing DHW priority) but makes no mention of modulation for A/C.

Dave Yates (PAH)

air balancing act

The only problem with variable speed air handlers centers around the duct design, which is based upon full flow. When speeds ramp down, those issues change and air will take the path of least resistance. Multiple floors will see an imbalance as air flow drops off. As Btu input drops, air temps will "feel" cold. Het pump delivery temps mimic those we deliver with radiant & isn't it interesting how vastly different comfort levels are under those circumstances.

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tim smith_2

variable speed

Take a good quality a/h, put a 3 phase single speed motor in it and install a telemechanique, ie square D fractional VFD drive or Danfoss on it. Use a delta P sensor if you want to install branch zone dampers on it to keep constant volume and use mixing or injection with a setpoint controller for the heat coil. The only problem with this is if you want cooling also. I have done the mixing and setpoint control but yet to find the right job for the whole thing. NOTE: they also make a VFD for single phase fractional also.

HP80

You might like to look at www.adpnow.com the literture here is a little outdated and I beleive the variable speed is now availible. Contact them and they should be able to clarify everything for you.

Eric

Holly Grail VAV system for heating or cooling?

Variable fan speed for cooling is standard comericial practice. Easy as cake with a VFD, espically with newer fraction horsepower single phase VFD's. Under $100. The problem is DX equipment has a hard time dealing with variable air flow. Thus bypass cooling systems.

Not the same for heating. Typically do not have to increase airflow for heating. Why because airflow is dictated by cooling cfm not heating cfm.

Why because cooling cfm typically only has a 15 degree delta T 55 to 70 (due to cold air dumping and mixing). Where as heating is typicaly 20 to 30 degree delta T 90 to 100 LAT (leaving air temperature).


We reduce airflow for heating and vary leaving air temperature. Modulate coil flow.

Why: We slow down fans to save fan energy. Its easier to keep a constant heating airflow and vary temperature. Why spend extra fan energy for increased heating cfm. Size diffusers properly for heating airflow and cooling airflow. Caution: Too low of airflow and diffusers don't work espically in heating, get stratification of warm air at ceiling and no heating to the space.

chris smith_3

holy grail

i agree with eric on this one why not modulate flow of hot water to the air handler to get your desired results as room temp goes futher below set point increase water flow or temp to the air handler

chris smith
paradise porter maine

Jack_23

Why not...

modulate the flow and the blower speed like the ecologix?

john wood

\"fanhandler\" brand control

There is a company I have seen info on that makes an after market control for most any airhandler that will do just what you are asking for. A thermistor in the supply air stream tells the control to adjust the airflow. Try a websearch. I saw the ad in the ACHR news, but not lately.