View Full Version : Split geothermal heat pump with FE4
02-03-2005, 12:45 PM
Seems like there was some discussion last year about using a geothermal heat pump with an Infinity air handler, but I can't find it now. I thought someone mentioned something about not being able to slow down the air flow in heating mode because the Infinity system would treat a geo heat pump as electric heat and speed up the blower accordingly. Is this right and a reason to not use an Infinity air handler with a geothermal heat pump? Does this change depending on whether the heat pump is a single stage or two stage (two stage requiring the interface module, I think)?
The Infinity feature that I'm most interested in is its unique zone controller. I like the idea of no bypass damper, varying the air speed to meet the need, and the modulating dampers.
Over in the "Wall of Pride" forum, mcair shows a nice install of a WaterFurnace split unit with which he used a Carrier FV4 air handler and Thermidistat for the upper unit and a packaged WaterFurnace for the lower unit. Since it is the zoning capability that really intrigues me, would it be better to go with a more vanilla, without all the bells and whistles, variable speed air handler and the Carrier zoning system instead of stepping up to the Infinity? What are the reasons to use a packaged unit over a split system?
[Edited by mjballweg on 02-04-2005 at 05:50 AM]
02-03-2005, 04:33 PM
Don't know about Carrier,but I have used American Standard variable drive air handlers with Commandaire split Geo-thermals and had very good results. Customers really like the comfort control of the varable drive. I would assume that the Carrier would be about the same with there thermostat ,as long as you staged it properly.
02-04-2005, 12:05 PM
Thanks aircooled. It's funny, the other setup I am considering is using American Standard 4TEE variable speed airhandlers and still use the separate Carrier zoning system. I'm just having a hard time deciding and my contractor will do either depending on what I want. Too much idle time before they start building!
Surprising that some of the Carrier people haven't said anything re the Infinity fan coils. I know there is a considerable wealth of Carrier knowledge here. Any takers?
02-04-2005, 12:52 PM
Originally posted by mjballweg
Seems like there was some discussion last year about using a geothermal heat pump with an Infinity air handler, but I can't find it now. I thought someone mentioned something about not being able to slow down the air flow in heating mode because the Infinity system would treat a geo heat pump as electric heat and speed up the blower accordingly. Is this right and a reason to not use an Infinity air handler with a geothermal heat pump?
You can use what Carrier terms a "non-communicating" air-source heat pump with the FE4- meaning a non-Infinity unit that would be controlled the old-fashioned way. It's not going to treat it like electric heat.
The FE has terminals in it to wire up to heat pumps with standard (C,R,O,W,Y, etc.) wiring. You can do it with a single speed or two speed unit- though I tend to agree, it seems like two speed would require a NIM. No big deal there, though.
On power up, once the Infinity control determines that it can't find an Infinity (communicating) outdoor unit, you tell it through the menus that the "outdoor unit" is a heat pump, one or two speeds, and the nominal BTU size of the unit. I don't see any reason that it would treat a water source unit any differently than an air source at that point- or any reason that it would really need to. You can specify the HP Comfort blower speed curve and it will run the blower slowly in heating mode- down to as low as 300 or 275 cfm/ton, I believe. You may actually find that to be overkill with a water-source system, since its output won't drop off in cold outdoor temps like an air source heat pump's would. If so, you could switch to the Efficiency or even Maximum fan profile if needed.
Infinity zoning is amazing, no doubt. If you're going for a fancy system already, I'd consider it a shame not to go that last little bit and get it. It's significantly better than any other zoning product in the way it understands duct capacity, noise constraints,
I'm basing this on my experience having an FE4/Infinity and non-Infinity outdoor unit installed in a two story condo association clubhouse (basically a single family home but nobody lives there); one zone per floor. I also have a non-zoned Infinity dual fuel system in my condo; and dual fuel with a non-communicating outdoor unit certainly takes a NIM. Mine is screwed to the side of the furnace.
The only caveat is that it might assume you have a Bristol compressor that runs at 50% for low speed, and the two speed WSHP you're looking at may have a Copeland unit that only steps down to 66%. Again, it looks to me like the same question as trying to run a non-communicating two-speed air source heat pump. It's not a simple system, but I just don't see why being water source would make a difference beyond that.
I am a homeowner/condo board member, not a pro here, but am certainly an Infinity enthusiast.
[Edited by wyounger on 02-04-2005 at 04:02 PM]
02-07-2005, 02:48 PM
Thanks wyounger. Your assessment is the logical response to my original post, but I had this bug stuck in the back of my mind that there was a potential problem with using a geothermal heat pump with an FE4 air handler. But, the problem was with my memory, not a prior post that I thought I remembered. I finally found the prior post - http://hvac-talk.com/vbb/showthread.php?threadid=59225 - and refreshed my recollection that what was being discussed was a hydro-air/Infinity system, not a geothermal/Infinity system. My bad! You may not be considered a pro here wyounger, but during the course of your excursion you've certainly made many valuable contributions to my understanding of the Infinity system.
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