Thread: ASHP question
View Single Post
Old 12-17-11, 04:37 PM   #4
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Quote:
Originally Posted by poleikleng View Post
This seemed to confirm that the downstairs, 1.5 ton heat pump, was not running correctly. I did call the company that installed the units and asked them to contact Fujitsu and see if this was a concern but have yet to receive a response. Have you had any other's who may have the same issue that I experienced? Also, today outside tempereaure is 40 degrees, remote set to 70 degrees, temperature from the 1.5 ton air handler is now 97 degrees.
Well, with the inverter technology, your heat pump is capable of outputting a variety of temperatures and air flow rates, depending on what it's little Japanese brain 'thinks' is appropriate at the time.

If it is putting out 97 degree air, that may mean that it is malfunctioning. It also may mean that hotter air is not required to maintain the current temperature.

So, is your unit keeping the part of the house that you want it to heat, comfortable?

Right now, my 3/4 Ton Sanyo is gently wafting out 87.6F air, and it is 40F outside, and the unit is set to 68F, which is exactly what the temp is inside (68F).

Here's an idealized chart that is supposed to explain how a mini-split operated:


The green line is supposed to show how a single-speed compressor would output temp to the room, with big overshoots and big undershoots.

The blue line is supposed to show how an inverter technology system operates, and indicates that in the beginning warm-up, extra power (higher compressor speeds) will bring the unit up to temp fast. Then when it approaches the set point, less power (lower compressor speed) is gradually selected automatically and the overshoot and undershoot are smaller. In my experience the inverter technology gives much smaller overshoot and undershoot than the chart might suggest.

Still think it is defective?

-AC_Hacker
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...

Last edited by AC_Hacker; 12-17-11 at 04:40 PM..
AC_Hacker is offline   Reply With Quote