Just looking for some advice and or pointers from people who either own one of these or who install them. I'm not looking to crucify the company we purchased and installed through as they are doing all they can to fix the issues to the best of their ability ( but this is one of the first ones they have put in) and we've also had technical reps from the unit manufacturers - fujitsu into the house on 3 occasions in the last 2 weeks to ascertain what's not working. Again, they are doing their best but with most problems and wider audience experiences I'm hoping we can shine additional light on the issues.
It's a whole house system split into two zones. That means 2 large outdoor units and 2 indoor air handling units in the ceiling space - each supplying air to the it's own zone through flexible ducting. There is an air return in each zone and various sized outlets. The zones are split into the 2 x living as zone 1 and the 5 bedrooms, long hallway as zone 2. This system was to replace several individual heatpumps and should have provided whole of house heating.
We appear to have several issues.
1) The air handler units are 'hung' from the trusses in the roofspace on threaded steel rods. I presume to isolate them as much as possible. They are big units and even with the best of intentions may be touching wood in some places. Installer confirmed this. They are also about 4 inches above the plasterboard ceiling. They run on 4 speeds. At speeds 3 and 4 the noise - mainly fan noise I presume is certainly very noticeable but does mainly reduce a fair amount at speeds 2 and 1. Several times a week we get a very loud and noticeable low frequency "hum" in the living areas when it's running - irrespective of the fan speed. As you walk around the living room the hum becomes appreciatively louder then fades away to almost nothing based on where you stand. Reminds me of school experiments and sounds waves doubling in amplitude or cancelling each other out from two different stereo speakers etc. Any ideas what's causing that?
2) There is surging when the unit is running. The fans ramp up and " blow " loudly through the outlet vents, then suck loudly back in through the air return in the ceiling space..Then ramps down, ramps up and repeats. Initial fix was to install larger air returns and straighten some of the tighter bends in the flexible ductwork. That didn't resolve it. Next fix is to install additional air returns in each zone as it appears the volume of air the return can deliver back to the handler is less than the volume the air handler can expel. Sounds plausible but prior to chopping more ceiling space out just wanted some thoughts.
3) The last issue is for zone 2 - the hallway with bedrooms coming off it. There are no outlets in the hallway and the idea is the heat from the bedrooms gets sucked out , flows up the hallway, into the return air vent at the end, through the handler, reheated, then back into the bedrooms, then into the hallway etc. Doesn't quite work like that in principle. What we end up with is two different issues - Temperature layers and generally poor heating across the rooms.
We notice in each room 3 distinct and easily measurable temps - super hot at the top, very cold at the bottom and mildly warm around waist height. Moving from rooms to the hallway and back again, you notice large increases or decreases in temps. You also notice a very hot head as you pass through each bedroom doorway which tells me the return is sucking high level / hot ceiling air back into it.
The second issue is the hallway and rooms don't appear to be heating. Last sunday when it was very cold outside we had the system running all day at 24 degrees on the controller and temps in the bedrooms barely got to 14 to 15 degrees C. Temps in the hallway were cooler. Electricity bill for one day was $37....!!! Shut any bedroom door and that room heats up to HOT HOT within 5 minutes so it appears something to do with the hallway and having the doors open for return air flow.
To me it appears that the forced air from the ceiling is not moving the cold air sufficiently, is subsequently being sucked back into the air return as it's highest level and spewed out again then repeated. I presume eventually it would displace enough cold air but instead of the claimed 20 minutes to bring it to temp its more like 20 hours.
Appreciate you reading and looking forward to moving this onto a better platform.
Thanks again
Trusted
