Hello all, this is my first post here.
I recently had a new Daikin heat pump system installed (outdoor unit RXSQ36TAVJUA, air handler FXTQ36TAVJUA w/ 5kW backup heat, Daikin thermostat). Unfortunately it has been performing poorly with difficulty maintaining indoor temperatures above the low 60s despite outdoor temps in 20s-30s at the lowest. The fan also seems to be operating only at the highest speed when the system is on (fan speed set to 'auto' and won't even decrease when manually changed to 'low'). Insulation is good in the house and I recently air sealed windows, doors, etc.
We have old ducts with all the supplies and returns run between joists and very little air flow in a few rooms. This seemed less apparent with our old system but we've had a lot of work done recently and I wonder if some connections were jostled loose.
Questions:
Could leaky ducts adversely affect a heat pump system more than a standard gas furnace given that heat pumps work by moving larger volumes of air over longer periods of time (and this is why I'm now noticing)?
Could leaky ducts alone account for this poor performance?
Could we expect the fan speed to decrease if everything were tighter? I assume a higher static pressure would dial this back automatically?
Is it even worth trying to Aeroseal ducts in a 75 year old house or should we start ripping up the ceiling in a few rooms to give 'em the mastic treatment?
Many thanks!
I recently had a new Daikin heat pump system installed (outdoor unit RXSQ36TAVJUA, air handler FXTQ36TAVJUA w/ 5kW backup heat, Daikin thermostat). Unfortunately it has been performing poorly with difficulty maintaining indoor temperatures above the low 60s despite outdoor temps in 20s-30s at the lowest. The fan also seems to be operating only at the highest speed when the system is on (fan speed set to 'auto' and won't even decrease when manually changed to 'low'). Insulation is good in the house and I recently air sealed windows, doors, etc.
We have old ducts with all the supplies and returns run between joists and very little air flow in a few rooms. This seemed less apparent with our old system but we've had a lot of work done recently and I wonder if some connections were jostled loose.
Questions:
Could leaky ducts adversely affect a heat pump system more than a standard gas furnace given that heat pumps work by moving larger volumes of air over longer periods of time (and this is why I'm now noticing)?
Could leaky ducts alone account for this poor performance?
Could we expect the fan speed to decrease if everything were tighter? I assume a higher static pressure would dial this back automatically?
Is it even worth trying to Aeroseal ducts in a 75 year old house or should we start ripping up the ceiling in a few rooms to give 'em the mastic treatment?
Many thanks!
source https://hvac-talk.com/vbb/threads/2235208-New-Daikin-heat-pump-system-poor-performance?goto=newpost
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