Is the backup oil system forced air or hydronic?
Why would you have oil backup with Greenspeed?
Do you have an Infinity matching FE fan coil?
Is the forced air zoned beyond just âÂÂ2-systemsâÂÂ?
Can your duct systems handle the required 1600cfm for the VNA48 & 2000cfm for the VNA60?
What is the temperature reading and set point at the infinity controller; are they the same?

20F is nothing for Greenspeed. It should still be running at a relatively low speed and still be quite quiet.

I sure hope you have a pair of FE4ANB0006 fan coils and not just an oil furnace!

IMO

SR

Heat pumps installed in the Northeast have to be sized for cooling. I find it odd that you have a 4 ton unit for the upper floor, and a 5 ton unit for the lower floor.

The price you pay for oil and electricity will determine which is more economical to run. Post those prices to get some feedback.

Are you saying the thermostat is set to 68 but the temperature only reaches 67? That would mean the heat pump would be running continuously. As stated above the Greenspeed should still generate a lot of heat at 25 degrees.

The Infinity controller actually has two lockout temperatures. You can set up a temperature band where both the heat pump and furnace can operate. I think this is off by default and needs to be set up.

Here in CT electricity is around 16 cents per kw delivered, oil is around 3 dollars a gallon. We have oil with hydrocoil forced air. 4ton uses fe4anb006 and 5 ton usesfe4anb006l00. Our previous units were 3 and 4. The upstairs was undersized so they recommended a 4ton. Installers said with heat loss 4 ton should meet the demand down to 20f and below that is cheaper with oil. The problem we observed was the set point was 67 yet numerous times reading 66 with no apparent request for heat. For some reason we were at 12$ that day 2x other days. I am starting to think my installers don't know how to configure such a new complicated system. We kept the oil because all installers said we still needed it.. We have certainly noticed odd things like the system coming on to 100% flow and then turning off. I am handy but worried I will mess up something in the settings. I certainly expected more savings then I am seeing. I need to find an expert that can double check it.

Your system is a most unusual configuration, certainly not one that I have seen nor one that I can imagine recommending. However, I have not seen your home.

I would like to know how this system configuration was presented (sold) to you. It appears to me (from a distance) that keeping the oil âÂÂhydro-coil forced airâ was a way for the installer to keep the installation price as low as possible while selling you a system as expensive as possible, perhaps without regard for operating and maintenance costs.

The âÂÂnormalâ way would have been to install âÂÂstagedâ backup electric elements in the FE fan coil units. However this might have meant an electrical upgrade if your electrical entrance is only 100-amps. Full capacity of 2-systems with 20kW electric elements running simultaneously would mean an electrical entrance upgrade to 400-amps; higher stage backup lockout would still require 200-amps. There would also have been the additional cost of oil system removal, furnace, tank, hydro-coil(s) and conversion of oil DHW tank.

Was this the reason for keeping the oil system as the backup?

You certainly have very high efficiency equipment in the Carrier Infinity Greenspeeds - but you donâÂÂt seem to have high-efficiency âÂÂsystemsâ as configured!

I have often seen the conversion to dual-energy systems without proper analysis and planning that has led to little or no savings. Conversely, I have seen these conversions leading to savings almost beyond the ownersâ wildest dreams!

IMPO

SR