Can an ERV push air through an existing HVAC system
As far as an ERV and if it is needed depends on how tight your house is.
How much do you need?
This again depends on your home. A newer home built in the last 20 years with a central heating system they can replace the make up air intake save a little of the outgoing heat pull the excess humidity out and improve over all air quality.
To really do this they need to be on more than the furnace or ac usually runs and on all the time is the normal recommendation. Without the radon concerns I recommend when occupied, with radon concerns 100% run.
A 150 scfm is a lot that is more than many bathroom fans running all the time this will increase your energy cost for both heat and cooling (the erv is not even close to 100% efficient)
this is one area I tell people don’t be over sold. Yes they recover energy but what size make up air do you have on your house now?
It’s easy to measure the duct size vs the wind speed. A simple handheld anemometer can provide the existing flow.
If you don’t have make up air now do you even need 150?
If you don’t have makeup air now and many homes do not going hog wild will increase your utility bills and a smaller system will probably improve the air quality.
The air handler is moving the air through the house not the erv.