You really need to know the input and the output of the original burner based on its nozzle size.

A proper load calculation should be done and a new oil furnace properly sized accordingly, based on its efficiency, hopefully at least 80% efficiency.

ThatâÂÂs one answer.

Another answer is if the old furnace is about 65% efficient then you would need about 87,000Btu to heat the home. If the new furnace is about 80% efficient then the 110,000Btu furnace should be about right. However, the original furnace may have been grossly over sized to begin with and even a new 110,000Btu 80% efficiency furnace might be too big, particularly if insulation has been added to the house since the installation of the old furnace.

Is natural gas available in your fatherâÂÂs area? Oil is such a nasty way to heat.

SR

Thanks for the answer. Nothing has been changed to the house since the old one was installed. So I guess either one would work for his size home. He just wanted to make sure if would heat the house properly. There are no gas lines around these homes so oil is the only heat.

What location?

What size home?

How is home's insulation properties?

Does home have AC?

Is nat gas service to home available?

Post back.

IMO

Forced air or hydronic (radiator) heat? When you wrote no changes to the house, there is no additional insulation, storm windows (improved windows), air sealing, ... that has been done?

I personally would never buy an Oil furnace.

The other furnaces are probably way oversized for your winter design conditions; which the Load-Calc will show you.

This Free online calc will help you determine equipment sizing & point-out areas that need efficiency retro-work - Once you calculate the page it saves the inputs for up to 24 minutes or, until you change inputs or close your browser.
You can easily reduce infiltration rates yourself, therefore, IâÂÂd use 0.4 ACH (Air Changes per Hour) be sure to add the (Air Changes per Hour) CFM into the âÂÂFresh Air Recommended âÂÂline-slot, or it wonâÂÂt figure the Infiltration & fresh air Btuh.

You can experiment with changing the design temperatures in both heat & cooling, (or start-over showing the New Retro-R-Values) also to see whether the equipment exceeds, at those particular temperatures & new retro conditions, (exceeds) the Btuh calculation load numbers, 'in each' of the 3 cooling categories; Total Btuh, Sensible Btuh & Latent Btuh.

You have to know you're doing the calc RIGHT.

Here is a link that might be useful: Free Online Whole House Load-Calc

"I personally would never buy an Oil furnace."

You like propane better?