epistemic "would"

Sir,

I would like to know if the following usage of "would"(I think it's termed as epistemic would) is possible.

If she comes,he would be happy.

(I'm well aware that it's a conditional sentence of type-1)

If it isn't correct why exactly so?

I also would like to know that if "would" in a similar sense can be used in a non-conditional sentence like the following one.

He would be delighted to invite some guests .

[piousoul]

Originally Posted by ratna

Sir,

I would like to know if the following usage of "would"(I think it's termed as epistemic would) is possible.

If she comes, he would be happy.

(I'm well aware that it's a conditional sentence of type-1)

If it isn't correct why exactly so?

I also would like to know that if "would" in a similar sense can be used in a non-conditional sentence like the following one.

He would be delighted to invite some guests.

Both of your base sentences sound fine to me.
As for the former, you could also say it like the following:

If she comes, he will be happy.

[riverkid]

Originally Posted by ratna

Sir,
I would like to know if the following usage of "would"(I think it's termed as epistemic would) is possible.
If she comes,he would be happy.
(I'm well aware that it's a conditional sentence of type-1)
If it isn't correct why exactly so?
I also would like to know that if "would" in a similar sense can be used in a non-conditional sentence like the following one.
He would be delighted to invite some guests .

PiousS has answered this well, but I'd just like to add that both a 'will' and a 'would' describe the same level of certainty, that is, 100% certainty. The speaker states that he/she is 100% certain that 'he' will/would/ be happy, if the condition, 'her coming' is fulfilled.