Replacing Family Home HVAC System

As some may know myself & kids moved into my grandparent's home late Spring 2020. We did this at the request of my older brother who needed help with repairs after the house was left to him. Those that have visited the home can tell you how much was needed. The home needed many repairs to ensure the home was suitable to live in. Repairs are still going on still today each time there is money built up to perform what is needed. At this time I am the only working  & all spare money that isn't paid towards household bills goes to needed repairs. This hasn't been an issue until now due to most of the repairs were managable.  Recently while preparing for the winter I was told the HVAC system needed to be replaced as soon as possible due to age and etc. Apparently the system has been like this for some time after my grandmother passed away a years back. My grandfather being on a fixed income couldn't afford to have it replaced when he was living. So now i have the task of getting it replaced so my family can stay warm this coming winter.  I have recieved 2 quotes which the amount I am asking help for. Anything over that amount will be given to charity. This is an extra expense I wasn't counting on but I know God will provide. Many of you know I am not the one to ask for help but instead the one giving the help out to those who need it.  So anything that you can give is much appreciated & I thank you.