Tenant compensation for non-working furnace?

[Ken P.]

We recently had a furnace conk out and when we called our previously-reliable HVAC guy, found out that he was not able to work for medical reasons.  It ended up taking about 2 weeks before we had the furnace replaced.  While it was out I provided electric heaters for the tenant to use, and the unusually warm weather we've enjoyed lately, and the apartment's location surrounded by other heated apartments, meant it was still habitable during the furnace outage, albeit cooler than normal.  The tenant's rent is $550/mo, and I was planning to credit him $100 for the inconvenience of having to use the electric heaters (and higher electric bill he'll no doubt be receiving).  Does this seem reasonable?