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View Diary: Saturday Morning Home Repair Blogging v3.51 (102 comments)

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  •  tax credit info and installation advice (6+ / 0-)

    Here's the tax credit info If you have a heat pump, then you will obviously need a heat pump as the replacement since a plain air conditioner won't provide heat to your home.  Given the age of your unit, you will need to replace both the indoor and outdoor units together.  

    For most circumstances, there's not much point in going to efficiency levels beyond the tax credit level.  Units with higher rated efficiencies than that (SEER >15) often don't perform that much better than the SEER 15 units as the manufacturers use various tricks to test higher even if they don't perform much higher in the real world.  Look at the EER numbers more than the SEER and you will notice they don't go up much beyond that.  

    The cost/benefit analysis will really depend on how much you currently spend on heating and cooling your home.  The new system may save you 30%-50% of that.  The tax credit should cover most or all of the extra cost to go from lower efficiency to higher efficiency units.  

    In terms of installers, make sure they know that they need to adjust the refrigerant charge for the lineset length and that they commission the unit (i.e., test it for proper operation after installation).  First, they should verify that the unit has proper air flow across the indoor coil.  Most contractors don't know how to measure this accurately but they should at least measure the temperature drop across the coil and compare that to the proper value given the operating conditions that they can find in a lookup table.  Second, they need to confirm that the charge is correct which, for a new system with a TXV, involves measuring the sub-cooling and comparing it to manufacturers' values.  

    good luck

    •  also... (5+ / 0-)

      Almost forgot.  The installer should look at properly sizing the unit.  Just replacing the existing unit with one that has the same output may not be ideal.  Most air conditioners are substantially over-sized, which not only results in higher cost for the unit itself, but can lead to poor humidity control in humid climates.  Often you can go with a unit a full ton or at least half a ton smaller -- unless you had problems with it being undersized before (not keeping up with the load).

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