You should at least have a pretty good idea of what kind of shape the duct system is in. I discovered that my wife's first house had a system that consisted entirely of duct board taped together with duct tape. In the eave space, the sticky on the tape went away, and entire runs of duct had unsealed gaps that belched conditioned air into the great outdoors. Not a very economical situation to say the least.
jhaas wrote: replacing the indoor AND outdoor control boards is a stab in the dark. hes just throwing parts at it. those boards are not cheap but not $1000.
Indoor control board may be a shot in the dark. The repairman did show me where the outdoor unit's control board was scorched. Coincidentally (or not?!) we had a pretty big t-storm here the night before...he asked if we'd had a power spike event recently, but stopped short of calling it lightning damage.
ive fixed A LOT of older HVAC untis on my properties. its only the boards 10-15% of the time. (especially both at once)
check the little transformer in the inside unit. it provides 24v power for boards and sensors etc. Ive had those go often. they are less than $10.
szeis4cookie wrote:jhaas wrote: replacing the indoor AND outdoor control boards is a stab in the dark. hes just throwing parts at it. those boards are not cheap but not $1000.Indoor control board may be a shot in the dark. The repairman did show me where the outdoor unit's control board was scorched. Coincidentally (or not?!) we had a pretty big t-storm here the night before...he asked if we'd had a power spike event recently, but stopped short of calling it lightning damage.
That's too bad, if it was, that would likley be covered under your Homeowners Insurance.
In reply to szeis4cookie:
Replacing the ductwork may be cost prohibitive. Improving it to function adequately is not.
But you probably won't find a contractor to do it. They don't know how to price it to make money on it.
It is easily within the abilities of an average DIYer.
In a 70's vintage Cape Cod, the only difficult parts may be high/ low ducts inside walls (which might be plaster). The answer on these is to not replace them, but seal them in a manner that incorporates the entire inaccessible part of the duct within the conditioned space. So, you seal it very well from under the house (or the attic) to prevent the duct from drawing from the unconditioned spaces, then treat the entire stud bay as part of the duct.
Your largest leaks will be the return system (starting with the return plenum, which can be repaired from the inside with mastic), then things like your bath vent fans, range hood exhaust, water heater and furnace make up air, exhaust fans, and dryer vents. ALL of these things are easily improved.
There are a lot of big improvements which can be made from the attic.
As I said, get a blower door test. A good one will be able to advise you on the most cost effective improvements, which you would be very capable of doing yourself at a minimal cost with some time and creativity.
Contractors will not give you good advice on this, because it is not something they can make any money at.
SVreX wrote: In reply to szeis4cookie: Replacing the ductwork may be cost prohibitive. Improving it to function adequately is not. But you probably won't find a contractor to do it. They don't know how to price it to make money on it. It is easily within the abilities of an average DIYer. In a 70's vintage Cape Cod, the only difficult parts may be high/ low ducts inside walls (which might be plaster). The answer on these is to not replace them, but seal them in a manner that incorporates the entire inaccessible part of the duct within the conditioned space. So, you seal it very well from under the house (or the attic) to prevent the duct from drawing from the unconditioned spaces, then treat the entire stud bay as part of the duct. Your largest leaks will be the return system (starting with the return plenum, which can be repaired from the inside with mastic), then things like your bath vent fans, range hood exhaust, water heater and furnace make up air, exhaust fans, and dryer vents. ALL of these things are easily improved. There are a lot of big improvements which can be made from the attic. As I said, get a blower door test. A good one will be able to advise you on the most cost effective improvements, which you would be very capable of doing yourself at a minimal cost with some time and creativity. Contractors will not give you good advice on this, because it is not something they can make any money at.
Your advice is well taken - but a bit out of scope of the issue at hand. The heat pump is currently non-functioning, and the decision is strictly repair vs. replace. I will probably do that at some point - but this is not the time.
I agree: get that puppy up and running first, then go back and work on the ducting. In a house that vintage, it would not surprise me to find that some of the metal ductwork is rotted from the inside. That was a problem with one run in my 1979 vintage crib, it's not hard to fix just dirty and time consuming. I agree that flex duct is probably worse than useless.
szeis4cookie wrote: The heat pump is currently non-functioning, and the decision is strictly repair vs. replace. I will probably do that at some point - but this is not the time.
I stand corrected. I got off track.
My vote is for "replace" and with the system you'll want after you optimize your envelope and air distribution system. Money is cheap to borrow now; pay it back from what you save against trying to rope another few years out of an old A/C. Same goes for the blower door test and the infrared scan (other methods for detecting air or energy leaks work well too).
Several grand look big now, but add up what you've spent on HVAC energy bills over the last year and compare.
No worries SVReX - I do appreciate the advice, and it is being filed away for the future :) Thanks everyone for the advice - we found a more reasonable contractor, and we'll probably end up going the replace route.
Watch this space for a learn me thread on ductwork...
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