HVAc system cost

[blackhat]

What are you getting for that money? If there is a lot of duct changes involved, it might be a reasonable price, if it's equipment swap, it's high IMO.

[daddo]

so you don't know if a system like I described starts at $1, $10k or $20k.

Certainly not $1. 



  I give in- I'll tell you want you want to hear- yes, given all that detailed info, that might be a good price.

[Mr_Mike]

Given the duct work issues, it might be OK. I think its still high, but what do I know.

[brnhornt]

Hey Terre...quick question...why do you think zone dampers are bad?  I have a Trane system that is from the late 80s.  We're running on borrowed time right now so I will be heading into this fun in the near future.  The system is installed on the right 1/3 of the house.  That 1/3 is always getting nice hot/cold air while the far left 1/3 ends up with trickles of air coming out of the vents.  Last tech I had out pointed out the fact that newer systems/blowers will do a better job...but noticed some duct issues, like the fact that there are (and excuse if I'm not using the right terms) feeder vents coming off the main trunk connected at the very end of the trunk...so the duct can't create back pressure.  Aside from getting those fixed at the time of replacement he mention dampers on the trunk so that way we can close them say half way and help push the air down the trunk line to where the "left side" feeder vents head up.

[brnhornt]

Gotcha...thanks...when I cross this bridge I hope to have a load test be done and buy the right unit.  I'll no doubt be posting here

[Mr_Mike]

Terre: To ask a side question...

Zoned systems: I agree not to zone to fix problems, however, how do you feel about zoning just because one wants different weather in different parts of the house? On my Tenn house, you have previously suggested replacing with a mini-split, which would effectively create unique zones for unique rooms, however, If I stick with conventional forced air, would zoning be appropriate? One zone for BR2/BR3 as they are not used much. One zone for LR,DR, Kit. One zone for master and master bath. Obviously with equipment properly sized.

[Mr_Mike]

I know I'm stepping on Mark's thread too much, so I'll quit here.

A mini-split does not necessary mean separate zones in each room.  Some manufacturers (Daikin, LG, Samsung, maybe more) offer a conventional 2, 3, 4 ton indoor fan coil unit that can be vertical upflow/horizontal with 0.5" external static pressure, suitable for a direct replacement of an existing split system (gas or heat pump).  IOW, if you currently have a 3-ton conventional, ducted system, those manufacturers offer an indoor unit that can be changed out without too much headache.  The benefit is the higher efficiency, quietness, etc., of the condensing unit.

Interesting. So, basically, a high efficiency split system and the "mini" designation is somewhat unnecessary. I'll dig some more in this issue.

As far as using a zone damper system, they MUST be designed and installed properly.  You cannot design and install them where the unit is covering east and west zones and expect the system and zone dampers to perform like magic.  The east side in the mornings of October and possibly November, along with April and May are going to be calling for cooling while the west side is satisfied or calling for heating and vice-versa in the afternoons.  The west and southwest sides might be calling for cooling at 3 pm in early November if there's a lot of glass and the north and east side will be wanting heat.  You can't do both.

Another problem with the zone damper systems is the ductwork seems to never be correctly sized nor the air distribution nor are there enough bypass dampers or are the bypass ducts large enough.

Another problem is that the zone damper systems never seem to be programmed correctly with the logic.

One other problem is that there's a thermostat for every zone damper.  If there's 4 zones in a house, most occupants have no idea how to operate the system correctly....and I'll admit it can take a while to fully understand how to best operate it.

They sound like the greatest thing since sliced bread on the surface but they are really a nightmare IMO/IME.

Thanks for the info.

It is quite obvious that I should pay for a complete system design regardless of my path forward.

Provided I need/want zoning, I do not intend to zone east/west, I'd zone based on usage of rooms. Solar gain over the day shouldn't be too much as the house has garages on both ends and adequate ceiling insulation.

Until I live in the house for a while, I'll not know how it works, so its theoretical at this point. Perhaps just proper balancing of the existing duct work is sufficient. Coming from a poorly working house, I just fear that the new one will be poor also.

This new house has a packaged heat pump right now running under the crawl space. To me, it would be prudent to re-jigger the ducting to accommodate a split system and, as previously discussed, add fossil fuel secondary or primary heat.

[daddo]

The information shared is truly helpful to decide for which system we should choose for our house.

 Really? (Scratching my head).