hello, we are in the process of building a custom home and I have to choose the HVAC sub-contractor. I have received bids from 3 different contractors. In trying to resolve differences in approach I am getting many conflicting answers, and I am now thoroughly confused. I'm hoping you can help me determine who is correct.
As background, it is a two story house. We are planning to do radiant heat on the 1st floor, and hi-velocity or forced air on the 2nd floor (except for tiled bathrooms). The hi-v/forced air duals as heat in the winter and A/C in the summer. There is also limited ducting for A/C on the 1st floor for cooling in the summer. House is about 9000 sq ft, 2nd floor has 9 ft ceilings, 1st floor has 10 ft ceilings. Also, we live in Seattle, so we have very hot days for about 3-4 weeks per year, and very cold similarly, but in between it's average. I am told this means it is a reasonable/good idea to focus heat on the 1st floor and A/C on the second, and only secondarily heat on the 2nd floor and A/C on the first.
Here are the issues. It'd be great to get answers to each so I can figure out who is giving me good answers.
1. Hi-velocity vs forced air. One person says that Hi-velocity is the way to go because heating the 2nd floor with will require "pushing" air away from registers in the high ceiling and forced air won't be good for that. For A/C they are equivalent. Another contractor says it makes no difference in comfort, and that Hi-V is just more expensive.
2. Zoning Hi-Velocity. Plan was to have 4 heating and A/C zones. 3 upstairs and 1 downstairs. One contractor says you can't zone Hi-Velocity, one says you can zone it no problem, and the other says it is not recommended because people mess it up but is ok if you know what you're doing.
3. A/C capacity. One contractor is proposing 2 5 ton units (1 each floor). This person says that we "need every bit of 5 tons each floor". Another is proposing 1 4 ton unit. He says the house calcs to 8 tons, but that a 4 ton unit will focus on the upstairs first (which will also benefit the first floor), and then supplement the 1st floor in its "spare" cycles.
4. A/C in parts of first floor. One contractor says we should run A/C to the whole first floor because otherwise it will create drafts. Another contractor says it is fine to A/C just portions (the large open areas) of the downstairs.
5. Chillers. One contractor says that the distance between A/C handlers and condensors cannot be more than 50 feet or they will lose efficiency. His solution is to use Chillers. Another contractor says 75 feet, and it's not an issue. Another says that chillers are not worth the money and only useful in commercial applications in the practical world.
6. Area over garage. We have a wing of bedrooms over the garage. One contractor is telling me that the area of the garage will not be affected by the temperature of the garage (because of the heavy insulation in the garage ceiling), and one is telling me I need to either radiant heat the garage or do a radiant floor in that whole wing.
7. Hot water heater. One contractor has proposed two 120 gallon heaters. One has proposed a 100 gallon heater. Another has proposed an 80 gallon heater. The last one says the 80 gallon heater is rated to 269 gallons in the first hour and that this will be plenty of hot water - figure maximum of 5 showers going at once.
8. Upstairs radiant. As indicated above we are planning to do radiant in the tiled areas upstairs. One contractor says this will be *very* expensive due to having to have a manifold per bathroom. For example, we have two bathrooms over the garage that are 50 feet apart. he says they need a manifold each due to distance.
9. One contractor has proposed a Viesman boiler, one contractor a Polaris or Triangle Tube, and one a York. The one proposing the York says the Viesman is barely better in the practical world and that it is more expensive due to bells and whistles only. I will want to eventually be able to automate the heating through a home auto system, so I need the ability to control the system somehow, but I don't need the boiler itself to be smart. He says the Viesman has things like ability to set a "party" setting for when guests will come over.
10. Piping/controls. Two say Wirsbo only, one says he has an equivalent product that costs less. Two say Tecmar controls, one says I need a different brand (sorry I forget the name) for home automation.
11. Heat pump. One person recommends a heat pump instead of the forced air or hi-velocity on either floor, with the idea being that the heat pump can do heating or cooling. He says there is a model that is really good that won't make much noise ("can barely hear it from 6 feet away"), and that it also means the fuel source can be either gas or electric.
Needless to say, the actual price from these contractors varies greatly, and I'm having a hard time deciding who is on target with their proposals. Any help you can give would be *awesome*!!!!!