HVAC Design Help for New Construction

[polakse]

Hello, I'm new to this forum, but from what I've seen so far, there appears to be a lot of good info and smart people on here! That being said, please forgive my HVAC ignorance. I'm definitely in the learning stages!

I'm in the planning/design phase for a house that I'm going to be building later this year or early next year. The house will be in a colder climate with low humidity (Colorado mountains). The house will be stick-built, with special consideration taken to create an air-tight envelope. I have chosen hydronic radiant subfloor heating as the primary heat source. Because the envelope will be air-tight, and my primary heating is radiant, I will be installing an HRV/ERV (with defrost mode) to maintain indoor air quality. Also, per code, I will have exhaust fans in the bathrooms (inline duct fan installed in the attic), and an exhaust hood over the range in the kitchen. At this point, those are all the HVAC related items that I'm fairly certain about.

Now... I'm also considering a smaller, efficient heat-pump unit to provide back-up heating (if something goes wrong with the hydronic), and to provide some cooling in the Summer, if necessary (probably only for a few weeks out of the year).

First of all, does it sound like I'm on the right track with my HVAC decisions? Or am I missing something? Second, if I do have a backup heat-pump unit installed, how does that ducting interact/coincide with the HRV/ERV ducting and/or the bathroom exhaust fan ducting? Do I have separate ducting for the heat-pump, the HRV/ERV, and the bathroom exhaust? Or are some of those combined?

If it helps with the decision, my primary goal for this project is energy efficiency, but at the same time I want to save as much money as possible.

Any help or advice you all might have is greatly appreciated. Thanks!

Scott

[beenthere]

The exhaust is seperated ducting from the ERV/HRV, and the heat pump.
The ERV/HRV ducting can be tied into the HP ducting.

You need someone to design the system for you.
Then a good contractor to install it. So you don't get burnt by the pitfalls that aren't obvious to the average person.

[polakse]

Thanks for the quick reply.

Anyone have any suggestions for books on HVAC design? The more technical/detailed, the better.

[bobb25]

If you hire a GC, remember most of them hire the cheapest subs possible. Not saying cheap subs do inferior work, but the odds go way up.

[polakse]

If you hire a GC, remember most of them hire the cheapest subs possible. Not saying cheap subs do inferior work, but the odds go way up.

I'm doing all the general contracting. Definitely hiring subs for things like HVAC, but some of the labor I plan on doing myself.

[bobb25]

If you can handle all the headaches and coordination problems, then you're probably better off. It's not for the faint of heart thought. Good idea to read as much as you can, but talk to neighbors, friends, relatives for names and then listen to their recommendations. Might be better to go in with an open mind. Only pick one that will do at least a Manual J.

[dash]

I'd look into using the HRV as the bath exhaust,this way when the bath exhaust runs,you don't get negative pressure in the home,as you are getting the same amount of fresh air as you exhaust.

You can have it operate on a timer or other means for fresh air also,but I think it makes sense to use it for the bath exhausts.

HRV ducts need to designed per Manual D,they can't always be the size of the HRV takeoffs.

[mississippi]

if youre going with an airtight design on you're home check into a daikin system very energy efficient they are also designed for fresh air intake.only drawback they are a little costly also be sure sub is knowlegable with these systems,they work on different princaples than standard hvac systems

[chucko615]

As long as you're putting in a HP as a back-up, you might as well put in a 95% furnace to back-up that HP. You know you can't have enough back-ups....