Hello all, I've spent countless hours here doing searches and reading as much material as I can, on radiant heat systems. My thanks to the folks who have unknowingly done so much to educate me. Question, and I will try to supply as much data as possible. New home construction in southwest Wyoming. We are installing hydronic radiant in the concrete floor of the basement and using staple up in our main floor. Second floor loft will use a simple wall unit. Basement is 1000 sf, main floor is 1600 sf, second floor is 400 sf. The token great room wall of windows with high ceiling to the loft area. Insulation is R50 foam in the ceilings and R26 in the walls. I have read here that condensation can be a huge issue with tightly sealed homes and radiant heat. And also for health reasons, we need to be exchanging the air within the house a few times per day. So, my question: is an HRV unit the best solution, or are there other highly effective options that, frankly, aren't in the HRV's $2500-$4000? range?

The radiant heat has nothing to do with humidity build-up in the house, only the tightness of the house does.

You don't necessarily need HRV to get ventiliation air- exhaust-only venting works fine in most colder climates, but an HRV system would ensure that the ventilation air is distributed where it's needed, and that it would be pulling that air from a known, clean area rather than the garage or sub-slab soil etc.

In new construction it's possible to install an HRV system in the $2.5-4K, or as much as twice that. If it's a fairly open floor plan you can get away with going ductless on the HRV with something like the Lunos system

You can get a good HRV for less than $700. If you leave interior doors open, then I believe that you will be OK with no or few ducts.

South of the Wind River range methinks you'd rather keep the doors closed, eh? ;-)

When it's cold out run the ventilation only when needed, to get rid of obvious air pollution and keep the humidity from creeping up over 40% RH @ 70F in winter, which can cause even some fairly high-performance windows to sweat a bit on the coldest days. In most houses (even pretty tight houses) leaving the bathroom fan on for a few hours per day can keep the whole-house humidity under control in a place like high & dry SW WY.

Yes, we're thinking of "closed door" solutions, ;) Our elevation is 6100 feet, so certainly high and dry. Though, if using 1-2 bathroom (or kitchen) fans, then where does the fresh air draw from if the house is tight? Sorry for the uninformed questions, I greatly appreciate the input and thoughts. Those Lunos solutions look pretty slick, though if I read their literature correctly, 2-3 pairs are needed for a home of my square footage.

If you (or builder) really went above and beyond, then you should get an HRV system. Most houses aren't near as "tight" as their owners would like to think though. Did you have a radon test or system installed? This becomes a bigger issue when your house is sealed

I'm building a 1200 SF home in northern California. I'm required to install some sort of whole house ventilation, and at first I was just considering getting a bath exhaust vent that would run constantly, but I, too, wondered how to work out incoming air esp. since there will be a wood burning stove for secondary heat during power outages or for the simple pleasure of a wood fire. Now I'm looking at a Broan HRV70SE that will draw air from bath and kitchen and exhaust it through a simple heat exchanger drawing in outside air and bringing it into the bedroom and living areas. It will move (in my case) 35 CFM drawing about 60 watts. I'm a little annoyed at the thought of building a tight house and then having to mechanically replace the inside air, esp. since the code doesn't consider an open window an adequate means of ventilation, but I also recognize that we don't often open our windows, and having fresh outdoor air in a house can't be a bad idea. We will have a radiant floor (already installed...I'd include photos of the construction process, but I can't figure out how to upload more than two photos to this site) heated by means of a geothermal heat pump. There will also be a single axis tracking solar array tied to the grid to provide electricity for the house. I understand that it's something of a phoney concept, but I'm trying for an energy neutral structure, but we'll see how that goes. The array will be similar to a larger one I posted about on the solar forum.

Ventilation is definitely necessary with a wood stove as the stove will consume oxygen from your living space. At least with an hrv system you can control your infiltration rate and not loose as much heat.

Posted By mmoreland on 10 Feb 2015 08:02 PM
 
I'm a little annoyed at the thought of building a tight house and then having to mechanically replace the inside air, esp. since the code doesn't consider an open window an adequate means of ventilation, but I also recognize that we don't often open our windows, and having fresh outdoor air in a house can't be a bad idea.

Building scientists have extensively studied and concluded that building an air tight home and venting it mechanically is the best approach to proper indoor air quality, occupant health and building an energy efficient home.

The electricity used to run the HRV/ERV is not even worth noting compared to building an inefficient home and letting the walls, windows and roof leak air. A proper ERV/HRV will filter the incoming air and condition the incoming air (90%) and provide healthy air for the homeowner occupants. That is not a bad thing.

Code doesn't recognize opening windows as proper ventilation because that would require the occupant to be "active" and opening windows in winter time when it's 15F outside or in the summer when it's 95F and humid is not efficient nor wise.

If you are going to have a woodstove in a tight house, you should probably look for a wood stove with an outside air kit.
Generally speaking, in cold climates a hrv is a more energy efficient solution to supplying make up air to a house. I am leery of using exhaust only ventilation with a wood stove because it increases the depressurization of the house, and can cause problems with back drafting the wood stove.
I would still use point ventilation ie a bath vent and a range vent.
Cheers,
Eric

Residential ventilation and solid fuel burning are not related. No part of a general ventilation, be it bath fan, HRV or ERV should be considered when designing for combustion air for any fuel burner.

Each manufacturer of fuel burning appliances will post the required CFM of "outside" air for their particular unit. If you are building your own, you should have the calculations done by an experienced designer familiar with the local mechanical code or the IMC at least.

As for general IAQ ventilation. If you are trying to keep the IAQ high while still staying GREEN you must invest in an ERV or HRV to recover the energy lost in general ventilation. This system is balanced, with neutral--no effect--on overall envelope pressure.

We use an ERV with push button timers in each location and timed general run in the house as a whole. If you have extraordinary loads an exhaust fan can generally be added for intermittent use without concern for depressurization as eric said.

Posted By tetonview on 10 Feb 2015 06:06 PM
Yes, we're thinking of "closed door" solutions, ;) Though, if using 1-2 bathroom (or kitchen) fans, then where does the fresh air draw from if the house is tight?

In my home I had ducts run to all the bathrooms. In each bathroom I have a switch (rotary manual timer) where the system runs on low all the time, when any switch/timer is engaged, the system goes into HI mode until the timer quits. So a shower happens, user cranks the timer, system runs HI for up to 60 mins after the shower. I airsealed like a crazy person. I still have holes in my house though (vent over gas hob not installed, etc) so its not final but system working very well and you can feel a pressure difference when opening the door to the garage - even still with some openings.

Lots of very useful and helpful information from all the responses, my sincerest thanks to everyone.