ICF Construction, mini splits and my exhaust problem

[rykertest]

So I'm in the final stages of my icf (insulated concrete forms) home design. It's all pretty much done and I am "set" on using a ductless mini split. I live in Missouri and also use wood heat for most(read 85%) of my heat in the winter. My only hang up is the whole house exhaust. Due to the ICF homes being so air tight, the sick home syndrome keeps popping into my head and I wonder how I can bring in fresh air (when opening a window isn't an option) and remove stale air and still make it cost effective. I know most of the major mini split brands have built in filters that "clean" the air, and that helps the issue some, but what other options do I have? I was thinking about using a erv type system, but if I need ductwork, then I'll just go with an old heat pump, which I don't want to do.

So, aside from just telling me to "use a traditional heat pump", anyone have any ideas on how I can solve this problem? Would haveing an exhaust fan of some type in a central location with a HRV or ERV be enough? How would you suggest I set up the erv?

Also, some additional questions are;

1) I'm looking at the daikin units that can run 4 or 5 indoor units, and I'm looking at the heat pump. No price questions, not even ballpark



2) I also see mixed reviews on their longevity. Are the comparable to a standard hvac unit, say a trane, york, etc?

3) being in the midwest our winters can get cold, near freezing sometimes at night, but not forlong stints. I've been using wood as my primary heat source for awhile now and don't feel the need to do any sort of aux. heat besides my heat pump and wood stove. I would think if I lived in Michigan, I would need somethign additional but not MO.

4) I saw a few posts on other hvac threads about parts being hard to find after just a few years, but was that the name brand systems or low end ones?

Thoughts?

Thanks in advance for any help you are able to provide.

[paul42]

mini-splits use very few standard parts, so replacement parts could become an issue. Finding someone that knows how to work on them can be another issue.

In my house, I have one conventional system, and one mini-split. If I had it to do over again, I would figure out some way to go with two conventional systems.

Designed and installed right, a conventional system can be much quieter than a mini-split. My mini-split is not loud, buy my conventional system is inaudible.

My Fujitsu mini-split is very poor at controlling humidity. The condensate drain tends to clog up, and the unit is in my bedroom which makes it a pain.

Fresh air is going to be an issue if you go with the mini-splits. You would need to add something like a whole house dehumidifier to bring in fresh air and control the humidity.

your wood burning furnace also needs a dedicated fresh air supply.

[Cold Feet]

An ERV with a central return isn't going to work well. Look at running 4" ducting from an ERV to selected rooms in the house. Deliver fresh air to the bedrooms and pull stale air from the bathrooms and kitchen.

In this market, Daikin multi splits cost about the same as high-end ducted heat pump setups.

As far as heating capacity goes, Daikin's 4 zone and 6 zone outdoor units lose only 30% of their nominal heating capacity at 17 degrees. They're quite capable of being used as sole-source heat in areas without bitter cold winters.

[temprite]

In Australia you can still get parts for Daikin units that are twenty years old. It is only the less reputable brands that are hard to get parts for.

[beenthere]

Where does the air come from for the wood stove?

Generally, you wouldn't use an exhaust fan with an ERV or HRV, since they are not fresh air make up units.

[Carnak]

Give Benoist's a call,

[rykertest]

Where does the air come from for the wood stove?

Generally, you wouldn't use an exhaust fan with an ERV or HRV, since they are not fresh air make up units.

Hey guys and thanks for everyones replies. I'm pretty well versed on wood stove protocol and mine as they all should, has it's own dedicated air supply from outside. That's how my new home will be as well.

[rykertest]

An ERV with a central return isn't going to work well. Look at running 4" ducting from an ERV to selected rooms in the house. Deliver fresh air to the bedrooms and pull stale air from the bathrooms and kitchen.

In this market, Daikin multi splits cost about the same as high-end ducted heat pump setups.

As far as heating capacity goes, Daikin's 4 zone and 6 zone outdoor units lose only 30% of their nominal heating capacity at 17 degrees. They're quite capable of being used as sole-source heat in areas without bitter cold winters.

Good to heat they heat pumps can handle my winters here from the sounds of it. question on your suggestion for fresh air/stale air handling. WHen you say 4" do you mean solid square duct work or the flex duct? Also, from the removal aspect from the bathrooms and kitchens, how would you suggest removing the air? Other than using a hood that exhausts outside and your standard vent fans I mean. I'm trying to visualize the set up in my head with the duct work and if an erv type system is used where it would be. Are you saying to not use an erv at all? Thanks again for the reply.

[Cold Feet]

Good WHen you say 4" do you mean solid square duct work or the flex duct?

4" round sheet metal.

Also, from the removal aspect from the bathrooms and kitchens, how would you suggest removing the air?

I mean by running exhaust ducting from the ERV (or HRV) unit to small intake vents in the bathrooms and kitchens.

In houses without forced air, ventilators are connected to their own network of dedicated ducting. In the typical configuration, an ERV will pull stale air from vents in the bathrooms and kitchen(s) and blow fresh air into the bedrooms.

See e.g. "Heat Recovery Ventilation" on http://www.walshenergy.ie/renewable_technology.htm . There are better reference sources out there but this is the only thing I can find at the second.

[rykertest]

thanks for the replies guys. I will look at the links you sent. 1 question about the erv/hrv. Where would I be best served to have this unit if I am pulling from the kitchens and bathrooms? In the attic or in the basement with the water heater?

[patchesj]

I wouldn't put it in the attic, you'll end up with frost problems on the exchanger in the winter.

[teddy bear]

So So, aside from just telling me to "use a traditional heat pump", anyone have any ideas on how I can solve this problem? Would haveing an exhaust fan of some type in a central location with a HRV or ERV be enough? How would you suggest I set up the erv?

3) being in the midwest our winters can get cold, near freezing sometimes at night, but not forlong stints. I've been using wood as my primary heat source for awhile now and don't feel the need to do any sort of aux. heat besides my heat pump and wood stove. I would think if I lived in Michigan, I would need somethign additional but not MO.

4) I saw a few posts on other hvac threads about parts being hard to find after just a few years, but was that the name brand systems or low end ones?

Thoughts?

Thanks in advance for any help you are able to provide.

Considering that you have a wood burner and need make-up air for your clothes dry, stove, kitchen hood, and bath fans, consider a make-up air ventilation system for the home. Blending 75-100 cfm of fresh make-up with house is enough fresh air to purge indoor pollutants and allow the exhaust fans to function without back-drafting the wood burner. Saving a small amount of heat is not big savings. During the summer, fresh make-up air also works well. Consider during the summer you will need some supplemental dehumidification during the wet cool weather when there little/no cooling load. A ventilating whole house dehumidifier is the ideal device for the summer humidity control, fresh make-up air ventilation for the whole year. I work for thermastor.com and we make the Ultra-Aire whole house ventilating dehumidifier. Many others are showing up in the market. Check it out. Regards TB