# H and V from scratch



## tortilla_flat (Aug 16, 2016)

I bought a major fixer of a house in San Francisco, 1700 sq ft, 2 units (a 1-story below a 2-story), and HVAC of any sort is one of the many things it lacks. 

Granted, we're in San Francisco, and on the "warm" side of the city where in an energy efficient building may never need heating or cooling, or may only desire it a few days a year. But: this house does have a converted attic which is where the bedrooms of the upper unit are, and with a west-tilting non-ventilating skylight it gets hot & stuffy up there. We want to ventilate that space especially. Also, if not expensive, an occasional-use heating element for both units (controlled separately) would be awesome. Humidity/moisture is not an issue here. By law can't have a woodstove here. 

What ventilation and heating options have folks in the same situation (converted attic) had good luck with / recommend we consider? 

- Anyone installed a Lunos system? I'm very interested in these!
- Would a very large plain ole bathroom/kitchen exhaust fan suffice for attic ventilation?
- What about an openable skylight? (I still feel we'd need additional ventilation beyond this but perhaps there's some skylight/fan product I'm unaware of)


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## joecaption (Aug 16, 2016)

What type roof?
Is there any soffit and roof venting?
How much insulation is in the attic?
Is it a a cathedral ceiling?
Old single pane windows?


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## tortilla_flat (Aug 17, 2016)

Hi! Thanks for your response. 

_What type roof? _Asphalt shingle; to be replaced in the next year or so
_Is there any soffit and roof venting? _No
_How much insulation is in the attic? _Hard to tell if there is ANY, since I bought the home tenant-occupied and can't go in headfirst swinging a sledgehammer at walls... but from the skylight well (pic 1 | 2), it looks to be about a foot of clearance. Who knows what's in there.  
_Is it a a cathedral ceiling? _Yes, albeit not a very tall one. Probably not even 8' at the tallest point. 
_Old single pane windows?_ Yup.


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## kok328 (Aug 17, 2016)

Sounds like a candidate for a whole house exhaust fan.


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## nealtw (Aug 17, 2016)

if a new roof is coming I would go with vented drip edge and ridge vent.
http://www.airvent.com/index.php/products/intake-vents/vented-drip-edge


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## oldognewtrick (Aug 17, 2016)

nealtw said:


> if a new roof is coming I would go with vented drip edge and ridge vent.
> http://www.airvent.com/index.php/products/intake-vents/vented-drip-edge



Only works if the rafter bays are unobstructed by blocking and or insulation.


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## nealtw (Aug 17, 2016)

Oh sure,:hide: come along with details

With no overhang and the drip with a long tail, maybe, just depends on how thing are constructed below.


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## oldognewtrick (Aug 17, 2016)

It's a great product, we've installed bunches of it over the years.


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## nealtw (Aug 17, 2016)

Years ago I helped a friend with a house very much like that but the liner and ship lap was rotting from no venting so we just extended the rafters and gave the house 12" overhang, soffit and vents. All houses here have overhang anyway so it looked better when done.


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## tortilla_flat (Aug 22, 2016)

nealtw said:


> if a new roof is coming I would go with vented drip edge and ridge vent.
> http://www.airvent.com/index.php/products/intake-vents/vented-drip-edge



very interesting... hailing from climates where no A/C was a death sentence, the vented drip edge and ridge vent are all new to me. I like that it doesn't require electricity. Watching some youtube videos and it doesn't look bad at all to install.


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## nealtw (Aug 22, 2016)

tortilla_flat said:


> very interesting... hailing from climates where no A/C was a death sentence, the vented drip edge and ridge vent are all new to me. I like that it doesn't require electricity. Watching some youtube videos and it doesn't look bad at all to install.



Well that is only the half of it.
A new house built like this would have rafters made from 2x10 to allow for insulation and air gap above that. 
You likely have 2x4 rafters full of insulation so no chance of air flow. So if that is the case venting may be a waist of time, so you have some investigating to do.


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## tortilla_flat (Aug 22, 2016)

oldognewtrick said:


> Only works if the rafter bays are unobstructed by blocking and or insulation.



We're planning to take out everything inside down to the rafters - one, because the walls were done poorly; two, so we can see the extent of the dry rot damage on the east side of the house where it can't be seen from the outside (the neighboring building was built about 12" from ours). But that's a whole 'nother thread altogether.


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## tortilla_flat (Aug 23, 2016)

Also found some groovy venting skylights. There is one currently, which will be replaced with a vented one. I might want a few. If I go this route, do I still need a ridge vent? (We keep our windows open for 90% of the year)

I will drool over this balcony skylight but I'm not paying that amount! 



kok328 said:


> Sounds like a candidate for a whole house exhaust fan.



While I've used large wall-mount fans in my kitchen before (where my range came with an over-the-range microwave and no exhaust hood) I've never used them in my attic. I was under the impression that the whole-house fan vented from the top floor through the ceiling and _into_ the attic, and hopefully out through a ridge vent. In this house, my master bedroom and home office will _be_ the attic itself, which I suspect has little if any insulation (TBD). Can I install a whole house fan high on the wall of the attic bedroom venting to the outside, much like my former kitchen's wall-mount fan? This is why I was interested in the Lunos system. 

The attic in my last house, too, was my master bedroom, although the major difference between that one and this one is the sheer height of that room - it was 16' tall at its highest point, this one is between 7' and 8' - obviously built with a complete disregard to code.  In my last house I installed (rather, I had installed by a professional) a Unico A/C only system and I couldn't have been happier with it despite its $12,000 price tag. However, it would be totally excessive in this moderate SF climate. In the brand-new apartment in which we currently reside (we can't move into our new house yet as it's tenant occupied) we have turned on the heat ~3 days and the A/C ~3 days over the course of the 1,167 days we have lived here.


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## thematrixiam (Aug 29, 2016)

What sort of heating is in the house now?
Do you have return air? If so, is the attic room attached to this return air system? If so, how?

The link you provided looks like something I would never use or trust. If you want an HRV system then get something that will return the heat properly. 

"The regenerative core is charged every 70 seconds,
afterwhich the fan reverses and the incoming air absorbs the stored heat on its way in."

That's not the way an HRV should work. 

Do you want to recover heat?
Why do you want that system over a proper HRV unit?

What type of seasons (heating cooling) will your house be going through? (not a question about the four seasons of the year).


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## tortilla_flat (Aug 30, 2016)

thematrixiam said:


> What sort of heating is in the house now?


No HVAC whatsoever... thus my post's title.  



thematrixiam said:


> Do you have return air? If so, is the attic room attached to this return air system? If so, how?


None whatsoever. 



thematrixiam said:


> Do you want to recover heat?
> Why do you want that system over a proper HRV unit?


No room for a proper system. Attic=master bedroom. It needs to have a tiny footprint. No need for anything extensive where I live. I'm mostly in it for the ventilation and the occasional desire for heat.   



thematrixiam said:


> What type of seasons (heating cooling) will your house be going through? (not a question about the four seasons of the year).


Not really sure what you mean here... where I live it rarely goes below 50°F or over 85°F year round.


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## nealtw (Aug 30, 2016)

If you only need heat a few days a year I would put in a few baseboard electric heaters.


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## thematrixiam (Aug 31, 2016)

the seasons question is a term about what your system goes through. If you don't even have a system then it's more about what you want your potential system to go through.

Some people only have one season, others two. Then you can get more technical with things like humidity and such. 

HVAC includes lots of things: furnaces, bathroom fans, air conditioners, range hoods, fresh air supply, combustion supply, make up air, return air, in floor heating, and even baseboard heaters.

You probably at least have bathroom fans and a range hood. 

Return air could also be simply holes cut under doors. It's not literally cut, it's just that the door is short on the bottom and allows air to move under the door when closed.

I'm also not sure on code down where you are. I'm from up in Canada, so our codes could very well be a little more strict than where you are.

Your main issue seems to be proper ventilation/circulation. Here you have to have a type of circulation system for any and all types of houses, even in floor heating. 

Do you have pictures?
How thick is your attic? The actual roof space, not the room.

A HRV unit is not meant to heat. It only recovers the lost heat going out. Even a make up air unit isn't supposed to be used to heat, it just raises the temperature of the outside air. 

Would you be better off sending it down or sideways?

Do you want to exhaust the air, or circulate the air? 

How sealed is your house? Does the pressure in one area affect another area? If you open a door somewhere does a door close or open somewhere else?


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## tortilla_flat (Aug 31, 2016)

thematrixiam said:


> the seasons question is a term about what your system goes through. If you don't even have a system then it's more about what you want your potential system to go through.
> 
> Some people only have one season, others two. Then you can get more technical with things like humidity and such.
> 
> ...


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## thematrixiam (Aug 31, 2016)

I would honestly wait until you move in to figure out things.

You're going to want bath fans and range hoods. That might be where all your moisture is coming from. I would recommend at least getting those sorted out and then going from there.


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## tortilla_flat (Sep 1, 2016)

thematrixiam said:


> I would honestly wait until you move in to figure out things.
> 
> You're going to want bath fans and range hoods. That might be where all your moisture is coming from. I would recommend at least getting those sorted out and then going from there.



Oh most definitely... I just want to spend the next few months figuring out what all my options are. The roof gets tackled pretty close to, if not right on day 1, so it's worth having some idea of what types of ventilation will be going in. The ridge vent & vented drip edge I do want, since I like the idea of non-mechanical ventilation. 

Bathrooms and kitchens will be gutted further down the line, after the (many) exterior woes are taken care of and the house has a foundation to sit on, and exhaust fans and range hoods will definitely factor in then. We don't plan on doing a whole lot of cooking at home in the meantime due to the state of the house.


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## nealtw (Sep 1, 2016)

So have the roofer install the boots for the bath and hood vent so you can tie to them when you do that work.


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## thematrixiam (Sep 2, 2016)

Take a look at your layout. You might want to vent out the side of the house instead of the roof.


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