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Old 04-24-12, 03:31 PM   #21
AC_Hacker
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Did it balance your + & - Ions?
... and I would add to that, if it did balance + and - ions, how do you actually know that it did?

...and would that have any effect on toxins out-gassing from materials inside the house?

Sure sounds like snake oil to me.

But it is true that indoor air quality is a serious problem. The multiple causes of poor indoor air quality are well understood. If you are fortunate enough to live outside of a toxic industrial air shed, the remedies for poor indoor air quality are well understood and pretty straight forward to implement.

It would be a big mistake to be lulled into thinking that the problem was cured by some cheap, ineffective trick.

What is health really worth?

-AC

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Old 04-24-12, 04:01 PM   #22
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I'm not arguing that air quality is unimportant. But most government or manufactures standards lean way to worst case and error on the side of profit over savings. I like the theory of HRV but the real ones I've seen operating here in MN have frosted to uselessness when needed most and have have not made it half thru their spec'ed life without severe corrosion. Most ness systems that include pretempering incoming air have not been operation long enough to judge except that they control frosting. These add-on systems are mechanically elaborate and need to be done at construction time to be at all cost effective. Which leaves out a build and test how tight it is approach. I'm not seeing the real positive results that passive solar design, super insulating, building smaller(better use of space), LED lighting(not CFL's), PV generation, radiant heating, energy/water saving appl, real "green"/recycling lifestyle(less waste) are showing. I'm not convinced that the current HRV's are the best or only answer to fresh air. No offense to anyone. I am following the DIY HRV thread.
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Old 04-24-12, 05:19 PM   #23
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I'm not arguing that air quality is unimportant. But most government or manufactures standards lean way to worst case and error on the side of profit over savings. I like the theory of HRV but the real ones I've seen operating here in MN have frosted to uselessness when needed most and have have not made it half thru their spec'ed life without severe corrosion. Most ness systems that include pretempering incoming air have not been operation long enough to judge except that they control frosting. These add-on systems are mechanically elaborate and need to be done at construction time to be at all cost effective. Which leaves out a build and test how tight it is approach. I'm not seeing the real positive results that passive solar design, super insulating, building smaller(better use of space), LED lighting(not CFL's), PV generation, radiant heating, energy/water saving appl, real "green"/recycling lifestyle(less waste) are showing. I'm not convinced that the current HRV's are the best or only answer to fresh air. No offense to anyone. I am following the DIY HRV thread.
You are correct that HRV's are not the only answer to fresh air. My energy auditor suggested using exhaust only ventilation and replacing the air intake that was plumbed directly into the furnace air return with a PVC pipe that runs towards the ground and then has an up-bend to stop convective air flow. He told me the same disadvantages about heat exchanger frosting and high unit cost just like you did. With the air intake setup, my natural vented furnace and water heater get their combustion air and the exhaust ventilation system would be able to get the intake air that it needs to actually ventilate the house.

The cheap and most electrically efficient option to this is by getting an energy star bath fan that is next to silent and also has the option for continuous airflow. I found the Samsung Whispergreen fan to be a great choice, one of the most efficient fans. It actually has a selector where you can choose the precise amount of airflow and it adjusts how much power to apply to the motor so that if there is negative pressure in the house or if its pushing against excess duct pressure that it will deliver the CFM that you set. Of course you need to use the ductwork size that they require and install it correctly to get that airflow.

Every HRV that I see seems to be massively expensive and pushes enough airflow for a house of 10 people. It's supposed to be about 15CFM per person with one of these fans you can adjust that airflow, with an oversized HRV you are pushing more air and using more power than you need to and since its exchanging that much air, the inefficiency of heat transfer might leave you worse off than adjusting for the exact level of airflow you really need and having no heat exchanger.

I think this system works great in the winter because you want some negative pressure on the house and the exhaust fan will ensure nothing goes positive and pushes the inside high dew point air through your insulation between you and the outside. In the summer though, it brings in high dewpoint air, in MN that air is higher dewpoint than basement temperatures or even most inside temperatures meaning that it might be a better idea to plumb the outside air into the return again and shut off the exhaust ventilator instead of allowing your intake to pull high humidity air directly into the basement.

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Old 04-24-12, 07:50 PM   #24
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I'm not arguing that air quality is unimportant... I'm not convinced that the current HRV's are the best or only answer...
From your previous description of the addition you intend to add to an existing structure, you likely will not reach critical infiltration sealing when you consider the entire structure... but if you do a blower door test, you will know for sure.


Fi-Wi HX

As for myself, I'm looking to get my hands on a Fi-Wi HX.

Best,

-AC
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Old 04-24-12, 11:14 PM   #25
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Honestly I can't believe there is doubt about fresh air here. If anyone has spent any amount of time in a really tight house you wouldn't question. You wake up half dead with no HRV running and every bit of BO or compost or onion sticks around. When spring comes and the windows open life is renewed.
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Old 04-25-12, 12:08 AM   #26
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I'm not at all doubting the need for fresh air I'm just cautious about how best to provide it. Being a doomer sort of guy I don't want a house that is so tight it's hell to live in if the power goes down for an extended period of time. So in my case super tight air sealing and an HRV is not a good choice.
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Old 04-25-12, 03:04 AM   #27
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Being a doomer sort of guy I don't want a house that is so tight it's hell to live in if the power goes down for an extended period of time. So in my case super tight air sealing and an HRV is not a good choice.
Doomer, huh?

Maybe something like this would work for you up there...


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Old 04-25-12, 09:23 AM   #28
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I am following Fi-Wi HRV's also, some of which are being designed as not whole house units not needing ducting. Have not found enough real working comments to see what issues they have with frosting. Their are HRV's that are supposed to swap humidity as well as Btu's but as yet they are all large and even more costly. Unfortunately climate, space size and its heat loss amount and other factors don't make a good solution the same for everyone everywhere. And I too,though I know for a fact that the construction I can build in a new shell that is as air tight as any, that I do not want to sleep with my possible life depending on a mech system or the power grid to supply it(even with not combustion in the space). I'm just looking at what real levels NEEDED air is(not the same for every space) and that there may be better suited methods recover or preheat that air exchange for small spaces designed for it. I has seen inexspensive DIY solar air collectors heat or nearly heat whole spaces making them quite capable of suppling more than needed "fresh air" if modified to take it in rather than heated space air. If a ground tube loop can preheat incoming air into the 50's and at a low demand is the cost of an HRV(and power to run it) a savings than just heating it another 20 dergrees? How many Btu's can be recovered from a grey water holding tank to run thru a DIY "A" coil to pre heat "fresh air? Closed liquid ground loops are already being used. There may be no better way than an HRV to best provide ACH but I think enough noncommericial research has been put into it yet. JMO.
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Old 04-25-12, 09:45 AM   #29
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You can crack a window if you loose power I guess. It's better than having a leaky house. how often do you loose power? I'm sure less often than the amount of time you have power. A ERV reclaims humidity. Panasonic makes a bath fan style ERV. Why I don't know as the bathroom is probably the absolute last place in a house where you'd want the humidity saved. Removing humidity is more than 1/2 the purpose of a bath fan.

One of the publicly funded programs out here used to install solar hot air gadgets that sound like what you're talking about. In the end they stopped because it was actually leading to higher energy costs. The reason was that the houses got tropical hot in the day and the occupants got used to it, keeping the thermostat way up at night.
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Old 04-25-12, 10:05 AM   #30
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For solar air, my idea was to have an insulated flap to block off the air flow that is connected to a thermostat circuit that also controls that fan to avoid overheating. ...if I can manage to get hot enough to where I'd consider raising the thermostat, I'd be extremely happy. Then again, the thermostat has to go up whenever I have people over for their different comfort needs than mine, so it isn't very high to begin with. If a unit produced around 15k during 'January full sun', I would have had next to zero heating bills all winter outside of the coldest points of the night. I'd have to do some math on that but my sizing is more or less stuck to the size of free glass I can get when I build it.

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