BabyBldr
Basic Member
Posts:123
 |
| 01 Jun 2011 08:29 PM |
|
I’m not sure what to do about ventilation in our new home in south-central PA. We plan to build as tight as we can, with Zip sht’g and caulking all interior wood-wood connections, and applying airtight drywall techniques. We’re planning DIY install mini-splits for heating/cooling. How it all shakes out is yet to be seen - but that’s our plan.
I like the simplicity of exhaust only, but am concerned about sucking humid summer air (we have plenty of it!) in through the wall assemblies of an AC cooled house.
I’ve read about ‘balanced’ systems with exhaust fan(s) and planned intake HOLES in the building envelop. I guess that beats sucking it though a wall assembly, but jeepers - gotta wrap your head around that one don’t ‘ya? Deliberate holes in the envelop after all that effort at air sealing! And I read that sometimes these systems don’t work as planned and the inlets don’t have much air flow, or even let air out - depending on a myriad of site specific issues.
I’m not totally opposed to the upfront cost of an ERV (balanced) system with dedicated duct work. But I've read forum posts where people just run them a fraction of the time due to all sorts of reasons. And then there are on-going costs with the unit. Well, it just seems like a lot of $ for the amount of use. On the other hand, what I like about the ERV is the ability to filter the incoming air - which would be good for the allergy sufferer in our household.
In our current house, which isn’t tight by any means, when I want to let some fresh air in I just crack a window or two (one downstairs and one up). South side windows in the winter, north side windows in the summer. After a while, I close them. It’s easy. It’s cheap (in terms of equipment). I’m not sure what the $ energy penalty is - but when considering costs of an ERV for the lifetime of its use- I start to wonder.
I certainly don’t want to sound anti-technology … I’m just wondering … and trying to decide. Is it worth it? I know one person who ducted for the unit, moved in, and then never installed it. Maybe his house didn’t turn out as tight as he thought it would, and just opening a window now and then was sufficient. I’m wondering if that is a possible strategy for me. Any advice? |
|
|
|
|
|
|
jonr
Senior Member
Posts:5341
|
| 01 Jun 2011 10:00 PM |
|
Using only exhaust fans with or without intake holes will put the house under negative pressure (ie, not so good). |
|
|
|
|
ICFHybrid
Veteran Member
Posts:3039
|
| 02 Jun 2011 12:53 AM |
|
But I've read forum posts where people just run them a fraction of the time due to all sorts of reasons. And then there are on-going costs with the unit. You only need to run them enough to achieve your aims. ERVs use very small amounts of electricity. 40 to 80 watts. If you run them even 10 hours a day, you use less than a kW a day. Opening a window brings in fresh air, but you also lose the heat in the air that goes out. ERVs recover that heat. |
|
|
|
|
acwizard
Basic Member
Posts:265
|
| 02 Jun 2011 02:00 AM |
|
Ashrae 62.1 dictates the minimum amount of ventilation required for occupants health. |
|
|
|
|
Bob I
Veteran Member
Posts:1435
|
| 02 Jun 2011 08:35 AM |
|
I think you're overthinking this. From what you've described you are building a very tight house, so you will need additional ventilation. You have to understand that you won't be able to tell exactly when you need it; when the CO level gets lower than needed, when the out-gassing from the sofa cushions gets too concentrated for good health. There aren't sensor's made (or at least readily available) that will tell you when your air quality demands fresh air. Install a good quality HRV or ERV, turn it on low speed and leave it on permanently, or as long and whenever the house is closed up. If you open the windows in the spring for a month, you can turn it off then, but turn it back on when you turn on the AC. Use booster switches in the baths to boost it to hight speed when you have concentrated air-change needs; it automatically resets to low speed after so many minutes. |
|
| Bob Irving<br>RH Irving Homebuilders<br>Certified Passive House Consultant |
|
|
jonr
Senior Member
Posts:5341
|
| 02 Jun 2011 09:13 AM |
|
There aren't sensor's made (or at least readily available) that will tell you when your air quality demands fresh air. Quite true - although this is unfortunate since buildings vary widely in how much ventilation is actually needed and there is some cost saving to be achieved by not over ventilating. I would at least turn off HRVs when no one is home. There should also be more emphasis on building with fewer things off-gassing nasty chemicals. |
|
|
|
|
Chloe Taylor
New Member
Posts:89
|
| 02 Jun 2011 11:20 PM |
|
Posted By ICFHybrid on 02 Jun 2011 12:53 AM
But I've read forum posts where people just run them a fraction of the time due to all sorts of reasons. And then there are on-going costs with the unit. You only need to run them enough to achieve your aims.
ERVs use very small amounts of electricity. 40 to 80 watts. If you run them even 10 hours a day, you use less than a kW a day.
Opening a window brings in fresh air, but you also lose the heat in the air that goes out. ERVs recover that heat.
Surely would be agreeing with you, as through going through forums, one is able to go and get the experience from users in trying out several experiments and use that knowledge for his benefit...... |
|
| <a href="http://www.capitalsteelbuildings.co.uk">Commercial Buildings for Sale</a> |
|
|
acwizard
Basic Member
Posts:265
|
| 03 Jun 2011 01:15 PM |
|
Posted By jonr on 02 Jun 2011 09:13 AM
There aren't sensor's made (or at least readily available) that will tell you when your air quality demands fresh air.
Quite true - although this is unfortunate since buildings vary widely in how much ventilation is actually needed and there is some cost saving to be achieved by not over ventilating. I would at least turn off HRVs when no one is home.
There should also be more emphasis on building with fewer things off-gassing nasty chemicals.
The comment made about the sensors is not correct. There are numerous mfgs. that make such a product. It would not be economical to apply this technology to homes do to the cost of the sensors and electronic controllers. |
|
|
|
|
jonr
Senior Member
Posts:5341
|
| 03 Jun 2011 01:44 PM |
|
Do you have an example of one that detects all of the substances that can create poor air quality? |
|
|
|
|
Dana1
Senior Member
Posts:6991
|
| 03 Jun 2011 05:33 PM |
|
Just curious, but do you have the tools & experience for charging the mini-splits with refrigerant? Are there any good installation guides available online?
It seems like only a few aspects of a mini-split installation would be easy DIY for the handyperson. Pouring a pad for the compressor and installing the power, sure, maybe even the refrigerant lines, but getting the full function & efficiency out of it depends lot on getting it right. The pros can usually install & test them quickly and easily, but I'd personally want to take the course first rather than just diving in. |
|
|
|
|
acwizard
Basic Member
Posts:265
|
| 03 Jun 2011 08:12 PM |
|
Posted By Dana1 on 03 Jun 2011 05:33 PM
Just curious, but do you have the tools & experience for charging the mini-splits with refrigerant? Are there any good installation guides available online?
It seems like only a few aspects of a mini-split installation would be easy DIY for the handyperson. Pouring a pad for the compressor and installing the power, sure, maybe even the refrigerant lines, but getting the full function & efficiency out of it depends lot on getting it right. The pros can usually install & test them quickly and easily, but I'd personally want to take the course first rather than just diving in. Companies like Vulcain,Critical Enviromental Technologies,or Acme might be a place to start. The price tag might get a little scary. As far as a DIY for a mini split install, the DIY would be in violation of the Clean Air Act unless certified by the EPA. |
|
|
|
|
BabyBldr
Basic Member
Posts:123
|
| 03 Jun 2011 10:22 PM |
|
Hello Everyone - Thanks for your time and effort. I don’t know anyone in my area, in an existing or new home who has an ERV or HRV. Of the several HVAC guys I talked to (back last June when our current HP quit after 20 yrs and we needed to get a replacement), none of them were familiar with the equipment or had ever installed it. So, it just gets me to wondern’… do I really need this and yada yada yada. But it's very good to hear your input and I'll push on with the plans for an ERV. Dana - I appreciate what you’re saying about the risks of a DIY mini-split install, believe me I do! I’m not saying we’ll do it come heck or high water no matter what … or that we’ll do every last task of the install. And for any DIY install, one has to accept that the warranty is void. So there is a risk to it. Here is a pretty good thread on some DIY experiences in this area. These guys seem to know their stuff and give a good sense of what a DIY person would be getting into. http://ecorenovator.org/forum/geoth...oject.htmlPersonally, I wouldn’t take on any of this DIY on my own. However, as a skilled and experienced machinist my husband designs, builds, and tests machines and all manner of parts for a living (and for fun in his spare time in his own shop). He feels that setting up this equipment & running lines is well within our (read that: his, with me as go-for) capabilities. As to final hook up, refrigerant, testing and possible diagnostics - we would need ample time, good install guides, possible access to tech support, a budget allowance for specialized tools, and the will to see it all through. ;-) We’re not sure this final part is worth it to us - and I hope I can find a qualified individual interested in only the final portion of the install job. I understand that I would likely be paying a premium for the installer's time & tools in such a case - and there would still be no warranty. I’m not saying I want to do the install - personally I’d rather be working in my garden. But if we can do it (not including final hook-up/testing) over a long weekend and save a good chuck of money - that might be worth it to us. The decision needs more research, quotes in hand, and then a realistic look at where we stand in the project and what time and talents we're able to apply. But thanks for the heads-up - I agree it isn't the typical DIY. |
|
|
|
|
Chloe Taylor
New Member
Posts:89
|
| 04 Jun 2011 01:54 AM |
|
Posted By jonr on 01 Jun 2011 10:00 PM
Using only exhaust fans with or without holes will put the house under negative pressure (ie, not so good).
Yes it will, but dont you think it will eventually help in keeping the place a lot cooler than before...... |
|
| <a href="http://www.capitalsteelbuildings.co.uk">Commercial Buildings for Sale</a> |
|
|
toddm
Veteran Member
Posts:1152
|
| 04 Jun 2011 08:43 AM |
|
Check Craigslist and eBay for hrvs and ervs. Seems like people buy them and reconsider after they get an idea of what an install involves. I am going to have one of each in my house: an hrv for recirc and fresh air, and an erv and power open vents for on-demand bathroom and kitchen venting. After buying the ductwork on CL, I'll have about $600 in it -- $1,600 after adding a dehumidifier with HEPA filter.
BTW, I am with a few tubes of caulk of being done with sealing. Would you be interested in a Ryobi power caulker and a Dow Pro foam gun, plus my left over foam and caulk? 50 cents on the dollar (which was well spent initially.) The power caulker is heavy and tricky (lighten up on the trigger after the gun comes up to full compression.) The foam gun is absolutely essential because you can start and stop it, put it away for a week or two and pick up and start again. |
|
|
|
|
HughS
New Member
Posts:7
|
| 04 Jun 2011 05:50 PM |
|
We have always put ERVs in our projects in hot and humid Texas. We are currently designing an ICF home that will be very tight. I have gone to a new engineer to run the Manual J and D and he discourages the use of an ERV. His claim is that it is more efficient to use good dual speed equipment that will dehumidify well enough. He also claims that, no matter how tight, there will be enough air exchange to keep up. This does not necessarily address the issue of indoor air quality beyond carbon monoxide. It seems to me that a big consideration is lifestyle. For example if you have a bunch of kids that are going in and out all of the time, the ERV is probably a waste. Also, what all gets hooked up to the ERV? If you are only hooking it to the HVAC unit, it also seems like a waste.
Hugh
StearnsDesignBuild.com |
|
|
|
|
Bruce Frey
Basic Member
Posts:429
|
| 05 Jun 2011 12:45 AM |
|
The normal parameter for demand based IAQ ventilation in offices is CO2, about max 500ppm IIRC. They make sensors that will detect just about anything in an industrial setting, but they are not cost effective in a normalized residential or office environment. VOC, etc., are typically not a part of daily life. After construction/remodel these pollutants can be an issue and there should be an out/off gassing period with a high ventilation prior to occupancy if there are not stringently enforced IAQ specs.
Specific tests can be done for specific pollutants, but I don't think it is prudent to add industrial grade sensors for a demand based ventilation system for situation that will likely never occur in normal use.
The problem with sophisticated systems is that they generally require sophisticated people with a adequate budget to operate and maintain them.
Dana, I don't know if you are replying to this thread, but one of the arguments that the manufacturers of mini-splits (Mitsubishi, Daikin, etc.) make for commercial applications is that the typical installations (wall mounts and lay-in ceiling cassettes) can be done with "low tech" people. Ducted systems still require tin-knockers and any AC system needs plumbers (for condensate) if you are in union territory. Controls and programming require trained techs in any case.
Bruce |
|
|
|
|
jonr
Senior Member
Posts:5341
|
| 05 Jun 2011 07:44 AM |
|
Is it worth it? John Bower (1995)1 calculated the cost for 80 CFM of continuous balanced ventilation in several U.S. cities, including Minneapolis, Minnesota, with and without heat recovery. A typical annual cost of 80 CFM of continuous ventilation was calculated at $86 with heat recovery and $188 without heat recovery. Of these amounts, approximately $42 is the cost of the electricity to run the 60 W fan).2 Systems requiring the furnace fan to run continuously will have additional costs for operation. Continuous operation of a typical furnace fan for heating or cooling and circulation would range from $0.40 to $1.00 per day. Note: raise figures substantially to account for the age of the study. |
|
|
|
|
cmkavala
Veteran Member
Posts:4327
|
| 05 Jun 2011 08:51 AM |
|
Bruce;
mini-splits are real simple to install, I installed one myself two years ago, all wires/terminals are numbered and freon lines precharged. 9000btu / 13 seer heat pump by Ramonda $800. delivered. Can't beat it!
|
|
| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
|
|
Chloe Taylor
New Member
Posts:89
|
| 08 Jun 2011 11:34 PM |
|
Posted By acwizard on 02 Jun 2011 02:00 AM
Ashrae 62.1 dictates the minimum amount of ventilation required for occupants health.
Are you sure about as to what ever you have quoted........ ? |
|
| <a href="http://www.capitalsteelbuildings.co.uk">Commercial Buildings for Sale</a> |
|
|
Ventolator
New Member
Posts:17
|
| 21 Jun 2011 05:24 PM |
|
I installed an ERV in my home (WI) as a central bath exhaust system, which doubles as whole house ventilation. It pulls from two baths and from the general kitchen area (for lingering odors and cooking moisture). The fresh air dumps into the furnace return. I only run the furnace blower fan constant 4 months during winter. The ERV has MERV 8 filters. (These do not filter air already in the house that is staying in the house. I have a good filter on my furnace for that.)
With this sytem, I have make up air (only for what is exhausted through the ERV) and energy recovery from what is exhausted. I adjust the master timer for desired air exchange and use the push button when spot ventilation is required. There is no noise at the exhaust points.
An ERV is an indoor air quality appliance that can save sensible and latent energy (when compared to exhaust only fans or opening windows). No ERV can dehumidify a house when outdoor humidity is higher than indoor; or generally in summer. As you move south, dehumidification becomes a higher priority. Then, only properly sized, dual stage A/C can dehumidify a house. If it can't, a dehumidifer is then needed.
An air handler can't bring in fresh air nor get rid of stale air. A tight house with only exhaust points is like a vacuum pump. You can't build a house too tight, but you can certainly underventilate it. Prioritize using closed combustion appliances; furnace, water heater, fireplace. (I have two out of three at this point.)
|
|
|
|
|