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This question is about indoor air purification - specifically, why is my HVAC releasing dirtier air than my air purifiers when both have HEPA filters attached? Context: I live in California. California is currently On Fire. My home has central air, two portable air filters, and I have an air quality meter. My meter just measured outside PM 2.5 at 521.9. For the record, the EPA considers a daily average of 12.0 or less to be safe, and spikes of up to 35.0 to be ok so long as the year still averages out to 12.0 or less per day. So we're at about 43.5x the recommended nonhazardous level of pollution. (Both figures taken from this chart.) I believe the medical term for air like this is "real fuckin' bad". Indoors, I am achieving PM 2.5 of about 40, sometimes as low as 20. This is worlds better than outside, but still not as good as I'd like. Weirdly, when I hold my air quality meter up to my HVAC vents I get a reading of about 70, much higher than desired. Holding it up to my purifiers shows a reading of about 20. Both the HVAC and the purifiers have HEPA filters, all filters are within their recommended lifespan (in fact, the HVAC's filter is only a couple months old). Why is my HVAC system not cleaning the air as well as my dedicated filters, and how can I go about making it work better?
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Aug 24, 2020 23:12
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Chimp_On_Stilts posted:This question is about indoor air purification - specifically, why is my HVAC releasing dirtier air than my air purifiers when both have HEPA filters attached? The HVAC ducts are likely not sealed well, and are picking up crap from whatever space they're in (attic, basement, etc). If you can reach them, you can go around with mastic and seal up every joint.
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Aug 24, 2020 23:49
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I've got an existing gas furnace and gas water heater that are getting a bit long in the tooth. Right now there are a lot of bay area incentive programs for lowering the cost of heat pump systems and I'm trying to evaluate whether it's worth it or not. I'm going to have someone out to evaluate my particular space to see about the particulars for our living space in a week or so. Overall though, how well do heat pump systems work? Do they last as long as traditional gas furnaces/water heaters? Bay area electricity is waaay more expensive than gas - so I don't think I'll save much money - but if they're safer or heat faster or last longer than previous generation options those are all considerations for me.
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Aug 25, 2020 04:00
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El Mero Mero posted:Overall though, how well do heat pump systems work? Do they last as long as traditional gas furnaces/water heaters? Bay area electricity is waaay more expensive than gas - so I don't think I'll save much money - but if they're safer or heat faster or last longer than previous generation options those are all considerations for me. Modern HP systems work really well, and especially somewhere like the Bay Area, where it's pretty temperate year-round. As you mentioned, cost to operate is highly dependent on your electric/fossil fuel prices, but over here in the Mid-Atlantic (cheaper gas, $0.13/kWh electric) I once did the math and my HP was cheaper than natural gas for heat down to about 40-45F. Longevity of the equipment is always a crap shoot, but because it is now running for heating as well, HPs tend to last less time than straight AC systems. 15 years is typical. Gas/propane/oil furnaces can last multiple decades if serviced, but again, it comes down to luck. HP with or without backup strips are inherently much safer than any fuel-burning appliance, and maintenance should be minimal.
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Aug 25, 2020 15:21
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B-Nasty posted:HP with or without backup strips are inherently much safer than any fuel-burning appliance, Are people still worried about natural gas appliance safety in the hellscape year of 2020? IIRC the most recent gas explosion in my city was a guy opening a gas valve on the side of a house because he thought it was water (it was for a natgas grill), then leaving it open. and the issues in Massachusetts a few centuries back were the gas supply company being cheap/incompetent and over-pressurizing lines. modern gas furnaces are pretty good at failing safe these days. quote:and maintenance should be minimal. Its the same maintenance as a regular split ac just with a few extra steps, to make sure it heats and defrost cycles. really the question is an economic one. you wanna save short term, and bet that gas will continue to be cheaper per therm and that the US will never decarbonize, get another furnace.
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Aug 25, 2020 23:17
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zenintrude posted:Thanks with the previous issue... solved simply by adjusting my AC schedule, now I’m cool all day. Is this in a particularly humid room or something? It seems odd to get condensation at the register, even if it was installed incorrectly.
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Aug 26, 2020 00:07
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MRC48B posted:Are people still worried about natural gas appliance safety in the hellscape year of 2020? In retrospect, I would have done a heat pump with gas furnance backup when replacing the HVAC. Best of both worlds! I don't know how much more expensive it would have been over a standard AC unit, but it's mostly the same components...
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Aug 26, 2020 15:01
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So the people who installed my AC never put in a filter, never connected the TXV, and also I'm almost entirely out of coolant 4 years after installation. Great work.
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Aug 26, 2020 21:21
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The trades are in a sorry state these days. No one trains anyone, work quality is shoddy, time pressure is ever present.
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Aug 26, 2020 23:58
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DIY secret santa maybe?
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Aug 28, 2020 00:36
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I have a cabin property with an A/C unit that was installed in the 90s. R22, needs a pound every ~4 years. For the usage it sees, and the budget I have, I am not replacing it, its fine. For the heat (baseboard electric $$$$, completely separate from A/C), I have a relay interrupting the low current 24VAC "call for heat" so I can control it remotely. The heat is literally two wires that a mercury thermostat controls, so I just put my relay in line. There are like 6 zones for heat, so I have 6 relays. Can I do something similar for the A/C? I don't so much need to turn it on remotely, but twice now I've had to drive the 6 hours round trip to turn it off. Time + gas wasted means come up with a solution. The homebrew relay system I have, I can add another circuit for basically free. I don't want some silly cloud bullshit smart thermostat for $100 that will stop working in 5 years, and I don't have a C-wire. The thermostat has a lot more wires than 2, which brings me to now. From this website, it looks like I can repeat the same concept. There is a (probably red, maybe blue) wire that is +24VAC that I can interrupt with a relay (suitably rated) to remotely kill it. Is this correct? Is this wise? Obviously the real solution is "dont forget to turn it off, dumbass" but I have have proof that I am a dumbass.
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Sep 7, 2020 06:41
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Yeah, you just put the NC contacts of your relay in series with the other control relay, instead of NO contacts in parallel as you did to force the heat on. (You use the NC ones so if the relay fails or the computer goes out to lunch and never comes back, the system operates normally.)
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Sep 7, 2020 07:19
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It sounds more like he'd want it to fail off; it sounds like it's pretty remote and doesn't see much use? I'd want the heat, at least some of it, to fail on, at a low temp, to keep the pipes from freezing and whatnot. Water damage is a lot more expensive than keeping the heat around 50ish.
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Sep 8, 2020 13:50
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Yea I am not sure which way I'd want it to fail. Most likely when I get hit by a bus, nobody will be able to figure how to work it, but I suppose that is no longer my problem. The heat was originally controlled by a contraption that would answer the phone line and interface to an X10 system, so that took a while to unravel and "improve" with my nonsense. I drain the supply pipes and propalyne-glycol the drains. Up about as north as you can get in the midwest with electric only heat is brutal even at 50F. A 4 day weekend ice fishing trip is easily $60 in electric heat alone. But cool, sounds like this isn't going to likely burn the building down and is straight forward.
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Sep 9, 2020 22:47
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I'm working on putting an office in my basement, and starting to think about how to heat it. The supply and return main ducts (trunks?) extend into the area where the new room is. Can I just add an adjustable vent onto the end of the supply trunk? There's already an adjustable vent on the supply just above where it comes out of the furnace (and it's been like that since the system was installed in 2010), so I feel like this could work, but I also don't want to gently caress up the whole thing.
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Sep 10, 2020 19:49
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Elder Postsman posted:I'm working on putting an office in my basement, and starting to think about how to heat it. The supply and return main ducts (trunks?) extend into the area where the new room is. Can I just add an adjustable vent onto the end of the supply trunk? There's already an adjustable vent on the supply just above where it comes out of the furnace (and it's been like that since the system was installed in 2010), so I feel like this could work, but I also don't want to gently caress up the whole thing. This is a "maybe/probably". How does your system work now? Good balance in all the rooms/floors? Does it have more than one zone? In the end, it's pretty low impact to just try it. And if it messes up your airflow somewhere else just close the vent/seal it off.
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Sep 11, 2020 15:57
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It shouldn't be an issue, but I will add that since it's so close to your unit, you're going to get a lot of airflow out of it. Even if it's closed all the way, and it will probably be loud.
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Sep 11, 2020 21:28
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Motronic posted:This is a "maybe/probably". How does your system work now? Good balance in all the rooms/floors? Does it have more than one zone? Single zone, has worked well enough, I've got no complaints. Bird in a Blender posted:It shouldn't be an issue, but I will add that since it's so close to your unit, you're going to get a lot of airflow out of it. Even if it's closed all the way, and it will probably be loud. Yeah, the furnace is going to be right on the other side of the wall so it's going to be noisy regardless, and I'm ok with that. I'll just plan on doing this, then. Thanks!
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Sep 11, 2020 22:48
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Do the smallest one you can find, You can always make it bigger latter. Making it smaller is hard.
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Sep 11, 2020 22:55
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MRC48B posted:Do the smallest one you can find, You can always make it bigger latter. Making it smaller is hard. This is the opposite of the "where's the cable stretcher?" problem. But yeah.....good plan.
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Sep 11, 2020 23:53
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Looking for some advice. The situation: Gutting and renovating a basement. Have access to all the vents but joists/existing stuff make our options for changing it limited. Two main (connected) living areas: 1. 15'x13' area, has the walkout area. Is probably only 25% below grade. Currently served by two branches from the main supply, close to the door out, and are not brought to floor. 2. An 8'x10' area with a window-well. Mostly below grade. Currently served by a half-assed hole cut into the main supply by the PO, with a grate screwed on top. Our ideal solution would be radiant floor heating. Hydronic hits some ceiling issues we'd prefer avoiding if we can. That leaves the thinner electric floor heating. Could we heat the space with electric floor heating? Would it replace or augment the current vent situation? Insulation is likely going to be closed cell spray foam. Thanks in advice.
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Sep 13, 2020 23:12
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Yeah, you can put radiant electric anywhere you can get power and isn't full of water. There are other options other than infloor. Wall mount units, and they also make little electric fancoils you can stick between ceiling joists. You don't say what the vent is from. is it cooling only, or do you have a furnace that also does heat? Do you already have hydronic in the house? You could do baseboard, wall mount, or ceiling heat with hot water as well. Also whats your latitude. It makes a big difference if you're up with the polar bears or down south in the tropics.
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Sep 13, 2020 23:29
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There's a furnace and ac hooked up. I'm in southwestern Ontario, region 6a. The in floor specifically are just from my spouse's wish list. So its the ideal choice. Barring that, were just looking for something that will keep the space comfortable/cozy. No existing hydronics.
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Sep 13, 2020 23:35
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just keep the infloor away from the the furnace thermostat and itll be fine. also follow manufacturers reccos when it comes to insulation underneath, vapor barriers, etc
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Sep 13, 2020 23:44
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So wildfires...I've got some home depot level 10 rated filters (which is like MERV 13 from what I can tell) being shipped to me that should arrive Thursday. Outside air quality will still probably be between 300-400 when they arrive. I in a new energy efficient home such that luckily the smoke infiltration isn't too bad but I still want to clean it up asap. How long can I run my HVAC in fan mode to filter all the inside air? (Edit without damaging the fan) I already have the external fresh air duct shut permanently in the off position as a side note.
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Sep 15, 2020 01:07
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Constantly. It's the same fan that runs in AC and heat mode, you can do whatever you want with it.
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Sep 15, 2020 01:35
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The fresh air dampers I've seen aren't 100% airtight, some laughably so. Also as discussed not long ago ITT, if your ductwork is in spaces with outside air ingress (likely it is, attic or crawlspace), it's possible to pull some outside air when it's running (some installs more than others). You may find it's best to just install the new filters and run as minimally as possible to maintain your setpoint. Good luck..
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Sep 15, 2020 01:44
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All certainly possible issues, I'm hopeful that with all the certification stuff (that I realize isn't really regulated) the hvac runs are well sealed. On Friday I should have an indoor air tester arriving and then I can do some A/B testing to an extent as well. Thanks for the answer on the fan runtime also.
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Sep 15, 2020 01:56
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tangy yet delightful posted:So wildfires...I've got some home depot level 10 rated filters (which is like MERV 13 from what I can tell) being shipped to me that should arrive Thursday. Outside air quality will still probably be between 300-400 when they arrive. I in a new energy efficient home such that luckily the smoke infiltration isn't too bad but I still want to clean it up asap. You can probably figure this out based on the size of your house, compressor, furnace, and most importantly air handler and return. The answer is actually pretty fast to cycle all the air in your house (think about how quickly your heater or ac change the temperature). I am in the same situation, new house in CA and have been using the AC with a Merv 13 filter to improve the air quality, I run it about six hours a day. Also new homes in California are required to have vent sealing testing, but not blower door testing.
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Sep 15, 2020 07:25
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I could use a reality check. I'd like to split a gas line to supply two natural gas fireplaces. The fireplaces are in the same location just on different stories. The top one already has the line run. The PO supplied the downstairs one via a line run outside directly to the meter with no safety valve. I have full access so would like to remedy but want to make sure the pipe can supply the needed gas and pressure. The existing pipe nominal 1/2 inch and is a run of about 20 feet, then up maybe 4 feet. The split would be after the same 20 feet, but down about 4 feet. Upstairs is 20k BTU. Downstairs 10k. Am I good? What's the available supply on such a line? Does anything here seem dumb?
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Sep 18, 2020 12:46
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https://fire-boulder.com/wp-content/uploads/2016/09/Gas-Line-Pipe-Sizing-Chart.pdf seems fine
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Sep 18, 2020 23:31
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Thanks. That note at the bottom does concern me a bit since I'd be tapping into an existing gas line, so Im not sure there'd be the required pressure for both fireplaces. I imagine it's be rare that I'd be running both fireplaces at once though. Hmm.
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Sep 19, 2020 01:32
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30ft of 1/2 in supplies enough gas for 60k btu. 20ft run teed off (+5) plus another 4ft. does the 20ft run zig back and forth?
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Sep 19, 2020 01:50
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Your question sent me down the right path. Thank you! I think I was way oversimplifying. I went back and took more accurate measurements. There are indeed some twists and turns so this is more complicated. So the main line into the house is T'd off and immediately turns via 2x 90 deg elbows. There's a union there, it continues a bit, hits a 1/4-turn safety valve, then turns up with a 45 degree turn. Shortly after it turns level with another 45 turn. It continues some ways before doing the same thing (up a short bit then level using 2x 45 degree elbows). It then runs straight a distance to the existing elbow that I'd like to convert to a T. It has a coupling in this run. I can't see it, but I have to assume there's another 90 degree elbow behind the upper fireplace where the flex pipe connects. It's more like 1 foot from the final elbow to the wall exit for upstairs fireplace, and would be 6' for the downstairs. Each fireplace would then need about 2' of flexible piping to hook into the fireplace. Assuming I can count flex as normal, and having measured each leg from, it would be 26 + 1 + 6 + 2x2 = 37 feet of pipe. In total I'd also have: 4x 90 deg. elbows 4x 45 deg. elbows 1x Union 1x Coupling 1x 1/4-turn Safety Valve 1x Tee For a total of 12 fixtures. Per your link, that's an extra 60 feet, for a total of 97 feet. In 1/2 inch pipe that's only 32k BTUs (@100'). The upstairs fireplace is 20k, existing downstairs is 10-15 (not sure how it's set that's per a manual I found online). That might explain the outside line. I do see here that calling it 5 feet per fitting may be pretty big overkill. I don't know what the reasoning behind the difference between the tables in that link and the 5' estimate are. But based on the link I have, I'd be looking at adding 1.55 feet for the 90 degree turns, 0.73 feet for the 45 degree turns, 3.1 for the T, and 0.36 for a gate valve. It doesn't mention anything for unions/couplings. That would be 12.58 equivalent linear feet instead, a lot less than 60, and put me at about 50 feet, for 46k BTUs. Now I'm OK. This still ignores the T off the main line. Presumably the truth is somewhere in between, but odds are I can hit 35k. I'm basically thinking out loud at this point, but starting to feel more confident it would work, though perhaps a bit tight for a DIYer. Hmmm.
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Sep 19, 2020 17:31
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Unions and valves don't count, and yeah, 5ft per fitting is a generous safety factor rule of thumb. If you're that worried about it, upsize the run to the tee to 3/4, and then branch 1/2 to each fireplace.
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Sep 19, 2020 17:39
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Yeah so a bit under 90 ft being ultra conservative, still a bit over 50 ft being more technical about it. So between 33 and 46 k btu. With the existing fireplaces that is at least within the given parameters up to being more than enough. Both of these fireplaces are likely oversized as they're just additional heat. Downstairs is only really meant to add heat to a living area of 300 sqft, though I'd expect pretty inefficient performance given its position near a sliding door. I think it makes sense to go for it. Thanks for your help.
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Sep 19, 2020 18:53
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I'm going to be building an outbuilding next year, and a small section of it will (I think) be best served by a heating/cooling AC. Since I know very little about AC (I know roughly how it works, own a portable unit, and understand why portable units are less effective), what would you need to know to give some basic advice on the best approach? I'll be hiring pros to do the work, but it'd be great to get some grounding before getting them involved.
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Sep 27, 2020 09:37
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Seems like a mini-split would best serve your needs
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Sep 27, 2020 10:23
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Elviscat posted:Seems like a mini-split would best serve your needs I haven't told you what my needs are yet! Or is it that simple?
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Sep 27, 2020 11:25
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Jaded Burnout posted:I haven't told you what my needs are yet! Or is it that simple? It's probably that simple. How many square feet (or square horse hands or whatever in the UK) is the space, and does it have 'rooms', or is it open.
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Sep 27, 2020 12:45
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