HRV for fumes
I saw a suggestion elsewhere which seemed to make a little sense, and I wanted to run it by folks more knowledgeable about HRVs. The idea is to use an HRV to vent solder fumes to the outdoors.
I work with solder, which produces some fairly nasty fumes. Contrary to popular belief, the issue is not lead, but the smoke from the flux. The standard solution is a filter with an intake right next to your iron. Home solderers often use chintzy filters that amount to a computer fan and a flimsy charcoal filter. They do little better than diluting the smoke before you breath it. More expensive units are like miniature vacuums with a HEPA filter and a heavy load of activated carbon. They’re quite effective, but the filters are extraordinarily expensive, and they draw up to 100W at full speed.
A super small HRV seems to make some sense. You get the fumes out of your workspace, and you don’t waste a ton of energy doing it. My two concerns are the long term effect of small quantities of mildly corrosive fumes on the core, and upfront cost.
I was also thinking that an exhaust fan, like in a bathroom, might be a better solution. It might be on for longer periods than a bathroom fan, but the air flow can be lower, since it will be ducted directly to the fume source. So, the energy penalty for running it might not be terrible.
I don’t have any specific question, but I’m curious about your thoughts?
–John
Rochester, Zone 5
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I don't think the HRV will move enough air to ventilate the space (even in boost mode). I've seen some DIY hood arrangements online that look promising but haven't tried them myself. Working outdoors with a fan is usually how I handle more involved soldering sessions. That probably isn't an option for part of the year in zone 5.
John,
The two simplest solutions are either a kitchen range hood or an inline bathroom exhaust fan.
If you use a kitchen range hood, just install it over your work bench. If you use an inline exhaust fan, you can connect ducts on both ends, and you can position the intake duct near your work area.
One thing that would worry me about extensive use of an HRV in our climate, is that they tend to pull a lot of moisture out of the air during the winter. You may end up with more ESD issues than you would like. (ESD=Electrostatic Discharge, for those who have never worn a wrist strap.) I think an ERV might not be so problematic in that area.
My understanding is that some HRVs defrost using internal air only too, so basically they would recycle fumes back in to your shop during that cycle.
BTW, my first thought was that there is an excellent surplus electronics store in Rochester. I bet they would have an actual fan designed for soldering station use. Unfortunately I don't see any evidence that they exist any more. (Can't remember the name, it's only been 35 years since I last went there! Seems like it was off Lyell Ave.)
The difference in the amount of moisture "reclaimed" or lost by an ERV compared to HRV in winter is trivial- it's "in the noise", and won't do anything for ESD issues. The only solutions are dialing back the ventilation rate, or actively humidifying the air if it drops below 30%.
We have Surplus Select and eTechSurplus, but I've never had occasion to visit them. We also still have a mom and pop electronics store, which is also kind of amazing.
Hoods aren't actually a great solution for soldering. Usually your head is hovering directly over the fume source, especially if you're working with tiny components under a microcope. (Today I was soldering parts that were 0.02" x 0.01") A flexible ducted solution that you can put right next to your iron is much better, pulling fumes to the side.
It sounds like an inline fan is probably a decent way to go. Humidity is just something I have to manage.
John,
I found this fume extractor (https://www.sheffield-pottery.com/Vent-A-Fume-Place-a-Vent-FE-500-Fume-Extractor-p/venfe500.htm) while shopping for solder. It looks like a good solution if you can vent the blower to the outdoors. It may be possible to DIY a similar vent as well.
I saw this DIY coraplast HRV years ago if your felling crafty.
https://www.youtube.com/watch?v=akkhDjxwIu0