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Air Filtration for Radiant Homes

haukeghaukeg Member Posts: 16

I have a few questions for adding an air filtration system after retrofitting a home from a forced air system to a hydronic radiant floor setup. Since we have lost any air filtration for the home that we had from the forced air filter, I am wondering if there is a moderately effective solution for adding a air filtration system above stand alone floor models?

For instance, I was wondering if something like a air filtration system could be installed in my attic and I could add simple vents into each room to slowly process air throughout the day (quiet and simple installation)? Or is there another conventional solution for this sort of retrofit?

My house is a 1959 brick rambler, so not completely air tight like new construction, but I want to ensure I am getting proper indoor air quality after this change. I have 2 little kids and worry that they may be developing asthma potentially due to indoor air quality issues. I have also looked into room air purifiers (Oreck models) and think that could work, but I...

1.) Dont like having a stand alone unit in a room instead of something less noticeable in each room of my house

2.) Do not believe this is a "whole house" solution and might not solve my concerns completely

Any advice or suggestions greatly appreciated!


  • BillWBillW Member Posts: 176
    Air filtration

    Are you planning for central air conditioning, or using splits or something else?  If you are planning on a central air system, both media or electronic filters can be used, built into the system.  However, in the winter, you would not be using the system;  in the time when the house is closed up, you will not have any way of removing particulates from the air.  Particles are the only things electronic or media filters remove.  They have no effect on gasses, odors and vapors, unless you use CPZ chemical filters.  Individual room units are an option, but can be noisy, use a lot of electricity and are effective only if the doors and windows to the room are kept closed.Individual room unit  filters need to be replaced regularly, and depending on your needs and the levels of particles in the air may have to be replaced monthly.  Units with HEPA filters work best.  Air filters are rated by MERV, with basic "home center" throw-away filters at the lowest , better retail and entry-level pro units at about MERV 8 and on up to HEPA.  Products marketed as HEPA-type, or HEPA- like are NOT HEPA filters, so be careful.  Sizing your fan is important, so that you still will get proper air flow as the filters load, since their resistance to air flow increases.  This problem does not effect electronic air cleaners, as long as their pre-filters are cleaned regularly.
  • haukeghaukeg Member Posts: 16
    No AC planned

    I am not planning to add AC because I live in the northwest and have little need for AC in this climate. Also, as you pointed out, it would only be effective in the summer months.

    My hope was that there would be a way to add a centralized fan in my attic, then put simple vents in each room to draw air through a HEPA filter/cleaner of some kind?

    other option I had heard bof was to put in a "whole house" fan and evacuate all the air in the house occasionally, but obviously that would be bad for winter months.

    I find it surprising no one has offered a air filtration system outside of forced air heating or air conditioning systems? I know many of the in room units I have looked at have HEPA and more, but filters are spendy and as you pointed out they can be loud and need doors to be shut to be effective.

    Any other suggestions or ideas greatly appreciated. Thanks for your reply!
  • BillWBillW Member Posts: 176

    You could fabricate an air handler, which is nothing more than a fan in a box, connected to ductwork, with discharges in whatever rooms you want, with a central return.  Insulated ductwork is best.  The filter can go on the central return, and can be a media or an electronic.   Since you have a boiler, you could put an hydronic coil (called a re-heat) in the duct or air handler to temper the air in the winter to take the chill off.  It would be controlled by a zone valve that only opened when the fan was running.  The re-heat ONLY tempers the air, and does not "heat" it, like a full sized coil or another heat source.  The coil also could be electric.  Put the discharges high on a wall where they will not blow on anyone.  You also could easily add an energy or heat recovery ventilator to the air handler as well, and bring in fresh air.
  • haukeghaukeg Member Posts: 16
    Love it

    Love this idea,

    That is very much along the lines of what I was thinking. I like the heat tempering idea as well. Great ideas, thank you for replying.

    I wonder - could the fan have any filtration to help clean the air? HEPA or other benefits?
  • BillWBillW Member Posts: 176
    Air Handler

    Picture a box with a "squirrel-cage" fan inside.  The air enters the bottom, pulled thru the filter by the fan, then discharges thru the tempering coil in the plenum to be distributed into your ductwork.  Filters and electronic air cleaners are made in standard sizes, and you need to design the system properly, and sizing the fan is probably the most important part.  It has to be able to move air to the farthest point in the system, be powerful enough to pull air thru a loading filter, but not so powerful it causes whistling and other noise.  You need a pro to size everything properly.
  • Tim_HodgsonTim_Hodgson Member Posts: 59
    Try a heat recovery ventilator

    This will ventilate the house and recover 65% of the heat or cool in a controlled manner. Install a short return duct to the unit and put the long discharge duct running most of the way through your attic. if you develop a leak, most likely it will be exhausting house air into the attic instead of attic air into the house.

    Good Luck,

    Tim Hodgson
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