Workshop dust and heat pumps - a no no!! What filter system?

[Ronald Kot]

WHAT FILTERS TO USE?
WHAT MICRONS SHOULD BE FILTERED OUT TO PROTECT A HEAT PUMP?

Air handlers for heat pumps do not do well with wood dust - gums up the coil, affects the system, can invalidate warranty on heat pump system. Need to isolate workshop and wood dust from where the air handler is.

Ok, seal off the workshop. But if dust some got through to the part of the basement where the air handler is in, and you had the cold air return ducts sealed, the only way the wood duct can get to the coil is through the filter. So what is the best filte for the heat pump?

FILTRATION REQUIRED

I think my oneida dust filter goes down to 1 micron but then there is the loose dust in the shop. WHAT MICRONS SHOULD BE FILTERED OUT TO PROTECT A HEAT PUMP?

FILTRATON OPTIONS

50% of people want a disposable filter, 50% want a cleanable filter. Electrostatic filters block airflow too much. MERV 10 max suggested for heat pumps. The higer the MERV number, the more is filtered out.

Choices seem to be:

1. Use the 1" rack in the air handler and a standard media filter. Example is
American Air Filter Strata Density. DISPOSABLE MEDIA FILTER.
This comes in 1" The AAF StrateDensity data sheet gives no info on what microns are filtered out. No MERV rating, but maybe performance resistance data covers that off, I dont know.


2. $1000 American Standard AccuClean or Trane Clean Effects (same thing)


3. Westinghouse Nordyne high efficiency media retrofit air cleaner. Retrofit rack into the cold air return, just like the $1000 solutions, and 5 14" thick pleated media filter.
Example: Westinghouse
http://www.westinghousehvac.com/West...er-p/media.htm
but his email called it a
NORDYNE High Effi ciency Media Retrofi t
Air Cleaner removes airborne particles down to
0.3 micron.


Comments please on:
What wood dust particles sizes harm a heat pump and need to be taken out?
What is the most effecive way to do this, with least work and cost?

Thanks!

[Jack Parks]

Ronald,

The best way for you to address this problem is to collect the dust at the source with a dust collection system. Also use a good vacuum with your sanders and other hand power tools. Additionally you can install a general area air filtration system in your shop. I have a 3hp cyclone dust collection system ducted to each of my stationary tools, most of my power hand tools are Festools and I use them with Festool vacs and I have two JDS 750 air filters hanging in the shop. I have heated and cooled the shop with a ductless heat pump for 5 years with no problems from dust entering the return. I just vacuum off the air filter periodically. Your lungs will thank you as well as your heat pump.

Jack

[Mark Paavola]

It depends. It doesn't matter if it is a H/P or Gas system. The question is airflow. The best for dust removal is a pleated filter like you have listed. The 5" media works well. The problem is making sure you have a large enough filter to keep the pressure drop across the filter to a reasonable level. Up to a 2.5 ton unit 1 - 20x25x5 pleated will work fine for most applications. Typically you need to keep the velocity of air below 300fpm across the filter for good filtration. I have a 2 ton H/P in my shop with a 20x25x2 pleated filter as a prefilter and then a 20x25x5 final filter in front of the air handler. The real key is to have enough filter area to keep the pressure drop as low as possible across the filter system. My system is setup to run the fan at all times when I am in the shop to act as an air cleaner. In the last 2 years I have changed the prefilter approx. 10 times but the final filter only twice. I use my shop as time permits, not an everyday occurence.

[Ronald Kot]

It depends. It doesn't matter if it is a H/P or Gas system. The question is airflow. The best for dust removal is a pleated filter like you have listed. The 5" media works well. The problem is making sure you have a large enough filter to keep the pressure drop across the filter to a reasonable level. Up to a 2.5 ton unit 1 - 20x25x5 pleated will work fine for most applications. Typically you need to keep the velocity of air below 300fpm across the filter for good filtration. I have a 2 ton H/P in my shop with a 20x25x2 pleated filter as a prefilter and then a 20x25x5 final filter in front of the air handler. The real key is to have enough filter area to keep the pressure drop as low as possible across the filter system. My system is setup to run the fan at all times when I am in the shop to act as an air cleaner. In the last 2 years I have changed the prefilter approx. 10 times but the final filter only twice. I use my shop as time permits, not an everyday occurence.

Thank you! Your point on pressure drop is well taken. My heat pump is a 3 ton, the filter size is not yet determined but will try to get the surface area up and the velocity down as you suggest. I do have a cyclone dust pickup to 1 micron, so the dust I am concerned about is that which escapes the cyclone, and I can keep the unheated shop door closed during operations. So I am not really loading the filters with much dust, just when the shop door is open, after not using the shop, some dust might get into the AHU area. Even then, with the return ducts sealed, the only way dust gets to the coil is through the filter...so I need a good, thick, filter for lower pressure drop big area, and with some capacity.

What cfm are you runing the AHU at? Mine is 1200cfm.
What MERV rating did you select for your 20 x 25 x 5 filter?
What make of 20 x 25 x 5 filter did you choose?

The choices for me now is not an electronic air cleaner and not the 1", for sure, going to a 4" standard commercial media filter (cheaper filters) or a 5" residential ....the LENNOX HC 10 looks good for a case and it takes lenox or honeywell filters.

Thanks! R

[Mark Paavola]

My system is running at 850 cfm. I live near Sacramento, CA which is a fairly dry climate. The 5" filter is a MERV 10. The brand is a called an EZ filter from Carrier. The Lennox, Honeywell or just about any of the 5" filters will work just fine. The 4" will also work. I would not use an electronic filter for this application. Again the key is keep the velocity below 300 fpm across the filter and let it do its job. I have been in the HVAC business a long time with lots of it spent doing airflow testing in residential and commercial. Also my AH has what is called an ECM motor which has the ability to compensate for additional restriction. Each time on startup it tests the load on the motor to determine what rpm it needs to run to deliver the desired cfm. A standard PSC motor will deliver lower airflows with more restrictive filters.

[raymond Abel]

In English, I think you have this expression: "The bigger, the better"
I think this expression is perfect for this topis.
I have a Laguna cyclone 3hp http://www.lagunatools.com/accessori...tor-cyclone2_3 that you can see on http://www.youtube.com/watch?v=EOhfxtDZCS4
& a air filter http://general.ca/site_general/g_pro...or/10-600.html that you can see on the same youtube video how much it is taking care of the "flying dust"
You could see it un almost all my little videos too.

Feel free to ask me any questions

RIP_Ray