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Testo 420
I am looking at obtaining a flowhood for residential work. Any negatives from anyone concerning the Testo 420 flowhood?
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Weve been selling them at TruTechTools since 2015.
I cant recall a complaint.
Pretty easy to set up.
It has Bluetooth, a barometric pressure sensor and a temp/humidity probe (in the air stream) so you get a lot of data and density corrected readings.
The manometer is detachable to use for other purposes.
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Thanks for your reply Bill! I ordered from my local distributor today.
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Works great for all return air measurements, and I assume large supply air vents. Not so good for residential supply air vents.
With that said, you can input an AK value of the supply vent.
I’ve found the 420 to be very accurate and consistent on return air.
I use my Alnor LoFlo for supply air.
"The only true wisdom is in knowing you know nothing" Socrates
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Like TT Bill stated, it’s nice to have a high end, detachable micro manometer to perform a Pitot traverse, or pressure differential in spaces like bedrooms and such. The manometer has an autozeroing solenoid bypass built in, and is Bluetooth.
"The only true wisdom is in knowing you know nothing" Socrates
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I am not a T&B expert needing a flowhood. Mainly residential, but a lot of customer's eyes glaze over when I discuss static pressures and related airflow. Thinking I can get homeowner to write down measured cfm's throughout the house after telling them how much air they should have for the system. Hoping to calculate delivered capacity and obtain more duct jobs. I am a big believer in single stage equipment with proper airflow and NOT selling higher SEER and multistage equipment on bad duct designs.
Did some testing on my own home before using on job next week. Was fairly easy to set up and start measuring. Below is what I came up with.
CFM DB RH
1 2020-09-11 14:27:54 -1046 73.4 66.3 8310 return air
2 2020-09-11 14:28:37 127 73.4 73.8 13666 front bedroom
3 2020-09-11 14:29:10 69 73.4 73.0 8468 office
4 2020-09-11 14:29:56 60 73.4 72.7 28687 hall bathroom
5 2020-09-11 14:30:41 69 73.4 71.5 37304 living room
6 2020-09-11 14:31:10 186 73.4 73.9 47655 dining room
7 2020-09-11 14:31:48 287 73.2 76.0 45395 kitchen
8 2020-09-11 14:32:19 164 73.2 74.3 15511 master bedroom
9 2020-09-11 14:32:43 151 73.6 74.4 44271 master bathroom
10 2020-09-11 14:33:17 72 73.9 73.0 15073 utility room
TOTAL SUPPLY 1185
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Originally Posted by
rglasgow
Hoping to calculate delivered capacity and obtain more duct jobs. Be careful what you wish for. Sadly, you're going to find it very difficult to sell the value of a well installed duct system that takes a week to install vs. the other guy that gets the system up and running in 2-3 days and costs half the price. All that, and not to mention burning yourself out on ducting installations. If you like to work harder for less money, go for it.
I am a big believer in single stage equipment with proper airflow and NOT selling higher SEER and multistage equipment on bad duct designs.
I disagree. I'm 180° from your position on staging equipment. I kind of agree on the SEER though. High SEER is ok if you're looking at a long term investment, but I don't sell SEER. I tell customers that SEER is a sales tool.
So, did you purchase the Testo 420 or is this another brand? Were you using the 24"x24" skirt for all measurements or did you purchase others? Did you use an AK for the supply air?
I'm happy to see another forum member with the 420. It's definitely a good product.
"The only true wisdom is in knowing you know nothing" Socrates
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I guess I wasn't clear about equipment. I believe in multistage(I have a 5 stage system), BUT would rather have single with proper duct vs multistage with crappy duct. I have worked for a company that would sell inverter units with NO consideration for ductwork.
Yes I purchased the Testo 420. I know ductwork is a hard sell but shows that I care about doing things right. I already have two problem jobs that others haven't made homeowner's happy. They definitely have issues with zoning and excessive flex runs.
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I did not use an AK factor. Dont understand why it would be necessary on a flowhood. Please elaborate. I understand using AK on anometer.
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Originally Posted by
rglasgow
I did not use an AK factor. Dont understand why it would be necessary on a flowhood. Please elaborate. I understand using AK on anometer.
Even though the Testo skirt is supposedly designed to straighten the flow, it still has issues with positive flow reading. Flow hoods can't be calibrated for every type of grille. So using a K factor for different types of grilles helps to gain accuracy. I won't pretend to be a know it all about air flow readings, because they are extremely difficult. I look forward to reading some of your posts on the subject. I find this forum excellent for group think.
I spoke with Testo North America and they told me that these hoods were not designed for small residential grilles, and using a K factor would help. It likely won't be the same aK factor as a vane or hotwire though. As we enter the slower season I look forward to messing around with this subject again. I have a new Testo 416 mini-vane to play with.
"The only true wisdom is in knowing you know nothing" Socrates
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Without using AK, I came up with 1185 cfm by adding each supply register. Furnace is set for 1200 cfm per dip switches and ecm motor. Return came up at 1046. Will let you know as I learn.
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Whats the 5 digit number on the data string mean?
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Originally Posted by
rglasgow
I am not a T&B expert needing a flowhood. Mainly residential, but a lot of customer's eyes glaze over when I discuss static pressures and related airflow. Thinking I can get homeowner to write down measured cfm's throughout the house after telling them how much air they should have for the system. Hoping to calculate delivered capacity and obtain more duct jobs. I am a big believer in single stage equipment with proper airflow and NOT selling higher SEER and multistage equipment on bad duct designs.
Did some testing on my own home before using on job next week. Was fairly easy to set up and start measuring. Below is what I came up with.
CFM DB RH
1 2020-09-11 14:27:54 -1046 73.4 66.3 8310 return air
2 2020-09-11 14:28:37 127 73.4 73.8 13666 front bedroom
3 2020-09-11 14:29:10 69 73.4 73.0 8468 office
4 2020-09-11 14:29:56 60 73.4 72.7 28687 hall bathroom
5 2020-09-11 14:30:41 69 73.4 71.5 37304 living room
6 2020-09-11 14:31:10 186 73.4 73.9 47655 dining room
7 2020-09-11 14:31:48 287 73.2 76.0 45395 kitchen
8 2020-09-11 14:32:19 164 73.2 74.3 15511 master bedroom
9 2020-09-11 14:32:43 151 73.6 74.4 44271 master bathroom
10 2020-09-11 14:33:17 72 73.9 73.0 15073 utility room
TOTAL SUPPLY 1185
This data string, last numbers just prior to room tag, whats that represent?
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Originally Posted by
mgenius33
Even though the Testo skirt is supposedly designed to straighten the flow, it still has issues with positive flow reading. Flow hoods can't be calibrated for every type of grille. So using a K factor for different types of grilles helps to gain accuracy. I won't pretend to be a know it all about air flow readings, because they are extremely difficult. I look forward to reading some of your posts on the subject. I find this forum excellent for group think.
I spoke with Testo North America and they told me that these hoods were not designed for small residential grilles, and using a K factor would help. It likely won't be the same aK factor as a vane or hotwire though. As we enter the slower season I look forward to messing around with this subject again. I have a new Testo 416 mini-vane to play with.
Didnt you find a length of cardboard added to the skirt gave you more consistency?
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Not sure what the 5 digit numbers are. May be unique to each test run. I took measurements as single measurements and not as multiple measurements. You save measurements then download to computer. Then copied and pasted info, so the format changed when I posted.
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Originally Posted by
heatingman
Didn’t you find a length of cardboard added to the skirt gave you more consistency?
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A box with a hypberbolic baffle improved consistency. I don't think it would work in all cases though.
https://www.youtube.com/watch?v=CX4nDBZzJJ0
If you listen toward the end of the video, I did set up my Retrotec duct blaster in a powered flow hood design and it came up about 126 cfm with and without the baffle box. There was no system effect with the powered hood measurement.
Here's another good read: https://www.osti.gov/servlets/purl/791782
"The only true wisdom is in knowing you know nothing" Socrates
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Originally Posted by
rglasgow
Without using AK, I came up with 1185 cfm by adding each supply register. Furnace is set for 1200 cfm per dip switches and ecm motor. Return came up at 1046. Will let you know as I learn.
I would trust the R/A measurement much more than the S/A.
I am finding your readings consistent with mine though. I measured about 13% increase in S/A you're around 12%. Again, from my testing I've found the R/A measurement to be really good. Most often in residential, we're looking for total volume so the 420 is a great tool. So, if you used a K factor to reduce your readings by 12% only when measuring supply air, I believe the accuracy would increase on supply air.
I had a duct lab set up with an in-duct fan in the middle of a 10" metal duct with a plenum on each end. The plenums having identical supply air vents for both R/A and S/A. Completely sealed. This lab rendered the same results.
"The only true wisdom is in knowing you know nothing" Socrates
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When I get a chance I will do a traverse and see what I come up with. May be a few days before I get a chance to complete.
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I'm using Testo 420 to Measuring air flow of (60*60 cm) filter boxes, I set the flowmeter setting to Actual but the k factor is 1 , I am wondering should i change the k factor ? if yes how I should calculate it ? by the way the duct of boxes are different in each box,
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This little paper from TSI explains uses of a k factor:
https://tsi.com/getmedia/ce8b8763-60..._8375?ext=.pdf
My summary:
1- to make 2 different hoods agree for a given set of conditions
2- to make a hood agree with a duct traverse given the same set of conditions.
The example they give shows a correction of 4%
So, for use when higher accuracy is needed, but you need another device to tell you the true flow.
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