I think Shortridge is the cream of the crop, but that perception is from years ago.
We have 2 Alnors that are OK.
Hopefully one of the pro balancers chimes in.


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There might be something wrong with our Shortridge hood. I've been getting extremely high airflow measurements, especially on smaller grilles. The flow baffles and grid are not quite in alignment, but I don't know how it would affect it that much. The meter works fine, with current calibration.

I'm not very motivated to try to fix it. It's so bulky and hard to use compared to the new hood.

 

The grid has some small wire spring things that secure it to the hood body, if the grid is not in the proper position, it will greatly affect your readings. Shortridge sells replacement spring thingy fairly cheap, I have had to replace them many times because of people trying to carry the hood by the velgrid attachment.

 

I assume you are partial to the digital hood. Most are now days but make sure whatever you buy has time weighted averaging. The first digital hoods were susceptible to pressure changes and were not very accurate.
I liked the Shortridge analog the best because I could rely on it to read slightly below a pitot traverse. I never knew where the digital was going to come in. Alnor actually made the original Shortridge meter.
The electronic meters in my experience were very reliable for pitot traverse.

 

I think I read that Alnor uses a hot-wire system? These new products on the market have really impressive specifications. But I understand that they're only accurate with a correctly-sized skirt, and when airflow is linear through the device.

This afternoon we read about 200 outlets, some were 700 CFM on a 20 foot ceiling, others were 75 CFM in small compartments. This was a piece-of-cake with the 3lb flowhood with extension pole and all the accessories. With the Shortridge, ... I don't even want to think about it. I'd be hating my life by about now.

The boss wants to buy either Shortridge or Evergreen because that's what the other techs in the area are using, and he's afraid of unknown brands. I'm trying to tell him that TSI, Testo, Dwyer, and a lot of other brands are a lot bigger and a lot older than either of these.

My understanding is that after Ernie Shortridge passed away, the company has been going downhill. They charge $595 to give you a calibration sticker, while the local shop can do the same thing for about $100 or so. This price doesn't include any repairs. The bad thing is that nobody else knows how to work on the contraption. I sent an email to the company with a technical question, and never got a response. The Shortridge website looks like it wasn't updated since W was president. It sounds to me like these guys are just milking their customers for whatever they can get.

 

I never found a shop anywhere that would calibrate a flow hood for $100.
I used a light weight flow hood on a try out basis. Contact the vendor and ask about doing that.
The weight of a flow hood was not the most important thing to me. How it stacked up to a pitot traverse was.

 

Maybe $100 was for the air meter only. One of the other techs uses a calibration lab in Oklahoma. I forgot how much they charged, but it was still a lot less than the factory.

When we get some free time, I'm going to take a few flow hoods to a site, read a branch, and compare it to a traverse. I think the results will be enlightening.

 

I used the Oklahoma lab all the time and was well satisfied with them.

You should compare the hoods with a pitot. You can check both accuracy and repeatability of the hood. I checked mine with the inclined manometer because it is more accurate than the high dollar electronic meters. Give it time to adjust to the room temperature because that and being level is the only thing you have to worry about.

 

As Wayne mentioned, measurements that can reasonably match up with a pitot tube traverse are what makes a flowhood reliable. I have used the dwyer and evergreen hood, both were nice and made things easier but were not as reliable in my opinion as the shortridge. Alnor has also been reliable the few times I used it.

 

I'm not sure about using a calibration shop other than factory for flow hoods ( digital). Reason the last time I checked the factory also upgraded the firm ware. Maybe other companies can too but it seems not likely they would have the ability to know the upgrade.
Other measuring devices would be easier.

 

I measured my return grille last weekend with a TEC flow grid on a DG-1000, and cpm[ared to a Testo flow hood. They both measured exactly 759 CFM. I had expected some difference but was impressed that they both read the same.

BTW, cleaning the blower wheel as it was a little dusty, certainly not loaded, increase air flow to 1049 CFM.

 

BTW, cleaning the blower wheel as it was a little dusty, certainly not loaded, increase air flow to 1049 CFM.

Man, I would have loved to see the before and after pics of the wheel, that is a significant gain.

 

In reference to your post #5 Robert Ernie Shortridge did pass away. I really liked and respected him. He would tell you to the smallest detail about anything you ask. I talked to him several times and never got the run around. I don't know how they are doing now.
Too high airflow measured with a flow hood is usually leaking sensor hoses or on the grid somewhere.