Dwyer® Liquid Filled Wall Mount Manometer, Mark II 25, 0-3" w.c., 3% Accuracy

With increasing combinations of heat and smoke in our area, we upgraded our air handler to accomodate a MERV16 4" filter. The filters are about $100 each and the default suggested lifespan is one year. It needed about 20 mintues to install this manometer and discover that at one year of age our filter was causing pressure drop far below the rating of our air handler. Given that interception by filters improves as they choke, the filter is doing fine. A six month extension of filter life in our case pays for half the cost of this device. Photo indicates simplicity of installation. Two holes in ductwork for tubing port attachment, double-sided tape to mount manometer. Note that the area marked "filter" on the air handler is superseded by the larger filter housing at right (it's important to make sure manometer tubing is correctly installed on upstream downstream sides of filter).

I am using this Manometer to allow for a visual identification of when my whole house furnace filter needs to be changed. As the filters are between $30 and $40 I do not want to change too often as I will be wasting money and if I wait too long potentially damaging my HVAC system which is less than ideal..... My current scheme is to pull the filter out and look at the color of the filter which is inaccurate to say the least, so after a recent cold snap and my furnace not operating due to a filter that needed to be changed I opted to do something about it. Competitive products seemed a little cheap to me so I went this route. As a mechanical engineer by training I was very pleased with the lab instrument quality of this Manometer, when you open yours up you will be surprised by the size of the this unit, fully 6"x6" or more. Everything that I needed to accurately measure a pressure differential was included as well as a surprise built in level for that really assisted with the installation of the product. What is extremely important about this Manometer is that the first inch of the water column is essentially more "horizontal" allowing for more accuracy in the first inch of the water column. The reason for this is that your furnace is most likely designed for about 0.5" of static external pressure. This is typically found on the HVAC systems label. So in my case when I installed the Manometer and zeroed it out with no filter in place, then added a new clean filter it measured .1" rise in the water column. That is about 20% of the total rise allowed by my HVAC units spec. (By the way that was a dead on match to the Filtrete specs for this filter, which is always nice) So I will need to change that filter when the water column reads .5" of water. Having that first inch essentially expanded out is really nice so I can see what is going on visually. Long story short, if this keeps my wife happy because her house is warm as her furnace filter was changed when it should have been then all things considered this was a great purchase. :-) Have a great day and some fun as a home geek. Jeff

Last week I noticed that our radon fan had stopped running. Who knows, maybe it was 6 months ago that it stopped. It's not something we regularly check on. Anyhow, since I had to replace the fan, I did a full check of our system, which is 25+ years old. I found this Dwyer manometer in the rafters, and the fluid was empty. Since the fluid alone is $25, and the probability was that there was a leak somewhere, I figured it was best to just replace it. I installed the fan earlier today, and when the manometer showed up, it only took about 10 minutes to fill, and calibrate per the instructions. A few minutes later, after screwing in to the existing holes, everything was working.

This is really useful. I was trying to find out how restrictive the Honeywell MERV 12 (1550 rating) filters are in my variable speed air handler. I'm using a 20 by 20 by 4 filter. The installed filter is a couple weeks old so the readings you see on the gauge are probably close to what it was when "new". The varying values you see on the gauge are due to the varying fan speed. The lowest value is probably around 500 CFM; the fairly high value of .45 in. wc is around 1,000 CFM. What this tells me is these are probably about the highest MERV rating filters I'm going to be able to get away with. On a unit like this you can definitely put in MERV 13 on up but it's going to create pressure differentials that exceed 0.5 in wc (along with the usual problems) and honestly if you want to do MERV 13 or better filtration you are going to be better off simply ducting a true HEPA system running at a couple hundred CFM right off the return. Note the Honeywell 18 watt UV-C lamp housing. Those things are unbelievable...low cost and, according to actual published studies that I have reviewed, the UV-C at 253.7 nm. will kill the coronavirus that causes COVID-19 and just about anything else. Watch your eyes though and watch your FILTERS. UV-C will totally destroy most (non-glass) based filters given enough time (you have to keep the light away from the filter!). Anyway, this is an excellent gauge and gives a really interesting window into what is going on with your filter and you can see all the pressure changes as fan speed varies (and as dirt accumulates, over time, in the filter media.

I have used Dwyer products for many years and have always been satisfied with their accuracy and quality. I'm using this manometer to monitor the air pressure drop over my premium in-line electronic air filter. The manufacturer of the air filter says it could go for up to nine months before servicing, but I never expected that kind of performance. The Dwyer manometer proves that my filter, in my application, must be serviced within 40 days or the system airflow becomes too restricted leading to excessive energy consumption. I'd rather clean the filter more often than pay extra for fuel and electricity. Looks great too! Comes with mounting screws, red indicating fluid, and tubing. You'll need to buy a pair of magnetic static tips to insert into your ductwork.

Arrived and works as described

I use this product to test Total External Static Pressure (TESP) on furnaces. It's also utilized to balance Heat Recovery Ventilation (HRV). The only suggestion would be adding magnets.

Buen aparato , lo hemos usado durante muchos años , aunque con la llegada de los menos complicados manómetros digitales , estoa aparatos no se usan mucho , excepto cuando se acompañan de un tubo pitot.