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Photo of installed PRV Thank you, Tomhttps://files.engineering.com/getfile.aspx?folder=23a581a6-91ee-4cd4-892e-63c95b5737a4&file=image001.png

I am commissioning a dual fuel natural gas/oil hydronic boiler by Bryan Boilers. Input MBH is 1200/600 and output is 1002 MBH. Boiler MAWP is 160 psig. I have attached a photo of PRV installed on top of boiler. Intuitively, a reduction in size from 2" to 3/4" orifice represents a significant...

Good morning, If I am interested in overall energy consumption from the heating boilers in a building, is it more advantageous to locate the energy meter in the hot water supply line or the hot water return line? Simple question but maybe not a simple answer! Tom

Good morning, I hope everyone is staying safe during Covid precautions. To provide some background, my installation is in a school in Edmonton, Alberta, Canada. A Daikin RCS045D condensing unit with 4 compressors provides cooling and hot gas bypass if required. The condensing unit is internally...

Thank you for the quick response. t

Hello, I have recently completed startup on several large air handlers. Each air handler has a service corridor maintaining room temperature. There are four transformers in each corridor and they all have surface temperatures of 150F. I expect high temperatures on transformers, but is this too...

Thank you ChasBean1, Except for basement and some areas on first floor, the velocities were generally above 500 fpm. Having said that, there were times when we just packed up because control and Cx were playing with the systems and our air flow dropped off to zero or near zero. While the theory...

Thanks again Lnewqban, Do the VAV boxes require 2 reference airflow measurements at calibration or is one airflow low reference sufficient? Thx,

Thank you Lnewqban for your input, We completed the VAV box calibration work in stages, by floor about 3 months ago. The air supply was spotty and very often we did not have enough air to meet the maximum flow even though there may have been 125 Pascals(1/2 iwc) or more at each box. Now when we...

We have tried to shorten the construction time of a 6 storey hospital building. There are 1626 supply, return and exhaust boxes controlled by a Honeywell ComfortPoint system. In the majority of areas, there are 1 or 2 ceiling diffusers for each VAV box. During construction, we blanked off duct...

Thanks dbill74, The refrigerant sitting in the pipe after a release is what got me questioning the design and configuration.

thanks BI

Thank you LittleInch, The refrigerant will evaporate immediately at approx. -14F(-26) and then it is all gas flow after that. It won't even accumulate for more than a couple of minutes. It also begs the question should the pipe be insulated; although an un-insulated pipe with condensation in...

LittleInch, B52 is the Canadian refrigeration Installation Code. I have also read ASHRAE 15 and 34 which cover mechanical room design. Each chiller contains 525 pounds of R134a, class A1 refrigerant. Evaporator has a 1" relief valve with a 200 psig rating at a flow of 48 lbs./min. The...

This is a new problem for me. I am commissioning a hospital with 5 Trane series RTHD chillers. Unfortunately, the machine room is located in the basement and in the center of the building footprint. The chiller pressure relief valves (3 per chiller) are piped and sized correctly into a common...

I always understood that counter flow positioning of temperatures was optimal for heat exchange. With this in mind, it seems to be intuitive that the return air in a rooftop package would first come in contact with the colder coil face. That is to say the side of the coil face where the...

thanks, pmover the boilers are new 2.5 MBTU replacing older boilers and the issue has been happening since start-up last spring.. all other accessories are new, water quality is within specs, thx,

I have two new low pressure steam (steam pressure set to 8 psig) boilers operating in parallel. These boiler have independent piping leading to separate pressure reducing valves. The valves are set to system pressure of 5 psig. Downstream of the PRV's is a steam header and off the header the...

We have continued the flush...overlap with occupancy. And we did have a IAQ plan during construction which included photos of the various dust control measures. All is documented and included on a trend from BAS. Thanks to all, Tom

We were 10 days into a 14 day flush prior to occupancy. I discovered the breakers to the outdoor air source had been inadvertently turned off for an inspection of the fire alarm relay and not turned back on. Breakers were off for 3 days before anyone noticed. Is the flush requirement...