[ej45]

Does anyone have a good bulletin on how approach temps, delta temps, and flows, and charge when troubleshooting condensers and evaporators?

 

[ozone drone]

Does anyone have a good bulletin on how approach temps, delta temps, and flows, and charge when troubleshooting condensers and evaporators?

No Bulletin ... but general rules of thumb

On Condensers or Evaps too fast a flow wiill result in higher approaches.
Fouled condenser tubes also result in high approaches (less heat transfer)
Low refrigerant charge also will raise the appoach temp..... but there's other factors such as % inlet vanes are open , % load and performance of the metering device, liquid level control that have to be considered before assuming you're really low on charge. Charge has to be checked under full load conditions.

By running a daily log you'll be able to tell when a rise in your condenser approach is telling you it's time to brush your tubes

 

[jayguy]

no bulletin that i could find either.

approach temps will rise as load increases. and you could have fouling on the refrigerant side of the machine as well (too much oil, burned oil, etc.) i overhauled a chiller that was 50% low on charge and had twice as much oil in it as it was supposed to. evap approach temps ran at 15F most of the time...always in low evap temp limit condition. we distilled the charge and brought the charge up to nameplate after repairing some leaks...<1F approach temps now.

it was 45% oil by volume in the chiller not to mention what was in the sump.

 

[txhvac]

Approach temps are very valuable troubleshooting methods. As far as bulletins, much like the others said more rules of thumb. Get the original start-up & spec sheets from the manufacturer or the building owners (if they have it). This will tell you what the machine was ORGINALLY designed for deltas, approach, GPM, kw, etc. You can compare this to what you are reading now. Chances are, if its an older bldg, there could have been load changes & renovations, hopefully the machine can keep up.
Also keep in mind the number of passes your barrel has 1,2,3,or 4. The longer the water is contact w/ the tubes the lower your approach will be. 3 & 4 pass barrels are more on the evap side (flooded chillers), however there are also 3 pass condensers. If you have a wide approach on a 2 pass barrel the less heat exchange is happening, gpm & load both affect approach temps. As well as, overall chiller mtc, tube brushing, proper charge, leaks,oil charge & return etc. Also building mtc men can affect the approach & overall machine performance.

 

[referteacher]

I have bulletins from Carrier, Trane, And Mcquay, that cover this subject nicely. BUT.............They're in storage. As soon as somebody hires me, I can get a house, and retreive my library, I'd be happy to post or e-mail them to you. BTW, storage is off limits until the missus gets her house.

 

[whec720]

Not a bulletin but a good brief read, (by McQuay, no less).

http://www.mcquay.com/mcquaybiz/literature/lit_systems/EngNews/ESS1202.pdf