musty/sewer smell in office

[hvac17011]

This one account we have has older ge split heat pumps.The problem we are having is the complaint of sewer/musty smell.(differing opinions).Note these units have been in operation for 15 plus yrs with these problems just starting to occur??????The condensate lines are tied into the vent stack for the bld plumbing.I have flushed all condensates cleaned pans coils look ok,ductwork has normal accumalation.All units have traps. The obvious thing would be traps going dry and then you have sewer smell from stack. Just wanted an opinion.Am I missing something or are we looking at either repipng all lines outside or condo pumps and why is this just starting now?

[binford]

Did you add water to the traps?

[market-tech]

What binford said!!! keep the traps full and the problem should go away.

[hvac17011]

yeah flushed all units.they say smell still exsists????????I dont think it smells like sewer more like a wet basement>??????????

[Randy S.]

I've worked on some buildings where floor drain P traps going dry somewhere make the whole building smell like a sewer.

[market-tech]

Are the evap coils clean and the drain pans clean. Mold/mildew and other slimey things in pans etc can cause a musty type smell.

[Timber]

Check all floor drains, fill with water. Happens a lot in my facility.....

[binford]

Good idea, pour water in the bathroom floor drains too. Could be the system is just spreading the smell. Don't laugh, but dead rats smell too. Ask if they use bait or sticky traps.

[hvac17011]

i have put water in bathroom traps.we have had problems in this building before. the coils look clean but who knows whats on them

[cxagent]

Check the depth of the traps also. If the trap is not deep enough the blower on draw thru systems can pull sewer gas past the water seal. Trane's web site has good information on this.

As others have said, I would be the problem is dry traps either in the units or the building have gone dry.

[brew]

To keep traps wet longer you can add a little mineral oil to them.

Also maybe a cracked sewer line. You could have a plumber do a smoke bomb in down the vent stack and see if you get smoke anywhere.

[The Penguin]

A trap primer can be installed to ensure traps stay wet.
However after 15 yrs there could have been some renos or mods done to the mechanical or building that could have left a trap some where not used.
Hot water tank drain pan trap?
most likely Id say you have a mold/mildew issue with one of your ahu's. Possibly you have a negative pressure in the building sucking damp wet air in where ever it can. Is you make up air heated? filtered? any rising damp issues? does the ahu fan stay on all the time keeping the air circulating. whats the humidity like?

possibly you need to fit a air purifyer like a sanovox to the ahu's once everything else has been eliminated.

Just a few ideas for you