Hmmm. Did someone claim DDC controls did not require maintenance? I must've missed that post.Originally posted by DeltaT
Don't have time to get into this but whoever previously compared lack of maintainance on pneumatic to where DDC controls need no maintenance is so full of themselves it's sick.
Chuckle. Very true, I've seen numerous buildings that're over 40 years old with still working pneumatics. I won't say that they're working as well as they were when they were first installed. But, they're still working well enough.Originally posted by DeltaT
I can take you to plants with faily new DDC controls that have not worked since the day they were installed. I can take you to buildings that are over 40 years old and still have the original pneumatic controls working just as well as they did when they were installed.
And, DeltaT, I could take you to several buildings that're less than 8 years old. Which were built using pneumatic controls. Which have had the pneumatic controls completely reworked and redone 2 to 3 times; and in one case completely ripped out and replaced with new pneumatics ... where the pneumatics have NEVER worked correctly. I know about those buildings, 3 of which are in this state, and one in the next state over, as we were finally hired in a last desparate attempt by the owners to get a control system which worked correctly. We offered to do the controls in pneumatics, or in DDC. Their pick. However, in either case, we wouldn't do it and offer any warranty or guarantee unless we ripped the whole existing mess out and started over again. As it turned out, they opted for DDC.
And liked the results ... a LOT.
But, as I pointed out to them. Their real problem had not been the original choice to go pneumatics. Their real problem had been hiring the cheapest SOB's they could find to install em. Then doing the same when it came time to hire someone to try to fix the mistakes of the first contractors.
I'll not argue about the rest of your point. Except to say that I think the 99.5% is a bit high.
However, certainly there are quite a few, too many, in the DDC installation biz who lack a lot of knowledge about HVAC systems. Other than what they might have learned in an introductory course, or from reading Honeywell's Gray manual. Which is a good reference, but hardly comprehensive as concerns all one needs to know.
And there are more than just a couple folks who call themselves HVAC techs, who could use a bit more education in that field, themselves.