New controls for a large industrial building

[Brucevaughan]

We have 12 Pace AHU and four large fan room that have been bid for new controls. The contractor has convinced the people in charge to eliminate all the transducers and go for on/off solenoid. Their belief is the transducers cost $800 dollors apeice and solenoids are cheap. I tryed to explain about going back 20 years in tech. but am having trouble comming up with facts to convence them. If anyone has the time, I think I need help with this one. It will be me that has to do the repairs. Thank you, Bruce

 

[kevinf]

Dear Brucevaughan,

First you need to put together 2 complete "controls" bill of materials so you know you're comparing an on/off control system to a modulating control system. Depending on your system, the thermostats (or controllers), valves, etc. will be different. You cannot simply compare transducers to solenoids, that isn't apples-to-apples. Contact a good HVAC controls distributor or dealer for pricing help.

Reducing initial cost by changing from modulating to on/off control on the units will probably save some money in initial cost but operating costs for the long run will be much greater. I suggest you contact the AHU supplier for operating costs for on/off control versus modulating control for the units; they should have that information. That payback and operating cost data should make your case for you.

And you are correct with the "20 year old technology". Besides having larger operating costs, the building owner will likely be unhappy with on-off control in terms of building comfort. There will be more comfort related service calls.

Hope this is helpful.
kevinf@kele.com